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Modeling Landscapes and Past Vegetation Patterns of New Mexico's Rio Del Oso Valley.
Abstract
Humans have interacted with the landscape and ecosystem of New Mexico's Rio del Oso Valley for thousands of years. Throughout the Holocene, various cultures have dramatically affected and altered the Rio del Oso. An interdisciplinary research approach, incorporating geomorphology, paleobotany, archaeology, and history, provides a broad range of methodologies and data sets of past landscape dynamics. Integrating such data sets in three-dimensional Geographical Information Systems (GIS) models of past vegetation and landscape conditions may enable a view of anthropogenic ecosystem change. Analyses of past land use through landscape models, geoarchaeology, and other methods can provide a greater understanding for current and future ecosystem management.
... This scenario would have been intensified through aridification trends and been associated with periods of greater rainfall or thunderstorm frequency and intensity, leading to associated periods of channel incision. In looking for possible climatic connections to floodplain dynamics, there are other well-dated alluvial sequences from the Southwest for comparison, particularly from Chaco Canyon and the McElmo Canyon drainages in the Four Corners area (Force, 2004) and from the Rio del Oso, New Mexico (Periman, 2005). In the Rio del Oso study, the Archaic period (ca. ...
... In the Rio del Oso study, the Archaic period (ca. 5500 B.C.–A.D. 600) landscape was comparable to that of the Rio Puerco, consisting of sparse juniper and grassland with oak and pine at higher elevations, associated with common fires and alluvial sedimentation interrupted by seven phases of cumulic soil development (Periman, 2005 ). Sandy alluvial sedimentation in the floodplain nearly doubled during the Puebloan occupation of the valley, and more than doubled subsequently, between A.D. 1400 and 1765 (Periman, 2005). ...
... 5500 B.C.–A.D. 600) landscape was comparable to that of the Rio Puerco, consisting of sparse juniper and grassland with oak and pine at higher elevations, associated with common fires and alluvial sedimentation interrupted by seven phases of cumulic soil development (Periman, 2005 ). Sandy alluvial sedimentation in the floodplain nearly doubled during the Puebloan occupation of the valley, and more than doubled subsequently, between A.D. 1400 and 1765 (Periman, 2005). In Force's (2004) study of the Chaco Wash and the McElmo Canyon drainages, archaeological and ceramic records were examined to determine temporal and spatial patterns of erosion and alluviation. ...
We describe a geoarchaeological survey of a 5-km reach of the Rio Puerco channel and its tributaries, centered on the Guadalupe Ruin, a pueblo of the late 10th–12th centuries A.D. in north-central New Mexico, with associated pollen, charcoal, micromorphological, and radiocarbon analyses. Severe erosion has drastically bisected the Puerco valley with four primary arroyos entering the western side of the Guadalupe reach of the valley: Tapia, Salado, Guadalupe and “No Name.” We recorded an 11-m-tall alluvial sequence marked by four phases of cumulic soil development, interrupted by six major periods of channel entrenchment that occurred at about 4100–3700 B.C. and 2900–2400 B.C., between 2200 B.C. and ca. A.D. 400, pre- and post-ca. A.D. 900–1300, and in the late A.D. 1800s. Relative floodplain stability and associated cumulic soil development occurred prior to ca. 5700 B.C., between ca. 2600 to 2200 B.C. and A.D. 350 and 550, and ca. A.D. 900–1300. Multiple signatures of fires (oxidized sediment and charcoal) were observed in the Arroyo Tapia tributary sequence, especially in deposits dated ca. 6000 and 2600 B.C. These fires may have helped to enhance food resources for game animals by encouraging grass and shrub growth and/or to increase the growth of wild plants and eventually cultigens such as maize. Palynological evidence of maize in the Arroyo Tapia, dated ca. 2600–2200 B.C. may be the earliest thus far identified in the Southwest. © 2009 Wiley Periodicals, Inc.
... Archaeologists have employed GIS to the greatest extent in studies at the regional scale, where researchers are using large datasets of archaeological and environmental variables for predictive modeling or other analyses (for example, Allen et. al. 1990;Hill 2000;Kvamme 1989;Periman 2005;Spikins 2000). A second major use of GIS within archaeology is in the practice of cultural resource management. ...
Archaeological collections are valuable, often irreplaceable scientific resources important in many ways to researchers, the institutions that hold them, and the public they serve. Many older collections are very large, complex, and unique. Unfortunately, the full potential of these cultural resources are often not realized, and thereby their value diminished. Research on these collections is hampered by traditional object-based collections management practices that are insufficient for maintaining the integral spatial component of archaeology collections in an accessible framework. Likewise, by maintaining our standard object-based curation methods, we risk rendering our most important new collections inaccessible for future work. Innovative use of Geographic Information Systems (GIS) in collection management offers an effective framework for re-establishing and maintaining critical spatial relationships, while providing a tool for traditional collections management purposes. A recent pilot study using GIS to rehabilitate the Marquette Mission site collection and conduct preliminary collections-based research is presented.
