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... The vegetation types in southern Brazil and Uruguay (Fig. 1B) are well described in previous publications (e.g. Hueck, 1966;Klein, 1978Klein, , 1979Por, 1992;Boldrini, 2009). In the study area, the vegetation distribution is mainly influenced by topography and climate. ...
... The coastal lagoons in southern Brazil and Uruguay are dominated by salty marshes with Cyperaceae, Chenopodiaceae and Amaranthaceae (Marangoni and Costa, 2009). The vegetation in the Rio de la Plata drainage Basin (Fig. 1B) is formed by a mixture of grasslands with gallery forests, dry forests and semi-deciduous forests (Hueck, 1966). ...
... This river drains the southern lowlands and northern highlands of the Rio Grande do Sul state (Fig. 1), where Araucaria forest and grasslands with gallery forests and other forests as well as coastal vegetation are found (e.g. Hueck, 1966). However, as the catchment area of the Jacuí River is not very large, its sediment discharge into the western South Atlantic is moderate, especially after flowing through the Patos Lagoon (Möller Jr and Castaing, 1999). ...
Vegetation and climate changes in southern Brazil, as well as the dynamics of the adjacent South Atlantic were investigated through the analyses of pollen, spores and dinocysts from marine sediment core GeoB6211-2 that covers the last 19.3 kyr. The pollen record indicates the dominance of grassland (campos) in southeastern South America (SESA), reflecting cold and/or dry conditions during the Last Glacial Maximum. Forests, mainly gallery forests, expanded slightly during Heinrich Stadial 1, suggesting slightly wetter conditions. A stronger expansion of the Atlantic lowland rainforest is noticed in the record after ca. 5.5 cal kyr BP, likely due to wetter conditions. The relatively high amount of exotic Nothofagus pollen, transported by wind, rivers and then by oceanic currents northwards to the study site, as well as the dinocyst Brigantedinium spp., indicate a noticeable influence of the Brazilian Coastal Current from the south between 19.3 and 14.8 cal kyr BP. After that, the decrease in Nothofagus and Brigantedinium spp. together with the increase in dinocyst Operculodinium centrocarpum indicate that the Brazil Current from the north dominated the coring site. The abundance of freshwater algae between ca. 19.3 and 17.0 cal kyr BP suggests that the Rio de la Plata mouth was located close to the coring site during this period, and its discharge of nutrient-rich freshwaters strongly affected the upper water column. Sea level rise decreased this impact during the late glacial phase by moving the coastline further away from the core site. The presence of the Brazil Current at the core site became stronger after ca. 15 cal kyr BP and strongest after 9 cal kyr BP. In summary, the pollen, spores and dinocyst records from core GeoB6211-2 provide important climatic records to reconstruct the environmental changes in SESA.
... Campos are rich in species of the Poaceae family, as well as Cyperaceae, Asteraceae, Apiaceae, Rubiaceae, and Fabaceae (Klein, 1978(Klein, , 1981. Additional detailed information is available in the literature (e.g., Hueck, 1966;Klein 1978Klein , 1981; Fundacaõ Instituto Brasileiro de Geografia e Estatística [IBGE], 1993). ...
... The pollen diagrams include individual records of the most abundant pollen and spore taxa (Fig. 4) and records of the following groups: ARF biome (trees and shrubs), campos (herbs), aquatic, Pteridophyta, tree ferns, and mosses, as well as concentration and accumulation rate of pollen and a cluster analysis dendrogram (Fig. 5). The grouping is based on vegetation surveys in southern Brazil (e.g., Hueck, 1966;Klein 1978Klein , 1981IBGE, 1993). The zonation of the pollen record is based on changes in the pollen assemblages and CONISS analysis. ...
A high-resolution pollen record of the Atlantic rain forest (ARF) biome from the coastal Serra do Tabuleiro mountains of southern Brazil documents an 11,960 yr history of vegetation and climate change. A marked expansion of Weinmannia into the grassland vegetation marks the latter part of the Younger Dryas, reflecting warm and relatively wet conditions. Between 11,490 and 9110 cal yr BP, grasslands became dominant again, indicating a long cold and dry phase, probably in response to the stronger influence of cold South Atlantic seawater and to Antarctic cold fronts. Between 9110 and 2640 cal yr BP, four distinct phases with strong or moderate expansions of different ARF biome taxa were recorded, reflecting warmer and relatively dry conditions with changes in rainfall and length of the annual dry season. After 2640 cal yr BP, the modern ARF biome became established with high amounts of ferns, reflecting somewhat cooler and wetter conditions with a reduced annual dry season. In particular, after 1000 cal yr BP tree ferns increased, reflecting wetter conditions with no dry season.
... The highest degree of endemism in Clade 2, however, is found in the South of Chile where all three native Clade 2b species recorded, P. aysenensis, P. distorta and P. valdiviana, are probable endemics. This is most likely a consequence of the millions of years of isolation of the perhumid Gondwanan Valdivian rainforests and Southern beech forests by the Pacific Ocean to the west and semi-arid environments to the north and east (Hueck 1966, Armesto et al. 1995, Seibert 1996, Hinojosa et al. 2006, Antonelli & Sanmartín 2011, Tecklin et al. 2011, Turchetto-Zolet et al. 2013. It is notable that in Clade 10 the four species from the P. kernoviae complex, P. chilensis, P. kernoviae, P. pseudochilensis and P. pseudokernoviae, are also considered endemic to the Valdivian rainforests ). ...
During 25 surveys of global Phytophthora diversity, conducted between 1998 and 2020, 43 new species were detected in natural ecosystems and,
occasionally, in nurseries and outplantings in Europe, Southeast and East Asia and the Americas. Based on a multigene phylogeny of nine nuclear and four
mitochondrial gene regions they were assigned to five of the six known subclades, 2a–c, e and f, of Phytophthora major Clade 2 and the new subclade 2g.
The evolutionary history of the Clade appears to have involved the pre-Gondwanan divergence of three extant subclades, 2c, 2e and 2f, all having disjunct
natural distributions on separate continents and comprising species with a soilborne and aquatic lifestyle and, in addition, a few partially aerial species in
Clade 2c; and the post-Gondwanan evolution of subclades 2a and 2g in Southeast/East Asia and 2b in South America, respectively, from their common
ancestor. Species in Clade 2g are soilborne whereas Clade 2b comprises both soil-inhabiting and aerial species. Clade 2a has evolved further towards an
aerial lifestyle comprising only species which are predominantly or partially airborne. Based on high nuclear heterozygosity levels ca. 38 % of the taxa in
Clades 2a and 2b could be some form of hybrid, and the hybridity may be favoured by an A1/A2 breeding system and an aerial life style. Circumstantial
evidence suggests the now 93 described species and informally designated taxa in Clade 2 result from both allopatric non-adaptive and sympatric adaptive
radiations. They represent most morphological and physiological characters, breeding systems, lifestyles and forms of host specialism found across the
Phytophthora clades as a whole, demonstrating the strong biological cohesiveness of the genus. The finding of 43 previously unknown species from a single
Phytophthora clade highlight a critical lack of information on the scale of the unknown pathogen threats to forests and natural ecosystems, underlining the
risk of basing plant biosecurity protocols mainly on lists of named organisms. More surveys in natural ecosystems of yet unsurveyed regions in Africa, Asia,
Central and South America are needed to unveil the full diversity of the clade and the factors driving diversity, speciation and adaptation in Phytophthora.
