Showing papers on "Biodiversity published in 1992"

The Diversity of Life

Abstract: Traces the processes that produce new species, explains the importance of biodiversity, and recommends steps to help preserve diversity and improve the general quality of life.

Biodiversity and Ecological Redundancy

Abstract: This paper addresses the problem of which biota to choose to best satisfy the conservation goals for a particular region in the face of inadequate resources. Biodiversity is taken to be the integration of biological variability across all scales, from the genetic, through species and ecosystems, to landscapes. Conserving biodiversity is a daunting task, and the paper asserts that focusing on species is not the best approach. The best way to minimize species loss is to main- tain the integrity of ecosystem function. The important ques- tions therefore concern the kinds of biodiversity that are sig- nificant to ecosystem functioning. To best focus our efforts we need to establish how much (or how little) redundancy there is in the biological composition of ecosystems. An ap- proach is suggested, based on the use offunctional groups of organisms defined according to ecosystem processes. Func- tional groups with little or no redundancy warrant priority conservation effort. Complementary species-based ap- proaches for maximizing the inclusion of biodiversity within a set of conservation areas are compared to the func- tional-group approach.

Global biodiversity: status of the earth's living resources.

Abstract: Part 1 Biological diversity: Systematics and diversity - genetic diversity, systematics and diversity, species concepts, species inventory Species diversity - an introduction, microorganisms, lower plant diversity, higher plant diversity, nematodes, deep-sea invertebrates, soil macrofauna, fishes, higher vertebrates, island species, centres of species diversity Special loss - species extinction, threatened species habitats and ecosystems - global habitat classification, biodiversity and global climate change, tropical moist forests, grasslands, wetlands, coral reefs, mangroves. Part 2 Uses and values of biodiversity: Uses of biological resources - plant use, animal use, valuing biodiversity, biodiversity and economics. Part 3 Conservation and management of biodiversity: National policies and instruments - national legislation, protected area International policies and instruments - multilateral treaties, international policy and legal assistance, international aid, management of international resources Biodiversity convention - current practices in conservation, the convention on biological diversity.

Conserving biological diversity in agricultural/forestry systems

Abstract: iological diversity is essential, whether for agricultural and forestry systems, pharmaceutical products, aesthetics, tourist income, evolutionary processes, stabilization of ecosystems, biological investigations, protection of overall environmental quality, or intrinsic worth of all species on Earth (Ehrlich and Wilson 1991, Wilson 1988a). Although approximately 90% of world food for people comes from just 15 plant species and 8 animal species (Wilson 1988a), several thousand other plant species are used as food by humans (Altieri et al. 1987a). Furthermore, both high agricultural productivity and human health depend on the activity of a diverse natural biota composed of an estimated 10 million (range 2-80 million) species of plants and animals that inhabit the world (Wilson 1988b). The United States is home for an estimated 500,000 species, of which small organisms, such as arthropods and microbes, comprise 95% (Knutson 1989). As many as 1 million species of plants and animals will be exterminated worldwide dur-

The early evolution of eukaryotes: a geological perspective.

Abstract: Molecular phylogenies of eukaryotic organisms imply patterns of biological and environmental history that can be tested against the geological record. As predicted by sequence comparisons, Precambrian rocks show evidence of episodic increases in biological diversity and atmospheric oxygen concentrations. Nonetheless, complete integration of the two records remains elusive and may require that the earliest macroscopic organisms be recognized as extinct experiments in eukaryotic multicellularity.

Conservation biology : the theory and practice of nature conservation, preservation, and management

Abstract: Part I: The natural order. Species richness in plant communities - P S Ashton Hierarchies of cause: toward an understanding of rarity in vascular plant species - P L Fiedler and J J Ahouse Peasant farming systems, agricultural modernization and the conservation of crop genetic resources in Latin America - M Altieri and M K Anderson The new paradigm in ecology: implications for conservation biology above the species level - S T A Pickett, V T Parker and P L Fiedler Part II: Processes and effects of change Reptilian extinctions: the last ten thousand years - T J Case, D T Bolger and A D Richman Loss of biodiversity in aquatic systems: evidence from fish faunas - P B Moyle and R A Leidy Threats to invertebrate biodiversity: implications for conservation strategies - J E Hafernik, Jr Forest fragmentation and the conservation of biological diversity - L D Harris and G Silva-Lopez Issues of scale in conservation biology - R F Noss. Part III: Population biology and genetics. Stochastic modelling of extinction in plant populations - E S Menges The effects of inbreeding on isolated populations: are minimum viable population sizes predictable? - R C Lacy Conservation of Asian primates: aspects of genetics and behavioural ecology that predict vulnerability - M C Pearl. Part IV: The practice of conservation, preservation and management. Genetic and demographic considerations in rare plant conservation - E O Guernant Ecological management of sensitive natural areas - C R Carroll Park protection and public roads - C Schonewald-Cox and M Buechner. From conservation biology to conservation practice: strategies for protecting plant diversity - D Falk Why should we conserve species and wild lands? - G L Stebbins.