... For more ancient time periods, the data related to the historical landscape morphology are unavailable; the difference between historical and modern morphology can be significant and in most cases it is not possible to use a modern DTM without considering the changes of the terrain. For this purpose, it is possible to use geomorphological, stratigraphic, geoarchaeological, and geobotanical data, which provide us with information about the changes in the landscape during long time periods (Arnaud-Fassetta et al., 2010;Lieskovský, 2011;Periman, 2005). ...
When combining spatial data from various sources, it is often important to determine similarity or identity of spatial objects. Besides the differences in geometry, representations of spatial objects are inevitably more or less uncertain. Fuzzy set theory can be used to address both modelling of the spatial objects uncertainty and determining the identity, similarity, and inclusion of two sets as fuzzy identity, fuzzy similarity, and fuzzy inclusion. In this paper, we propose to use fuzzy measures to determine the similarity or identity of two uncertain spatial object representations in geographic information systems. Labelling the spatial objects by the degree of their similarity or inclusion measure makes the process of their identification more efficient. It reduces the need for a manual control. This leads to a more simple process of spatial datasets update from external data sources. We use this approach to get an accurate and correct representation of historical streams, which is derived from contemporary digital elevation model, i.e. we identify the segments that are similar to the streams depicted on historical maps.
... Furthermore, whilst palynological evidence is often used to draw inferences about the influence of anthropogenic factors on vegetation during the Holocene, the vast majority of such studies have focused upon Europe (e.g. Mudie et al. 2007; Rubiales et al. 2007; Gonzalez-Samperiz et al. 2008) or the Americas (e.g. Brown and Hebda 2003; Periman 2005; Niemann and Behling 2008). A few studies have ventured further afield into Africa (Brncic et al. 2007), the Near East (Neumann et al. 2007), Southeast Asia (Dam et al. 2001; Maxwell 2004) and the Loess Plateau of China (He et al. 2002), but little such work has yet been undertaken in Southwest China. ...
... GIS have permeated all aspects of archaeology, revolutionizing research by permitting easy access to vast quantities of information, new techniques of data visualization that promote insight through pattern recognition, and unique methodologies that permit new approaches to the study of the past (Kvamme 1999). Recent GIS research has been directed towards an array of archaeological approaches such as modeling population settlement patterns (Anderson and Gillam 2000), determining ancient land uses (Hill 2004), reconstructing paleoenvironmental conditions (Spinkins 2000;Periman 2005;Fyfe 2006), illustrating stratigraphic and site contents (Spinkins et al. 2002;Nigro et al. 2003), and examining landscape settings of site locations (Bevan and Conolly 2002;Bauer et al. 2004;Fry et al. 2004). ...
... Furthermore, whilst palynological evidence is often used to draw inferences about the influence of anthropogenic factors on vegetation during the Holocene, the vast majority of such studies have focused upon Europe (e.g. Mudie et al. 2007;Rubiales et al. 2007;Gonzalez-Samperiz et al. 2008) or the Americas (e.g. Brown and Hebda 2003;Periman 2005;Niemann and Behling 2008). A few studies have ventured further afield into Africa (Brncic et al. 2007), the Near East (Neumann et al. 2007), Southeast Asia (Dam et al. 2001;Maxwell 2004) and the Loess Plateau of China (He et al. 2002), but little such work has yet been undertaken in Southwest China. ...
This paper uses pollen analysis to investigate and document the changing climate
and vegetation during the Holocene based on a 400 cm core in depth obtained at a wetland site at Haligu (3,277 m a. s. l.) on the Jade Dragon Snow Mountain in Yunnan, China. By applying the Coexistence Approach to pollen data from this core, a quantitative reconstruction of climate over the last 9,300 years was made based on each pollen zone and individual core sample, which reveals the temperature and precipitation change frequently during that time. The qualitative analyses show that from 9300 to 8700 cal. yr BP, the vegetation was dominated by needle-leaved forest (mainly Pinus and Abies), indicating a slightly cool and moderately humid climate. Between 8700 and 7000 cal. yr BP, evergreen broad-leaved forest, dominated by Quercus, became the predominant vegetation type, replacing needleleaved
forest at this elevation, implying a warmer and more humid climate. During the
period 7000 to 4000 cal. yr BP, the vegetation changed to mixed needle-leaved and
evergreen broad-leaved forest, indicating a warm and moderately humid climate, but
somewhat cooler than the preceding stage. From 4000 to 2400 cal. yr BP, the vegetation
was again dominated by evergreen broad-leaved forest, but coniferous trees (mainly Pinus)began to increase, especially relative to a decline in Quercus. This implies that the
climate remained warm and humid but slight drier than previously. The evergreen
Quercus phase (8700–2400 yr BP) was designated as the Holocene climatic optimum
in the Haligu core sediments. It is correlated with a markedly greater abundance and
diversity of pteridophytes spores than was recorded before or after this period. From
2400 cal. yr BP to present, the vegetation was dominated by needle-leaved forest, of
which Pinus formed the predominant component, accompanied by Abies and Tsuga.