... Floristically and ecologically related is the "Campina" forest in the lower Río Negro (Takeuchi 1961(Takeuchi , 1962Anderson et al. 1975;Anderson 1981). The name of Amazon caatinga has been adopted to distinguish it from the dry caatinga vegetation of the Brazilian north-eastern region (Hueck 1966;Klinge and Medina 1979). ...
... The coastal lagoons of southern Brazil and Uruguay are dominated by salt marshes composed of Cyperaceae, Chenopodiaceae and Amaranthaceae (Marangoni & Costa, 2009). The vegetation of the drainage basin of the Rio de la Plata is formed by a mix of grasslands, gallery forests, dry forests, and semi deciduous forests (Hueck, 1966). ...
Vegetation and climate changes in southern Brazil are described based on the palynological analysis from marine core SIS 188, collected on the continental slope, which records the interval between 47.8 and 7.4 cal ka BP. The pollen record indicates that the grasslands dominated the landscape in southern Brazil throughout the studied period. During the last glacial period, the forests were reduced. Between 32.8 and 20.2 cal ka BP, there is an increase in grassland and reduction of arboreal palynomorphs, coinciding with colder and drier climatic conditions of the Last Glacial Maximum (LGM). From 30 to 25.2 cal ka BP, an increase in the sedimentation rate and concentration of most pollen indicators is observed. This change could be related to low sea level, which exposed the continental shelf to eolian erosion and fluvial inputs that transported sediments and palynomorphs to the ocean. A significant decrease in sedimentation rate is recorded between 19.5 and 12.6 cal ka BP, probably related to sea-level rise during deglaciation. During deglaciation and beginning of the Holocene, the increase in arboreal pollen indicates the expansion of forests, reflecting warmer and wetter climate. Heinrich event 1 is marked by a peak in the percentages of the arboreal vegetation at 15.9 cal ka BP. Around 8.5 cal ka BP, there seems to be another interval of higher moisture, indicated by the composition of the palynological association, formed by pteridophytes Blechnum, Huperzia, Polypodiaceae, Pteridaceae and Cyatheaceae. These results show that the palynological record from the SIS188 marine core is sensitive to global climatic changes and can provide a reliable paleovegetational reconstruction for the continental environment. Keywords: Pelotas Basin, paleoclimate, palynomorphs, palynology, Quaternary.
... Further, the Valdivian rainforests are considered a Gondwana relic, sometimes referred to as a 'tropical rainforest in a nontropical climate' and a 'biogeographic island' (Hueck 1966, Armesto et al. 1995, Seibert 1996, Tecklin et al. 2011. They are floristically related to temperate rainforests in New Zealand, Tasmania, New Guinea and New Caledonia, but have been isolated by the Pacific Ocean to the west and semi-arid environments to the north and east for many millions of years. ...
During extensive surveys of global Phytophthora diversity 14 new species detected in natural ecosystems in Chile, Indonesia, USA (Louisiana), Sweden, Ukraine and Vietnam were assigned to Phytophthora major Clade 10 based on a multigene phylogeny of nine nuclear and three mitochondrial gene regions. Clade 10 now comprises three subclades. Subclades 10a and 10b contain species with nonpapillate sporangia, a range of breeding systems and a
mainly soil- and waterborne lifestyle. These include the previously described P. afrocarpa, P. gallica and P. intercalaris and eight of the new species: P. ludoviciana, P. procera, P. pseudogallica, P. scandinavica, P. subarctica, P. tenuimura, P. tonkinensis and P. ukrainensis. In contrast, all species in Subclade 10c have papillate sporangia and are self-fertile (or homothallic) with an aerial lifestyle including the known P. boehmeriae, P. gondwanensis, P. kernoviae and P. morindae and the new species P. celebensis, P. chilensis, P. javanensis, P. multiglobulosa, P. pseudochilensis and P. pseudokernoviae. All new Phytophthora species differed from each other and from related species by their unique combinations of morphological characters, breeding systems, cardinal temperatures and growth rates. The
biogeography and evolutionary history of Clade 10 are discussed. We propose that the three subclades originated via the early divergence of pre-Gondwanan ancestors > 175 Mya into water- and soilborne and aerially dispersed lineages and subsequently underwent multiple allopatric and sympatric radiations during their global spread.
... In the higher portions, there is a mosaic of Araucaria forest and grasslands. Araucaria forests are found between 24° and 30°S and between 1,000 and 1,400 m of altitude (Hueck, 1966), and are mostly represented by Araucaria angustifolia, Podocarpus lambertii, Mimosa scabrella, Ilex spp., and Dicksonia sellowiana (Boldrini, 2009). The grasslands, which occupy vast areas of southern Brazil, are dominated by the Poaceae, Cyperaceae, Asteraceae, Apiaceae, and Fabaceae families, which are associated with cooler and drier climates (Mourelle and Prieto, 2012). ...
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.
... As it has the broadest distribution of all Nothofagus taxa, reaching from Tierra del Fuego up to the north of Neuquén, lenga is well adapted against cold, stormy and perhumid climate. In the south it reaches altitudes of 500-600 m a.s.l., in the National Parks Nahuel Huapi and Lanín it climbs up to 1,200-1,300 and 1,700 m a.s.l., respectively (Seibert 1982;Hueck 1966). ...
ÜBERWACHUNG DES SCHWEREGRADS VON WALDBRÄNDEN ANHAND
VON LANDSAT-ZEITREIHEN – EINE FALLSTUDIE DES LAGO EPUYÉN
IN PATAGONIEN, ARGENTINIEN
... The Vinaceous-breasted Parrot geographic range covers approxi- Our estimated VBP range exceeds the area of past Araucaria forest mapped by Hueck (1966) and includes vast areas of the Atlantic forest biome that have been cleared. Nonetheless, both vegetation site covariates-Araucaria and Atlantic forest cover-had strong positive effects on site-occupancy probability. ...
Aim
Mapping species distributions is a crucial but challenging requirement of wildlife management. The frequent need to sample vast expanses of potential habitat increases the cost of planned surveys and rewards accumulation of opportunistic observations. In this paper, we integrate planned-survey data from roost counts with opportunistic samples from eBird, WikiAves and Xeno-canto citizen-science platforms to map the geographic range of the endangered Vinaceous-breasted Parrot. We demonstrate the estimation and mapping of species occurrence based on data integration while accounting for specifics of each dataset, including observation technique and uncertainty about the observations.