Global warming and biological diversity

Abstract: This book discusses in detail the consequences of global warming for ecosystems and includes commentary by distinguished scientists on many aspects of this critical problem Considering a variety of specific ecosystems (tropical forests, the deciduous forests of eastern North America, the forests of the Pacific Northwest, Mediterranean-type ecosystems in California, arctic tundra and arctic marine systems), experts describe responses of animals and plants to previous climate changes, interactions between various environmental components, and synergies between climate change and human activites such as deforestation The theme of the book is that global warming could cause profound disruption of natural ecosystems and could threaten many species with extinction Warming, coupled with the effects of habitat destruction, could cause massive waves of extinctions such as have not been seen for millions of years The goal of the book is therefore to ensure that furtuer scientific and policy discussions of global warming pay adequate attention to natural ecosystems

Tropical forest biodiversity: distributional patterns and their conservational significance

Abstract: Phytogeographical knowledge of two major patterns important to conservational planning―the distribution of diversity and endemism in tropical forests―are summarized. High diversity forests occur on all three continents and are concentrated in lowland areas with high and evenly distributed rainfall, but with greatest diversity usually occurring in northwest South America forests. Tree and liana species richnessis greatest in upper Amazone and non-tree species richness greatest in the northern andean foothills and southern Central America, suggesting conservational priority for these areas. Endemism is only partly correlated with diversity and is concentrated in isolated patches of unusual habitat, in cloud forsts, in topographically dissected montane areas, and on continental fragment islands, areas which also deserve conservational priority (...)

Putting biodiversity on the map: priority areas for global conservation.

Abstract: This is an important document prepared by ICBP. Based on worldwide studies, it states that because much of the world's threatened biodiversity can be found in comparatively small areas, protection of these areas would ensure the survival of a disproportionately high variety of species. Birds are good indicators of these key areas, and analysis of distribution has revealed that species of restricted range tend to occur together, in Endemic Bird Areas (EBAs). The survey identifies some 221 EBAs, with most (76 percent) occurring in the tropics. The report concludes that as these same areas are generally also very important for other species, the future of all EBAs is critical for global biodiversity conservation.

Dispersal Can Limit Local Plant Distribution

Abstract: The ability of species to establish new popuiations at unoccupied sites is a critical feature in the maintenance of biological diversity, and it has taken on new importance as a result of global climate change and expected changes in species distributior~ To examine the dispersal potential of plant specie~ seeds of four annual piant species were exper- imentally dispersed 40 to 600 m from existing populations in Massachusetts (U.Xik ) to 34 nearby unoccupied but ap- parently suitable siteg At three of these site~ new popula- tions were established that persisted for four generations and expanded slowly in area At seven site~ a small tnttial pop- uiation eventually died out At the 24 other siteg new pop- ulatiom did not become established, indicating that the sites were in some way unsuitabl¢ that not enough seeds arrived, or that conditions suitable for seed germination do not oc- cur every year. These results suggest that some species may be unable to disperse naturally out of their existing ranges in response to global climate changg particularly if habitat fragmentation creates barriers to dispersal These species may have to be assisted to reach suitable sites nearby to prevent their extinction in the wild.

Loss of Biodiversity in Aquatic Ecosystems: Evidence from Fish Faunas

Abstract: Fishes are appropriate indicators of trends in aquatic biodiversity because their enormous variety reflects a wide range of environmental conditions. Fish also have a major impact on the distribution and abundance of other organisms in waters they inhabit. Examination of trends in freshwater fish faunas from different parts of the world indicate that most faunas are in serious decline and in need of immediate protection. Species most likely to be threatened with immediate extinction are either specialized for life in large rivers or are endemic species with very small distributions. We conservatively estimate that 20 percent of the freshwater fish species of the world (ca. 1800 species) are already extinct or in serious decline. Evidence for serious declines in marine fishes is limited largely to estuarine fishes, reflecting their dependence on freshwater inflows, or to fishes in inland seas. The proximate causes of fish species’ decline can be divided into five broad categories: (1) competition for water, (2) habitat alteration, (3) pollution, (4) introduction of exotic species, and (5) commercial exploitation. Although one or two principal causes of decline can be identified for each species, the decline is typically the result of multiple, cumulative, long-term effects. Ways to protect aquatic biodiversity include the implementation of landscape-level management strategies, the creation of aquatic preserves, and the restoration of degraded aquatic habitats. Without rapid adoption of such measures we are likely to experience an accelerated rate of extinctions in aquatic environments as human populations continue to expand.