This reflects a slightly cooler, humid climate but also correlates with a period of
increasing human settlement on the lower slopes of the mountain. At this elevated
site, several hundred metres above the highest present day settlements, direct palynological evidence of anthropogenic activity is uncertain but we discuss ways in which
the marked decline in Quercus pollen during this period may reflect the impact of
ways in which natural resources of the mountain have been utilised.
Este artigo tem como objetivo fornecer análises preliminares e sugerir a elaboração de um modelo preditivo para a arqueologia no extremo sul do estado do Piauí, levando em consideração as características geoambientais da região e um sítio paleontológico e arqueológico no município de Corrente, Piauí. A área de estudo apresenta arenito silicificado e abundantes artefatos líticos, produzidos essencialmente a partir dessa matéria-prima, além de restos fósseis de Eremotherium laurillardi, uma espécie de mamífero típica do Pleistoceno final americano. Acreditase que a presença de instrumentos líticos esteja ligada à disponibilidade da matéria-prima, portanto, um modelo preditivo considerando esse padrão prevê a probabilidade de recursos arqueológicos em outras áreas que expõem camadas sedimentares com arenito silicificado. Embora tenha sido observada a presença de artefatos líticos na área dos fósseis, análises estratigráficas e paleoambientais detalhadas do afloramento, bem como a datação das evidências, serão necessárias para melhor entender a relação entre o ser humano e a megafauna nesse local.
Spatial technology is integral to how archaeologists collect, store, analyze, and represent information in digital data sets.
Recent advances have improved our ability to look for and identify archaeological remains and have increased the size and
complexity of our data sets. In this review we outline trends in visualization, data management, archaeological prospecting,
modeling, and spatial analysis, as well as key advances in hardware and software. Due to developments in education, information
technology, and landscape archaeology, the implementation of spatial technology has begun to move beyond superficial applications
and is no longer limited to environmental deterministic approaches. In the future, spatial technology will increasingly change
archaeology in ways that will enable us to become better practitioners, scholars, and stewards.
The Central Peruvian Andes stand out as a globally important center of cultural and biological evolution. This is supported by its location at the heart of the former dominating Inca civilization (AD 1440-1534), itself built on remarkable preceding civilizations. These civilizations have arisen in this area possibly because of its exceptional natural biodiversity and its prominence as a center of domestication for numerous high altitude crops growing between 2000-4500 m a.s.l. Continuous environmental records for the Holocene from lake basin deposits in the Cuzco area would provide valuable information on how early human impact occurred. They would also assist in determining when the transition to agriculture took place in the southern highlands of present day Peru. A pollen record from Marcacocha, an in-filled lake basin at 3300 m near Ollantaytambo indicates evidence of a deforested agricultural landscape earlier than 4000 years ago. Major local climatic events at about AD 100 and 1050 in the record separate three contrasting land-use phases and may be linked to climatic events of a wider geographical occurrence. Most importantly these data furnish valuable insight into which cultures in Peru appeared to manage these fragile mountainous environments with minimal impact, and even evidence of agro-forestry using Alnus on a major scale. These are numerous lakes in the Cuzco area to provide a complete regional overview. A selection of these sites is presented. It is suggested that a series of continuous records at different altitudes may fill the gaps in our understanding of the composition of natural vegetation communities, including the distribution of Polylepis forest in existence prior to human impact. All this information will be important to agronomists, archaeologists, ecologists, and palaeoclimatologists alike.
Human alteration of Earth is substantial and growing. Between one-third and one-half of the land surface has been transformed
by human action; the carbon dioxide concentration in the atmosphere has increased by nearly 30 percent since the beginning
of the Industrial Revolution; more atmospheric nitrogen is fixed by humanity than by all natural terrestrial sources combined;
more than half of all accessible surface fresh water is put to use by humanity; and about one-quarter of the bird species
on Earth have been driven to extinction. By these and other standards, it is clear that we live on a human-dominated planet.
Microscopic organic-walled fossils are found in most sedimentary rocks. The organic particles - spores, pollens and other land and marine derived microfossils, representing animals, plants, fungi and protists - can be extracted and used to date the rock, reveal details of the original sedimentary environment and provide information on the climate of the time. The mix within a sediment of whole organic particles - palynomorphs - and organic fragments - palynodebris - form palynofacies. This book presents research work on the sedimentation of components of palynofacies and details their importance for sequence stratigraphy and the interpretation of ancient biologic and geologic environments. A comprehensive introduction to the subject is presented in the first chapter. Palynosedimentation in modern environments, the reconstruction of terrestrial vegetation and the application of the data to sequence stratigraphy are then considered. Later chapters detail various quantitative methods and their specific applications in the subject. This is a valuable reference work for palynologists and sedimentologists and also for paleobiologists, and for professionals working in the hydrocarbons industries.
