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Late Quaternary grassland (Campos), gallery forest, fire and climate dynamics, studied by pollen, charcoal and multivariate analysis of the São Francisco de Assis core in western Rio Grande do Sul (southern Brazil)
Abstract
We present a detailed pollen and charcoal record of a 368-cm-long sediment core from the lowland Campos (grassland) region near the city of São Francisco de Assis in the western Rio Grande do Sul State in southern Brazil. Based on four AMS radiocarbon dates, the record represents the last about 22,000 cal yr BP. The region was naturally covered by Campos throughout the recorded glacial and Holocene period under cold and relatively dry and warm and dry condition, respectively. Initial expansion of gallery forest after 5170 cal yr BP indicates a change to wetter climatic conditions. Maximum extent of gallery forest after 1550 cal yr BP reflects the wettest recorded period. There is some evidence of plant migration from the eastern Atlantic coastal lowland reaching the western lowland, first after mid Holocene times by Cecropia and, possibly, species of Myrsine and Moraceae and later, after about 1000 cal yr BP, by species of Alchornea and Acalypha. Multivariate analysis revealed that the long-term pollen composition dynamics is a two-phase process, with random, chaotic changes characterizing some periods when climate conditions were likely more stable, and directional compositional changes (phase transitions) in periods coincide with major climate and/or anthropogenic changes. Natural fires were rare during full- and lateglacial periods, but became frequent at the beginning of the Holocene, suggesting the beginning of human occupation of the western lowland at that time. Highest fire frequency is found during the wet late Holocene period, suggesting an increase of indigenous populations in the São Francisco de Assis region.
... In contrast to the current mosaic of grasslands and forest formations, the landscape during glacial periods was predominantly treeless, with riparian vegetation restricted to the margins of freshwater bodies, due to the colder and drier climatic conditions (Behling, 2002;Mourelle et al., 2020). Pollen records from such periods indicate that Poaceae and Cyperaceae were the most common taxa (Behling et al., 2005), with C 3 grasses being dominant (Mourelle et al., 2020). It should be noted that the collection points Concheiros, Albardão, and Hermenegildo were considered as a single site named Hermenegildo due to their proximity. ...
... These herbivores played an important role in the maintenance of these ecosystems, but grazing alone cannot prevent changes in plant composition and ecological succession (Metera et al., 2010). The climate in the region transitioned from dry and cold in the Late Pleistocene to warm and dry in the early Holocene, which was followed by a decrease in Poaceae, particularly C 3 plants of the subfamily Pooideae, and an increase in Cyperaceae (Behling et al., 2005;Mourelle et al., 2020). Finally, after 5.1 ka BP, there was an expansion of gallery forests due to wetter conditions (Behling et al., 2005). ...
... The climate in the region transitioned from dry and cold in the Late Pleistocene to warm and dry in the early Holocene, which was followed by a decrease in Poaceae, particularly C 3 plants of the subfamily Pooideae, and an increase in Cyperaceae (Behling et al., 2005;Mourelle et al., 2020). Finally, after 5.1 ka BP, there was an expansion of gallery forests due to wetter conditions (Behling et al., 2005). These environmental changes, coupled with the arrival of humans in southern Brazil around 13 ka BP (Noelli, 2000;Santos, 2023), may have been disadvantageous to these animals. ...
The southern Brazilian Pleistocene fauna exhibited a rich diversity of large mammalian herbivores, which are now extinct or locally extinct. In this study, we employed stable isotope analysis to investigate the past ecology of these animals. Specifically, we examined the carbonate fraction of bones and teeth and utilized compiled carbon and oxygen isotopic ratios from previous research publications. The δ13C values indicated that most specimens inhabited grassland environments, which aligns with environmental reconstructions based on pollen records of the "Campos" region. The dominant food resource for these herbivores consisted of C3 photosynthesizers, mainly cool-season grasses. This preference can be attributed to the higher abundance and nutritional quality of cool-season grasses compared with warm-season grasses employing C4 photosynthesis. The variability in δ18O values within and between taxa may suggest a seasonal climate. Based on these findings, we conclude that the environmental changes during the Pleistocene-Holocene transition were detrimental to the survival of these large herbivores.
... The vegetation is herbaceous, besides some sparse trees (Boldrini, 2009). Grassland vegetation is the predecessor of forest vegetation in the Pampa biome (Lindman, 1906;Rambo, 1956;Behling et al., 2005), where the vegetation formations make up the forest-grassland mosaics, identifying different phytogeographic provinces. Vegetation mosaics of grassland/savanna and forest can be found in many tropical and temperate regions of the world, such as tallgrass prairies in North America (Fuhlendorf and Engle, 2004) and upland grasslands throughout Africa (Wakeling et al., 2012). ...
... Occupying extensive areas from cold and dry weather periods in the past, grasslands are naturally losing ground to forest in current climate conditions (Behling et al., 2005), particularly since the Holocene (Bauermann et al., 2011). A change to humid conditions is reflected by the development of gallery forests and the start of forest expansion in 5, 170 B.P. (Behling et al., 2005). ...
... Occupying extensive areas from cold and dry weather periods in the past, grasslands are naturally losing ground to forest in current climate conditions (Behling et al., 2005), particularly since the Holocene (Bauermann et al., 2011). A change to humid conditions is reflected by the development of gallery forests and the start of forest expansion in 5, 170 B.P. (Behling et al., 2005). In southern Brazil, the colonization by forest species leads to vegetation change at the edge of grassland-forest systems (Forneck et al., 2003). ...
Edaphic influence on plant distribution is essential to community ecology studies, and for vegetation management and restoration in grasslands-forest ecosystems. Pampa biome is a subtropical grassland with high floristic diversity and with an important role in food production in South America, including tree plantations where recent changes in land use soil has been questioned about the impacts on water consumption, soil degradation and potential biodiversity loss. We assessed the relationship of soil physical, chemical and morphological properties with forest and grassland species occurrence, to improve our understanding of soil and landscapes with grasslands-forest mosaics, and contribute to ecological restoration in the biome. Soil physical and chemical
properties were determined in different toposequences localized in two forest farms in southern Brazil, both covered with grassland and native forest use. Natural fertility of the studied soils was highest in the lowlands, along with highest moisture and lowest toxic aluminum content. Soil saturated hydraulic conductivity was
highest in the summit and backslope soils, influenced by coarser fractions in the granulometry. Soil bulk density, total porosity, microporosity, macroporosity, saturated hydraulic conductivity field capacity, permanent wilting point and available water content, influenced by sand, silt and clay contents, varied among soils and landscape and contributed to vegetation diversity. Some of the plant species occupied specific soils and landscapes. The
greatest vegetation frequency was of grassland species (Poaceae and Asteraceae) in both study sites. Grasslandforest area has forest individuals in the middle of the grassland and riparian, while in grassland area the riparian vegetation is composed naturally by grassland. Forest fragments expanded in grassland-forest area during the 15 years prior to our study, but in the grassland area there were no changes in the phyto-physiognomy, demonstrating that the vegetation of grassland occurs naturally in the riparian environment. This study highlights that many of sites covered naturally by grassland, in the Pampa biome, should be protected from disruptive activities and/or recovered with species endemic to the ecosystem, without necessarily by forest enrichment as usually recommended for restoration activities.
... Grassland was first vegetation to establish in the state of RS, in a drier climate, while current presence of forest taxa results from changes towards wetter conditions (Bauermann et al., 2008). Grassland as the predominant vegetation in the Pampa biome traces back at least 22,000 years, whereas forests species occupy areas along rivers and forming small clusters since about 5,170 years before present (Behling et al., 2005). Richness of plant species is evident, with a staggering 2,200 grassland species inhabiting an area of 280,000 km 2 . ...
... Nonetheless, in the Campanha region of southern Brazil and the broader Pampa biome, research with a palynological focus is still in its early stages. There are two pioneering studies in this regard, namely Behling et al. (2005) in a peat environment and Evaldt et al. (2014) in sedimentary sections of fluvial deposits. These studies are insufficient to support scientifically-based projects aimed at improving degraded soils and riparian zones, as well as establishing permanent preservation areas. ...
... Soil organic matter was influenced by species with C4 photosynthetic cycle (grasses), which represents the absence of significant changes in the vegetation for a long period of time, as observed by Andriollo et al. (2017) in the Cerro do Batovi forest. The predominance of taxa indicative of grassland vegetation was also recorded in other environments of the Pampa biome through palynological analysis (Behling et al., 2005;Bauermann et al., 2008). ...
Pampa biome vegetation is characterized by extensive areas of native grassland, interspersed with forests close to water courses. An understanding is been searched on how grassland and forest dynamics to contribute for the conservation and management practices suitable for the biome. The objective of this study was to asses if landscape-soil-pollen relationships are determinant of grassland-forest mosaics, by analyzing summit, footslope
and toeslope positions in the landscape, in the Campanha region of the Pampa biome. We collected 32 samples in three soil profiles in topossequence under natural grassland of the Pampa biome, in southern Brazil. These samples were treated following standard methodology used in palynology studies. The pollen percentage diagrams were generated to represent the identified pollen set, while cluster analysis was used to define the paleoecological zones. The results found were supported by radiocarbon dating (age of subsurface soil varying from 3,460 to 4,090 calibrated years before present), and particle-size analysis. The paleoecological zones, for each soil profile, indicate a predominance of grassland vegetation, especially Poaceae pollen, whereas Fabaceae and Piper were predominant in forest sites. The pollen set obtained in the three soil profiles indicates hegemony of the sites, even under climatic conditions of increased moisture. Rare pollen grains from forest taxa suggests
that trees and shrubs existed in isolated form. The presence of bryophyte spores and taxa associated with soil wetness indicates that the region was once dominated by extensive wetlands and moist landscapes. Our findings enhance the comprehension of the Pampa flora, and are applicable in restoration of degraded areas. The preservation of pollen grains in soil profiles shows the potential of minerals soils to reconstitute Pampa biome vegetation, representing a site for palynological research advance, and demonstrate grassland formations maintain their supremacy even under unfavorable climatic conditions. Thus, this study expands the frontier of palynological work, encompassing new sites and new opportunities to evaluate land use/land cover changes.
... According to palynological studies, this vegetational association was Fig. 1. a) Location map of the RPG (Paruelo et al., 2007); b) Campos region and Cacequi Municipality; c) geological map of Cacequi Municipality and sampling location of the analyzed peat bog (modified from Wildner et al., 2006). shaped during the Quaternary after the ending of the Last Glacial Maximum (LGM), which occurred between 23,000 and 19,000 years B. P. Behling et al., 2005;Tonello and Prieto, 2010;Mourelle and Prieto, 2016;Gu et al., 2018). ...
... Paleoecological studies in the RPG are concentrated in Argentina, with few publications in Uruguay (Mourelle and Prieto, 2016;Gu et al., 2018) and Rio Grande do Sul State, Brazil (Burjack and Marques-Toigo, 1980;Bauermann et al., 2005;Behling et al., 2005;Ribeiro et al., 2020). Since the pioneering work of Erdtman (1934), the study of pollens and spores preserved in peatlands has proved to be an important tool in paleoecological interpretations (Charman, 2002). ...
... These studies, associated with geochronological and stratigraphic data, have contributed to detailing the paleoecological and paleoclimatic changes that occurred during the Quaternary in the RPG (e.g. Iriondo and García, 1993;Borromei, 1995;Behling et al., 2005;Iriarte, 2006;Tonello and Prieto, 2010;Medeanic and Corrêa, 2010;Evaldt et al., 2014;Mourelle and Prieto, 2016;Gu et al., 2018). ...
Multy proxy study from Río de La Plata Grasslands during Late Pleistocene and Holocene.
... According to palynological studies, this vegetational association was Fig. 1. a) Location map of the RPG (Paruelo et al., 2007); b) Campos region and Cacequi Municipality; c) geological map of Cacequi Municipality and sampling location of the analyzed peat bog (modified from Wildner et al., 2006). shaped during the Quaternary after the ending of the Last Glacial Maximum (LGM), which occurred between 23,000 and 19,000 years B. P. Behling et al., 2005;Tonello and Prieto, 2010;Mourelle and Prieto, 2016;Gu et al., 2018). ...
... Paleoecological studies in the RPG are concentrated in Argentina, with few publications in Uruguay (Mourelle and Prieto, 2016;Gu et al., 2018) and Rio Grande do Sul State, Brazil (Burjack and Marques-Toigo, 1980;Bauermann et al., 2005;Behling et al., 2005;Ribeiro et al., 2020). Since the pioneering work of Erdtman (1934), the study of pollens and spores preserved in peatlands has proved to be an important tool in paleoecological interpretations (Charman, 2002). ...
... These studies, associated with geochronological and stratigraphic data, have contributed to detailing the paleoecological and paleoclimatic changes that occurred during the Quaternary in the RPG (e.g. Iriondo and García, 1993;Borromei, 1995;Behling et al., 2005;Iriarte, 2006;Tonello and Prieto, 2010;Medeanic and Corrêa, 2010;Evaldt et al., 2014;Mourelle and Prieto, 2016;Gu et al., 2018). ...
ABSTRACT
The paleoecological evolution of a peat bog in the Campos region, Rio Grande do Sul State, Brazil, was determined based on an integrated study of stratigraphy, palynology, and geochronology. The peat bog is constituted
of silty-clay material, with high levels of ash (residue on ignition) and organic matter content that was deposited
on a sandy substrate. Palynological analysis show that grassland taxa dominated from the base of the core at the
early deglacial (~17.4 cal kyr B.P.) to the Present. Four pollen zones were identified: CCQ I Zone (3.20 m to 2.50
m), covering the deglaciation (Upper Pleistocene), corresponding to dry climate conditions; CCQ II Zone (2.50 m
to 1.60 m, latest deglaciation and Early Holocene), associated with a slightly humid climate; CCQ III Zone (1.60
m to 0.50 m, mid to late Holocene), established under very humid climatic conditions; and CCQ IV Zone (0.50 m
to 0.00 m, last ~500 years), representative of a low-humidity period. The floristic composition of grassland
communities observed throughout the drill core is very similar to that found in the region where the municipality
of Cacequi is located, in which Poaceae, Asteraceae, Fabaceae, and Rubiaceae were identified as the most
abundant families. Consequently, although in the last ~17.4 cal kyr B.P. the humidity oscillated, the grassland
vegetation remained predominant, although not being represented by the same families, as indicated by changes
in the floristic composition among the four pollen zones. Palynological and geochronological data, when
compared with other sectors of the Río de la Plata Grasslands, show a predominance of dry conditions over the
studied interval. From the early deglacial until the Present, climatic fluctuations shaped the diversity of plant
communities and affected the particularities of each sector of the Río de la Plata Grasslands, including the
Campos region. High ash content was detected along the core, similar to what occurs with other peatlands
already studied in Brazil. In the peat bog analyzed, Poaceae is the predominant family, being known as a major
producer of biomineralized structures, which would explain the high ash content recorded.