Location
Argentina, Brazil and Paraguay.
Methods
Our analysis illustrates (a) the incorporation of sampling effort, spatial autocorrelation and site covariates in a joint-likelihood, hierarchical, data integration model; (b) the evaluation of the contribution of each dataset, as well as the contribution of effort covariates, spatial autocorrelation and site covariates to the predictive ability of fitted models using a cross-validation approach; and (c) how spatial representation of the latent occupancy state (i.e. realized occupancy) helps identify areas with high uncertainty that should be prioritized in future fieldwork.
Results
We estimate a Vinaceous-breasted Parrot geographic range of 434,670 km², which is three times larger than the “Extant” area previously reported in the IUCN Red List. The exclusion of one dataset at a time from the analyses always resulted in worse predictions by the models of truncated data than by the Full Model, which included all datasets. Likewise, exclusion of spatial autocorrelation, site covariates or sampling effort resulted in worse predictions.
Main conclusions
The integration of different datasets into one joint-likelihood model produced a more reliable representation of the species range than any individual dataset taken on its own, improving the use of citizen-science data in combination with planned-survey results.
... Our estimated VBP range exceeds the area of past Araucaria forest mapped byHueck (1966) and351 includes vast areas of the Atlantic forest biome that have been cleared. Nonetheless, both 352 vegetation site-covariates-Araucaria and Atlantic forest cover-had strong positive effects on probability. ...
Mapping species distributions is a crucial but challenging requirement of wildlife management. The frequent need to sample vast expanses of potential habitat increases the cost of planned surveys and rewards accumulation of opportunistic observations. In this paper, we integrate planned survey data from roost counts with opportunistic samples from eBird, WikiAves and Xeno-canto citizen-science platforms to map the geographic range of the endangered Vinaceous-breasted Parrot. We demonstrate the estimation and mapping of species occurrence based on data integration while accounting for specifics of each data set, including observation technique and uncertainty about the observations. Our analysis illustrates 1) the incorporation of sampling effort, spatial autocorrelation, and site covariates in a joint-likelihood, hierarchical, data-integration model; 2) the evaluation of the contribution of each data set, as well as the contribution of effort covariates, spatial autocorrelation, and site covariates to the predictive ability of fitted models using a cross-validation approach; and 3) how spatial representation of the latent occupancy state (i.e. realized occupancy) helps identify areas with high uncertainty that should be prioritized in future field work. Our results reveal a Vinaceous-breasted Parrot geographic range of 434,670 square kilometers, which is three times larger than the Extant area previously reported in the IUCN Red List. The exclusion of one data set at a time from the analyses always resulted in worse predictions by the models of truncated data than by the full model, which included all data sets. Likewise, exclusion of spatial autocorrelation, site covariates, or sampling effort resulted in worse predictions. The integration of different data sets into one joint-likelihood model produced a more reliable representation of the species range than any individual data set taken on its own improving the use of citizen science data in combination with planned survey results.
... Los efectos combinados de estos factores determinan el desarrollo de la Diagonal Árida (DA), una franja continua de clima árido que cruza el territorio en sentido SE-NO, desde el extremo SE de Sudamérica hasta c. del ecuador en la costa Pacífica (Villagrán 2018Abraham et al. 2000;Garleff et al. 1991). La DA actúa como barrera para la dispersión de la flora más higrófila a lo largo del corredor andino y se instituye así como el factor principal que determina el actual aislamiento de los bosques subtropical-templados de la costa Pacífica de Chile, uno de los rasgos más característicos de la biogeografía de Sudamérica (Hueck 1966). De acuerdo con los antecedentes paleobotánicos de Chile central, durante el óptimo climático del Mioceno Medio se produce la expansión de un bosque de carácter más moderno, consignados como "Paleoflora Subtropical Neógena". ...
Some biogeographical features of bryophytes associated with subtropical-temperate ecosystems in Chile are examined, including diversity, concentration of species richness, endemism, biogeographical composition and disjunctions. The historical-biogeographical interpretation of these characteristics considers the major evolutionary changes of the group in three different temporal scenarios, according to geological, paleobotanical and molecular evidences. First, simple- and complex-thalloids liverworts represented in Chile are examined, belonging to the Classes Haplomitriopsida and Marchantiopsida- Marchantiidae, archaic lineages linked to the pre-Cenozoic colonization of the Pangea mega-continent. Examples of simple-thalloids liverworts of Class Jungermanniopsida-Pelliidae, hornworts of the Class Anthocerotopsida and mosses of the Classes Bryopsida and Polytrichopsida illustrate the paleo-austral distribution patterns of bryophytes from the temperate region of Chile, related to the Gondwana breakup and expansion of Angiosperms during the Cretaceous/Paleogene. A second scenario, considers the final uplift of the Andes and the development of the Arid Diagonal of South America during the Neogene, processes that have played a major role in the biogeographical structure of the Chilean and South American floras. In this context, leafy liverworts associated with the relict forests of the Chilean semi- arid coast stand out, particularly epiphyllous liverworts of the two most diverse families of the Class Jungermanniopsida-Jungermanniidae, Lejeuneaceae and Plagiochilaceae, adapted to microclimates favored by coastal fogs. The last scenario discusses the significant role of the Pleistocene glacial cycles in the expansion of the sub-Antarctic temperate-cold element throughout central-southern Chile, and its effects on the concentration of bryophyte richness associated with Chile’s temperate-rain ecosystems.
... This study was carried out in the Highland Grasslands region, in the municipalities of Painel, Campo Belo do Sul and Abelardo Luz (in the state of Santa Catarina), and in the municipalities of Palmas and Tibagi (in the state of Paraná), between latitudes 24°and 30°S, 1.000-1.400 m above sea level (Hueck, 1966). This area was located in the region of the original distribution of the South Brazilian grasslands ( fig. 1). ...
Degradation and habitat loss of natural grasslands in Southern Brazil has a negative impact on native organisms, potentially including the composition of anuran helminth communities. Here, we characterized the richness, abundance, taxonomic composition, prevalence and intensity of helminth infection in four anuran species. Host anurans were collected in 34 ponds (19 in native grasslands with livestock and 15 in agricultural cultivation) from the highland grasslands in the Brazilian states of Santa Catarina and Paraná. Our results showed a significant difference between native grasslands with livestock and agricultural cultivation regarding the structure of helminth communities for the hosts Aplastodiscus perviridis and Pseudis cardosoi. We also found a greater prevalence and intensity of infection in anurans in areas of agricultural cultivation than in native grasslands with livestock. We found that the environmental descriptors (local and landscape) seem to explain most of the differences in anuran parasitism recorded between native grasslands with livestock and agricultural areas. Thus, we emphasized that the loss of grassy habitat due to conversion to agricultural cultivation can alter helminth communities in anurans, with further work needed to understand the mechanisms involved.
