History Of Human Disturbance Research Articles

Population genetic patterns among social groups of the endangered Central American spider monkey (Ateles geoffroyi) in a human-dominated landscape.

Spider monkeys (Genus: Ateles) are a widespread Neotropical primate with a highly plastic socioecological strategy. However, the Central American species, Ateles geoffroyi, was recently re-listed as endangered due to the accelerated loss of forest across the subcontinent. There is inconsistent evidence that spider monkey populations could persist when actively protected, but their long-term viability in unprotected, human-dominated landscapes is not known. We analyzed noninvasive genetic samples from 185 individuals in 14 putative social groups on the Rivas Isthmus in southwestern Nicaragua. We found evidence of weak but significant genetic structure in the mitochondrial control region and in eight nuclear microsatellite loci plus negative spatial autocorrelation in Fst and kinship. The overall pattern suggests strong localized mating and at least historical female-biased dispersal, as is expected for this species. Heterozygosity was significantly lower than expected under random mating and lower than that found in other spider monkey populations, possibly reflecting a recent decline in genetic diversity and a threat from inbreeding. We conclude that despite a long history of human disturbance on this landscape, spider monkeys were until recently successful at maintaining gene flow. We consider the recent decline to be further indication of accelerated anthropogenic disturbance, but also of an opportunity to conserve native biodiversity. Spider monkeys are one of many wildlife species in Central America that is threatened by land cover change, and an apt example of how landscape-scale conservation planning could be used to ensure long-term persistence.

A dendroclimatic assessment of habitat specificity: Use of a functional trait to classify white oak1

Habitat specificity of tree species has traditionally been determined by identifying synchronous abiotic characteristics and species presence on the landscape. On a local scale this identifies many species as specialists; however, on a regional scale, most tree species are classified as generalists because individual species are present across a wide-range of edaphic and topographic conditions. To improve our ecological understanding of habitat specificity in trees, we classified white oak (Quercus alba) based on two performance currencies: responsiveness to climate and maximum tree age. We sampled tree rings from both ridge and valley stands in the southern Appalachian Mountains to contrast the dendroclimatic response at these topographic positions. White oak had radial growth responses to Palmer Drought Severity Index, temperature, and precipitation that was not dependent upon topographic position (ridge vs. valley), suggesting that white oak is a generalist species. A dendroclimatic response that is not dependent upon topographic position should allow white oak to adapt readily to climatic shifts that span a range of environmental conditions. Tree age has served as a successful performance currency in relatively undisturbed forests; however, in the southern Appalachian Mountains where there is a long history of human disturbance, maximum tree age revealed more about regional logging history than about white oak habitat specificity. Understanding habitat specificity of plant species improves predictions of species' response to environmental change. Traditionally trees have been classified based on occurrence on the landscape; however, in heavily-impacted forests occurrence is a reflection of land-use history. Dendroclimatology offers a more accurate tool to assess a tree's habitat specificity and was successfully applied in several ridge and valley sites in the Appalachian Mountains to identify white oak as a generalist species.