... According to palynological studies, this vegetational association was Fig. 1. a) Location map of the RPG (Paruelo et al., 2007); b) Campos region and Cacequi Municipality; c) geological map of Cacequi Municipality and sampling location of the analyzed peat bog (modified from Wildner et al., 2006). shaped during the Quaternary after the ending of the Last Glacial Maximum (LGM), which occurred between 23,000 and 19,000 years B. P. Behling et al., 2005;Tonello and Prieto, 2010;Mourelle and Prieto, 2016;Gu et al., 2018). ...
... Paleoecological studies in the RPG are concentrated in Argentina, with few publications in Uruguay (Mourelle and Prieto, 2016;Gu et al., 2018) and Rio Grande do Sul State, Brazil (Burjack and Marques-Toigo, 1980;Bauermann et al., 2005;Behling et al., 2005;Ribeiro et al., 2020). Since the pioneering work of Erdtman (1934), the study of pollens and spores preserved in peatlands has proved to be an important tool in paleoecological interpretations (Charman, 2002). ...
... These studies, associated with geochronological and stratigraphic data, have contributed to detailing the paleoecological and paleoclimatic changes that occurred during the Quaternary in the RPG (e.g. Iriondo and García, 1993;Borromei, 1995;Behling et al., 2005;Iriarte, 2006;Tonello and Prieto, 2010;Medeanic and Corrêa, 2010;Evaldt et al., 2014;Mourelle and Prieto, 2016;Gu et al., 2018). ...
... The dominance of grasslands in the Brazilian Pampa is regarded as inherited from past drier climates, as indicated by plant species with adaptations to hydric stress and by pollen records (Rambo 1956, Lindman and Ferri 1974, Behling et al. 2005. Understanding of the environmental history of the Pampa is hampered by the scarcity of deposits with preserved palynomorphs representing long time intervals, the only palynological succession described so far covering the last~21 000 years and obtained in a peat deposit in western Rio Grande do Sul (Behling et al. 2005). ...
... The dominance of grasslands in the Brazilian Pampa is regarded as inherited from past drier climates, as indicated by plant species with adaptations to hydric stress and by pollen records (Rambo 1956, Lindman and Ferri 1974, Behling et al. 2005. Understanding of the environmental history of the Pampa is hampered by the scarcity of deposits with preserved palynomorphs representing long time intervals, the only palynological succession described so far covering the last~21 000 years and obtained in a peat deposit in western Rio Grande do Sul (Behling et al. 2005). ...
... If this is the case, its isotopic ratios would point to a period with summer temperatures and rainfall that allowed for the development of C4 plants, similar to the conditions at the times the other mammals in the assemblage lived (Fig. 4), or ingestion of less 18 O-enriched CAM or long-lived perennial C3 plants fully adapted to arid conditions that prevent evaporative water loss and thus reduce 18 O-enrichment (Gat et al. 2007). Although the pure C3 diet and lower δ 13 C of the LGM H. paradoxa relative to PV1154 could indicate a wetter environment, its higher δ 18 O indicates drier conditions, and thus is consistent with the ingestion of 18 O-enriched/ 13 C-depleted grasses, shrubs or possibly trees, although arboreal vegetation seems to have been scarce in the Pampas during the LGM (Prieto 2000, Behling et al. 2005, Mourelle et al. 2020. ...
Here we present paleoenvironmental and paleoclimatic reconstructions of the Brazilian Pampa based on stable isotopes (δ13C, δ18O) in tooth enamel of the Pleistocene camelids Lama guanicoe and Hemiauchenia paradoxa from the Chuy Creek fossil assemblage, including one H. paradoxa from a stratigraphic level within a loess unit deposited during the Last Glacial Maximum (26.5–19 ka b2k). The δ13C results show that both species fed mostly on C3 plants, although the mixed diets of L. guanicoe included ~30% C4 or CAM plants. H. paradoxa had C3 diets with <10% C4 or CAM plants. Both species exhibit higher δ18O and aridity indexes compared to other mammals from the assemblage, consistent with ingestion of 18O‐enriched water from plants growing in arid/semi‐arid conditions. A comparison with δ13C of camelids from Argentina indicates the camelids from Chuy Creek fed on vegetation similar to that of Dry Pampa, Monte and Patagonic xerophytic steppes. Aridification and expansion of dry steppes in southern Brazil suggest a climate‐driven northeastwards shift of the Arid Diagonal of South America that may have contributed to local extinction of the Pleistocene megafauna. These Lateglacial environmental changes are reflected in the characteristics of the plant and mammalian assemblages of the modern Brazilian Pampa.
... En cuanto a la dinámica de los biomas abiertos y biomas de bosque para la región, estudios palinológicos del sur de Brasil indican que el clima es uno de los determinantes de los mosaicos de biomas abiertos y biomas de bosque. Entre la última glaciación y el Holoceno temprano, dominaban únicamente los biomas abiertos, mientras que a partir del Holoceno medio comenzaron a desarrollarse biomas de bosque, que coexisten hasta la actualidad con los biomas abiertos (Behling et al. 2005;. Estos cambios de cobertura de biomas se relacionaron con cambios de climas fríos y secos o calientes y secos a climas más húmedos (Behling et al. 2005. ...
... Entre la última glaciación y el Holoceno temprano, dominaban únicamente los biomas abiertos, mientras que a partir del Holoceno medio comenzaron a desarrollarse biomas de bosque, que coexisten hasta la actualidad con los biomas abiertos (Behling et al. 2005;. Estos cambios de cobertura de biomas se relacionaron con cambios de climas fríos y secos o calientes y secos a climas más húmedos (Behling et al. 2005. El fuego y el pastoreo también pueden influir en la dinámica de estos mosaicos de biomas. ...
... Si el arbustal no fuera un estado estable y no hubiera limitantes abióticas, y si se evitan los controladores como el fuego o ganado doméstico, podría ocurrir que este arbustal se transforme en un bosque. Sin embargo, en el marco de la teoría de Estados Alternativos de Biomas, y en coherencia con la evidencia palinológica de la región, los biomas abiertos podrían considerarse anacronismos paisajísticos de un sistema natural anterior (Behling et al. 2005;Bond 2019;Pausas and Bond 2020). Incluso, se podría considerar que los ecotonos dominados por arbustos aquí descriptos son un estado final (en cuanto a cobertura). ...
La teoría de Estados Alternativos de Biomas (EAB) contribuye a explicar la presencia de biomas abiertos (pastizales, arbustales) en ambientes suficientemente cálidos y húmedos para el desarrollo de biomas de bosque. En estos ambientes se pueden encontrar áreas dominadas por biomas abiertos que, según esta teoría, responden principalmente al fuego y a la herbivoría. El objetivo de este trabajo es identificar si existen diferentes tipos de ecotonos entre biomas de bosque-biomas abiertos en base a la composición leñosa, describirlos y explorar su relación con el manejo ganadero y las condiciones ambientales, utilizando como caso de estudio un área protegida en Uruguay. Muestreamos la vegetación leñosa y otras variables ambientales en transectas (delimitadas en 200 m) en 10 sitios que abarcan cuatro manejos ganaderos. Identificamos dos tipos de ecotonos entre bioma de bosque y bioma abierto. Uno, dominado por arbustal, y otro, dominado por pastizal. Nuestros resultados concuerdan con la teoría de EAB en que los mecanismos que parecen determinar la composición leñosa y la estructura de la vegetación en ecotonos son el ganado y uso de fuego o segadora. Los cambios en la estructura de la vegetación y en la riqueza de leñosas fue, en parte, abrupto, en coincidencia con lo que propone esta teoría. Sin embargo, la composición también interactuó con factores de sitio como la rocosidad y la distancia al curso de agua, lo cual sugiere que variables ambientales a nivel de sitio estarían actuando de forma sinérgica con la remoción de la vegetación para determinar la composición de la vegetación. Encontramos que estos ecotonos son sensibles a manejos y variables ambientales, por lo que es necesario incorporar esta heterogeneidad de paisaje y de sitio para articular la actividad productiva con la conservación de la naturaleza.
... The Pleistocene climate was marked by several glaciation events that favored the development of grasslands in southern Brazil due to the colder and drier conditions (Behling 2002). However, from ca. 18 ka onward, the last deglaciation process began (Cruz et al. 2006;Denton et al. 2010), increasing temperatures and humidity since mid-Holocene times (Behling et al. 2004(Behling et al. , 2005Medeanic and Corrêa 2010). Climate amelioration led to changes in vegetation composition: a progressive decrease of grassland pollen types, following an increase in forest taxa (Cordeiro and Lorscheitter 1994;Lorscheitter and Dillenburg 1998;Behling et al. 2004Behling et al. , 2005Macedo et al. 2007;Masetto and Lorscheitter 2019;Roth et al. 2021). ...
... However, from ca. 18 ka onward, the last deglaciation process began (Cruz et al. 2006;Denton et al. 2010), increasing temperatures and humidity since mid-Holocene times (Behling et al. 2004(Behling et al. , 2005Medeanic and Corrêa 2010). Climate amelioration led to changes in vegetation composition: a progressive decrease of grassland pollen types, following an increase in forest taxa (Cordeiro and Lorscheitter 1994;Lorscheitter and Dillenburg 1998;Behling et al. 2004Behling et al. , 2005Macedo et al. 2007;Masetto and Lorscheitter 2019;Roth et al. 2021). With the loss of grassland habitats, the extant Lamini became restricted to the Andean region, where cold and temperate weather is still predominant (González et al. 2006;Scherer 2013). ...
... Hence, based on their modern diet, it is possible to infer that the results found in the present study reflect the consumption of grasses rather than shrubs or trees. In addition, pollen analyses indicate a predominance of grassland environments in southern Brazil during glacial periods (Behling et al. 2005;Roth et al. 2021), which corroborates the high consumption of grasses by the Lamini camelids. ...
Camelids (Camelidae) were a diverse and widely distributed group in South America during the Pleistocene. According to the fossil record, three species inhabited southern Brazil in the recent past: Hemiauchenia paradoxa , Lama guanicoe , and Vicugna vicugna . The analysis of carbon and oxygen stable isotope ratios in bioapatite provides insight into the paleobiology of nonliving animals and the environment they used to inhabit. We applied this tool to investigate the diet of camelids from two geological localities in southern Brazil: Touro Passo and Santa Vitória Formations ( H. paradoxa , n = 7; L. guanicoe , n = 6; V. vicugna , n = 4). Carbon stable isotopes from enamel, dentin, and bone indicated that H. paradoxa and L. guanicoe had diets comprising mostly C 3 grasses, but the latter showed a broader diet due to one individual with a mixed diet, whereas V. vicugna had a mixed C 3 –C 4 diet. These different foraging behaviors may have minimized interspecific competition and favored niche partitioning and the coexistence of related species. Combined oxygen and carbon isotope data showed a consistent diet according to climate, probably due to the greater availability in glacial periods of cool-season grasses, which mainly use the C 3 photosynthetic pathway. Given their adaptations to grazing, the climate amelioration, followed by the loss of grasslands, likely had a great impact on camelid populations, leading to their extinction in southern Brazil. These results, therefore, contribute to the understanding of the dynamics of paleocommunities in this region.
... Local vegetation includes grasslands with herbaceous and shrubby formations, and trees are concentrated mostly along riverbanks and hillslopes (Overbeck et al., 2007;Pillar et al., 2009;Verdum et al., 2019). The presence of relict elements of xerophytic woodlands indicates dry environments during glacial periods (Klein, 1975;Pillar & Quadros, 1997;Behling et al., 2005). ...
... The fossil mastofauna of the Pampa landscape of southern Brazil indicates predominance of open environments such as grasslands and woodlands developed under drier climate during the Pleistocene (Oliveira, 1999). In fact, the modern flora contains plant relicts of drier environments, but palynomorphs show that this flora has changed through time in response to variations in moisture, temperature, and CO 2Atm driven by glacial-interglacial cycles (Klein, 1975;Behling et al., 2005;Pillar et al., 2009). ...
... If both species were sympatric in the area of Pessegueiro Creek, the landscape could be characterized as open, C4-dominated grasslands with closed riparian forests along riverbanks and hillslopes, similar to the modern landscape ( Figure 5; Klein, 1975;Pillar et al., 2009), and apparently not subject to large seasonal variations in composition of plant assemblages, although the ~30% of C3 plants in the diet of Megatherium could indicate seasonal shifts. Pollen data show that during the last glacial period the central-western Rio Grande do Sul and northern Uruguay were dominated by grasslands (campos) with scarce arboreal vegetation, which expanded as riparian forests during the Early Holocene interglacial as the climate became warmer and wetter (Behling et al., 2005;Iriarte, 2006;Mourelle et al., 2018;. ...
The Pampa in subtropical Brazil (State of Rio Grande do Sul) is the only area of South America known so far where fossils of the Pleistocene giant megatheriid sloths Megatherium americanum, characteristic of subtropical-temperate areas, and Eremotherium laurillardi, widespread in the tropical zone, were discovered in the same deposits (Pessegueiro Creek and Chuí Creek), but it is not clear whether this co-occurrence is a product of taphonomic mixture, or co-existence, which would imply niche partitioning. In order to understand their paleoecology and reconstruct the associated paleoenvironments, dentin samples of both megatheriids from the two sites were analyzed for their carbon (δ13C) and oxygen (δ18O) isotope ratios. The δ13C values of Megatherium indicate mixed diet of C3-C4 plants with higher content of the latter in Pessegueiro Creek, whereas the δ13C values of Eremotherium indicate C3-dominated diets, the more negative value in Pessegueiro Creek possibly related to the canopy effect. The δ18O of Eremotherium points to 18O-depleted water sources, possibly also influenced by the diet, whereas Megatherium ingested 18O-enriched water. The results show that co-existence of both megatheriids would have been ecologically possible, and that the Pampa was occupied by open grasslands/woodlands, with closed forests in Pessegueiro Creek. The δ13C of Eremotherium from intertropical Brazil indicate a more generalist habit than Megatherium from subtropical Brazil and Argentina, which probably facilitated its dispersion from the tropics up to subtropical areas along two different routes, one along the coastal plain, and the other along the Paraná River Basin across central South America, following the southward expansion of riparian forests during warmer stages. The reduction of those forests during intervening cold stages possibly led to its disappearance in southern Brazil. Keywords: Quaternary, paleobiogeography, stable isotopes, Pampa, coastal plain, megafauna.