The present work deals primarily with a determination of the relative pollen productivity of various trees from North Europe by means of their representation in pollen analyses of surface samples from forests, with the aim to calculate correction factors for pollen diagrams.Surface samples from 2 forests in Denmark were examined. The forest composition was determined by tree crown areas and tree basal areas in small sample plots. The relation of the tree crown areas to the tree basal areas was determined for the various tree species, and the data for crown area composition, basal area composition and tree frequency were compared.The pollen preservation in the various surface samples was examined.Data on wind conditions are mentioned in the chapter about pollen dispersal in the forest, and the various modes of pollen transfer are discussed. The amount of exotic pollen in the samples is used as a calculation basis for the tree pollen frequencies, and the occurrence and composition of the exotic pollen is discussed.The relationship of the forest composition to the tree pollen deposition is discussed. Pollen deposition and pollen productivity is expressed by a regression equation. The relative pollen productivity of the tree species is expressed in relation to a reference species, in the present case Fagus silvatica. Pollen representation and relative pollen representation are determined by a comparison of pollen percentages with percentages for areal frequency.Pollen productivity factors, pollen representation and correction factors were determined for Danish species of Quercus, Betula, Alnus, Carpinus, Ulmus, Fagus, Tilia and Fraxinus by means of the pollen frequencies in the surface samples. Corrected pollen percentages were compared with the tree areal percentages in the sample plots. Data for the pollen frequencies of forest plants other than the trees are presented. The data on trees from Denmark are compared with other data from Northern Europe, and correction factors were calculated for species of Pinus, Picea and Abies.Tree pollen spectra from outside the forest are discussed and the relative pollen representation is calculated. The present calculations of the relative pollen productivity of the trees are compared with previous estimates, and the application of the correction factors to pollen diagrams is discussed.
The last 20 years have witnessed a proliferation of new approaches in archaeolog ical data recovery, analysis, and theory building that incorporate both new forms of information and new methods for investigating them. The growing importance of survey has meant an expansion of the spatial realm of traditional archaeological data recovery and analysis from its traditional focus on specific locations on the landscape-archaeological sites-to the incorporation of data both on-site and off-site from across extensive regions. Evolving survey methods have led to experiments with nonsite and distributional data recovery as well as the critical evaluation of the definition and role of archaeological sites in data recovery and analysis. In both survey and excavation, the geomorphological analysis of land scapes has become increasingly important in the analysis of archaeological ma terials. Ethnoarchaeology-the use of ethnography to sharpen archaeological understanding of cultural and natural formation processes-has concentrated study on the formation processes underlying the content and structure of archae ological deposits. These actualistic studies consider patterns of deposition at the site level and the material results of human organization at the regional scale. Ethnoarchaeological approaches have also affected research in theoretical ways by expanding investigation into the nature and organization of systems of land use per se, thus providing direction for further study of the material results of those systems.
I am pleased to present this volume of invited reviews and research case studies, produced to mark the retirement of Professor A. G. Smith - one of the leading researchers in Holocene palaeoecology. A. G. Smith took his first degree at the University of Sheffield, graduating in 1951 with a first-class honours degree in Botany. His doctorate was awarded in 1956 for a study in late-Quaternary vege tational history, based in the Sub-Department of Quaternary Research at the University of Cambridge, under the supervision of the late Sir Harry Godwin, FRS. He then researched and taught at Queen's University, Belfast, from 1954, leading the Nuffield Quaternary Research Unit there, becoming Co-Director of the Palaeoecology Laboratory from 1964. He was appointed Professor and Head of the Department of Botany (later, Plant Science) at University College, Cardiff, in 1973, and retired from the School of Pure and Applied Biology at the renamed University of Wales College, Cardiff, in August 1991. Although his principal interests have been concerned with the post-glacial environmental history of the British Isles, Professor Smith has significantly in fluenced many researchers elsewhere in their interpretation of biological and other evidence for human modification of the natural environment.
1.
A broad outline is presented of the chronology of earliest human impact on the world’s vegetation, as shown in pollen and charcoal remains.
2.
The range of dates, and the diversity in ages reported, both within and between regions, are unlikely to represent the first human impact, by virtue of the inadequacy of palynology as a sensor and because they do not all relate to the same phenomenon.
3.
A set of criteria is suggested under which a broad consensus could be found for attributing a palynological change to human impact.
4.
The authors report on the huge gaps and discuss the possible reasons behind the lack of palynological information on human impact from regions that are otherwise known to have practised agriculture. These regions are contrasted against those that are devoid of archaeological evidence for agriculture, but have practised slashand-burn activity for millennia.
1.
Attention is drawn to a number of themes in the work of A.G. Smith that relate to the interaction of Mesolithic communities in Britain with their natural environments.
2.
Evidence is briefly discussed from the period preceding the establishment of deciduous forests, the actions of humans within it, and the transition period from a dominantly hunter-gatherer culture to an agricultural one.
3.
The second of these themes is then amplified with work from North Yorkshire, looking in particular at the results of fineresolution pollen analysis (FRPA) of peats from the later Mesolithic.
4.
These findings are then put into the wider context of the likely dynamics of the deciduous woodlands of that time, and one possible avenue for further research is indicated.
1.
Results of pollen and charcoal analysis of blanket peat sites from northern Dartmoor demonstrate the influence of burning and grazing on the transition from hazel woodland to blanket peat during the early and mid Holocene.