... We also tried buffer radiuses of 5 and 50 km in exploratory analyses, but elected to use a 17-km buffer because it corresponds to the longest single-day displacement recorded for radio-tagged VBPs (Prestes et al., 2014), and indeed resulted in the highest (positive) slope for the relationship between Araucaria cover and λ. Araucaria forest cover data resulted from the intersection of two maps: a map of the potential range of South American Araucaria Forest drawn by Hueck (1966) and georeferenced by Hasenack et al. (2017), and Ribeiro et al.'s (in prep.) map of existing Atlantic Forest remnants that are larger than 30-by-30 meters in area. ...
Population size is a key predictor of extinction risk and is critical to listing species in IUCN threat categories. Assessing population size can be particularly difficult for gregarious species, such as parrots—one of the most threatened bird families—whose ecology and behavior generate multiple sources of uncertainty that need to be addressed in monitoring efforts. To improve estimates of abundance for the endangered Vinaceous-breasted Parrot (Amazona vinacea), we combined extensive roost counts over the global range of the species (Argentina, Paraguay, Brazil) with an intensive regional survey designed to address five sources of uncertainty about parrot abundance in western Santa Catarina state (WSC), Brazil, in 2016 and 2017. We estimated abundance at both regional and whole-range scales using N-mixture models of replicated count data, which account for imperfect detection. The regional-scale estimate was 1826 ± 236 and 1896 ± 105 individuals for 2016 and 2017, respectively; global abundance was estimated at 7789 ± 655 and 8483 ± 693 individuals for the same two years. We found no statistical evidence of population change at either scale of the analysis. Although our assessments of abundance and geographic range are larger than those currently reported by the IUCN, we suggest the Vinaceous-breasted Parrot should remain in the ‘Endangered’ IUCN threat category pending further investigation of population trends. We recommend that roost-monitoring programs for parrots consider and address sources of uncertainty through adequate field protocols and statistical analyses, to better inform assessments of population size, trends, and threat status.
... The pollen diagram includes records of the most abundant pollen and spore taxa (Fig. 3), and records of the groups: campos de altitude (herbs), montane forest (trees and shrubs), tree ferns and ferns, and moss spores. The clustering of pollen taxa into the ecological groups of campos de altitude, montane forest as well as ecological characteristics is based on modern vegetation surveys in SE Brazil (e.g., Rizzini, 1954;Brade, 1956;Hueck, 1966;Lima and Guedes-Bruni, 1997;Safford, 1999cSafford, , 2001Safford and Martinelli, 2000). ...
We present a high-resolution pollen and charcoal record from the 350-cm Agulhas Negras (AN) sediment core from the Serra do Itatiaia, Itatiaia National Park, located at 2410 m altitude in Rio de Janeiro State, southeastern (SE) Brazil. Diverse campos de altitude (high elevation grassland) with small areas of montane forest and periodic fires dominated the landscape during the period of the last 7430 cal yr BP. Montane forest expanded after 4870 cal yr BP, reflecting a transition to wetter late Holocene climatic conditions. Araucaria angustifolia was rare in the Serra do Itatiaia and is evidenced only after 4200 cal yr BP. Fires may have markedly reduced montane forest cover between 4450 and 4000 cal yr BP. Continuous expansion of montane forest under moister conditions and the general absence of fire after 1960 cal yr BP was interrupted by a local fire event at about 530 cal yr BP. Increased fires may have limited montane forest expansion under the wet climatic conditions of the last 600 years. During this period Araucaria angustifolia became more frequent in the montane forest. Further paleoecological work is necessary to better document the natural and human-influenced relationships between climate, vegetation and fire in the high mountain vegetation of SE Brazil.
... Today, the northernmost limit for A. angustifolia (Bertol.) Kuntze is 18°S (Hueck, 1966). Several isolated pockets exist in valleys between 1300 and 2000 m a.s.l. and at the cloud forest-grassland ecotone with Araucaria in the mountain ranges between 23° and 18°S. ...
To improve our understanding of the Atlantic Forest responses to climate changes in space and time, it is essential to explore how the Brazilian Atlantic rain forest is structured as observed in modern pollen assemblages and which climate parameters determine these patterns. In this context, we compiled 196 modern pollen samples including 125 from the Atlantic Forest biome and assigned each sample to one or more eco-physiognomies. We identified seven eco-physiognomies of which four clusters of one or two eco-physiognomies were clearly distinguished, namely (1) Araucaria forest with high elevation grassland, (2) lowland rain forest, (3) semi-deciduous with riverine forests and (4) northeastern Atlantic rain forest. Climatically distinct, these clusters reflect a general temperature increase and precipitation increase from the first to the fourth cluster. Furthermore, comparison of the modern pollen dataset with the Côlonia pollen record from southeastern Brazil revealed that vegetation attributed to Araucaria forest with high elevation grassland showed an important variability with several shifts towards the lowland rain forest. As illustrated by comparison with the long fossil pollen record of Côlonia, developing such a modern training set is crucial for the understanding of responses of Atlantic Forest to environmental changes. However, additional samples are still necessary to improve characterization of different eco-physiognomies at a local scale following a defined floristic and climatic gradient. This sampling effort is becoming increasing urgent as a result of strong biodiversity loss and habitat destruction in this region.
... doi: bioRxiv preprint first posted online Oct. 29, 2018; the World 2016). The third is the potential range of South American A. angustifolia forests as mapped by Hueck (1966) and georeferenced by Hasenack et al. (2017). When using population size as listing criteria, the IUCN employs a number of reproductively mature individuals, rather than total population size. ...
Population size is a key predictor of extinction risk and is critical to listing species in IUCN threat categories. The population size of parrots, one of the most threatened bird families, is often assessed using roost counts, which suffer from multiple sources of uncertainty that need to be addressed in monitoring efforts. To improve estimates of abundance for endangered Vinaceous-breasted Parrot ( Amazona vinacea ), we compared extensive roost counts over the whole range of the species (Argentina, Paraguay, Brazil) with an intensive regional survey designed to address five sources of uncertainty about parrot abundance in western Santa Catarina state (WSC), Brazil, in 2016 and 2017. We estimated regional-scale abundance using a sampling design that minimizes double counting and an N-mixture model of replicated count data, which accounts for imperfect detection, implemented in a Bayesian framework. The whole-range counts amounted to 3,888 and 4,084 individuals in 2016 and 2017, respectively; regional estimates were 945 50 and 1,393 ± 40 individuals, for the same two years. We found no evidence of population growth because the increase in numbers matched an increase in observation effort on both spatial scales. When extrapolating the WSC abundance estimate to three hypothetical geographical range areas of the species, under the simplifying assumption of homogenous density, we obtained values above the whole-range counts, but within the same order of magnitude, putting the global population size of Vinaceous-breasted Parrot in the thousands of individuals. Although our estimates of abundance and geographic range are larger than those currently reported by the IUCN, we suggest that Vinaceous-breasted Parrot remain in the Endangered IUCN threat category pending further investigation of population trends. We recommend that roost-monitoring programs for parrots consider and address sources of uncertainty through field protocols and statistical analysis, to better inform assessments of population size, trends, and threat status.