Book review: Bread, butter and marmite

ISSN 1948‐6596 news and update book review Bread, butter and marmite Climate change impacts on freshwater ecosystems, by Martin Kernan, Richard W. Battarbee and Brian R. Moss (eds.) Wiley–Blackwell, 2010, 328 pp. ISBN: 978‐1405179133 Price: £45 (Hardback) http://www.wiley.co.uk/ This book summarizes the outputs of Euro‐ limpacs, a major European Union (EU)‐funded pro‐ ject which investigated the impact of global change on freshwater ecosystems. As the title of the book suggests, the focus is on assessing the impacts of climate change on lakes, rivers and wetlands. However, the breadth of the material covered here is greater. The book aims to quantify and model past and recent climatic impacts on freshwater ecosystems, but also to predict the consequences of future change. The book also covers the numerous problems such as contami‐ nation with pollutants and structural modifica‐ tions that will influence potential responses of inland waters to climate change. The pervasive nature of such problems means that they must be considered in order to give useful insights into future climate impacts. The material covered thus more truly concerns global and environmental change than simply climate change. The scope of the project acknowledges the importance of con‐ sidering processes at a catchment scale and thus some of the material considers how terrestrial responses translate into changes in water bodies. The policy implications for the work are also con‐ sidered, with chapters covering implications for existing legislation (with a focus on the EU Water Framework Directive) and ideas for translating science into policy. As might be expected of an EU‐funded pro‐ ject, the majority of the work within this book concerns research in Europe. The geographical context is important because there is great diver‐ sity in climatic conditions across Europe which opens up possibilities for research (e.g. spatial comparisons), but also increases the challenge of mitigating and adapting to future change. Europe also has a long history of human disturbance, with some areas being intensely affected by anthropo‐ genic change and others being relatively pristine. There are also barriers to dispersal of organisms across parts of Europe that will influence how spe‐ cies ranges adapt to climate change. The context in which climate change is being dealt with there‐ fore varies spatially. Thus, although there has been a marked growth in research on climatic im‐ pacts on freshwater globally, there are good rea‐ sons to focus on Europe. As might be expected, European studies are placed into context by refer‐ ence to literature from other geographical re‐ gions. This book should attract a broad readership because of the range of subject matter covered. In contrast to similar books (e.g. George 2009) it deals with rivers, lakes and wetlands and there‐ fore should appeal to a wider spectrum of fresh‐ water scientists. It acknowledges the importance of anthropogenic stressors in chapters on hydrol‐ ogy and morphology (Chapter 4), eutrophication (Chapter 6), acid deposition (Chapter 7) and per‐ sistent organic pollutants and mercury (Chapter 8) and so should be of interest to researchers in these fields. One of the interesting aspects of this book is that it includes a diverse array of methodologi‐ cal approaches. The scientific studies presented use long‐term monitoring programmes, spatial surveys, palaeolimnology, experiments (from mi‐ crocosm to ecosystem scale) and various model‐ ling approaches across a broad range of scales. There are also chapters that may interest social scientists concerned with policy development and implementation (e.g. Chapter 11 – “Tools for bet‐ ter decision making: bridges from science to pol‐ icy”). This combination of material creates a book that facilitates the cross‐fertilization of ideas among subject areas and disciplines. The presentation of this book is stylish, with frontiers of biogeography 3.1, 2011 — © 2011 the authors; journal compilation © 2011 The International Biogeography Society

Towards a biogeographic regionalization of the European biota

AbstractAim To determine if it is possible to generate analytically derived regionalizations for multiple groups of European plants and animals and to explore potential influences on the regions for each taxonomic group.Location Europe.Methods We subjected range maps of trees, butterflies, reptiles, amphibians, birds and mammals to k‐means clustering followed by v‐fold cross‐validation to determine the pattern and number of regions (clusters). We then used the mean range sizes of species in each group as a correlate of the number of regions obtained for each taxon, and climate and species richness gradients as correlates of the spatial arrangement of the group‐specific regions. We also included the pattern of tree clusters as a predictor of animal clusters in order to test the ‘habitat templet’ concept as an explanation of animal distribution patterns.Results Spatially coherent clusters were found for all groups. The number of regions ranged from three to eight and was strongly associated with the mean range sizes of the species in each taxon. The cluster patterns of all groups were associated with various combinations of climate, underlying species richness gradients and, in the case of animals, the arrangement of tree clusters, although the rankings of the correlates differed among groups. In four of five groups the tree pattern was the strongest single predictor of the animal cluster patterns.Main conclusions Despite a long history of human disturbance and habitat modification, the European biota retains a discernable biogeographic structure. The primary driver appears to be aspects of climate related to water–energy balance, which also influence richness gradients. For many animals, the underlying habitat structure, as measured by tree distributions, appears to have a strong influence on their biogeographic structure, highlighting the need to preserve natural forest formations if we want to preserve the historical signal found in geographic distributions.