2.
Within a general phase of enhanced burning between 7700 and 6300 BP the site at Pinswell at an altitude of 461 m shows how woodland was transformed over a period of 600–1000 years into blanket peat via a phase of acid grassland, in some ways similar to heath-derived grassland found on Dartmoor today
3.
The results clearly implicate Mesolithic communities, and their use of the high moorland, in the development of the open peat-covered landscape that is so characteristic of the present Dartmoor environment.
Fossil pollen assemblages from Cliff Palace Pond, Kentucky, characterize changes in forest composition through the past 9,500 years of the Holocene. Early-Holocene spruce and northern white cedar stands were replaced by mixed mesophytic forests after 7300 B.P. Hemlock declined around 4800 B.P., and eastern red cedar became locally important. After 3000 B.P, mixed oak-chestnut and pine forests were dominant. The fossil charcoal record from Cliff Palace Pond demonstrates that Late Archaic and Woodland peoples cleared forest gaps to cultivate native plants in the Eastern Agricultural Complex and that anthropogenic fires served to increase populations of fire-tolerant oaks, chestnut, and pines in upland forests of the northern Cumberland Plateau.
Presents a broad-based synopsis of how natural and cultural agents have transformed the Earth's surface over the past 3 million years. Two main parts cover firstly temporal aspects of environmental change: the Quaternary, the evolution of modern humans, animal domestication and the spread of agriculture; and secondly, changes over the last 200 years due to industrial development and agriculture and more recently, changes due to tourism, recreation and biotechnology. There are 9 chapters: environmental change: agents, processes and the Quaternary; environmental change in the late- and post-glacial periods; prehistoric communities as agents of environmental change; environmental change in the historic period; post-1700 industrialisation; impact of agriculture in the developed world; impact of agriculture in the developing world; forestry, recreation, tourism, sport and biotechnology; and conclusion and prospects. -M.Dean
Erosion surfaces in the Española basin formed before 350 ka and between 350 and 240, 240 and 130, and 130 and 80 ka, probably in response to climatic change and regional uplift. The surfaces are cut on Miocene, Pliocene, and Pleistocene deposits and range from about 200 m to 15 m above the present Rio Chama/Rio Grande system. Periods when the surfaces formed were dated using varnish-cation ratios from exposed clasts, the mass of soil carbonate, and amino-acid ratios in Pleistocene gastropods from underlying deposits. Thorium/uranium ages from soil carbonate were used to calibrate a local curve for varnish-cation ratios. The range in age determined for a given surface, although derived from different dating techniques, implies that parts of the surface were sites of erosion or aggradation after the surface formed. From 1.1 Ma to present, denudation rates averaged 10 cm/1,000 yr from weakly lithified sandstone, less than 7 cm/1,000 yr from indurated tuff and boulder gravel, and about 4 cm/1,000 yr from tuff and basalt. Erosion surfaces were preserved as upland benches and terraces by stream incision during periods of pluvial climate and regional uplift, but our data do not permit clear separation of the two causes.
1 Presettlement fire regimes in north-eastern North America and their dependence on climate, fuels, and cultural patterns are poorly understood due to lack of relevant historic or palaeoecological data. Annual records of sediment charcoal accumulation were compiled from seven sites spanning the last 2000 years and representing important climate, vegetation, and cultural settings. Results were compared across sites and across changes in Indian cultures to determine whether fire patterns might be explained by one or more of these variables. 2 Clearly interpretable fires were restricted to the western (most xeric) portion of our study region in Pine Hardwoods of Minnesota, a single fire in Northern Hardwoods of northern Wisconsin, and cultural burning near an Iroquois village in southern Ontario. Other sites in Northern Hardwoods and Hardwood Hemlock forests did not show clear evidence of fire. Spectral analysis suggested instances in which local fire regimes departed from regional ones. 3 Our interpretation suggests substantially longer intervals between fires than reported in previous sediment charcoal studies. We did not find evidence for fire in mixed oak forests, where it has been speculated that fire might be necessary for oak recruitment, suggesting need for further analysis. 4 A single site in northern Wisconsin was the only Algonquin site showing a clear increase in charcoal suggesting local fire. Algonquin use of fire for hunting may not have affected our sites. A single site in Sioux territory experienced such frequent fire that cultural effects were not evident, even when Sioux were replaced by Chippewa (Algonquin) in the 18th century. One of two Iroquois sites showed clear increases in charcoal during occupation. The second site may not have had settlements nearby.