... In addition, prevalence of evergreen laurel-and Magnolia-like leaves and tropical flower types, lush growth of epiphytes and lianes, and occurrence of large buttress-roots give this forest a habitus similar to tropical rainforests. Therefore, the Valdivian rainforest is considered a tropical rainforest in a non-tropical climate originating as a Tertiary relic from the supercontinent Gondwana (Hueck, 1966;Seibert, 1996). Due to the diverse flora with a high degree of endemicity, the Valdivian rainforest constitutes one of the global hotspots associated with severe dieback of Valdivian rainforest trees, in particular D. winteri, Luma apiculata, Nothofagus dombeyi and the endangered Saxegothaea conspicua. ...
... Junk (1983) stated that the decomposition of organic material would be expected to proceed much more rapidly than the high production rate of aquatic and semiaquatic macrophytes. Hueck (1966) referred to the importance of high temperature in decomposition in the region. Junk (1983) referred to the structures of the cell wall of aquatic and semi-aquatic macrophytes in relation to rapid decomposition. ...
A summary of the peat formation process, and the classification and characterization of the peatlands in Southeast Asia, particularly those in Kalimantan in Indonesia was undertaken through a review of published studies. Based upon the location, mode of formation, and age of the peat deposits, ombrotrophic and eutrophic peatlands, or topogenous and ombrogenous peatlands are developed by the accumulation of plant debris in coastal and sub-coastal areas, inland areas and high altitude areas. In the areas along the coastline, the youngest peat formation started to occur between 3500 and 6000 years BP in response to the wet conditions generated by rising sea levels at the end of the last glacial period. In comparison, peat in inland peatland areas began to form much earlier, more than 20,000 years BP during the late Pleistocene era. Some tropical peatlands are likely to have been involved in the global carbon cycle before the initiation of boreal and temperate peatlands. One of the characteristics of the peatlands in Southeast Asia is the formation of a convex-shaped dome that formed beyond the extent of river floodwater and under rain-dependent conditions. This is known as ombrogenous peat.
... This location is about 130 km to the south of the southernmost occurrence of Araucaria forest in the southern Brazilian highlands (Fig. 1). According to the survey on the distribution of Araucaria angustifolia in Brazil by Hueck (1953Hueck ( , 1966, there is no evidence of the natural distribution of this tree in the lowlands of Rio Grande do Sul. It is therefore possible that this occurrence is due to post-Columbian settlers, which would have planted these trees on their lowland farms for wood as well as for the nutrient supply provided by the seeds (Cordenunsi et al. 2004;Bello-Perez et al. 2006). ...
Little is known about the southernmost occurrence of small areas with Araucaria angustifolia populations in Caçapava do Sul in low elevated areas of Rio Grande do Sul State, about 130 km to the south of to the highlands of southern Brazil where the main distribution of Araucaria is found. This occurrence is about 130 km further south to the main area of Araucaria angustifolia which is on the highlands in southern Brazil. The question is whether this occurrence is natural, due to indigenous peoples, or due to plantation by post-Columbian settlers. To trace the origin of this little known southernmost existence of Araucaria angustifolia trees is of particular interest for conservation issues. To address this question we did a vegetation survey and studied a 150 cm-long radiocarbon dated sediment core from the Fazenda da Mônica by pollen analysis. The vegetation survey of the study area indicates that also other typical taxa of the Araucaria forest as well as the Atlantic lowland rainforest are found in the present-day semi-deciduous forest, such as Podocarpus, Ilex, Myrsine and Prunus for the former, and Alchornea, Moraceae, Arecaceae, and Myrtaceae for the later. The pollen record, due to bad pollen preservation, starts only after 44 cm core depth, which is about 515 cal yr BP old (AD 1490), indicating that Araucaria angustifolia as well as other Araucaria forest and Atlantic rainforest taxa occurred in this area since the beginning of the pollen record. The occurrence of these taxa can be seen as natural and not introduced during the post-Columbian colonisation. First settlers at the beginning of the 19th century reduced existing population of Araucaria markedly and in particular since about AD 1950. The population of Araucaria angustilfolia before the post-Columbian settlement was much larger than today.
... It is the southernmost, hence marginal, outlier of the East African Tropical Coastal Forest , 1998, Burgess & Clarke 2000)-a member of the global Tropical and Subtropical Moist Forest Biome. As such it can be classified as the 'Subtropical Coastal Forest Biome'-an interesting geographical analogue of the 'Mata Atlântica', the subtropical coastal forest of the Atlantic seaboards of eastern Brazil (Hueck 1966), experiencing a fate very similar to the IOCB (Por 1992). The IOCB lost its natural 'forest face' due ...
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.
Amazon caatinga is frequent in the upper Río Negro basin on sandy soils with low nutrient status, low water holding capacity, and recurrent flooding during heavy rainy days. Climate is very humid with mean monthly rainfall near or above 100 mm and average temperature above 25 °C. Rainfall seasonality is expressed by the number of dry days per month (15–20 days during the dry season to about eight days during the rainy season). Vegetation is dominated by sclerophyllous species, tolerant to pulses of short-term hypoxia during flooding, and water stress after spells of dry days. Nutrient-poor soils, high rainfall, and sandy textures lead frequently to podzolization. Dominant vegetation has high leaf mass/area ratios (>150 g m−2), low concentration of N (<10 mg g−1) and P (< 0.7 mg g-1), and molar N/P ratios <18. Leaves show strongly negative δ15N values despite consistently positive soil values. These values are associated with the widespread occurrence of mycorrhizal symbiosis and the extreme N deficiency in white-sand soils. Caatinga sclerophylls are highly sensitive to air humidity. Stomates close progressively during rainless days shortly before noon and do not recover in the afternoon. Amazon caatinga species have relatively long leaf lifespans (>1 year), and low maximum rates of photosynthesis, Amax averaging 5–8 μmol m−2 s−1. Endomycorrhizal species are common in all caatinga sites, while ectomycorrhizal species are restricted to a relatively small number of genera, belonging mostly to Fabaceae, Nyctaginaceae, and Polygonaceae.KeywordsWhite sand vegetationPodzolsNutrient limitationSclerophyllyStable isotopes
Tropical zonobiome II, characterized by a 12-month thermal growing season, is frost-free like ZB I in the lowlands, but already exhibits a noticeable annual variation in temperature. Heavy cenital rains fall during the warm, mostly perhumid season, and the cooler season is arid. The hygric climate of ZB II is characterized by a pronounced hygric seasonality with a rainy and a dry season, whereby the length of the hygric growing season, i.e. the number of humid and arid months, determines the hygric character of the respective savannah landscape from semihumid, semiarid to arid. Thus, rainfed moist forests, dry forests, moist and dry savannahs to thorn savannahs can be distinguished.