... A recuperação de grãos de amido e de fitólitos de milho provenientes da cerâmica do Sítio Bonin corrobora evidências, cada vez maiores, como isótopos de carbono encontrados em ossadas (DeMasi, 2001), ou em resíduos aderidos a cerâmica (DeMasi, 2007, Iriarte et al., 2008, e também o pólen de milho encontrado em vários sedimentos lacustres (Behling et al., 2005(Behling et al., , 2007a(Behling et al., , 2007bGessert et al., 2011), o que indica que o milho foi um item importante no sul do Brasil. Esta evidência arqueológica é reforçada pela existência de uma raça específica de milho Kaingang no sul do Brasil descrito por Brieger et al., (1958) e o fato de que os grupos Jê do Sul modernos como os Kaingang têm mitos sobre a origem do milho, feijão e abóbora (Borba, 1908). ...
... O pólen de milho tem sido documentado em regiões localizadas nas proximidades de sítios Tupi-Guarani desde ca. 1810 AP (Behling et al., 2005(Behling et al., , 2007a(Behling et al., , 2007b. No Delta do Paraná, a análise de isótopos estáveis de Loponte & Acosta (2007) demonstra que esqueletos de contextos funerários Tupi-Guarani tinham um conteúdo médio de δ 13 C enriquecido em comparação com esqueletos de sítios de caçadores-coletores da mesma região, confirmando o consumo de milho pelos Tupi Guarani. ...
O sul do Brasil tem uma presença de longa duração das sociedades Jê, os atuais Kaingang e Xokleng. Estes povos criaram paisagens compostas por uma diversidade de lugares e espaços de coexistência e circulação com diferentes funcionalidades, que interagem entre si por meio de uma estrutura sociocosmológica própria. Ao longo de mais de 2000 anos de história, as sociedades Jê prosperaram e se expandiram, criando engenhosas construções em terra e uma paisagem cultural própria, cheia de referências simbólicas, que podem ser percebidas até hoje.
Este livro reúne textos de arqueologia que se entrelaçam e versam sobre temas como paisagens construídas, manejo agroflorestal, paisagens funerárias e paisagens persistentes, gerando assim novas interpretações sobre a história dos povos indígenas no sul do Brasil.
Os dois primeiros capítulos debatem assuntos como a interação entre pessoas e o lugar em que elas habitam e a construção das paisagens sociais.
Na sequência, dois outros capítulos abordam a questão contemporânea sobre a antropização dos ambientes, em especial, sobre as evidências de manejo da floresta de araucária e da produção de alimentos a partir de cultivos.
Depois, a construção e uso de monumentos como as grandes praças de cerimonias funerárias é abordada em outros dois capítulos, interpretando-as como centros de coesão social com grande importância tanto nos aspectos políticos como cosmológicos.
Por fim, os capítulos finais retratam um dos mais significativos sítios de arte rupestre do sul do Brasil, estudado com técnicas inovadoras de arqueologia digital e arqueometria e interpretado com documentação etnográfica e histórica.
No sul do Brasil as sequências arqueológicas se sobrepõem a relatos históricos e etnográficos, mostrando que os povos Jê tem uma história de expansão, mas também de resistência e luta. Com livros como este, esperamos que a arqueologia possa ajudar os povos originários a recuperar sua dignidade e seus direitos.
... The transition from a pristine to a promoted landscape [24] began with the arrival of the first humans in the region (Figure 7b). Anthropogenic fires were frequent starting from the early Holocene [108,109], which, added to wildlife grazing, caused changes in the physiognomy and composition of the vegetation, favouring grasses and herbs in the grasslands [110][111][112]. Hunting and gathering activities were favoured [113], and greater security was obtained in inhabited environments, among other benefits. ...
... The transition from a pristine to a promoted landscape [24] began with the arri the first humans in the region (Figure 7b). Anthropogenic fires were frequent starting the early Holocene [108,109], which, added to wildlife grazing, caused changes Figure 7d shows the encounter between Indigenous and colonial cultures, a period marked by interimperial logics, commercial interests and processes of active and passive border claims and by new configurations between native and introduced herbivores such as cattle and horses. Cattle introduction was key to affirming the pastoral destiny of the Pampa biome and, in particular, the Butia landscape, where the coevolution of grasses and herbivores shaped the landscape of the grasslands, or campos. ...
The Butia odorata palm grove in southeast Uruguay forms a particular landscape of the Pampa biome, which has been inhabited and transformed since the early Holocene. The forms and meanings of this contemporary landscape are the result of the historical interaction between culture and nature. The conservation of its natural and cultural heritage has been compromised by anthropic activities, leading to conservation proposals from different disciplinary perspectives that are partial and do not consider the landscape’s integrity. In this article, we propose a comprehensive approach, integrating the ecological, cultural and socioeconomic aspects through a historical look at the domestication process of this landscape. This approach is based on a transdisciplinary narrative aimed at generating a multidimensional and diachronic characterisation of the palm grove landscape on which to base a participatory definition of the most appropriate instrument for conservation through sustainable use.
... Although massive ice sheets did not reach southern South America, the area was under a drastic reduction of temperature and moisture during the glacial periods. Studies based on pollen and genetic data suggest an expansion for species that occupied grassland landscapes, mostly herbaceous plants (Behling et al., 2005). During the interglacial periods, the increase in temperature and moisture affected the cold-adapted plants distributed in open biomes, which stayed restricted to higher elevation areas, whereas species adapted to forest regions predominated in lower and warmer regions (Behling, 2002;Behling & Negrelle, 2001;Behling & Pillar, 2007). ...
... Ramos-Silva-Arias et al., 2017). During the glacial periods, cold and dry climate conditions affecting the large rivers in South America shaped shallow water bodies that maintained the florestal species into gallery forests along the rivers(Behling et al., 2005), and changing the flooding gradients in subtropical grasslands in southern South America. Such climatic conditions were favourable to herbaceous plants and could allow species like P. parodii to disperse along or even through the riverbanks, isolating populations and lineages in each riverside that could promote diversification (e.g.Mäder et al., 2013). ...
Aim
Pleistocene climate oscillations influenced the species distribution and genetic diversity in grasslands, and such climatic changes promoted expansion and contraction cycles, leading to fragmentation and isolation of evolutionary lineages in refuges. This study aimed to infer the evolutionary processes that most influenced the genetic diversity of a South American nightshade Petunia inhabiting subtropical grasslands under the Pleistocene influence.
Location
Pampa and Chaco.
Taxon
The widely distributed herb Petunia axillaris subsp. parodii (Solanaceae).
Methods
We obtained high-density genome coverage throughout the geographical distribution of Petunia axillaris subsp. parodii. We estimated the genetic diversity and structure to evaluate population differentiation and applied a model-based demographic analysis to investigate the scenarios that could have influenced the species' evolutionary history. We evaluated the association between neutral and outlier polymorphisms with environmental variables to distinguish the influence of the geographical distance and environmental differences between populations.
Results
There are three evolutionary lineages in P. axillaris subsp. parodii. The origin and differentiation of these lineages were related to the Pleistocene refuges and rivers acting as barriers to gene flow. We also identified 496 outlier loci related to adaptation to environmental conditions.
Main conclusion
The Pleistocene climate changes drove lineage diversification isolated in micro-refugia. Rivers and changes in their courses may have also acted on the population divergence, serving as barriers to gene flow or even as corridors for species range expansion. These findings contribute to the knowledge of the evolutionary processes that influenced the lineage diversification of South American subtropical grassland species.
... It has been suggested that together with climate change, humans may have acted as complementary drivers of forest expansion due to transportation of seeds (Lauterjung et al., 2018;Reis et al., 2014Reis et al., , 2018Robinson et al., 2018) and maintained grassland using fire (Behling and Pillar, 2007;Iriarte and Behling, 2007;Jeske-Pieruschka et al., 2010). A second and marked expansion of the Araucaria forest is documented in the highlands of Santa Catarina and Rio Grande do Sul for the last 1100 years (Behling, 1995;Behling et al., , 2004, at about 1400 cal yr BP in the highlands of Paraná (Behling, 1997) and in Santa Catarina State it occurs at 930 cal yr BP (Behling et al., 2005). ...
Forest-grassland mosaics are ecosystems with sharp contrasts. Factors controlling their heterogeneity have interested researchers worldwide. To date, only few natural remains of these ecosystems exist, such as the Araucaria and Campos region in southern Brazil. Different paleoecological studies elucidate the vegetation and climate history of the region, documenting shifts between forests and grasslands since the Middle Holocene. However, uncertainty remains about whether system shifts were sudden or gradual and on the importance of driving factors and triggers such as climate, change and disturbance. We reconstruct the paleoecological history of the Araucaria forest-grassland mosaics in Paraná state in decadal to sub-decadal resolution during the Holo-cene. High resolution pollen analysis documents that in this region the expansion of woodlands occurred gradually while sedimentological analyses reveal stepwise shifts of the precipitation regime of the region. During the Early Holocene (10300-8300 cal yr BP), the landscape was characterized by grassland-dominated Campos vegetation, with sporadic occurrences of arboreal taxa. Araucaria angustifolia was present initially in small abundances. In the Mid-Holocene (8300-4000 cal BP), a transition to more humid conditions fostered the development of woodlands. The establishment of Araucaria angustifolia near the lake occurred around 7300 cal yr BP, together with a general expansion of woodlands. In the Late Holocene (4000-150 cal yr BP), Araucaria angustifolia became dominant within forest patches with a second stepwise expansion around 3300 cal yr BP. The onset of Euro-American land use during the last two centuries intensified erosion and altered species composition , reflected in sediment and pollen data. In addition, Lagoa Dourada documents vegetational changes that seem to coincide with the 8.2 ka event and the Little Ice Age.
... After the last transgressive maximum (5600 yr B.P.), the expansion of the elements of the Atlantic rainforest occurred over the coastal areas concomitantly with an increase in humidity and environmental desalination (Roth, 1990;Behling and Negrelle, 2001;Bauermann et al., 2005;Behling et al., 2004;Roth et al., 2021). From 4000 yr B.P. to the present an increase in humidity and temperature has led to the expansion of forest taxa (Medeanic et al., 2003;Behling et al., 2005;Medeanic, 2006;Leal and Lorscheitter, 2007;Weschenfelder et al., 2008;Macedo et al., 2009;Leonhardt and Lorscheitter, 2010;Hadler et al., 2013;Roth et al., 2021). ...
The reconstruction of climatic conditions through continental records controlled by radiometric dating in a single columnar profile from Águas Claras peatland (30º06'24.39" S; 50º49'04.90") in the inner portion of the coastal plain of in Rio Grande do Sul State, Brazil (CPRS) within the Late Pleistocene/Holocene (38,900-38,155 cal yr B.P. to 1,590-1,515 cal yr B.P.) allow conjecturing that the continental J o u r n a l P r e-p r o o f subtropical regions experienced a similar climatic variation frequency as identified in marine sediment cores from high northern latitudes, evident in marine isotopic stage (MIS) system proxies. The interstadial MIS 3 record was confirmed in the basal facies association (FA) II [m-fS/om], dated at 38,900-38,155 cal yr B.P., under cool paleoclimatic Dansgaard-Oeschger (D-O) 8 substage conditions. The age of 14,865-14,230 cal yr B.P. corresponds to the topmost MIS 2, which coincides with the onset of the West Antarctic Ice Sheet retreat. The background charcoal concentrations found in samples dated as MIS 3 and MIS 2 were attributed to fires from different environments, deposited in shallow ponds and marshy environments, and linked to regional rather than local fires. The 7,329-7,165 cal yr B.P. palynological record is related to a sudden decrease in temperature after the Holocene thermal maximum. A change toward higher temperatures and humid pet-generating environments was detected at 5,640-5,635 cal yr B.P., immediately after the maximum sea level transgression in southernmost Brazil (approximately 5,600 cal yr B.P.). At 1,590-1,515 cal yr B.P., sharp changes in the palynological assemblages and evidence of a major local fire indicate a decrease in humidity and drier conditions in the peatland area and its surroundings.
... ) are outside this cluster by an artifact caused only by the presence of Ericaceae pollen, indicative of cool and moist environments.The relatively close proximity of the marine record (Jaguaribe River Delta-GeoB 3104-1, site 48) to Amazonian sites (Humaitá, site 44 and Serra dos Carajás, site[46][47] can possibly be explained by close floristic similarities imposed by the expansion of cold-and humid-adapted arboreal taxa during the LGM as well as by long-distance pollen transport to coastal marine deposits. ...
The presence of Andean plant genera in moist forests of the Brazilian Atlantic Coast has been historically hypothesized as the result of cross-continental migrations starting at the eastern Andean flanks. Here we test hypotheses of former connections between the Atlantic and Andean forests by examining distribution patterns of selected cool and moist-adapted plant arboreal taxa present in 54 South American pollen records of the Last Glacial Maximum (LGM), ca. 19–23 cal ka, known to occur in both plant domains. Pollen taxa studied include Araucaria, Drimys, Hedyosmum, Ilex, Myrsine, Podocarpus, Symplocos, Weinmannia, Myrtaceae, Ericaceae and Arecaceae. Past connectivity patterns between these two neotropical regions as well as individual ecological niches during the LGM were explored by cluster analysis of fossil assemblages and modern plant distributions. Additionally, we examined the ecological niche of 137 plant species with shared distributions between the Andes and coastal Brazil. Our results revealed five complex connectivity patterns for South American vegetation linking Andean, Amazonian and Atlantic Forests and one disjunction distribution in southern Chile. This study also provides a better understanding of vegetation cover on the large and shallow South American continental shelf that was exposed due to a global sea level drop.
... Ma), grasslands, steppes, and shrublands dominated the region associated with a rich fauna of megaherbivores accompanied by drier and cooler conditions (Burkart 1975;Ortiz-Jaureguizar and Cladera 2006;Barnosky and Lindsey 2010). In more recent times, especially from the Pleistocene onward, the fossil record indicates a drastic modification in the taxonomic and ecological composition of the Pampa flora, from the onset of more humid and stable climatic conditions, and the expansion of non-grasses pollens (Prieto 1996;Iriondo 1999;Prieto 2000;Iriarte 2006;Ortiz-Jaureguizar and Cladera 2006;Behling et al. 2005Behling et al. , 2007Behling et al. , 2009Chaneton et al. 2012). Altogether, these observations are consistent with our findings, which recovered a small number of old in situ speciation events in the Pampa and a greater lineage turnover from the Pliocene onward. ...
The Pampa, also known as Río de la Plata grassland region, is arguably one of the most diverse and largest grassland areas in the world, yet timing, origin, and assembling of its flora are not well understood. Here, we provide a first comprehensive overview of the angiosperm historical biogeography in the Pampa and neighboring regions, by integrating a comprehensive phylogeny with 70,040 species, occurrence datasets, and models of geographical range evolution. The richness distribution of species sampled in our analyses is highly congruent with reports from the literature, where the Campos subregion in the North has higher levels of absolute species number and endemism. Also, our results corroborate long-standing views from phytogeography, such as a great number of lineages shared among the Pampa, Atlantic Forest, Cerrado, Chaco, and Andes, and a great exchange of lineages among these regions. Our results suggest that the Pampa is a macroevolutionary sink of angiosperm diversity, where a strong asymmetry of lineage exchange from other areas to the Pampa was detected. Our results are also in agreement with evidence from the fossil record, placing both lineage exchange (dispersals) and sympatric events (diversification) related to the Pampa very recently in geological time, with estimates concentrated in the Pliocene onward (with a great increase during the Pleistocene). Altogether, our results demonstrated the complex origin and dynamism of the Pampa flora and the importance of dispersal events for its assembly. Finally, putative caveats and future directions to further uncover the origins of the Pampa flora are discussed.