The Pajarito Plateau of northern New Mexico contains a rich and diverse record of late Quaternary landscape changes in a variety of geomorphic settings that include gently-sloping mesa tops, steep canyon walls, and canyon bottoms. A broad range of investigations during the past decade, motivated by environmental and seismic hazard concerns, have resulted in examination of the characteristics, stratigraphy, and age of sediments and soils at numerous locations throughout the Plateau. Geochronologic control is provided by >140 radiocarbon dates supplemented by soil characterization and tephrochronology. In this paper we first summarize some of the results of recent and ongoing work on late Quaternary deposits on the Pajarito Plateau, illustrating both the complexity of the geomorphic record and some common elements that have been observed in multiple locations. We then use these observations, in combination with other work in the Southwest, to make some inferences about the local geomorphic response to regional climatic changes. Because the geomorphic and paleoclimatic records are fragmentary, and because the relations between large scale climate changes and local variations in precipitation, vegetation, and geomorphic processes are not fully understood, many uncertainties exist concerning the response of the local landscape to past climatic fluctuations. In addition, variations in local landscape sensitivity related to prior erosional history and spatial variations in vegetation, and the localized nature of many storms, probably contribute to the complexity of the geomorphic record. Nevertheless, the work discussed in this paper suggests a strong relation between regional climatic changes and local geomorphic history, and provides a framework for considering relations between modem processes, the record of past landscape changes, and future erosion and deposition on the Plateau and in surrounding areas.
Negotiators hammering out the details for implementing the Kyoto climate change treaty have agreed that changes in forest
cover since 1990 can be counted for--and against--a nation trying to meet its carbon dioxide emissions obligations. But the
treaty is hazy about how to calculate forest carbon stocks and whether nations can use forestry projects in developing countries
to claim carbon credits. Efforts to clarify the CO-forest connection have just begun in earnest, with a U.N. workshop scheduled
for September, and the results will be critical to the treaty's success. Scientists are therefore mounting an ambitious effort
to trace the flux of CObetween land and air.
1 According to the Prentice-Sugita model, pollen loading (PL) is linearly related to the distance-weighted plant abundance (DWPA) surrounding a sedimentary basin. Since source trees of pollen far away from a basin have much less influence on pollen representation than source trees near a basin, the correlation between PL and DWPA should approach an asymptote as the vegetation sampling area increases. The 'relevant source area' for pollen can be defined as the area beyond which the correlation does not improve. 2 A simulation experiment using patchy vegetation landscapes illustrates this principle, demonstrating that r(2) and likelihood function scores do not improve when vegetation sampling increases beyond certain distances. This suggests that very little additional information on the pollen-plant abundance relationship will be gained by a vegetation survey beyond the 'relevant' distance when data are collected from regions of similar vegetation type and spatial pattern. 3 The 'relevant' source area for pollen in lakes in the simulated landscapes is within 50-100mm from the lake edge for forest hollows (radius of hollow R = 2m), 300-400 m for small lakes (R = 50 m), and 600-800 m for medium size lakes (R = 250 m). Although only about 30-45% of total pollen loading comes from within these distances, the model demonstrates that when the background pollen is consistent, this proportion is adequate to reflect local vegetation composition. 4 The simulation results show that pollen data from large lakes (R = 750 m) show little site-to-site variation, especially for a species that grows in small patches (radii of 80 m in the simulated landscape). Linear regression and maximum likelihood methods therefore do not provide accurate estimations of pollen productivity and background pollen loading. Vegetation may appear homogeneous even when the actual pattern of vegetation is heterogeneous and patchy, depending on the size of lake relative to the size of patches. 5 The pollen-plant abundance data should be collected from regions with similar forest composition to determine the 'relevant' source area and the parameters of a linear relationship between PL and DWPA. Otherwise, either the linear regression or maximum likelihood methods provide inaccurate estimates of the relevant source area and parameters even when the simulation data with no sampling and counting errors are used.
Each taxon's pollen deposition rate is assumed to be an independent linear function of its abundance within a fixed distance of the depositional site. Pollen data are assumed to consist of relative counts, rather than estimates of absolute deposition rates. Different approximations lead to 2 alternative models relating pollen counts to relative tree abundances. Maximum likelihood estimates and standard deviations are obtained numerically for the parameters of both models. The models are illustrated and compared by using surface pollen data and forest inventory data from Wisconsin and Upper Michigan; the models explain 70-80% of the variance in the pollen data and give interpretable and congruent results.-from Authors
R-values are ratios of pollen to vegetational percentages for different taxa. They may be used as correction factors for Late Quaternary pollen spectra—subject to certain caveats. The use of R-values implies a particular mathematical model, which is discussed in depth. Various problems are shown to arise; three computer-based statistical approaches are described in an attempt to overcome these problems. The first uses cluster and principal component analyses to group modern sites according to “R-spectra” and to detect departures from the model. The other two approaches obtain maximum likelihood estimates of (a) R-values and (b) representation coefficients and “background” coefficients in a model that attempts to allow for long-distance transport. Each approach is illustrated by application to Livingstone's surface pollen and forest-inventory data from southeast Canada. It is shown how long-distance Quercus (oak) pollen inflates R-values for oak at sites where oak trees are scarce. Livingstone's average R-values for oak was much too high since it was heavily biased by these sites. Maximum likelihood estimation gave a more realistic overall figure. Background oak pollen values estimated via the third approach are close to total oak pollen percentage at many sites, i.e. the method ascribes much of the incoming oak pollen to non-local sources. It is concluded that the three approaches together will make it possible to avoid the worst statistical problems associated with R-values, although vegetational heterogeneity and differential pollen transport will continue to limit achievable precision in the reconstruction of vegetation.