Male and female range use in a group of white‐bellied spider monkeys (Ateles belzebuth) in Yasuní National Park, Ecuador

Spider monkeys (Ateles sp.) live in a flexible fission-fusion social system in which members of a social group are not in constant association, but instead form smaller subgroups of varying size and composition. Patterns of range use in spider monkeys have been described as sex-segregated, with males and females often ranging separately, females utilizing core areas that encompass only a fraction of the entire community range, and males using much larger portions of the community range that overlap considerably with the core areas of females and other males. Males are also reported to use the boundary areas of community home ranges more often than females. Spider monkeys thus seem to parallel the "male-bonded" patterns of ranging and association found among some groups of chimpanzees. Over several years of research on one group of spider monkeys (Ateles belzebuth) in Yasuní National Park, Ecuador, we characterized the ranging patterns of adult males and females and evaluated the extent to which they conform to previously reported patterns. In contrast to ranging patterns seen at several other spider monkey sites, the ranges of our study females overlapped considerably, with little evidence of exclusive use of particular areas by individual monkeys. Average male and female home range size was comparable, and males and females were similar in their use of boundary areas. These ranging patterns are similar to those of "bisexually bonded" groups of chimpanzees in West Africa. We suggest that the less sex-segregated ranging patterns seen in this particular group of spider monkeys may be owing to a history of human disturbance in the area and to lower genetic relatedness between males, highlighting the potential for flexibility some aspects of the spider monkeys' fission-fusion social system.

Comparison of breeding bird and vegetation communities in primary and secondary forests of Great Smoky Mountains National Park

We compared breeding bird communities and vegetation characteristics at paired point locations in primary (undisturbed) and mature secondary forest (70–100 years old) sites in Great Smoky Mountains National Park, USA to understand how sites logged prior to creation of the park compare to undisturbed sites following 70 years of protection from human disturbance. We found that bird and vegetation communities are currently similar, but retain some differences in species composition. Rank abundance curves for primary and secondary forest bird communities showed very similar patterns of species dominance. Species composition was also similar on the two sites which shared 24 of the 25 most frequently recorded species. Nonetheless, comparisons of density estimates derived from distance sampling showed three bird species were more abundant on primary forest sites and that one bird species was significantly more abundant on secondary forest sites. Notably, comparisons based on raw counts (unadjusted for potential differences in detectability) produced somewhat different results. Analyses of vegetation samples for the paired sites also showed relative similarity, but with some differences between primary and secondary forests. Primary forest sites had more large trees (trees greater than 50 cm diameter at breast height) and late successional species. Primary forest sites had a denser tall shrub layer while secondary forest sites had a denser canopy layer. Nonetheless, tree species richness, basal area of live trees and number of standing snags did not differ between primary and secondary forest sites. Results indicate that breeding bird communities on sites within the park that were logged commercially 70 years ago are currently quite similar to bird communities on sites with no history of human disturbance. Similarities between the bird communities on previously disturbed and undisturbed sites in Great Smoky Mountains National Park may exceed those on more fragmented landscapes because large patches of primary forest, adjacent to commercially logged sites, remained in the park when it was established in 1935. These patches of primary forest may have served as source areas for commercially logged sites.

Niches, null models, and forest birds: Testing competing community assembly hypotheses in disturbed and undisturbed hardwood forest

ABSTRACT Processes that structure bird communities can be divided into two general categories: niche-based and dispersal-based. By examining the proportion of coniferous specialist individuals and the species composition in two forest bird communities, we tested the relative importance of habitat preference and availability (niche-based process) versus random settlement of individuals (dispersal-based process) in determining community composition. We examined two sites on Cape Breton Island, Nova Scotia, Canada: one undisturbed, the other with a history of human disturbance. To test for random settlement, for each forest type we generated model communities based on a random selection of individuals, weighted by the relative proportions of individuals and species in the observed community. In both communities, the proportion of individuals that were coniferous specialists deviated from random. In the disturbed forest, the proportion of coniferous specialist species increased as coniferous habitat increased...