... Nonetheless, direct evidence for the antiquity and consumption of maize in pre-colonial Southeastern Brazil is severely limited to occasional finds of microfossils (i.e. phytoliths, starch and pollen) from both the inland [20][21][22][23] , and the coast 3,24,25 , an approach not without methodological limitations 26 . Stable isotope analysis of human remains from inland Guarani has highlighted the dietary importance of maize 20,27,28 but in coastal settings this approach is limited by the near absence of skeletal remains. ...
Understanding long-term dynamics of past socio-ecological systems is essential for their future management. The southern Atlantic Forest coast of Brazil with its biodiverse littoral zone and artisanal fishing communities, is a priority for conservation. Traditional maritime knowledge is thought to have a deep-history and indeed, marine exploitation can be traced back to the middle Holocene. As part of one of South America's largest diasporas, Guarani groups reached the southern Brazilian coast at around 1000 years ago. Their impact on the long-standing coastal economy is unknown, due to poor preservation of organic remains. Through the first organic residue study on Guarani pottery, we show that maize rather than aquatic foods was the most dominant product in pottery at this time. By developing a mixing model based on carbon isotope values of saturated and mono-unsaturated fatty acids we propose new criteria for the identification of maize, opening up avenues for future research. Our data confirms the importance of maize to the pre-colonial Guarani, even in a highly productive coastal environment. The Guarani occupation of this region marks a significant departure from previous socioeconomic systems, potentially leading to loss of traditional knowledge and alleviating anthropogenic pressure, albeit temporarily, on the marine environment.
... The exclusion of highly flammable savannah grasses reduces the incidence of fire, leading to a positive feedback loop between gallery forest species regeneration and fire suppression. Given that climate change will likely alter water availability and fire frequency in the tropics (Ranasinghe et al. 2021), and consequently the competitive ability of the fire-resistant plant communities surrounding gallery forests, gallery forests can be expected to be highly sensitive to predicted changes in climate (Behling et al. 2005, Leal et al. 2016). ...
Interactions between anthropogenic pressures make it difficult to predict biodiversity change and plan conservation interventions. Climate change is expected to drive widespread ecological change in the tropics over the coming decades, but it is unclear where and when these changes are going to intensify, or reduce, the impacts of additional pressures from human land use. To address this uncertainty, we apply a novel risk assessment framework to show how land use configuration modifies risks arising from climate change to gallery forests, an important vegetation type in tropical savannahs. Our analysis shows that the spatial distribution of climate change (specifically, change in annual rainfall) interacts with the spatial distribution of land use (specifically, cropland), as well as the biophysical context of the study site (the W-Arly-Pendjari transboundary protected area in West Africa), to shape the risk that changes in rainfall pose to gallery forests in the region. Due to the pathways by which rainfall change and land use interact, risks are especially elevated in core protected areas, warranting particular attention from conservation managers. Overall, our work illustrates how unexpected patterns in risks can arise through interactions between pressures on biodiversity, highlighting the importance of considering mechanistic pathways for predicting biodiversity outcomes under multifacetted global environmental change.
... Aprè s 14 ka BP, la sé dimentation fluviale a é té influencé e par les changements climatiques associé s à la derniè re dé glaciation. Ainsi, la phase de sé dimentation a culminé avec la transgression marine de l'Holocè ne Moyen Stevaux, 2000) et l'extension de la pé riode saisonniè re sè che et froide dans les cours supé rieurs des bassins des fleuves Uruguay et Paraná (Behling, 1998(Behling, , 2002Behling et al., 2005 ;Eidt et al., 2019 ;Jeske-Pieruschka et Behling, 2012 ;Ledru et al., 2016Ledru et al., , 1996Paisani et al., 2019a ;Costa Spalding et Lorscheitter, 2015). ...
Between 13,000 and 7000 BP, the territory of southern Brazil was
occupied in a stable and diverse manner, with the main anthropic
trace being in lithic material. Archaeological research has provided
more consistent evidence of occupation in different environments
and associated with different stratigraphic formation processes
since the Late Pleistocene. Therefore, this paper proposes to analyse
the history of the earliest evidence of pre-colonial occupation in
southern Brazil from a geoarchaeological point of view, focusing on
stratigraphic and chronological data and the process of formation
of archaeological layers. Thirty-three stratigraphic sections were
analysed from 31 archaeological sites distributed along the Parana´,
Uruguay and Atlantic basins. Evidence of archaeological levels was
found in different geomorphological contexts: plateau, slopes,
valley bottom, alluvial plains and rockshelters. The results indicate
that the oldest archaeological levels in the region were formed in
the Late Pleistocene, associated with periods of fluvial incision that
signal important changes in the southern river systems, characte�rized by the formation of alluvial and colluvial-alluvial terraces in
the valley bottoms. This is followed in the Lower Holocene by
widespread colluvial processes in the incised valleys, alluvium in
the middle river courses and anthropogenic deposits in the
rockshelters that formed the main ancient levels. In the early
Middle Holocene, sedimentary deposits containing archaeological
material decrease significantly, marking regional changes in lithic
industries. The data indicate that there appears to be a threshold
between deposition and archaeology in the Early Holocene,
characterized by high stratigraphic resolution, where stratigraphic
sequences show greater thickness and density of archaeological
levels. Finally, the diversity of inter-regional lithic assemblages is
clearly highlighted, marked by the predominance of industries on
pebbles and blocks, the debitage of flakes and blades as a support
for various tools in the interior basins and the shaping of small
projectile points on the Atlantic slope.
... Further paleoclimate studies in the Pampas (Iriondo and Garcia 1993), indicated the predominance of dry and cold climates between 18.000 and 8.500 years, followed by wet subtropical conditions between 8.500 and 3.500 years, followed by a dry phase that lasted until about 1000 years ago, when wet conditions returned. However, Behling et al. (2005) and Neves et al. (2001), studying forest-grasslands transitions, showed that the postulated Mid Holocene wet phase indicated by Iriondo and Garcia (1993) did not occur in western Rio Grande do Sul, based on 14 C dating and palinological studies. Gallery forests started their expansion around 5000 years ago, indicating a temporary shift to wetter conditions, but the maximum expansion of gallery forests only occurred in the last 1500 years, approaching the current conditions. ...
Cerrados are the savanna-like vegetation of central Brazil. The first accounts on Cerrado soils date back to the 1950´s, but increasing knowledge about soil characteristics under this vegetation derived from the outstanding expansion of modern agriculture on mostly low fertility, acid and deep cerrado soils. We report the current knowledge about soils under Cerrado vegetation within the Brazilian territory, emphasizing its genesis and classification considering the Brazilian System of Classification of Soils-SiBCS, and land use aspects. In central Brazil, the Cerrado Biome covers extensive areas of Goiás, Distrito Federal, Tocantins, Bahia, Maranhão, Mato Grosso, Mato Grosso do Sul, Minas Gerais, Piauí, Rondônia and São Paulo states, and many disjunct, isolated areas across Brazil, occupying more than 2,000,000 km2. Geomorphologically, cerrados are mainly found on extensive highland plateaus, but also occur in gently dissected to hilly landforms. Most Cerrado soils are dystrophic (base saturation less than 50%), and the few eutrophic soils identified always present strong limitations to a normal plant development, either physical or chemical. With the exception of clayey Latossolos of high plateaus, practically all other soils, besides the low natural fertility, present some physical limitations to plant development, such as: presence of abundant gravels and/or concretions (petroplinthite, mainly); high water table; high stoniness or rockiness; low water holding capacity; sandy or medium light texture; shallow depths. The Latossolos with clayey texture of the Central Tablelands and Plateaus are the preferred soils for high tech grain production, and commonly have an acric character, with positive ΔpH, in addition to the low natural fertility. Other Latossolos under Cerrado are either (i) of medium texture and low water retention capacity, or (ii) are clayey with very low CEC. The high aluminum saturation (>50%), postulated by pioneer authors as a conditioning factor of the Cerrado vegetation is controversial, and has not been confirmed, since many soil surveys throughout Brazil revealed the occurrence of Cerrado vegetation on soils without high Al saturation (such as the acric types). It is consensual that Cerrado occurrence is more related to soil water availability than to soil fertility, even though Cerrado on waterlogged soils are also found. The Central Brazilian Plateau, representing the core area of Cerrado, is part of a very old and stable landmass, unaffected by marine invasions and glaciers, where widespread planation and erosion allowed a very extensive smooth surface to develop. Most vegetation in the Central Plateau has been subjected to Quaternary climate oscillations, from semiarid climates during glacial periods, to humid climates during interglacials. The common occurrence of Cerrado in the Central Plateau High Tablelands (Chapadas) is closely associated with deep Latossolos of clayey or very clayey texture. However, different types of Cerrado, from Grassy to Woodland (Cerradão), are found, and such variations cannot be explained solely by chemical or physical attributes, but rather by external, anthropogenic factors, such as burning intensity, cattle grazing and selective clearing for wood or charcoal production, besides topographical and hydrological attributes. Despite the general low fertility, high productivity and high yields of soya, sugarcane, eucalyptus, rice, wheat, cotton and maize are commonplace in the cerrados, highlighting the robust knowledge Brazil attained in converting low fertility soil into areas where two successive crops are now possible. However, conservation issues are now pressing, since Cerrado vegetation, a major biodiversity hotspot in the neotropics, is vanishing at alarming speed.KeywordsCerrado soilsSavana soilsBrazilian Central plateauAcid soilsAluminum toxicityTropical pedologyNeotropical soilsDeep weathered soils
... Further paleoclimate studies in the Pampas (Iriondo and Garcia 1993), indicated the predominance of dry and cold climates between 18.000 and 8.500 years, followed by wet subtropical conditions between 8.500 and 3.500 years, followed by a dry phase that lasted until about 1000 years ago, when wet conditions returned. However, Behling et al. (2005) and Neves et al. (2001), studying forest-grasslands transitions, showed that the postulated Mid Holocene wet phase indicated by Iriondo and Garcia (1993) did not occur in western Rio Grande do Sul, based on 14 C dating and palinological studies. Gallery forests started their expansion around 5000 years ago, indicating a temporary shift to wetter conditions, but the maximum expansion of gallery forests only occurred in the last 1500 years, approaching the current conditions. ...
The Brazilian Amazonia region can be conveniently separated into 11 sectors, which represent large pedoenvironments at a continental scale. In a global panorama of the region, from this simplified and useful division, there is a high pedodiversity in the Amazon, despite the predominantly monotonous landforms, at macroscale. Soils of the Sedimentary Basins vary according to strong geological-structural control, coincident with the division of the sub-basins. Close to the Andes fold belt, soils of the Acre Basin, above the Iquitos Arch, have an Andean influence and are mostly young (Cambissolos, Luvissolos, and Argissolos), eutrophic, and high-activity clay. However, the aluminic character is very common. Between the Iquitos and Purus Archs, in the Solimões or Upper Amazonas basin, soils have Plinthite to varying degrees (Plintossolos and Argissolos), but mostly dystrophic. Downstream the Purus Arch to the Monte Alegre Arch, the mid-Amazon basin is strongly associated with Latossolos or Argissolos (always dystrophic), usually yellowish, derived from the pre-weathered Alter do Chão or Belterra Formations. At the low Amazon and Marajó island, under the influence of strong marine tides and by the gigantic sedimentary and hydrological load of the great Amazon river, extensive floodplains have Neossolos Flúvicos, Gleissolos, Plintossolos, and Planossolos. In the crystalline basement rocks of the Amazon Craton, gently dissected landforms reveal dominance of Argissolos or Latossolos (yellow and red-yellow), and generally dystrophic, except where mafic rocks occur. The floodplain soils of the tributaries are almost always dystrophic. The presence of petroplinthite in shallow soils under wet climates suggests that they formed under past climates much drier than the present ones. Anthropogenic soils (Indian Black Earths), with high levels of SOM, Available P, and CEC, occur frequently not only on the bluffs above the floodplain on well-drained lands of the Amazon region, but also on the Várzea floodplain, as buried paleosols. The Roraima and Rondônia Highlands have varying shallow or deep, dystrophic or eutrophic soils, depending on landforms and lithology. A few high-fertility soils, derived from mafic rocks, occur in both highland regions and are usually intensively cultivated. Sandy soils resulting from the extreme podzolization, with the formation of deep, acidic and chemically poor Espodossolos, are characteristic of the Rio Negro Basin. They occur in extensive flat and low-lying plains, under Campinarana vegetation. These extensive Tropical Podzols were formed by the clay destruction of a previous Latossolos mantle under super humid climates. Also, Savanna islands (cerrado, campos) occur throughout Amazonia, and are mostly associated with poorly drained or imperfectly drained soils, but may also occur in higher ground (yellow Latossolos), impermeable parent materials (Monte Alegre) or sandy soils (Alter from the ground). They are floristically much poorer, compared to the core savannas of the Central Plateau. The Amazon/Solimões River floodplains, together with the Purus and Juruá rivers, constitute the largest eutrophic alluvial space in Brazil, and one of the most extensive worldwide, making the use and sustainable cultivation virtually continuous since pre-Columbian times.KeywordsAmazon soilsRainforest soilsAmazon Forest soilsTropical pedologyAmazonian landscapesNeotropical soils
... Further paleoclimate studies in the Pampas (Iriondo and Garcia 1993), indicated the predominance of dry and cold climates between 18.000 and 8.500 years, followed by wet subtropical conditions between 8.500 and 3.500 years, followed by a dry phase that lasted until about 1000 years ago, when wet conditions returned. However, Behling et al. (2005) and Neves et al. (2001), studying forest-grasslands transitions, showed that the postulated Mid Holocene wet phase indicated by Iriondo and Garcia (1993) did not occur in western Rio Grande do Sul, based on 14 C dating and palinological studies. Gallery forests started their expansion around 5000 years ago, indicating a temporary shift to wetter conditions, but the maximum expansion of gallery forests only occurred in the last 1500 years, approaching the current conditions. ...