An interim hierarchical classification (i.e. biogeographical regionalisation or area taxonomy) of the world’s terrestrial regions is provided, following the work of Morrone published in Australian Systematic Botany in 2015. Area names are listed according to the International Code of Area Nomenclature so as to synonymise redundant names. The interim global terrestrial regionalisation to the subregion level recognises 3 kingdoms, 2 subkingdoms, 8 regions, 21 subregions and 5 transition zones. No new names are proposed for the regions; however, Lydekker’s Line is renamed Illiger’s Line. We note that some regions still require area classification at the subregion level, particularly the Palearctic, Ethiopian and Oriental regions. Henceforth, the following interim global regionalisation may be used as a template for further revisions and additions of new areas in the future.
Evolutionary biogeography identifies areas of endemism and establishes their relationships with other areas, providing the information required to develop a hierarchical system of natural regionalization. The closely related geological and biological evolution of the planet is manifested in the existence of endemic biotas, as result of geographical and ecological barriers. The current challenge of evolutionary biogeography is to document the existence of biotas representing the evolutionary structure of ecosystems and their functionality, that could contribute to the establishment of conservation priorities. In this contribution, the fundamental characteristics of the biogeographic units of Argentina are described, and the respective maps are provided, as a general reference system for ecological, evolutionary and biogeographic studies, and in education and decision-making regarding conservation and sustainable use. For each biogeographic unit, we present its valid name and synonyms, its geographic location, distinctive characteristics, dominant landscape and vegetation types and its endemic species. Also, the typical landscapes and some endemic or characteristic species of each biogeographical unit are illustrated. Their biotic relationships, geobiotic evolution and regionalization to the district category are also discussed. In the scheme presented herein 16 provinces are recognized in the country, which in turn are grouped in the Neotropical region (Yungas, Parana, Araucaria Forest, Esteros del Iberá, Chaco and Pampean provinces), South American Transition Zone (Puna, Cuyan High Andean, Monte and Comechingones provinces) and Andean region (Patagonian, Maule, Valdivian Forest, Magellanic Forest, Falkland (Malvinas) Islands and Magellanic Moorland provinces). The Yungas province has three districts: Transition Forests, Montane Jungles, and Montane Forests. The Parana province includes the Campos and Mixed Forests districts. The Esteros del Iberá province stat. nov. includes three districts: Delta of Paraná stat. rev., Uruguay River stat. nov. and Paraná Flooded Savannas stat. nov. The Chaco province includes the Eastern Chacoan, Montane Chacoan stat. rev. and Western Chacoan districts. In the Pampean province five districts are recognized: Austral Pampean, Eastern Pampean, Espinal, Western Pampean and Uruguayan. In the Argentinean part of the Puna province the Jujuyan district is recognized. In the Cuyan High Andean province three districts are identified: Diaguita nom. nov., Cuyan ubic. nov. and Huarpe nom. nov. The Monte province includes four districts: Prepuna, Northern, Eremean and Southern. In the Patagonian province we recognize five subprovinces: Central Patagonian (Chubut and Santa Cruz districts), Fuegian, Payunia (Northern and Southern Payunia districts), Subandean (Meridional Subandean Patagonia, Austral High Andean, and Septentrional Subandean Patagonia districts) and Western Patagonian. In the Argentinean sector of the Maule province is present the Pehuén district. The Valdivian Forest province is represented by the Valdivian district. The Falkland (Malvinas) Islands province has two districts: Falkland Islands and South Georgia Islands.
Paraná pine has a marginal distribution in Argentina; however, it is the native species most planted in the country. Its uses, cultural meaning, and current conservation status are summarized in this chapter, together with a brief history of its use in productive plantations. The reproductive biology of the species has a deep effect on the conservation and use of its genetic resources. Therefore, limitations for the pollination and seed formation are detailed together with information on pollen dispersion and variation of productivity through time and its relationship with climatic variables and seed production. Genetic variability of natural populations was studied by means of AFLP genetic markers. The breeding and conservation strategies for the species are delineated, also describing the outstanding case of a multi-provenance plantation over 70 years old. Provenance tests are revised together with their conclusions on genetic variation in quantitative traits. Base, selected, breeding, and propagation populations for an incipient improvement program in Argentina are defined. Grafts of selected individuals were used to install clonal seed orchards, alongside corresponding progeny tests. Final concerns and actions for conservation are discussed.
The cool-temperate (nemoral) zone is currently the most densely populated zone on Earth; its vegetation has therefore been altered considerably over the past centuries. Particularly in Europe and East Asia, anthropogenic land use (forest plantations, agricultural and settlement areas, including many neobiota) has replaced the summergreen broad-leaved forest, which mostly constitutes the natural zonal vegetation. Furthermore, under extremely oceanic conditions, there are evergreen laurel and Nothofagus forests on the western side of the Andes and the Southern Alps of New Zealand, and tall nemoral coniferous forests on the Pacific side of North America. A distinctive feature of the summergreen broad-leaved forests is the seasonal rhythm of the vegetation of the tree and field layers, from leaf development in spring to leaf shedding in fall, with abundant geophytes in spring.
Of all coastal ecosystems, mangroves are in particular need of conservation and restoration because of their widespread degradation and regional extinction. Mangroves are significant habitats for highly specialized species, and they offer numerous ecosystem services, among others coastal protection. They colonize flat coasts and estuaries, and are subject to the tides. Thus, mangrove trees must be able to cope with the change between high and low tide, high salinity, oxygen deficiency in the soil, and unstable substrates. Their life cycles and physiological characteristics are therefore discussed in detail. Freshwater wetlands include tropical floodplains, which have pronounced flooding dynamics, as seen in the example of the white and black water rivers in the Amazon lowlands, as well as swamplands such as the Pantanal in Brazil and the Okavango Delta in Botswana. Of the tropical mires, forest peatlands are of particular global importance as carbon sinks.
The zonal vegetation of the subtropics with year-round rain (“wet subtropics”) consists of evergreen and semi-evergreen laurophyllous forests. Because they are located on the eastern sides of the continents, these forests receive rainfall throughout the year; towards the interior of the continents, maximum rainfall shifts into summer. Particularly in the Southern Hemisphere, these forests often include archaic conifers of the genera Araucaria and Podocarpus. It is remarkable that grassland occurs extensively, particularly in South America (campo, pampa), but also in South Africa, despite the consistently humid climate that would allow forest to occur. This grassland is considered to be a relic of postglacial dry periods; it is maintained by fire and grazing.