A consideration of the theoretical relationship between vegetational percentages and the percentages of pollen in sediments makes it obvious that where species differ in the amounts of pollen they contribute to sediments, pollen diagrams cannot be interpreted quantitatively by means of traditional methods. Under ideal conditions it should be possible, however, to interpret fossil pollen percentages objectively by means of correction for observed differences in pollen contribution. This method is described and demonstrated by its application to the Pine Pollen Zone in a pollen diagram from Vermont. The results imply that our previous subjective vegetational and climatic interpretation of this zone has been without validity. The departures of the real situation from the conditions of an ideal model are used to illustrate a general discussion of some of the subtle but potentially important sources of error that must be evaluated before pollen analysis can be used as a reliable paleoecologic technique.
After describing the theory developed for estimating plant abundances from pollen numbers, we introduce a general model for linear regression of pollen percentages against plant percentages and describe the mathematical and empirical conditions under which this model is appropriate. The slope term derived from this model accounts for the over- and under-representation of plant percentages by pollen percentages, and the y-intercept term accounts for pollen from plants not growing in the area of vegetation sampled about each pollen site. The model is evaluated empirically by applying it to 181 paired pollen and tree samples from Wisconsin and western Upper Michigan. The pollen data are from the surficial sediments of lakes, and the tree data are estimated from tree-inventory plots within 30 km of each lake. A sum of the sixteen most important tree taxa is used to calculate the percentages.
Abstract The myth persists that in 1492 the Americas were a sparsely populated wilderness, “a world of barely perceptible human disturbance’ There is substantial evidence, however, that the Native American landscape of the early sixteenth century was a humanized landscape almost everywhere. Populations were large. Forest composition had been modified, grasslands had been created, wildlife disrupted, and erosion was severe in places. Earthworks, roads, fields, and settlements were ubiquitous. With Indian depopulation in the wake of Old World disease, the environment recovered in many areas. A good argument can be made that the human presence was less visible in 1750 than it was in 1492.
1 We compared modern pollen assemblages from 60 moss polster sites in northern New York with forest composition data within 20–120 m of the sites using extended R-value (ERV) models, which correct for non-linearities arising from use of pollen percentage data. Our sites were concentrated in two regions, one dominated by Tsuga and hardwood (Acer, Betula, Fagus) forests, and the other by Tsuga, Pinus, Betula, Acer and Quercus forests.
2 Our results confirm that forest-floor pollen assemblages are dominated by pollen originating from trees growing more than 20 m from the site of deposition. However, our results suggest that background pollen percentages were overestimated by Jackson & Wong in 1994, owing to unusually high Pinus pollen production in the year of their sampling.
3 Expansion of our vegetation sampling radius from 20 to 120 m resulted in modest but consistent improvement in model fit and a decrease in background pollen percentages.
4 ERV model parameters (slope and background) differed substantially between the two study regions, primarily owing to differences in background pollen productivity and dispersal from regional sources.
5 High background pollen percentages may lead to poor estimation of calibration parameters in regions of complex vegetation patterns. Expansion of the vegetation sampling radius to reduce the background component may lead to better parameter estimates.
6 Calibration of pollen–vegetation relationships requires definition of the vegetation term so that it approximates the vegetation sampled by the pollen assemblages. Critical challenges are to define better the appropriate vegetation sampling area and distance-weighting functions for application to pollen–vegetation calibration.
Pre-Columbian Amerindian agriculturalists developed technologies and management practices with which to crop a wide range of ecological conditions, giving rise to a multiplicity of cultivated landscapes. This variety was particularly evident in Mesoamerica, where agricultural practices ranged from swiddening to multicropped, hydraulically transformed wetlands. Here we explore these indigenous cultivated landscapes as they existed about the time of the Columbian Encounter. We illustrate them through the examination of three transects approximating the courses of the initial Spanish entradas through this diverse region: the first extends from the Gulf coast to central Mexico; the second traverses the Yucatán peninsula from north to south; and the third climbs into highland Guatemala from the Pacific coastal plain.
Second, we broadly sketch the major changes that took place in these landscapes during the first phase of Spanish domination and some of the forces that shaped these changes. Three processes were especially significant: the Amerindian depopulation, the introduction of exotic biota and technologies, and the reordering of land and the rural economy. Ultimately, however, reconfigured “hybrid’ landscapes resulted that reflected the union of cultures.
Last, we argue that the scale of environmental transformation of Amerindian agriculture has not always been fully appreciated, the scale of environmental degradation associated with Spanish introductions has been overstated at times, and the contrasting ideologies of nature between the two cultures has been oversimplified.
Recent progress in the study of aquatic food-cycle relationships invites a reappraisal of certain ecological tenets. Quantitative
productivity data provide a basis for enunciating certain trophic principles, which, when applied to a series of successional
stages, shed new light on the dynamics of ecological succession.