The Pantanal is a large tectonic depression located between the Andean slopes and the Brazilian Central Plateau, and the largest continental wetland worldwide, with great biodiversity and pedodiversity, driven by alternating cycles of flood and drought. In this rich Brazilian biome, subtle changes in relief and hydrological condition change soil properties, and affect the distribution of the highly diverse flora and fauna. The wetland soils of Pantanal are closely related to the nature of sediments, and vary according to changes in erosion and deposition/sedimentation rates. Depending on the amount of sand, primary minerals and watertable level, many different types of soils are formed. Quaternary Climatic changes associated with various glacial/interglacial periods occurred in the region, allowing changing pedoclimates with contrasting soil formation processes. The pedoenvironments and soils present in the Pantanal subregions strongly vary according to small topographical variations. Altimetric differences, even a few centimeters, have great influence in soil formation, determining the flood and drought periods at different parts of the landscape. Some soil characteristics also influence the internal flow of water, both vertical and lateral. These differences result in varying intensities of hydromorphism, present in all soils of Pantanal. Even at the highest landscape, soils show signs of hydromorphism, identified by the presence of grayish colors, and Fe3+ reduction process. Paludization, gleying, laterization (plinthite formation), solodization, salinization, argilluviation and podzolization are common pedogenic processes in Pantanal, and are strongly driven by the flooding regime. The main soils in Pantanal are (in decreasing order of total area): Planossolos Nátricos (23%) > Plintossolos (21%) > Espodossolos Ferrilúvicos (19%) > Planossolos Háplicos (11,8%) > Gleissolos (11,7%) > Vertissolos (5,8%) > Argissolos Vermelho-Amarelos (4,8%) > Other minor soils (Neossolos Litólicos, Neossolos Quartzarênicos, Chernossolos Argilúvicos, Neossolos Flúvicos, all with less than 5% in total). The Pantanal wetlands, one of the richest biomes in the neotropics, are under severe threat of vegetation loss and widespread burning due to the intensification of land use, with replacement of the traditional cattle ranching, and climate changes.KeywordsBrazilian pedologyInundated Savanna soilsTropical pedologyTropical wetlandsParaguay River basinNeotropical soils
... Further paleoclimate studies in the Pampas (Iriondo and Garcia 1993), indicated the predominance of dry and cold climates between 18.000 and 8.500 years, followed by wet subtropical conditions between 8.500 and 3.500 years, followed by a dry phase that lasted until about 1000 years ago, when wet conditions returned. However, Behling et al. (2005) and Neves et al. (2001), studying forest-grasslands transitions, showed that the postulated Mid Holocene wet phase indicated by Iriondo and Garcia (1993) did not occur in western Rio Grande do Sul, based on 14 C dating and palinological studies. Gallery forests started their expansion around 5000 years ago, indicating a temporary shift to wetter conditions, but the maximum expansion of gallery forests only occurred in the last 1500 years, approaching the current conditions. ...
The Restinga is one of the ecosystems of the Atlantic Rainforest biome in Brazil. It is characterized by extremely nutrient-poor soils formed in sandy coastal sediments from the Quaternary age. The highly dynamic environment of sandy coasts causes landforms with different microrelief. This, in combination with the poor and harsh conditions strongly influence both vegetation composition and ecological succession. Consequently soil formation and vegetation has remarkable variation at short distances within the Restinga ecosystem. This variation strongly depends on (i) geomorphological evolution (deposition/ erosion and age), (ii) particle size of the sediment (sand or clay), (iii) drainage conditions, and (iv) organic matter inputs. Soils from the Restinga ecosystem include Espodossolos (Podzols), Neossolos Quartzarênicos (Arenosols), Organossolos (Histosols), and Gleissolos (Gleysols). However, poorly drained Espodossolos (Podzols) dominate this forested landscape due to the low and flat relief of the shoreline and large amounts of dissolved organic matter (DOM) produced upon decomposition of litter and roots in H, O, and A horizons. The morphology of Espodossolos in the Restinga ecosystem is complex, with a large short-distance variability in depths and shapes of the E- and B-horizons. In order to interpret soil-forming processes in the context of the landscape, transects of related profiles are studied in detail in the different geomorphic units. We connect soil morphology, micromorphology, organic matter chemistry, and microbiology with geomorphology at the ecosystem level.KeywordsTropical podzolBrazilian coastal plainPodzolizationPodzol morphologyPodzol micromorphologyBh degradationIchnofossil
... Palynological studies in Rio Grande do Sul showed that grasslands are the dominant vegetation in this area since the Pleistocene, 42,000 cal yr BP (Behling et al. 2004, Behling et al. 2005. By the end of the last glacial period, which indicates the beginning of the Holocene (11,500 cal yr BP), a cold and dry climate became gradually warmer. ...
Different types of grasslands cover much of the Earth’s surface. At a closer look, these grasslands present unique and specific floristic and biophysical characteristics. Following an ecosystem approach, we propose a new regionalization of the grassland landscapes that correspond to two thirds of the surface of the state of Rio Grande do Sul. The biophysical factors that control energy and water availability for living organisms are the basis of our analysis. The dominant macroclimate is humid subtropical, but at a meso-scale (1:250,000), additional constraints such as relief
and soils modulate this availability. With the support of Geographic Information Systems it was possible to delimit ten grassland ecological systems based on the flora and its relationship to the respective biophysical characteristics as derived from elevation, slope, and soil data. Our analysis adds
the currently available floristic data on grasslands to previously established vegetation maps of the same geopolitical territory. Therefore, we extend the hitherto limited understanding of the complexity of the grassland systems. The results add new knowledge to the regionalization of the grassland
vegetation of southern Brazil. The proposed delimitation provides a framework for various purposes, such as ecological and biodiversity studies, conservation and mitigation strategies, and sustainable land use.
... The plains of southeastern South America are a highly biodiverse ecosystem, containing an extensive and ramified river network along the banks of which subtropical gallery forests extend. Abrupt climatic changes occurred during the post-glacial period, the Pleistocene-Holocene transition and the early Holocene, that drastically modified the environmental conditions, fauna and vegetation (Iriondo, 1999;Prieto, 2000;Zá rate, 2003;Ubilla et al., 2004;Behling et al., 2005;Kerber et al., 2014). These changes have a significant impact on the human groups inhabiting the region (Suá rez, 2003(Suá rez, , 2011a(Suá rez, , 2015a(Suá rez, , 2017Bueno et al., 2013). ...
... These results are consistent with studies showing the expansion of grasslands during glacial periods, in which species adapted to open areas show population expansion (e.g. Lorenz-Lemke et al., 2010;Fregonezi et al., 2013;John et al., 2019;, whereas forest species show the opposite trend (Behling et al., 2005;Behling & Pillar, 2007). Moreover, there are many other examples of plants from southern South America that had changed their evolutionary histories and genetic diversity under the Quaternary cycles (e.g. ...
Climate changes and associated glacial and interglacial cycles during the Quaternary strongly influenced the evolutionary history of countless number of species. Subtropical highland grasslands (SHG) in southern South America constitute a distinct vegetation type with high diversity and endemism rates. The most recent common ancestor of the genus Petunia (Solanaceae) originated in lowland grasslands, and some lineages secondarily migrated to SHG. Here, we describe the evolutionary history of an SHG species, P. altiplana, distributed throughout a wide area in a river-fragmented landscape. We used plastid and nuclear markers to evaluate the role of the Pelotas River and Quaternary climate cycles over the genetic structure and historical demography of this species based on a phylogeographical approach. We found moderate population expansions during the last 25 kyr, with a more recent (c. 1.6 kya) divergence between two groups of populations from opposite river margins, possibly caused by the expansion of the Araucaria Forest along the river valley, effectively isolating distinct grassland patches.
... The palaeoenvironmental events of the southern region also seems to be well understood (Behling 1998(Behling , 2001(Behling , 2007Behling et al. 2004Behling et al. , 2005. It is relatively well agreed that the Last Glacial Maximum was dry and cold, with a vegetation mainly of grasslands or cerrado (savanna grassland with trees), followed by a gradual change to warmer and wetter conditions during the Late Glacial Interstadial and the Holocene (Behling 2002). ...
Shell mounds, or middens, are artificial accumulations of food remains such as shells, sediments, artefacts and remains from daily life and funerary rituals, which were deposited in our study area by groups of Sambaquian fisher-hunter-gatherers. These mounds contain remains, which are representative of the fauna and flora at the time they were formed, enabling the recovery of palaeoenvironmental data related to biodiversity of taxa and biogeography, 14C dating and analysis of changes in the patterns of marine biodiversity and ocean circulation. This paper uses the Casa de Pedra shell mound rock shelter, located in São Francisco do Sul, state of Santa Catarina, southeastern Brazil, to study aspects of the palaeoenvironment through analyses of the archaeological material of the site, which contains well-preserved phytoliths and sponge spicules. Among the phytoliths, those from grasses predominate and some trees and palms were present, with no variation in vegetation type during the period of site occupation, between 5,470 and 4,460 years bp. Despite the general stability of the vegetation, a small increase in the density of the tree cover was identified from the base to the top, which may be related to an increase in precipitation, and is in agreement with other palaeoenvironmental studies carried out in southern Brazil.
... Further, by the end of the Pleistocene, fire frequency increased in some regions of the RPG (Behling et al. 2005), likely due to the change from cold and dry to warm and humid climatic conditions, which increased primary production, and to the direct fire ignition by humans. In addition, the lack of large grazers may have been an important factor for this change of fire frequency. ...
Abstract. The Río de la Plata Grasslands (RPG) are one of the largest areas of open ecosystems (grasslands, shrublands and savannas) in the world. Historically, these systems have experienced, and continue to experience, an enormous loss of natural habitats. Moreover, their importance has been largely invisible in comparison to forested systems. The remaining area of open ecosystems in the RPG region varies according to the source from 38 to 58% of the original area. Open Ecosystems (OE) are a special case of agroecosystems because they can combine the supply of both provisioning and regulating and supporting ecosystem services (ES). Preserving the provision of ES in these natural habitats depends, in part, on understanding the role of the two main disturbances operating in them: grazing and fire. Although these two disturbances are natural components of OE, both are manipulated by humans. In this paper we reviewed the role played by fire and grazing in the structure and functioning of the RPG starting from the late Pleistocene and Holocene, and summarizing current evidence on the effects of fire and grazing on vegetation, fauna and biogeochemical processes. The evidence indicates that among agricultural activities, direct grazing systems in OE have the lowest environmental footprint. At the same time are the key for habitat preservation and ES supply. Overall, the OE of the RPG still represent a high proportion of the area, are capable of covering 2.5% of the world's population needs of high quality protein and, at the same time, guarding the regulation of key processes.
Resumen. Herbívoros y fuegos: Su rol en la configuración de la estructura y el funcionamiento de los pastizales del Río de la Plata. Los Pastizales del Río de la Plata (PRP) son una de las áreas más extensas de ecosistemas abiertos (pastizales, arbustales y sabanas) del mundo. Históricamente, estos sistemas han experimentado, y lo siguen haciendo, una enorme pérdida de hábitats naturales. Más aun, en buena medida, su importancia ha sido invisibilizada frente a sistemas boscosos. El área remanente de ecosistemas abiertos (EA) varía según las fuentes del 38 al 58% del área original. Los EA son agroecosistemas particulares porque pueden combinar el suministro tanto de servicios ecosistémicos (SE) de provisión como de regulación y soporte. La maximización del suministro de SE en estos hábitats naturales depende, en parte, de comprender el papel de las dos principales perturbaciones que operan en ellos: el pastoreo y el fuego. Aunque estas dos perturbaciones son componentes naturales de los EA, son manipuladas por prácticas humanas. En este artículo revisamos el papel del pastoreo y el fuego en la estructura y el funcionamiento del PRP, partiendo de su papel durante el final del Pleistoceno y el Holoceno, y resumiendo evidencias de los efectos actuales del pastoreo y el fuego sobre la vegetación, la fauna y los procesos biogeoquímicos. Las evidencias muestran que los sistemas ganaderos en EA tienen, en dimensiones claves de la huella ambiental tales como la preservación de hábitats y la oferta de SE, el menor impacto entre las actividades agropecuarias. Los valores estimados de producción de carne equivalente en los EA representan una alta proporción de la producción total de la región, un volumen de producción capaz de cubrir el consumo de un 2.5% de la población mundial.
... The paleoenvironmental scenario of the southern region also seems to be well understood (Behling, 1998(Behling, , 2001(Behling, , 2007Behling et al., 2004Behling et al., , 2005. It is relatively consensual that the Last Glacial Maximum was dry and cold, with a predominance of grasslands or cerrado (savanna), subject to a gradual change to warmer and wetter climates during the Late Glacial Interstadial and the Holocene (Behling, 2002). ...
Shellmounds, or middens, are artificial accumulations constituted by food remains, sediments, artifacts, and vestiges of daily life and funerary rituals, and built by groups of fishermen-hunter-gatherers. These archaeological sites contain groups of organisms representative of the fauna and flora existing at the time they were formed, enabling the recovery of paleoenvironmental aspects related to species biodiversity and biogeography, studies with 14 C dating, and analysis of changes in the patterns of marine biodiversity and ocean circulation. This paper uses the Casa de Pedra Shellmound under rock, located in São Francisco do Sul, Santa Catarina, to infer aspects of the paleoenvironment through analyses of phytoliths extracted from the archaeological matrix of the site. The material presents a good quantity of well-preserved phytoliths and sponge spicules. Among the phytoliths, those from grasses predominate with the presence of some trees and palms, with no variation in vegetation type during the period of site occupation, between 5,470 and 4,460 years BP. Despite the vegetation stability, a small densification of the tree cover was identified from the base to the top, which may be related to an increase in humidity, and is in agreement with other paleoenvironmental studies carried out in the southern region of Brazil.
... A partir del final del Último Máximo Glacial, el nivel del mar comienza a subir. Así, durante el final del Pleistoceno las condiciones climáticas generales comienzan a mejorar, haciéndose menos rigurosas, pasando de frías y secas a ligeramente áridas y frías, sub-húmedas/húmedas en Uruguay, Pampa (Argentina) y el sur de Brasil Behling et al., 2005;Iriondo, 1999;Prieto, 2000). Para el sur de Brasil, Pampa y Uruguay, extensas praderas de gramíneas dominan el paisaje antes y durante el final del Último Máximo Glacial, el final del Pleistoceno y durante el Holoceno , Behling and Pillar 2008, Iriondo, 1999, Prieto, 2000, Suárez 2011a). ...