The introductory chapter provides the basic knowledge needed in order to understand the conditions under which the present zonal, azonal and anthropogenic vegetation on Earth has developed. This includes, among other things, an introduction to the evolution of vascular plants, their geographical distribution on the continents (“phytoregions”) and the main features of phytodiversity. In addition, the components of the macroclimate that are decisive for zonal vegetation types, their graphic representation (“climate diagrams”), the terminology and ecological properties of zonal and azonal soils, and the ecozones fundamental to the book are explained. A considerable part of the chapter is devoted to the derivation and definition of the plant formations of the world on the basis of physiognomic plant functional types (pPFTs). Finally, the principles according to which the vegetation of the high mountains of the Earth is subdivided as well as the properties of azonal and anthropogenic vegetation are presented. The boxes accompanying the text contain additional information on various topics, e.g. the origin of grasslands, phylogenetic evolution and quantum evolution, the origin and geographical distribution of the genus Nothofagus, and leaf functional traits and their ecological significance.
The zonal vegetation of the dry midlatitudes consists of natural grasslands, the steppes of Eastern Europe and Russia, and the prairie in central North America. The reason for the absence of trees is the combination of seasonal aridity (usually during summer), very low temperatures in winter, and fine-grained soils with a low skeletal content. The vegetation is characterized by grasses with deep root systems rich in fine roots, herbs with striking flowers and, particularly in areas with aridity in early summer, by geophytes. In nemoral winter rainfall areas, dry woodlands occur. In the center of the dry midlatitudes, where annual precipitation is very low, there are deserts (such as the Gobi in Central Asia) as well as extensive semi-deserts in which the vegetation is characterized by salt-tolerant dwarf shrubs.
This chapter describes the vegetation of the largest ecozone on Earth, which covers 21% of the entire land surface. It includes xerophytic dry forests and shrublands as well as succulent, dwarf shrub, halophyte and grass semi-deserts; furthermore, hot deserts with a plant cover only in ephemeral riverbeds and in areas with fog precipitation are discussed in this chapter. The diversity of the vegetation is attributable to the temporal variability of precipitation, which is characteristic of the transitional area between the tropics and subtropics. Both individually and in combination, the flora exhibits a wealth of strategies to ensure survival under hot and dry site conditions; these are reflected in the growth and life-forms of the species, i.e. stem and leaf succulents, phreatophytes, xerophytes, halophytes, ephemerals, fog-harvesting plants, and others.
Das durch 12 Monate lange thermische Vegetationszeit gekennzeichnete tropische Zonobiom II ist wie ZB I im Tiefland frostfrei, aber weist bereits einen merklichen Jahresgang der Temperatur auf. In der warmen, meist perhumiden Jahreszeit fallen starke zenitale Regen, die kühlere Jahreszeit ist arid. Das hygrische Klima des ZB II ist durch eine ausgeprägte hygrische Saisonalität mit einer Regen- und einer Trockenzeit gekennzeichnet, wobei die Länge der hygrischen Vegetationszeit, d.h. die Anzahl der humiden und ariden Monate über den hygrischen Charakter der jeweiligen Savannenlandschaft entscheidet. Demgemäß kann man das ZB II in semihumide (7-9 humide Monate) regengrüne Feuchtwälder und Feuchtsavannen, semiaride (4-6 humide Monate) regengrüne Trockenwälder und Trockensavannen und aride (1-3 humide Monate) regengrüne Dornwälder und Dornsavannen unterteilen (► Abb. D-52).
Neotropical Biogeography: Regionalization and Evolution presents the most comprehensive single-source treatment of the Neotropical region derived from evolutionary biogeographic studies. The book provides a biogeographic regionalization based on distributional patterns of plant and animal taxa, discusses biotic relationships drawn from track and cladistic biogeographic analyses, and identifies cenocrons (subsets of taxa within biotas identified by their common origin and evolutionary history). It includes maps, area cladograms and vegetation profiles. The aim of this reference is to provide a biogeographic regionalization that can be used by graduate students, researchers and other professionals concerned with understanding and describing distributional patterns of plants and animals in the Neotropical region. It covers the 53 biogeographic provinces of the Neotropical region that are classified into the Antillean, Brazilian and Chacoan subregions, and the Mexican and South American transition zones.
Key message
Genetic variability of Araucaria angustifolia populations in Argentina was moderate-to-low and reduced by logging. Some studied populations and the plantation are valuable gene pools for conservation and management.
Abstract
The main forces shaping genetic variability of woody species in fragmented forest are the geographical distribution and demographic history of populations. We conducted molecular analyses to evaluate how these factors have affected Araucaria angustifolia genetic variability in the Argentinean Parana Forest and to identify valuable gene pools for conservation and management purposes. Using 706 polymorphic AFLP (Amplified Fragment Length Polymorphism) markers, we analyzed nine native populations with different logging history and one plantation (312 individuals) of an uncertain origin. Average genetic diversity for the native populations was moderate-to-low (He = 0.128) in accordance with their marginal location within Araucaria’s range. In general, genetic diversity of populations decreases from east to west with increasing distances from the main area of species distribution on southern Brazil. Logging may have been responsible for further reduction of genetic variability in the more intensely exploited populations of the southern region and in some private fields. The moderate genetic differentiation among populations (ΦPT = 0.080) suggests an increase in the genetic structure of remnant populations because of fragmentation. UPGMA and Bayesian analyses agreed with the geographic location of populations. Populations from the southern Provincial Parks at Araucaria’s range edges grouped and differed genetically more from other populations. The highest genetic diversity of the plantation (He = 0.155) suggests that its individuals could have originated from seeds collected from different and/or highly variable sources of Brazil and the northeast of Argentina.
Why are some dry plant formations rich in tree- or shrub-succulents and others not, in spite of similar amounts of rainfall and similar numbers of arid months per year? This question is discussed in detail in the German text, mainly concentrating on Cactaceae in America and succulent Euphorbiaceae in Africa (Fig. 1 and 2). In the main it may be answered as follows.
Der Flaschenbaum, Ceiba chodatii, ist ein mittelgroßer Baum, der in Paraguay, in den nördlichen Teilen von Argentinien und in einigen angrenzenden Ländern vorkommt. Er fällt durch seinen angeschwollenen Stamm und den oftmals auftretenden Schrägstand auf.
Secondary forests are an increasingly important component in the neotropical landscape matrix. As deforestation rates in many Latin American countries continue to be high, secondary forest resources may contribute to timber supply. Using a process-based forest growth model, we studied the prospect of secondary forests in eastern Paraguay for sustainable timber harvesting under different logging and fragmentation scenarios. The timber yield is low under all scenarios (0.75–1.73 m3 ha−1 year−1). Only silvicultural treatments may increase the commercial value of secondary forests. For large landholdings, labour-and capital-extensive land-use systems such as secondary forest management may be an option to diversify farm income. This particularly holds for Paraguay facing an increasing scarcity of timber resources.