Vegetation and disturbance history of a rare dwarf pitch pine community in western New England, USA

AbstractAim This study documents the vegetation history and age‐structure of a rare, ridgetop dwarf pine–oak community and compares the dynamics of this unusual vegetation with similar dwarf pine communities found elsewhere in the north‐eastern United States (US).Location The study area is located on the summit of Mt Everett in the Taconic Mountains of south‐western Berkshire County, Massachusetts, USA (42°06′N 73°26′W).Methods Vegetation composition, tree age‐structure, physical site characteristics, and evidence of fire and other disturbances were determined for twelve 15 × 15 m plots in dwarf pine–oak vegetation and two plots in oak forests on the summit. Age‐structure analyses, tree‐ring patterns, and historical records of human and natural disturbance were used to investigate the long‐term history and dynamics of the summit vegetation.Results The summit of Mt Everett has been dominated by dwarf pines (1–3 m tall) and ericaceous shrubs similar to the modern vegetation throughout the historical period; there is no evidence that tall‐stature forests occurred on the site at any point in the past few centuries. The summit supports uneven‐aged stands; pitch pine (Pinus rigida) recruitment began in the 1830s and occurred in every decade since the 1860s. Average pitch pine age is seventy‐eight with a range of 12–170 years. Red oak (Quercus rubra) and red maple (Acer rubrum) increased in importance in the twentieth century, with most stems establishing from 1940 to 1980. Pitch pine radial growth rates averaged <0.5 mm year−1 while red oak and red maple averaged 1.0 and 0.8 mm year−1, respectively. In some areas, hardwoods have overtopped pitch pines, apparently resulting in pitch pine mortality. Whereas most dwarf pitch pine communities occur on sites that burn frequently and have a high degree of cone serotiny, we found no evidence of recent fires or cone serotiny. Small amounts of macroscopic charcoal that we documented may have resulted from fires in the pre‐European or early historical periods.Conclusions Harsh edaphic conditions and chronic low‐level disturbances on the summit, including frequent winter storms, have apparently contributed to the establishment, long‐term persistence, and slow radial growth of dwarf pitch pines on Mt Everett. The ability of dwarf pines to persist on a site in the absence of frequent fire is highly unusual among North‐eastern barrens and has not been well‐incorporated into previous conceptual ecological models of these communities. Our results suggest that even among North‐eastern barrens, the summit of Mt Everett is characterized by highly unusual vegetation and dynamics. The site has long been recognized as regionally significant and should be afforded the strictest conservation protection. With no evident history of human disturbance or recent fire, there is no apparent need for immediate active management of the site.

A invasão de um fragmento florestal em São Paulo (SP) pela palmeira australiana Archontophoenix cunninghamiana H. Wendl. & Drude

Biological invasions are a threat to the maintenance of biological diversity, especially in small, isolated habitat fragments. This work reports the invasion of the Reserve of the Cidade Universitaria Armando de Salles Oliveira (23o34' S, 46o43' W), a small (10 ha) forest fragment, by a palm native of Australia, describing spatial patterns, size structure and dynamic features of its population. Adult individuals (DBH > 25 cm) occur in a large portion of the Reserve. In a 2.1 ha area inside the Reserve, A. cunninghamiana was the species with the highest density among trees with DBH ³ 9.5 cm, with 305 individuals (22.5% of total). The species was absent from sites with a recent history of human disturbance, suggesting preference for establishment in shady sites. The size structure analysis indicates a future increase in the relative density of the species. Seedlings (with pinatissect leaves, without woody stem) were absent from only three out of 87 studied quadrats (10 m x 10 m) and juveniles (with woody stem) with DBH < 9.5 cm were absent from 19 quadrats. Two surveys with a 2.5 years interval (DBH ³ 9.5 cm) showed the death of three of the initial 154 individuals and the recruitment of 89 more, leading to a population growth of 19.4%.year-1, very high in comparison with literature data. The high density already achieved by the invader and its tendency to increase even more call for management actions in order to reverse the invasion process.

Comparison of geographic classification schemes for Mid-Atlantic stream fish assemblages