Much of the early prehistory of the Americas lies underwater along its coastlines and in the submerged caves
and cenotes of Florida and Central America. A cenote (from Yucatan Maya dzoonot ‘well’) is a deep natural
pit, or sinkhole, resulting from the collapse of a doline or limestone bedrock that exposes groundwater
underneath. Cenotes are a unique resource in a dry land, especially associated with the Yucatan Peninsula
and some nearby Caribbean islands, and were sometimes used by the ancient Maya for sacrificial offerings. In
times of lowered sea level and drier climate, as prevailed in the terminal Pleistocene, they were rare sources
of freshwater for people and animals. Cenotes and the extensive cave systems to which they are linked have
become the focus of palaeontological and palaeoanthropological studies by North American and Mexican
Prehistorians, with the Vice-Directorate for Underwater Archaeology, National Institute of Anthropology and
History (INAH) commanding several of these efforts. The search for early humans in the Yucatan Peninsula
started more than a century ago when Henry Mercer arrived in search of early Americans; however, only in
the last fifteen years have systematic efforts been undertaken. Efforts by archaeologists and cave-diving
explorers have already resulted in the discovery of numerous assemblages of Pleistocene megafauna and
pre-Maya humans. Finds near Tulum, Quintana Roo state, include some of the most complete early Americans
skeletons, as well as a largely varied faunal complex including numerous examples of extinct megafauna.
Some of the human skeletons are thought to be among the oldest in the hemisphere and they are so well
preserved that now they are providing enough organic material for ancient DNA analysis and stable isotope
studies. Associated concentrations of bat guano, wood, wood charcoal and calcite formations hold promise
for advances in palaeoecology and sea-level history. Despite their great scientific value, these deposits are
increasingly at risk from water pollution, salinization, tourism and urban development. As such dangers
threaten inundated caves and cenotes all over the world, a major concern for UNESCO and other international
and national agencies has been to set minimal standards for protecting this important heritage, which includes
detailed recording at the sites and maintaining the materials in situ whenever possible.
... A partir del final del Último Máximo Glacial, el nivel del mar comienza a subir. Así, durante el final del Pleistoceno las condiciones climáticas generales comienzan a mejorar, haciéndose menos rigurosas, pasando de frías y secas a ligeramente áridas y frías, sub-húmedas/húmedas en Uruguay, Pampa (Argentina) y el sur de Brasil Behling et al., 2005;Iriondo, 1999;Prieto, 2000). Para el sur de Brasil, Pampa y Uruguay, extensas praderas de gramíneas dominan el paisaje antes y durante el final del Último Máximo Glacial, el final del Pleistoceno y durante el Holoceno , Behling and Pillar 2008, Iriondo, 1999, Prieto, 2000, Suárez 2011a). ...
... Data from the subtropical highland grasslands showed that humidity slowly changed across the continent, and grassland conversion into forests reached the maximum ca. 1.1 kya (Behling et al., 2004(Behling et al., , 2005Behling and Pillar, 2007). ...
Recently diverged species may hybridize in their contact zones if complete reproductive isolation has not yet emerged. Petunia inflata and P. interior are closely related species with a narrow geographic distribution in Argentina and southern Brazil. They share morphological features, genetic markers, pollinators, and occupy a transitional area between the Pampa grasslands and the Brazilian Atlantic Forest. Here, we used genomic data to verify species boundaries, identify putative hybrids, and shed light on their speciation process. We characterized 59 individuals from allopatric and contact zones using genotyping-by-sequencing technology, resulting in a final dataset with 21,759 neutral single nucleotide polymorphisms used to perform structure, demographic, and hybridization analyses. These species belong to distinct evolutionary lineages that hybridized after secondary contact. A combination of geographic distance, elevation, and climate explains the genetic divergence between species. Niche overlap analysis revealed that even though these species have overlapping distributions and similar habitat preferences, they are more distinct than expected by chance, rejecting the niche conservatism hypothesis. Demographic analysis suggested that the Pleistocene climatic changes led species to diverge but they came into secondary contact during the Holocene. The secondary contact led to limited gene flow between species and bidirectional introgression. The distribution expansion of these species’ ancestor to a transitional zone between biomes, associated with elevational ranges and habitat fragmentation promoted speciation and niche differentiation.
... Despite the climate changes during the Pleistocene have been less impacting in South America, with no massive ice sheets covering the lands, severe changes in temperature and moisture affected the vegetation. Colder and drier periods allowed the expansion of the grassland areas, whereas warmer and wetter climate conditions favoured the expansion of forest-adapted species (Behling et al., 2005). Such expansion-contraction cycles promoted the diversification of some plant species and the colonization of new environments (e.g., Barros et al., 2015;Lorenz-Lemke et al., 2010;Reck-Kortmann et al., 2014. ...
Speciation begins with the isolation of some individuals or subpopulations due to drivers promoting a diverging genetic distribution. Such isolation may occur, followed by different processes and pressures. Isolation‐by‐distance (IBD), isolation‐by‐adaptation (IBA), and isolation‐by‐colonization (IBC) have been recognized as the main divergence patterns. Still, it is not easy to distinguish which one is the main pattern as each one may act at different points in time or even simultaneously. Using an extensive genome coverage from a Petunia species complex with coastal and inland distribution and multiple analytical approaches on population genomics and phylogeography, we showed a complex interplay between neutral and selective forces acting on the divergence process. We found 18,887 SNPs potentially neutral and 924 potentially under selection (outlier) loci. All analyses pointed that each subspecies displays its own genetic component and evolutionary history. We suggested plausible ecologic drivers for such divergence in a southernmost South Atlantic coastal plain in Brazil and Uruguay and identified a connection between adaptation and environment heterogeneity.
... Como ya se planteó, la flora de los bosques serranos de Uruguay está estrechamente ligada a la flora paranaense mediante el corredor biológico Sierras del Este-Quebradas del Norte Gutierrez et al., 2015). Dicha flora se encuentra en expansión desde hace miles de años (Behling, 1995;Behling et al., 2002) y recientemente este proceso se ha acelerado según reportes de Uruguay y el sur de Brasil (Oliveira et al., 2017). Esto indicaría que los procesos de dispersión a través del corredor serrano son un proceso central y que esta flora no se encuentra en equilibrio. ...
Understanding the patterns of biodiversity and the drivers of the ecosystem and species distribution is crucial within the context of global change. As diversity patterns are scale-dependent, applying multi-scalar approaches is essential for understanding underlying processes. Forests are the most biodiverse terrestrial ecosystems on the globe and provide multiple ecosystem services. The forests of the Campos region in the Rio de la Plata Grasslands (RPG) have been scarcely studied, in particular the hillside and ravine forests (HRF) of eastern Uruguay, which harbor flora linked to the forests of southern Brazil, and which represents the southern limit of species distributions of Atlantic and Paranaense Provinces. In a scenario of climate and land-use land cover change, understanding the role of climate and other environmental factors on the distribution and diversity of these forests is a highly relevant ecological question and an essential baseline for management. The aim of this thesis is to map the distribution and coverage of HRF in Uruguay and to evaluate the role of environmental factors on its distribution and diversity at different spatial scales.
In Chapter 1, a detailed cartography (resolution: 0.5 ha) of the HRF-2015 was generated using Landsat 8 satellite images and high resolution images from Google Earth, showing that the forest occupies 328,601 ha and is largely distributed in three ecoregions of Eastern Uruguay: Eastern Sierras, Basaltic Slope and Gondwanic Sedimentary Basin. Forest cover was highly variable among pixels, with an average cover of 69% (100 ha pixel). In Chapter 2, the occurrence and cover of the hillside forest was modeled according to environmental predictors (climate and geomorphology, topography), using BRT, GAM and SDM niche modeling techniques. Forest occurrence and coverage was strongly determined by the slope and the annual temperature range, and to a lesser extent by precipitation, rockiness and soil texture. The environmental suitability area for the ecosystem was approximately twice the observed distribution (786,400 ha). According to the estimated potential distribution, most of the environmentally suitable area for the forest is currently occupied by hillside grasslands under grazing (mean livestock density: 0.64 LU / ha).
In Chapter 3, the spatial pattern of tree species richness of hillside forest at mesoscale (cell size: 66,000 ha) was studied and modeled. Species richness ranged between 70 and 30 species per cell, decreasing with latitude. Two cores of high species richness were identified in the northeast of Uruguay (Rivera-Tacuarembó and Cerro Largo). The best adjusted model (GAM) accounted for 87% of the geographic pattern of species richness, with habitat availability (forest cover) being the main determinant. Climate variables linked to energy and water availability were also positively associated with species richness. In contrast to previous studies on the Paranaense Flora of Southern Brazil, there was no evidence of a limitation by minimum temperature, but a negative relationship with temperature variability was found. Likewise, species richness spatial variation was not related to environmental variables, which suggest the effect of biological corridors, mass effect or historical processes such as the existence of Pleistocene refuges.
Finally, in Chapter 4 the diversity of trees in 12 communities of hillside forests (0.1 ha plots) was studied, covering the entire latitudinal and longitudinal range of the forest in Uruguay. Local diversity (species richness and composition) was strongly linked to regional diversity (cells 66,000 ha). Both locally and regionally, Myrtaceae was the species-rich taxonomic family in hillside forests. Local environmental effects were not detected on tree diversity in hillside forests. In contrast, macro-environmental variables such as climate, ecoregion, dominant soil and the average distance between localities were associated with species composition in the communities of the hillside forest.
4
This study provides the first ecosystem-scale assessment of hillside forests in Uruguay. It contributes to forest delimitation and understanding the environmental determinants of occurrence, coverage, and diversity at different spatial scales and the connection among them. The results of this thesis allow for a better understanding of the functioning of forest ecosystems in Uruguay and constitute an important contribution for its management and conservation in a scenario of global change.
... As seasonal shifts can be excluded due to the sampling strategy (see Methods), the diet shift observed between the m1 and m2 could record a change in the local plant types during its lifetime caused by environmental or ecological processes. Although environmental changes driven by mechanisms operating in orbital timescales such as Milankovitch and glacialinterglacial cycles affected plant communities in the Pampas (Behling et al. 2005;Tonello and Prieto 2009;Mourelle et al. 2020), such changes may not be distinguished in fossil isotopic records spanning from a few years to decades. In the United States, changes of vegetation from C4-dominated parklands to C3dominated deciduous woodlands between the last glacial maximum (LGM, 26.5-19 ka ago) and the latest Pleistocene led to a diet shift in mammoths and mastodons (Baumann and Crowley 2014), although it is recorded in fossils of individuals that lived hundreds to a few thousands of years apart. ...
Palaeoecological studies on South American mastodons using stable isotopes from isolated teeth indicate variable diets, but represent only a short portion of the total lifetime of the studied individuals. Here is presented an analysis of the carbon (δ13C) and oxygen (δ18O) isotope ratios on three molariforms (m1, m2 and m3) from the jaw of a sub-adult mastodon found in southern Brazil, aimed at understanding its long-term feeding habits. The individual died at about ~26-30 years of age, and the isotopic signal recorded in each tooth spans up to ~3-5 years based on estimates of tooth development from enamel thickness, but apparently there were significant temporal gaps (>5 years) between the mineralisation of each tooth. The δ18O did not vary significantly between the teeth, but the more positive δ13C in the m1 indicates a diet with higher proportion (>30%) of C4 plants, whereas the m2 and m3 indicate considerably less (<20%) C4 plants ingested. This diet shift could have been the result of ontogenetic development, migration, or some disturbance in plant communities driven by environmental stresses. The results indicate that mastodons were able to change their diets at shorter timescales than can be addressed from the analysis of isolated teeth.
... Paleoecological studies carried out in the grasslands suggest that natural fire events were rare during the Late Quaternary glacial period (ca. 40,000 years BP), becoming frequent in the early Holocene (Behling et al. 2004(Behling et al. , 2005. This increase in fire frequency coincides with the initial occupation of the area by humans (Dillehay et al. 1992). ...
Fire is a frequent disturbance in most grasslands around the world, being key for the structure and dynamics of the biodiversity in such ecosystems. While grassland species may be resilient, little is known on how plant–pollinator networks reassemble after fire. Here, we investigate the structure and dynamics of plant–pollinator networks and the variation in species roles over a 2-year post-fire chronosequence on grassland communities in Southern Brazil. We found that both network specialization and modularity were similar over the chronosequence of time-since-fire, but in freshly burnt areas, there were more species acting as network hubs. Species roles exhibited high variation, with plant and pollinator species shifting roles along the post-disturbance chronosequence. Interaction dissimilarity was remarkably high in networks irrespective of times-since-fire. Interaction dissimilarity was associated more with rewiring than with species turnover, indicating that grassland plant and pollinator species are highly capable of switching partners. Time-since-fire had little influence on network structure but influenced the identity and diversity of pollinators playing key roles in the networks. These findings suggest that pollination networks in naturally fire-prone ecosystems are highly dynamic and resilient to fire with both plants and pollinators being highly capable of adjusting their interactions and network structure after disturbance.
... Further, by the end of the Pleistocene, fire frequency increased in some regions of the RPG (Behling et al. 2005), likely due to the change from cold and dry to warm and humid climatic conditions, which increased primary production, and to the direct fire ignition by humans. In addition, the lack of large grazers may have been an important factor for this change of fire frequency. ...
The Río de la Plata Grasslands (RPG) are one of the largest areas of open ecosystems (grasslands, shrublands and savannas) in the world. Historically these systems have experienced, and continue to experience, an enormous loss of natural habitats. Moreover, their importance has been largely invisible in comparison to forested systems. The remaining area of open ecosystems in the RPG region varies according to the source from 38% to 58% of the original area. Open Ecosystems (OE) are a special case of agroecosystems because they can combine the provision of both provisioning and regulating and supporting ecosystem services (ES). Preserving the provision of ES in these natural habitats depends, in part, on understanding the role of the two main disturbances operating in them: grazing and fire. Although these two disturbances are natural components of OE, both are manipulated by humans. In this paper we reviewed the role played by fire and grazing in the structure and functioning of the RPG starting from the late Pleistocene and summarizing current evidence on the effects of fire and grazing on vegetation, fauna and biogeochemical processes. The evidence indicates that among agricultural activities, direct grazing systems in OE have the lowest environmental footprint. And, at the same time are the key for habitat preservation and ES supply. Overall, the OE of the RPG still represent a high proportion of the area, are capable of covering 2.5% of the world's population needs of high quality protein, and at the same time guarding the regulation of key processes.