Central Chile extends under a mediterranean type of climatic influence between the 30th and 38th grades of southern latitude. Due to a great concentration of population and the agricultural activity this part of the national territory practically is lacking in natural vegetation in the interiors valleys and coastal sectors of the precordillera.
Therefore, a descriptive analisis of the vegetation is more realistic if we do it in the Andes and in the coast ranges, following the criteria of altitudinal zonalization.
The northern sector of the region shows in its vegetation levels a certain similarity in its composition and physionomy with the natural formations of lowlands and plain regions which belong basically to latitudinal grouping typical of the region.
However, south of the 33 latitude, this similarity begins to disappear mainly due to high humidity registered in the mountains. The sclerophytal woods are replaced by mixted formations where the predominant species are the Fagaceae, Lauraceae and conifer.
Between the 37 and 38 grades of southern latitude, in both mountains ranges an almost pure formation of Araucaria araucana woods, an endemic conifer of South America is developed. In the coastal range, this formation reachs its optimun ecology between 800 and 1300 meters aproximately while in the Andes this one is achieved only at 1.600 meters of altitude.
The altitudinal descent of both ranges is almost parallely with the latitudinal development to the south and this is one of the reasons why some trees have a wide distribution in some attitudinal levels. (Nothofagus obliqua, Nothofagus alpina, Nothofagus dombeyi).
It is worth noting that at present, the anthropologycal action and the reforestation with foreign species are seriously affecting the preservation of the natural woods on this mountain ranges.
With this theme we enter into one of the most controversial recent debates between ecologists, nature conservationists and biologists on the one hand and the representatives of big business, timber industrialists and investment groups on the other. Without offering any solution for the dramatic situation in forest destruction, we can only quote from an FAO report which speaks clearly: each year 7,500,000 ha of closed tropical forest and 3,800,000 ha of open woods are being destroyed. If this continues at its present rate, in a mere 20 years all will be over. For the year 1995 the world consumption of wood is forecast at 2,300,000 m3 of industrially used trees. This is a 75% increase of the present demand (Catinto 1972, UNESCO/FAO Report no. 14,1978, Neil 1981, Bruenig 1972).
The natural distribution of “pinheiro do Paraná” (Araucaria angustifolia) is restricted to the southern hemisphere, occurring mainly in Brazil, small areas in Argentina as well as Paraguay. The continuous distribution in Brazil is situated almost exclusively in the three southernmost Brazilian states: Paraná (PR), Santa Catarina (SC) and Rio Grande do Sul (RS). There are small populations in the northernmost part of the range where the forests can be found between 1200 and 1800 m above sea level. It is a species of economic importance for the southern region of Brazil, and for many years it has played an important role in generating export revenues. Due to exploitation, the primary forests were drastically reduced to less than 0.66 % of the original area. If the present rate of exploitation is maintained, the last remnants of the valuable primary forests containing A. angustifolia will soon disappear. Therefore, studies are necessary to elucidate the genetic basis of the remaining populations aiming at their genetic conservation. Seed from 130 trees from populations representing 3 geographic locations (Campos do Jordão — SP, Irati — PR and Caçador — SC) were analyzed using 8 enzyme gene loci (GOT—A, GOT—B, GOT—C, PGM—A, SKDH—A, SKDH—B, MDH—B and 6-PGDH—B) to determine patterns of genetic structure and variation. Populations were polymorphic at 49 % of the loci. They had an average of 1.58 alleles per locus and 2.10 alleles per polymorphic locus. Mean expected heterozygosity (H
e
) was 0.142, and mean observed heterozygosity (H
a
) was 0.141. The northern population was much more variable than the southern populations as measured by several parameters. The northern population was also strongly differentiated from the southern populations, which differed little from each other. A provisional evaluation of part of the data revealed a relationship between geographic distance among populations and their genetic distance.
In south and southeast Brazil land use caused profound changes in natural vegetation and consequently the value of the pollen composition in surface samples as modern analogues. In order to test the capability of modern pollen to represent the natural vegetation, three different time slices of pollen assemblages from 27 sites spread over southern and south-eastern Brazil and the Misiones Province in Argentina were collated. Pollen samples from the pre-colonization period, selected from the moment just before abrupt changes evidenced on pollen diagrams caused by the colonization process throughout the last 500 years, were assumed to represent the natural vegetation conditions once the climate remained stable within this period. Thus we used pre-colonization assemblages to compare with modern samples to explore to what extent surface pollen may be biased in representing the natural vegetation types. Furthermore, to compare man made vegetation change to climate driven vegetation change we also compared to these 20 out of 27 samples dated to 3,000 years bp. Guided by ordination and cluster analysis, but using abundance thresholds of indicator taxa we classified the pollen spectra of pre-colonization time into seven groups consistent with the main vegetation types in the area. Ordination analyses capture the differentiation between grassland and forested vegetation and between tropical and subtropical vegetation types. Comparing the pre-colonization with other time slices we observed that based on Poaceae abundance, 70 and 85 % respectively of sites from 3,000 bp and modern assemblages maintained their classification. Based on finer classification criteria these values decreased to 40 and 52 % respectively. Square chord dissimilarity indicates that colonization impact altered the pollen composition as strongly as 3,000 years of climate induced vegetation change. The surface samples still represent important environmental gradients; however, their use as modern analogue requires careful treatment and eventual exclusion of highly impacted sites.
The purpose of this paper is to review Latin American forest resources, to find out the underlying causes of deforestation in the tropical zone of this continent and to analyze the prospects for deforestation and sustainable forest management. In the forest resources description, Latin America is clustered in three regions, but frequently Brazil is analyzed as a separate entity due to its vast extension and prominent position in the continent. The natural forests of Latin America covered an area of approximately 960 million hectares in 1990. This vast area represents the largest closed broadleaved forest reserve of the world. The characteristics and approximate location of five major types of forests are presented. In 1981–1990 the annual average tropical deforestation area in the continent was 7.7 million hectares, the largest in the developing world. Eight models for explaining deforestation were estimated. Evidences were found for determining that growing population pressure is increasing deforestation. In addition, increasing incomes, deforestation costs and deforestation risks lead to decreasing deforestation. We made three simple scenario models. According to these scenarios a reduction of 21–28% of the total forest area of 1990 could be expected until the year 2020.
This study of the leaf-venation of some tropical plant-families was initiated by Prof. Dr Ingrid Roth. In her book “Stratification of Tropical Forests as seen in Leaf Structure”, Roth investigated nearly 50 anatomical leaf characteristics in 230 species; the venation patterns, however, were not included. Roth gave approximate estimates of vein density as well as measurements of vein spacing taken from leaf-transsections. These observations have paved the way for a further examination of the same material with regard to the venation patterns and to the exact vein density, the more so since Pykköö (1979) in her investigations on the same material had already given new impetus to this field of study.
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