Understanding the influence of geographic factors in structuring fish assemblages is crucial to developing a comprehensive assessment of stream conditions. We compared the classification strengths (CS) of geographic groups (ecoregions and catchments), stream order, and groups based on cluster analysis of fish assemblage data from 200 wadeable streams in the Mid-Atlantic Highlands. We 1st calculated intersite similarity indices (Bray–Curtis on relative abundance; Dice–Sørensen on presence/absence), then compared overall mean within-group similarities (W̄) with among-group similarities (B̄). We used subsets of the data to test CS from: 1) 31 reference sites defined on chemistry and habitat criteria, and 2) 21 samples from 8 sites that had been resampled within and between years to estimate the maximum similarity expected for any of the classifications. We assessed the strength of each classification by determining the degree to which W̄ was greater than B̄. Sites classified by taxonomic clusters had higher CS than did sites grouped by stream order, US Geological Survey 4-digit Hydrologic Unit Code (HUC) catchments, and ecoregions. Except for taxonomic clusters, the CS values were greater when all sites were used in the analysis than when only reference sites were used. The mean similarities for the revisits were 2 to 3 times greater than for all other classifications. We used nonmetric multidimensional scaling as an alternative approach to detecting geographic structure in the data. We found little separation of ecoregion or catchment groups except at very broad spatial scales. The relatively weak CS of any of the geographic groups suggests that the interaction of complex zoogeographic patterns and a long history of human disturbance has masked any fine-scale structure of regional fish assemblages.

Forest recovery in abandoned agricultural lands in a karst region of the Dominican Republic

This study documents the status of forest vegetation in the karst region of Los Haitises National Park, Dominican Republic, following the abandonment of pastures ( 5 years), young ( 5 years) ‘conucos’ (mixed plantings), old (7‐30 years) conucos, and cacao plantations (> 25 years). We compared these sites to vegetation characteristics of patches of forest in karst valleys (‘old forest’‐too old to know their exact land use) and on mogote tops with no recent history of human disturbance. The youngest sites date to when squatters were removed from Los Haitises National Park. Forest structure (density, basal area, and species richness of woody plants 1c m DBH) were all significantly affected by land use. Density was highest in intermediate-aged valley sites (old conucos )a nd mogote tops, while both basal area and species richness tended to increase with age of abandonment. Although cacao plantations had been abandoned for more than 25 years the species diversity was low, due to continued regeneration of this persistent crop. Abandoned pastures had the greatest nonwoody biomass and were dominated by the fern Nephrolepis multiflora which had completely replaced pasture grasses. An ordination of the woody plant communities separated the mogote tops from valleys, emphasizing the strong control that topography has on the forest community in moist and wet tropical forests on karst substrates. Valley sites were arranged in the ordination in order of their age, suggesting a successional sequence converging on the composition of the ‘old forest’ sites.

Diversity and Abundance of Litter Frogs in a Montane Forest of Southeastern Brazil: Seasonal and Altitudinal Changes1

ABSTRACTWe sampled litter frogs in an 1800‐ha mid‐elevation seasonal forest in southeastern Brazil. One hundred 8 * 8‐m plots were sampled during the dry/cold season and wet/warm season (unburned areas); we also examined the effects of fire in recently burned areas. A total of 267 frogs (305 g), belonging to 16 species (4 families) were caught. A single species comprised 78.5 percent of the individuals in the dry/cold season and 54.3 percent in the wet/warm season. The density of individuals did not change significantly with season, biomass did. Density and biomass of frogs were positively correlated with altitude. A Mantel test indicated that biological data (species and their abundance) were significantly associated with environmental parameters. The burned areas showed low values in richness, density and biomass of frogs. Harsh seasonal climate and a history of human disturbance may produce the low observed diversity values. The greater densities of frogs in sites of higher elevation may primarily result from mist‐generated humidity, which diminishes the harshness of the dry/cold season in relation to lower sites.

Is there a future for elephants in West Africa?

AbstractThe elephants of West Africa have experienced a long history of human disturbance. Before 1800 they were much affected by the precolonial empires of the savanna and Sahelian zones, the trans‐Saharan trade routes, and the coastal trade established by the Europeans. During the 19th century, the increasing demand for ivory from Europe and North America, the European penetration of the region, and the evolution of breech‐loading rifles devastated the remaining elephants. The elephant population of West Africa collapsed before the outbreak of World War I because of intense hunting for ivory. This collapse pre‐empted the decline that would have occurred anyway due to the rapid growth of the human population and consequent loss of habitat. Elephants now find themselves in about 70 small isolated populations that cover only 5% of the region. These fragments are very vulnerable – whether in the arid lands or the humid forests – to poaching and general human disturbance. There are few data on numbers; most of the population estimates are guesses. Two‐thirds of the populations are thought to consist of fewer than 200 animals and therefore have a low probability of surviving the next century.As more habitat is lost to human activities, West African elephants will soon remain only in protected areas. But many parks and reserves are managed poorly and cannot offer effective protection; they do not guarantee a future for elephants. In addition, their crop‐raiding habit makes elephants unpopular in rural communities surrounding protected areas. Human populations are expected to continue growing and resources for conservation are scarce. The future of West African elephants lies in a small network of well‐protected areas.