This paper presents the results of the investigations that defined the formation of the sedimentary deposits and the chronological sequence of the Foz do Chapec´o archaeological area in the Volta Grande of the Upper Uruguay River, Southern Brazil. This research was undertaken to contribute to the definition of the diachronic, sedimentary and stratigraphic context of the archaeological occupations. To achieve these goals a geoarchaeological prospection by land and water was conducted, focusing on the valley bottoms, in the whole Volta Grande area. It comprehended the characterization of surface sedimentary deposits, the exposure and analysis of stratigraphic profiles, and sedimentological analysis. Four superficially exposed deposits were identified: i.e., fluvial conglomerates, fine sediments with sandy texture, clay colluviums and current and recent alluvial deposits. Six interesting points for the opening of stratigraphic profiles were identified, and subsequently resulted in the identification of sedimentary facies associated with river-bed, colluvial and colluvial-alluvial deposits. Three of these points presented a clear sequence of archaeological levels in the stratigraphic context. The results indicated that the local sediments are predominantly composed of a variable mixture of silt and clay, with sands occurring predominantly in an interdigitated form. The stratigraphic structure of the identified layers led to the establishment of 7 sedimentary facies, associated with colluvium (Cm), colluvium-alluvium (Sm) and alluvium and fluvial channels (Sm, Fl, Gms, Gt, Gp, Gh). The radiocarbon dating gives an age between 12.0 and 0.3 cal kBP, indicating that the filling of the local valley occurred during the end of the Pleistocene and throughout the Holocene by means of both fluvial and colluvial systems. Nine distinct archaeological levels, with a clear stratigraphic, chronological, and technological characterization were identified. The pre-ceramic archaeological sequence shows the following chronology: the oldest occupation occurred between 12.0 and 11.0 cal kBP (Cm facies); this was followed by an occupation between 10.5 and 9.5 cal kBP (Cm, Gt, Gp and Gh facies in three archaeological sites with eleven 14C data), then an occupation between 8.7 and 8.5 cal kBP (Cm facies), another between 5.7 and 5.5 cal kBP, one more between 4.8 and 4.6 cal kBP (Cm facies), and the last between 3.4 and 3.3 cal kBP (Cm and Sm facies). The ceramic phase seems to form a single dense component with the anthropogenic soil formation, and was dated between 0.5 and 0.3 cal kBP (Sm facies). These data present a previously unpublished chronostratigraphic sequence that is unique for the context of open-air sites in inner southern Brazil.
Today’s Campos Sulinos have witnessed important paleogeographic, paleoclimatic, and paleoenvironmental shifts in the last 300 million years. When this history is evaluated through the perspective of fossil-bearing sedimentary rocks, it can be divided into four major events: Permian deglaciation and evolution to an alluvial plain in Pangean condition; Triassic recovery of a massive extinction and development in alluvial plains in Pangean circumstances; establishment of an aeolian system under desertic conditions during the Jurassic-Cretaceous; and the Pleistocene onset of megafauna and dominance of grassland vegetation responding to glacial and interglacial cycles. Permian biotas range from marine parareptiles, such as mesosaurs, to fully terrestrial fauna, including large herbivores such as provelosaurids, a saber-toothed herbivore, and large carnivores. Terrestrial environments were dominated by a Glossopteris Flora, with large pteridophytes and primitive gymnosperms. Triassic biota vary from near-the-water parareptiles, temnospondyls, and archosauromorphs, right after the most impressive mass extinction on our planet, to the onset of dinosaurs and the evolution of cynodonts. The Triassic also witnessed one of the main vegetation transitions in Earth’s history: environments once dominated by a Glossopteris Flora gradually became occupied by Dicroidium and Coniferous Floras. The Jurassic faunas are mostly represented by dinosaur footprints from a desert-dominated environment prior to the South America/Africa breakup. Late Pleistocene biota includes large-bodied mammals and reptiles, representatives of the so-called Pleistocene Megafauna. In addition, extant taxa are also present in the fossil record. The Late Pleistocene paleobotanic fossil record demonstrates widespread grasslands that were only slowly subject to the expansion of forests.
The Campos Sulinos are a complex of grassland ecosystems occurring in Brazilian territory that belong to two phytogeographical domains, the Brazilian Atlantic Forest and the Pampa. Floristic and phylogenetic analyses have pointed to the division of the region based on ecological divergence. Thus, it is crucial to understand the processes driving plant diversity within each region. Here, we discuss the microevolutionary processes in plants from the Campos Sulinos, mainly using plant genera that originated and diversified in the region. As the Pampa ecoregion extends to Uruguay and Argentina, some examples were included with distribution beyond the Campos Sulinos. We also explored some perspectives to employ population genetics data in conservation efforts. The current species distribution and intraspecific diversity result from an intricate and complex net between historical and contemporary processes and species-specific characteristics. Although the influence of past climate changes on the habitat distribution is associated with the diversification patterns in plant species from the Campos Sulinos, the rapid changes coupled with the habitat loss due to land use can threaten the persistence and evolution of species. Finally, we argued that, whenever possible, the management in the Anthropocene should include the conservation of population genetic diversity.
In many parts of southern Brazil, mosaics of grassland and forests are found, but little is known how this vegetation pattern has been formed. Are these mosaics partly natural or made by humans? Paleoecological information is needed for understanding the origin of these ecosystems. Data on development, dynamic and stability, their response to environmental change such as climate, and the role of human impact are also essential for conservation and management of the highly diverse mosaics of forest and grassland in southern Brazil. In this context, knowledge on the natural stage of the vegetation and the potential modifications by pre- and post-Columbian anthropogenic activity are also important. In this chapter, paleoecological and paleoenvironmental data based on pollen and charcoal analysis of radiocarbon-dated environmental archives from peat bogs from southern Brazil are used to provide an insight into past vegetation changes and fire history. This also improves our understanding of the modern vegetation and to develop conservation and management strategies for the grasslands in southern Brazil that today are strongly affected by anthropogenic changes.
The South Atlantic Convergence Zone (SACZ) profoundly modulates precipitation from central to southeastern Brazil in the present‐day climate. However, the understanding of its long‐term behavior responding to various climate forcings remains limited. Here, we use an isotope‐enabled atmospheric general circulation model (ECHAM4.6) to examine the precipitation response of the SACZ during the mid‐Holocene about six thousand years ago. The model simulates a northward intensification of the SACZ in the mid‐Holocene, resulting in a dipole anomaly pattern relative to today's climate. The mid‐Holocene precipitation increased along the northern margin of the SACZ due to the strengthening of easterly winds across the tropical Atlantic, while an eastward deflection of the South American low‐level jet reduced moisture transport to southern Brazil, resulting in reduced precipitation along the southern margins of the SACZ. The north–south dipole response in precipitation is consistent with the mid‐Holocene hydroclimate change observed in proxy records from the region.
Changes in land use are considered the main factor in the degradation of ecosystems, especially in continental aquatic environments. In this study, we evaluated the genotoxicity potential of the environmental matrix using tadpoles from three anuran species as a model, to test whether more genetic damage and changes in oxidative stress biomarkers occur in ponds on farms than in native grasslands. Tadpoles were sampled from ponds in the subtropical highland grassland region of southern Brazil. We quantified DNA damage in tadpoles of Scinax squalirostris, Ololygon aromothyella and Odontophrynus asper using the comet assay and oxidative stress changes using glutathione as a biomarker. Our results demonstrated that the tadpoles of the three anuran species collected in agricultural ponds accumulated greater DNA damage and alterations in biomarkers of oxi-dative stress when compared with those collected in ponds in the native grassland, corroborating our initial hypothesis. The DNA damage detected in tadpoles from farm ponds suggests that these populations are suffering impacts from environmental contamination, mainly from heavy metals and fertilizers, as indicated by our complementary data. Our results highlight the importance of grassland remnants for the conservation of amphibians in the subtropical region, which are under severe threat due to the replacement of natural areas by agriculture. Moreover, we emphasize the importance of monitoring and quantifying agrochemicals in habitats and organisms to ensure the viability of populations and support adequate management and conservation strategies for the species of pond-breeding anurans in the region of subtropical grasslands in southern Brazil.
Survey on the tribe Tigridieae (Iridaceae) in the Campos of Southeast South America (SESA Grasslands). Iridaceae is one of the largest families of monocots and is an important constituent of grassland ecosystems across the globe. The tribe Tigridieae is exclusive to the Americas, with an important center of diversity in the Andean region, in the Campos of Southeast South America, in Mexico and in the southern United States. In this study, a survey of the Iridaceae-Tigridieae native to the Grassland Ecosystems of Southeast South America (=SESA Grasslands) is carried out. The SESA was divided into four regions: Campos, Campos de Altitude, Chaco Húmedo and Pampa. The Iridaceae-Tigridieae are represented by a total of 65 species (including ten subspecies), distributed in ten genera. The genus Cypella with 30 species and eight subspecies is the most diverse, followed by Calydorea (13 species), Herbertia (11 species) and Gelasine (four species and two subspecies). A total of 87% of the taxa occurring in the SESA are endemic, most of them exclusive to the Campos region, which includes 54 taxonomic entities, of which 41 taxa are endemic The Campos de Altitude region is represented by 15 taxa, including six endemic species. The Pampa region includes six taxonomic entities, being one of them endemic. The Chaco Húmedo region comprises five species, none of which are exclusive to the latter region. Key words: Bulbous, Grasslands, High Grasslands, Humid Chaco, Geographic distribution, diversity, Pampa.
Glaciogenic dust has a strong relationship with global climate and ocean biogeochemical processes especially during glacial periods, being a major source of nutrients, mainly iron, that increase marine productivity. Different studies have attributed higher marine paleoproductivity along the southwestern Atlantic during the last glacial period to fluvial inputs and upwelling, but the possible influence of continental dust on that process is still unknown. This paper presents evidence suggesting that eolian-sourced glaciogenic dust favored higher ocean productivity during the last glacial, recorded in three sediment cores obtained on the lower continental slope off southern Brazil (~29°-30°S, ~47°W) at water depths between
1,514 and 2,091 m. The sampled sediments are silt-dominated terrigenous siliciclastics, but higher proportions of sand-sized biogenic carbonate (mostly foraminifer tests) at intervals corresponding to the stadials MIS 4 and 2 and parts of the interstadial MIS 3 point to intervals of increased productivity, correlated with pulses of higher deflation of dust from southern South America as recorded in the EPICA Dome C ice core in Antarctica. It is proposed that glacial climate-driven increased eolian processes transported iron-bearing dust produced by the expanded Patagonian ice sheet up to the southwestern Atlantic, fueling higher phytoplankton productivity and thus favoring the proliferation of planktonic and benthic foraminifera recorded in the cores. Eventual anthropogenically-driven reduction of tropical-sourced summer rainfall reaching southern South America, driven by equatorial ocean warming and deforestation in the Amazon region, may increase dust deflation and thus affect ocean productivity along the southwestern Atlantic in the future.
Grassland biomes are either of azonal nature or, when zonal, associated with regions experiencing prolonged periods of drought. In the Southern Hemisphere, natural (climato-genetic) temperate grasslands are found on every continent except for Antarctica. The grasslands found in the rain shadow of the Southern Andes in Patagonia are recognised here as a member of a new zonobiome—Austro-Steppe Zone. This zonobiome is fundamentally different from its Northern Hemisphere analogon—the Northern Steppe Zone (zonobiome G1), the latter having predominantly summer-rainfall region, while the Austro-Steppe shows winter-rainfall regime. One of the core analyses featured in this chapter is dedicated to the origins and natural vs anthropogenic status of the South American Pampa-Campos sulinos biome. A new hypothesis suggests that the intriguing current treelessness of these grasslands is a result of system hysteresis, making these grasslands relict and natural. In Africa, the Southern African Highveld, Manica Highland and Angolan Escarpment Grasslands, Australian natural grasslands (incl. Bunya Balds Grasslands, the Monaro grasslands, and the Tasmanian Tussock Grasslands) are also natural. They all represent ecotonal biomes showing diversified links to the neighbouring zonobiomes T3, T4, T5, and E2. The South Island Chionochloa grasslands of New Zealand are essentially an outcome of relatively fast, historical deforestation. Nevertheless, the existence of relict natural grasslands in a sub-arid area of the Otago Region is considered a possibility.KeywordsAfrican Montane GrasslandsAngolan Montane GrasslandsBunya Grassy BaldsCampos sulinosHighveldHysteresisManica HighlandsMāori Monaro Tussock GrasslandsPampaRelict biomeSouth Island Chionochloa GrasslandsTasmanian Tussock Grasslands
The Mixed Prairies region of southern Brazil, popularly known as “Pampa Gaúcho”, constitutes one of the most important and exceptional landscapes in the country, dominated by gentle undulating relief with hilly slopes, known as “coxilhas”. Grasslands are dominant in the pampas, representing a relict of drier past climate, and constrained by the anthropic pressures, burning, and clearing for expanding cattle or agriculture. The past drier phase left a legacy of high fertility soils, expansible 2:1 clays, calcium carbonate concretions, and polychromy. However, dystrophic soils of low natural fertility also occur, notably on quartz-rich sandstones, also prone to severe water and wind erosion under the current climate, and unfavorable to agriculture use, forming widespread arenization. Although livestock is the dominant activity in the pampas, irrigated rice cultivation also has a marked geographic and economic importance in wetland areas. Increasing grain production in the recent decades mainly occurred with the incorporation of sandy, fragile areas into the production process. The use of shallows soils, such as Neossolos Litólicos (Lithic Leptosols) and Neossolos Regolíticos (Regosols) by rice cultivation in a flooding system raises concerns about the sustainability of this intensive use, despites the natural high fertility of the soils. Regarding the Vertissolos (Vertisols) and Chernossolos (Chernosols), clayey or very clayey textures and the predominance of expansible 2:1 clays makes these soils extremely fragile when intensive agricultural use is adopted, besides the natural vulnerability to compaction and water erosion, due to high dispersibility of the clay fraction and poor drainage. Erosion features, such as rills and gullies are commonly found. A rich and diverse Grassland is typical of the pampas, and this rich flora sustains the traditional livestock in the Campanha but has been gradually modified by anthropic action, with burning cultivated pastures Pine and Eucalyptus reforestation and agriculture. The “southern Grassy fields”, Pampas, constitute a neglected biome, with only a minor part duly protected by Conservation Units (UC), equivalent to less than 0.5% of the total area. The Domain of Mixed Prairies (pampas) in Southern Brazil is the only true temperate/subtropical landscape in the country, with high aesthetic value, beauty of ecological and cultural importance. Its unique soils result from past and present climates, shaping a polycyclic landscape with a singular and dominant grassland vegetation. The long-term sustainability of the Pampas in Brazil is challenged by a combination of widespread eolian and water erosion, rapid expansion of forestry monoculture, technological advance of cash-crops, and urbanization.KeywordsBrazilian subtropicsTemperate soilsPrairies soilsTropical pedologyNeotropical soils
This study sought to understand the role of continental influence on ocean productivity along the late Quaternary
based on the comparison between continental palynomorphs and paleoproductivity proxies from the marine
sediment core SIS188. Retrieved from the slope of the Pelotas Basin at a depth of 1,514 m, the core documents
the time interval between 47.8 and 7.4 cal ka BP, including the Marine Isotope Stages (MIS) 3, 2 and 1. The
palynological content found in the core SIS188 indicates a typical flora of the southern Brazil highlands, which is
at the same latitude as the core. Thus, continental input sources, such as wind-borne dust and discharges from
the Mampituba and Araranguá rivers, would more likely account for the palynological content than the Brazilian
Coastal Current (BCC). During the glacial intervals (MIS 3 and MIS 2), paleoproductivity (indicated by the proxies
coccolith numbers, N Ratio, and TOC content) suggest the intensification of upwelling and transport of wind dust,
the latter of which may have transported pollen grains to the core region. There is a concentration decrease of
continental palynomorphs at the end of MIS 2, which is accentuated during MIS 1 when the sea level is higher.