General Land Office Survey (GLOS) records from the A.D. 1840s provide data for quantitative characterization of presettlement
vegetation across western Mackinac County, Michigan, located within the mixed conifer-northern hardwoods forest region. We
analyzed data from land survey plat maps and 1958 bearing, witness, and line trees from 162 surveyed section and quarter-section
corners in order to map vegatation cover types at a level of spatial resolution appropriate for characterizing landscape heterogeneity
using standard landscape ecological metrics. As also demonstrated by a number of both classic and contemporary plant-ecological
studies, the distribution of landforms, soils properties, hydrology, and location of fire breaks all contribute to the heterogeneity
in vegetation observed at a landscape scale in the region. Through a series of spatial landscape analyses with differing grain
of resolution, in this study we determine that a grid cell size of 65 ha (0.5 mi×0.5 mi or 0.25 mi2) to 259 ha (1 mi2) gives a conservative characterization of landscape heterogeneity using standard metrics and is therefore appropriate for
use of GLOS data to study historical landscape changes.
The future of most landscapes is increasingly being determined by human activities. These activities modify existing landscape patterns and processes either deliberately or inadvertently. It is becoming increasingly apparent that an understanding of these landscape level patterns and processes is essential for rational land use planning and management both for production and biodiversity conservation.The science of landscape ecology aims to provide this understanding. I argue that landscape ecology has so far failed to integrate the various disciplines it brings together and lacks a coherent theoretical structure and principles of relevance in practical terms. While advances have been made in the study of landscape structure and change, landscape function is often still poorly understood. Flows of biota, water, nutrients and materials across landscapes are determined, in large part, by landscape patterns, but an appreciation of the functional links between patterns and processes has been slow to evolve. If landscape ecology is to provide useful input into land use and conservation issues, greater effort needs to be expended in understanding the functional aspects of landscapes. I suggest that the future of landscape ecology depends on whether landscape ecologists make the decision to take an active part in determining the future of our landscapes. This involves active efforts to produce a truly integrated science, the development of sound landscape design principles and increased interaction with policy, planning and management. Failure to meet this challenge will relegate landscape ecology to being a pleasant academic pastime with little relevance to today's pressing environmental and social problems.
Two methods of analyzing charcoal in sediment reveal changes in charcoal accumulation across temperate eastern North America during the last several hundred years. In one method the analyst counts mostly small particles that reflect regional emissions; in the other, the analyst counts only larger particles derived mostly from such local sources as catchment fires. We used these methods to compare charcoal accumulation at 14 lakes from the prairie/forest border in Minnesota to eastern Maine. The two methods gave concordant accumulation rates for sediments of pre-1850 age at each of 4 lakes analyzed by both methods. This concordance is consistent with the interpretation that pre-1850 emissions were controlled by broad-scale factors, such as climatically controlled regional differences in fuels and moisture. Since 1900 large particles decreased greatly, and small particles decreased slightly, in Minnesota and Wisconsin. By contrast in the Northeast the large particle accumulation has remained at the low values measured in pre-1900 sediments at most sites, while small particles increased everywhere east of central New York and Pennsylvania. The observed patterns suggest that (1) large particles primarily reflect local fires that were common in the Midwest before fire suppression became effective, (2) large particles were rare in the Northeast, especially before extensive land clearance, (3) small particles reflect regional combustion that increased in the Northeast after extensive use of fire for land clearance and wood burning for industrial purposes of the 19th century, and (4) small particles remain abundant in the Midwest long after effective fire suppression, probably because these well-dispersed small particles have a large source area that extends beyond the local wildfires that account for large particles before European settlement.
Human alteration of Earth is substantial and growing. Between one-third and one-half of the land surface has been transformed
by human action; the carbon dioxide concentration in the atmosphere has increased by nearly 30 percent since the beginning
of the Industrial Revolution; more atmospheric nitrogen is fixed by humanity than by all natural terrestrial sources combined;
more than half of all accessible surface fresh water is put to use by humanity; and about one-quarter of the bird species
on Earth have been driven to extinction. By these and other standards, it is clear that we live on a human-dominated planet.
Thesis (Ph. D.)--University of New Mexico, 2001. Includes bibliographical references (leaves 255-282). Microfilm.
Palyenology, phytolith, and microscopic charcoal analyses of Rio del Oso Unpublished report, Golden, CO: Paleo Research Institute Vegetation change during the Mesolithic in the British Isles: Some amplifications
- Scott Cummings
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The hunter-gatherer, agriculture transition and the pollen record in the British Isles The cultural landscape-past, present and future
- K J Edwards
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In H.H. Birks, H.J.B. Birks, P.E., Kaland, & D. Moe (Eds.), The cultural landscape-past, present and
future (pp. 255-266). Cambridge: Cambridge University Press.
Space, time, and archaeological landscapes Coming to grips with the world's greenhouse gases
- J Rossignol
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The changing cultural landscapes of New Mexico's Rio Del Oso valley. Doctoral dis-sertation Maximum likelihood linear calibration of pollen spectra in terms of forest composition
- R D Periman
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Landscapes of cultivation in Mesoamerica on the eve of the con-quest. Annals of the Association of American Geographers
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