Changing headwater suspended sediment yields in the LOIS catchments over the last century: a paleolimnological approach

This paper describes the methods used to reconstruct suspended sediment yields over the last century, based on 210Pb and 137Cs dated bottom sediments in nine lake and/or reservoir catchments. Magnetic susceptibility and dry bulk density are used to correlate between multiple cores taken from each lake/reservoir basin in order to estimate sediment influx through time and reconstruct sediment yield histories. The catchments represent a range of morphological and land use systems, including upland moorland, upland forestry and upland and lowland agricultural systems. The reconstruction provides some background information on pre-20th century sediment yields and permits an evaluation of the effect of 20th century land management systems, especially upland afforestation and agriculture, on changing suspended sediment yields. Reconstructed sediment yields over the last century range from c. 7 to 86 t km−2 yr−1. Average post-1953 yields from pasture, arable, moorland and forested catchments are 13, 31, 29 and 13 t km−2 yr−1, respectively. The history of human disturbance in individual catchments is clearly recorded in the reconstructed sediment yields. Short-lived disturbance, such as afforestation, produces high yields (over 40 t km−2 yr−1) for up to a decade after planting, but yields subsequently decline to pre-planting levels (c. 12 t km−2 yr−1). Sustained increases in sediment yield are associated with arable, mixed agricultural and, to a lesser extent, grazing systems. While the strong controls exerted on sediment yield by human disturbance mask the potential effect of regional contrasts in runoff and topography between catchments, there is some evidence to suggest that a long-term climate change signal is recorded in the temporal trends in sediment yield from an analysis of Lamb weather types. Copyright © 1999 John Wiley & Sons, Ltd.

Patterns of allozymic variation within calluna vulgaris populations at seed bank and adult stages

We investigated the spatial genetic structure within and between two plots of Calluna vulgaris and the extent to which the soil seed bank differed genetically from adults at seven allozyme loci. Averaged over the two plots, the seed bank and adult populations contained very similar levels of genetic diversity. Moreover, seeds contained in a single soil core (100 cm3) exhibited similar mean allozyme diversity to the surrounding adult population, indicating that the seed bank preserves genetic diversity at a very local scale. Few differences in allelic frequencies were found between the seed bank and its surrounding adult population in each plot. Mean GST indicated a lack of differentiation between the two plots at adult (GST = 0.008) and seed bank (GST = 0.002) stages. Low interplot differentiation is consistent with the outcrossing mating system of the population (tm = 0.91 in one plot) and its history of human disturbance. In contrast, spatial autocorrelation analysis of adults indicated a genetic structure at a very local scale, with positive autocorrelation for all alleles below 2 m in one plot and with a pattern of positive autocorrelation below 8 m in the two plots. Current limitation to seed dispersal rather than spatial extension of clones is thought to be responsible for local genetic structure.

A 10,000 Year Diatom Record from a Glacial Lake in Costa Rica

Paleoclimatological reconstruction from lake sediments is hampered in Central America by a long history of human disturbance, which can mask evidence of climate change (Bradbury, 1982). The difficulty of teasing apart climate and human disturbance signals is particularly great in the case of pollen and charcoal records from lowland sites, where human population densities were highest. Even remote mountain sites, however, may record past human disturbance. The analyses of diatoms and other lake-based indicators may provide records of past climate less influenced by human activity than terrestrial indicators, particularly at sites distant from human settlement. We have undertaken studies of diatoms in Costa Ri-