Paleoproductivity was high during MIS 1, especially from the Holocene onwards, although the concentration
of continental-derived palynomorphs decreases sharply, showing that the rise in sea level interferes with the
fertilization of marine waters far from the coast by continental input.
The degradation of natural ecosystems due to land use changes has been increasing, altering ecosystem composition, structure and processes, which negatively affects biodiversity. Herein, we explored how the diversity patterns of anurans respond to the scenario of extensive replacement of grasslands with agriculture in southernmost Brazil. We determined possible changes in the species richness, taxonomic composition, and structure of pond-breeding anuran communities in the grassland ecosystems of the South Brazilian Grasslands (SBG). Using the survey at breeding sites method, we sampled a total of 238 ponds, 153 from extensive livestock grazing on grasslands and 85 from agricultural areas. The higher species richness was found in the livestock areas on grasslands. There was a significant nestedness pattern associated with agricultural areas, indicating a non-random process of community simplification by species loss. Seven anuran species were considered land use indicators, of which five were considered indicators of grasslands with livestock, and two as indicators of agricultural areas. Generalist species were persistent and dominant in agricultural areas, while habitat specialists disappeared from these areas. Land use was a significant factor explaining the community structure segregation between land uses regardless of the natural variation reported at the local and regional levels. We highlight the importance of grasslands for the conservation of pond-breeding anurans in non-forest landscapes of the subtropical region, and we discuss the view that extensive livestock production needs strategic incentives to help the conservation of SBG biodiversity, such as multi-institutional measures.
Apresentação sintética e global das características geográficas gerais do Pleistoceno e do Holoceno do Rio Grande do Sul, a partir do término da última glaciação, englobando as transformações de longa duração: climáticas, florísticas e faunísticas. A reconstituição dos pelo-ambientes não é apenas importante para o estabelecimento de quadros geo-cronológicos ou para a análise estratigráfica, mas serve de apoio imprescindível para a interpreação dos contextos pré-históricos e para o estudo das correlações entre os grupos de caçadores-coletores e de horticultores com as particularidades de seus nichos ecológicos. O conhecimento das condições de desenvolvimento sócio-cultural destes grupos pré-históricos, bem como o das transformações graduais do meio ambiente, são elementos complementares fundamentais para a compreensão objetiva do povoamento inicial do Rio Grande do Sul e áreas vizinhas. AAK
The paper responds to the question: How should one go about designing the statistical analysis of biodiversity if it had to be done across scales in time and space? The conceptual basis of the design is the definition of biodiversity as a convolution of two community components. One of the components is richness, the product of species evolution, and the other structure, the consequence of environmental sorting (biotic, physical). The method of choice takes information in the manner of frequency distributions, and decomposes the associated total diversity into additive components specific to the deemed sorting factors. Diversity quantities are supplied by the analysis by which the relative importance of sorting factors can be measured and the dynamic oscillations which they generate in diversity can be traced. Examples support the a priori idea that the velocity of compositional change in the community during the late quaternary period has co-varied closely with the specific components of Kolmogorov-type complexity, Anand's structural complexity and Rényi's entropy of order one. The paper explains what is involved and why is it important.
The characteristics discussed are measurable on the process "trajectory", the path traced out by vegetation transitions in time. It is argued that since the trajectory is symptomatic of factor influences and governing principles, it has to be an object of central interest in dynamic studies. Theoretical points, scaling scenarios, and analytical tools are the main topics. Numerical examples illustrate the applications.
It is shown that community dynamics is neither haphazard nor completely directed. This is quite clear from our examination of a concrete example where recovery dynamics in vegetation progressed from an early phase of strong linear determinism to intense randomness with phase transition defined by density. Is it possible to reconstruct the two phase structure in simple mathematical terms? The results show that it is, and that the model is very simple: a discrete-time Markov chain with white noise. Interestingly, the long-term behaviour of the model is complex chaotic and explosive, suggesting that progression from dominant randomness to determinism is a distinctly probable event. And thus a conceptual foundation is laid, through interlinking initial condition, phase structure and explosive chaoticity, for a unifying theory, in which the classical hypotheses of community dynamics appear as special cases.
Stratigraphically constrained cluster analysis is a multivariate method for quantitative definition of stratigraphic zones. As opposed to ordinary, unconstrained cluster analysis, only stratigraphically adjacent clusters are considered for merging. The method of incremental sum of squares has been used widely for unconstrained analyses and has proved particularly satisfactory for pollen frequency data. CONISS is a FORTRAN 77 program for stratigraphically constrained cluster analysis by this method. Several data transformations lead to different implicit dissimilarity coefficients. As an option, the program also will perform an unconstrained analysis, which can be useful for comparison with the constrained analysis.
Palynological studies have been carried out on three highland peat bogs, and one situated on the Atlantic coastal plain. In the highlands, the late Pleistocene (14,000 - 10,000 uncal B.P.) vegetation was dominated by campos (grassland). Scattered stands of Araucaria forests were preserved in deep valleys. In the region of the sites at Morro da Igreja and Serra do Rio Rastro, the dominance of campos vegetation continued until about 1000 B.P. while at the Serra da Boa Vista site there was an expansion of Atlantic pluvial forest elements followed by Araucaria forests at the beginning of the Holocene. A general expansion of A. angustifolia, clearly related to a change towards an increasingly moist climate, can be dated to the present millenium. On the coastal plains, the late Pleistocene vegetation was dominated by Myrtaceae which were replaced by tropical taxa in the Holocene. The lowland profile (Poo Grande) also covers part of the upper Holocene, where the rich flora of the Atlantic pluvial forests can be characterized by taxa including Alchornea, Urticales and Rapanea. Close to the coring site, there was a repeated alternation between two different dune communities (4840 - 4590 B.P.), followed by a lake stage with aquatic plant succession (4590 - 4265 B.P.), plant communities dominated by Rapanea (4265 - 4230 B.P.) and the spread of Alchornea (4230 - 3525 B.P.). Late Pleistocene climate conditions (14,000 - 10,000 B.P.) can be described as cold and relatively dry, possibly including an equivalent of the Younger Dryas period. In the Holocene, there were changes from a warm and drier climate (10,000 -3000 B.P.) to a cool and more moist regime (ca. 3000 -ca. 1000 B.P.) and finally to a cool and very moist period (from around 1000 B.P.).
Traditional syntheses of the archaeology of the late Pleistocene period in South America have focused primarily on the peopling of the continent by North American cultural groups and on identifying associations among regional sites. This focus has tended to ignore the widespread culture diversity of the period and the possible effects of different paleolandscapes on human migration and colonization, such as the presence of unglaciated tropical and temperate environments in the northern lowlands, the gateway to the interior. The earliest known cultural assemblages are characterized by various unifacial and bifacial lithic industries that may represent regional processes reminiscent of an Archaic lifeway. The major archaeological sites and associated artifact assemblages are examined in terms of regional and continental patterns of environmental and cultural change. Results suggest that the Pleistocene archaeological record of South America must be explained in its own terms and that the events and processes producing this record either occurred earlier than previously thought or are very different from those in North America.
Fourteen pollen records from the south (S) and the southeast (SE) Brazilian regions have been synthesised. Late Glacial records from S Brazilian highlands document the predominance of grassland (campos) where today Araucaria forests occur. Records from SE Brazil show that during pre- and full-glacial times modern tropical semideciduous forest and cerrado (savanna to dry forest) were mostly replaced by grassland and some subtropical gallery forest. Modern montane Araucaria forests and cloud forests in SE Brazil were mostly replaced by grassland during pre- and full-glacial times. There is evidence that the modern tropical Atlantic rainforest in S Brazil was significantly reduced and replaced by cold-adapted forest taxa or grassland during glacial, especially during full-glacial times. The synthesis indicates that grasslands dominated the S and SE Brazilian landscape during the Late Pleistocene where today different forest ecosystems exist. Grassland extended over 750 km from S to SE Brazil from latitudes of about 28°/27° S to at least 20° S. These results indicate that climates in the region were markedly drier and 5–7°C cooler during glacial times. Antarctic cold fronts must have been much stronger and more frequent than today. Studies from S Brazil show that huge areas of Late Pleistocene campos vegetation were still found on the S Brazilian highlands during early and mid Holocene times, reflecting dry climatic conditions with an annual dry period of probably 3 months. Modern wet climatic conditions with no or only short dry periods were not established until the Late Holocene period when Araucaria forests replaced large areas of grassland vegetation after about 3000 14C yr B.P. and especially after 1500/1000 14C yr B.P.
Holocene paleoenvironments have been interpreted from a radiocarbon dated pollen and charcoal record of the São Francisco de Paula region on the southern Brazilian highland. Today the region is characterized by pastureland and small patches of disturbed Araucaria forest. The region receives 2450 mm per annum. This is the highest precipitation rate in southern Brazil. Studied surface samples represent the modern pollen analog of the anthropogenic influenced vegetation. Pollen analytical studies of the 84 cm long core, collected from a small basin with clay, organic matter and peat deposits, show that pollen and spores of the lower core section (84 and 46 cm depth) have been almost destroyed. This period between ca. 7500 and 4000 14C yr bp was too dry for conservation of pollen and spores in the basin. Climate must have been markedly drier than today during early and mid Holocene times. After 4000 14C yr bp, preserved pollen grains reflect wetter conditions than before and indicate the predominance of campos (grassland) vegetation with small areas of Araucaria forest in the study region. Forest expansion is documented since 1060 14C yr bp and expansion of Araucaria angustifolia trees itself since 850 14C yr bp. During the last 1000 yr, rainfall must have been much more intensive with no or only short dry periods such as the modern climate. The results confirm the vegetational and climatic changes documented from the Araucaria forest region of Santa Catarina and Paraná State. Concentration and accumulation rates of carbonized particles are somewhat higher during the last 850 14C yr bp than before, indicating an increased fire frequency.
Late Quaternary vegetation, fire and climate dynamics have been studied based on high-resolution dated pollen and charcoal samples and multivariate data analysis. The samples were taken from a 212-cm-long sediment core of a bog in the Cambará do Sul region on the highlands of northeastern Rio Grande do Sul State, Brazil. The records, including seven AMS radiocarbon dates, span 42 840 14C years, for the first time extending the reconstruction of past environmental changes on the southern Brazilian highlands back to the Last Glacial Maximum (LGM) and pre-LGM times. The last 1100 years provide a decadal resolution. Initially the site was a permanent shallow lake which became seasonally dry after 26 900 14C yr BP. Seasonal climate with a long annual dry period prevailed until the late Holocene. The climate was somewhat wetter from 42 840 to 41 470 14C yr BP and from 41 470 to 26 900 14C yr BP than during the LGM and the late-Glacial period. Natural fires were rare, but became very frequent after 7400 cal BP, suggesting human occupation of the southernmost Brazilian highlands since that time. The records suggest that a species-rich Campos (grassland) vegetation existed in the area under a relatively dry and cold climate during glacial times under possibly as low as −10°C. The record also suggests that small populations of Araucaria were probably only present in refugia of deep and protected valleys and/or on wetter coastal slopes. Campos vegetation existed through the early and mid-Holocene until 4320 cal yr BP, after which Araucaria forest expanded into the network of gallery forests along the streams. By 1100 cal yr BP the Araucaria forest replaced the Campos vegetation reflecting the onset of the wettest period with no marked annual dry season. The marked expansion of the Araucaria forest coincided with the reduction in fire. Between AD 1520 and 1770 Weinmannia became a common taxa in the Araucaria forest, suggesting a shift to warmer climatic conditions on the highlands. This interval was synchronous with a cool phase within the Little Ice Age known from North Atlantic land records. After about AD 1780 human activities changed the original forest composition, first by introducing cattle into the forest and than by selective logging of Araucaria trees. Multivariate analysis of the pollen data shows compositional changes that follow a trajectory alternating undirectional, random phases and phases with directional, sometimes fast transitions. The results also show that compositional changes in the vegetation are slower during cool periods (LGM compared to pre-LGM) and faster in warm periods (Holocene).
Colleagues interested in this report should also consider downloading:
“Statistical multiscaling in dynamic ecology”
“Multi-scale trajectory analysis”
“The vegetation process”
“Quantum analysis of primary succession”
These essays present powerful conceptual tools and examples of application for the analysis of long chronoseres, such as the palynomorph spectra taken from sediments.
New palynological and charcoal data from a bog (24°40′S, 50°13′W, 1200 m asl) of Serra Campos Gerais, northeastern ParanáState, allow a complete and detailed reconstruction of the late Quaternary vegetation and climate history of the South Brazilian highlands. The late-glacial period, which starts at 12,50014C yr BP, indicates the predominance of a diverse grassland vegetation (campos) with scattered stands of Araucaria forest and Atlantic rain forest, probably growing in valley bottoms. This suggests 3 to 5°C colder and drier climates than at present. Judging from the absence of charcoal, fires must here been rare during late-glacial times. The early and mid-Holocene (until 285014C yr BP) is marked by a predominance of campos vegetation on the highlands and expansion of tropical rain forest trees in the valleys, indicating warm climates and perhaps an increase in annual precipitation compared to the late-glacial. A migration of Araucaria forest from the valleys onto the highlands did probably not occur. Seasonal drought is probably the major factor explaining the absence of an expansion of Araucaria forests on the southern Brazilian highlands in the early and mid-Holocene. Palaeofires were more frequent at the beginning of the Holocene, probably ignited by Amerindians at that time. First expansion in the valleys or an initial migration of Araucaria angustifolia from valleys into the Serra Campos Gerais highland occurred during the late Holocene (2850-153014C yr BP), indicating a wetter climate with a shorter dry season. Fires during this period had the highest frequency and may have influenced the migration of Araucaria into the campos areas. A marked expansion of Araucaria forest, forming a mosaic of grassland and Araucaria forest patches on the highlands, took place only in the last 1500 years. This suggests onset of a high precipitation climate without a strong annual dry season. Fires were also less frequent. Logging of Araucaria forests occurred during the last centuries.
Long-term vegetation dynamics based on paleo-pollen data display transient behaviour, often alternating in phase between predominant determinism and predominant 'turbulence', when viewed as a trajectory in a multivariate phase space. Given this, the metaphor of vegetation dynamics as a 'flowing stream', first introduced by Cooper in his classic 1926 paper entitled "The fundamentals of vegetation change", is re-examined and revealed to be not only useful, but strikingly realistic. Vegetation dynamic theory is reviewed and classic theories are found to reflect reality poorly. It is suggested that vegetation dynamics is a far from equilibrium system, and that the application of nonequilibrium thermodynamic theory is appropriate.
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