Tropical Forest Disturbance: Paleoecological Records from Darien, Panama

The first paleoecological data from the Darien of Panama, a remote region rich in endemic species and purported to be one of the last untouched neotropical wilderness, demonstrate a 4000—yr history of human disturbance. Unstable climate is recorded as changes in precipitation inferred from the diatom record, but a more important source of disturbance has been human activity. Pollen, and phytoliths of Zea mays, and charcoal from grass fires confirm historical and archaeological judgments that the region has a long history of human settlement.The data are consistent with depopulation and abandonment of most agriculture following the Spanish conquest, showing that the local modern forest has developed in recent centuries. Four millennia of disturbance that preceded the decline of human populations may have had a profound effect upon the modern forest associations. The apparently pristine forests appear to have regrown in just 350 yr, probably from populations fragmented by previous agricultural disturbance. However, the modern richness of the Darien forests suggests that local biodiversity was maintained throughout 4000 yr of indigenous agriculture.

The history and impact of air pollution at ?ertovo Lake, southwestern Czech Republic

This multi-disciplinary investigation documents the longterm effects of atmospheric pollution of metals and acids on a geologically sensitive catchment in the Sumava Mountains, southwestern Czech Republic, a region with a long history of human disturbance. A 30 cm long sediment core (I) from Certovo Lake was analyzed for natural and artifical radionuclides, metals, diatoms, chrysophytes, and pollen in sediments accumulated during the last 200 years. A second core (II), extending to 95 cm, included sediment judged to be free of atmospheric deposition of pollutants associated with the Industrial Revolution. Chronostratigraphic markers include several changes in the pollen assemblages corresponding to well-documented changes in land-use, and distinct distributions of 137Cs, 134Cs and 241Am from weapons testing and the 1986 nuclear accident at Chernobyl, Russia. These markers corroborate the 210Pb dating and, together, produce a reliable chronology extending back nearly to 1800 A.D.

Long-term human disturbance of an urban park forest, New York City

Development of an urban park forest, the Turtle Pond Watershed, Alley Park, Queens, New York, was analyzed from historical, vegetation, and pollen records. After 1800, the forest began to develop as a hickory ( Carya spp. Nutt.) dominated stand following release of the land from agricultural use. Pollen and sediment analysis of a section from the bog in Turtle Pond showed that before 1900, residential development introduced pine ( Pinus spp. L.) to the area, reduced the hickory population, and caused the Pond to change from bog to fen conditions. From 1908 to 1912, the hickory bark beetle reduced hickory and chestnut blight killed off American chestnut ( Castanea dentata (Marsh.) Borkh.). Although the area containing the Watershed forest was incorporated into Alley Park in 1927, private structures were not removed until 1937. Forest canopy inventory data from 1936 showed canopy gaps left open by the losses of American chestnut and hickory trees permitted flowering dogwood ( Cornus florida L.) to become the forest dominant. Comparison of the 1936 data with an inventory of the forested Watershed in 1987 indicated the flowering dogwood was decimated in the intervening years and the open growing space was occupied by maple ( Acer spp. L.), birch ( Betula spp. L.), American beech ( Fagus grandifolia Ehrh.), sweet gum ( Liquidambar styraciflua L.), black gum ( Nyssa sylvatica Marsh.), black cherry ( Prunus serotina Ehrh.), and oak ( Quercus spp. L.). The pollen record indicates that stresses of recreational use and abuse in the Watershed forest since 1973 have negatively affected reproduction in maple, birch, and sweet gum. The history of human disturbance provides information to guide recreation of past forest types and to increase diversity through the selection of hardy species to plant.

Relation of plant species to substrate, landscape position, and aspect in north central Massachusetts

Vegetation–site relationships in the region about the Harvard Forest in north central Massachusetts were explored by means of contingency table and cluster analyses of presence–absence data. Most of the arboreal species, the shrubs, and the ferns were strongly associated with segments of a microclimate – soil moisture gradient determined by landscape position and substrate. Cluster analysis of the species suggested the existence of a fertility gradient, with the more nutrient demanding white ash (Fraxinusamericana L.), sugar maple (Acersaccharum L.) and basswood (Tiliaamericana L.) on one end of the gradient and pitch pine (Pinusrigida Mill.), scrub oak (Quercusilicifolia Wangenh.), and aspen (Populus sp.) on the more impoverished sites. An analysis of the feasibility of determining vegetation–site relationships in an area with a long history of human disturbances concludes the report.