The ecology of fynbos: nutrients, fire and diversity.

Abstract: Introduction: The Fynbos Biome Project Biogeography: Selective regime and time Flora and vegetation Plant diversity and endemism History of the Cape flora Ecology: Plant reproductive ecology Plant-animal relationships Competition and coexistence Plant structure and function Functional perspectives of ecosystems Management: Human settlement Plant and animal invasions Preservation of biotic diversity Ecosystem management Global perspective: A Californian's view of fynbos.

Terrestrial Ecosystems Through Time: Evolutionary Paleoecology of Terrestrial Plants and Animals

Abstract: Breathtaking in scope, this is the first survey of the entire ecological history of life on land--from the earliest traces of terrestrial organisms over 400 million years ago to the beginning of human agriculture. By providing myriad insights into the unique ecological information contained in the fossil record, it establishes a new and ambitious basis for the study of evolutionary paleoecology of land ecosystems. A joint undertaking of the Evolution of Terrestrial Ecosystems Consortium at the National Museum of Natural History, Smithsonian Institution, and twenty-six additional researchers, this book begins with four chapters that lay out the theoretical background and methodology of the science of evolutionary paleoecology. Included are a comprehensive review of the taphonomy and paleoenvironmental settings of fossil deposits as well as guidelines for developing ecological characterizations of extinct organisms and the communities in which they lived. The remaining three chapters treat the history of terrestrial ecosystems through geological time, emphasizing how ecological interactions have changed, the rate and tempo of ecosystem change, the role of exogenous "forcing factors" in generating ecological change, and the effect of ecological factors on the evolution of biological diversity. The six principal authors of this volume are all associated with the Evolution of Terrestrial Ecosystems program at the National Museum of Natural History, Smithsonian Institution.

Drought and biodiversity in grasslands

Abstract: The local species richness of four different grassland fields fell an average of 37% during a 1988 drought that decreased above-ground living plant mass by an average of 47% Despite the return to more normal plant mass and precipitation during the next two years, there was no significant recovery in species richness in the 46 permanent plots, suggesting that local species richness became recruitment limited The drought led to the loss of annual species independent of their abundance For perennial grasses, perennial forbs, legumes and woody species, the probability of a species being lost from a plot was significantly negatively correlated with its predrought abundance These results demonstrate that environmentally extreme conditions can limit species richness by causing the local extinction of rare species Because droughts of this intensity occur about every 50 years in the prairie, periodic drought may have limited prairie diversity Moreover, if the accumulation of greenhouse gases leads to a more variable or extreme climate, it could cause increased rates of species extinctions

Boreal Forests—The Focal Habitats of Fennoscandia

Abstract: This chapter deals with the question of maintaining biological diversity in the boreal forests of Fennoscandia, i.e. the Scandinavian Peninsula and Finland. The boreal coniferous forest, or taiga, is the dominant biome, with a latitudinal extension from 56°N to 69°N (Fig. 7.1). The total area of the Fennoscandian forest amounts to more than 50 million ha, of which 13% occurs in Norway, 40% in Finland and 47% in Sweden (Nordic Statistical Secretariat, 1990). Man has utilized the boreal forest, for various purposes, during a very long period of time (Tenow, 1974). However, the most intense utilization has occurred during the last 300 years in connection with the development of the forest industry. At present, Fennoscandian forestry is amongst the most mechanized and efficient in the world. The result is that almost all forest land is now used for production of saw-timber and wood pulp. This has a tremendous impact on the structure and function of the boreal ecosystem. Cutting of old-growth forest and other consequences of forestry have a destructive impact on a large number of boreal organisms, despite the fact that some species are favoured by forest management. The result is decreasing populations for many hundreds of plants and animals, as reflected in recent Red Data lists (Andersson et al., 1987; Ahlen & Tjernberg, 1988; Databanken for hotarer och Naturvardsverket, 1991).

The value of managing for biodiversity

Abstract: The concept of biological diversity (biodiversity) is reviewed, with special attention to its measurement and natural trends. While generalizations regarding the necessity of biodiversity need to be interpreted with caution, it is argued that biodiversity should be protected in more ecosystem and landscape reserves, and that biodiversity is a reasonable management objective on timber lands as well. Maintaining biodiversity is important because we cannot always identify which individual species are critical to ecosystem sustainability, nor which species may be useful to mankind in future. Many wild species can provide useful natural products and genetic material, and can serve as ecological indicators. Diversity reduces pest and disease problems, and encourages recovery from disturbance. Uncertainty exists with regard to climate change and future socioeconomic values. It is therefore prudent to maximize flexibility by promoting a wide array of species and potential products. Suggestions are offered on how ...

Stream habitat fragmentation - a threat to biodiversity

Abstract: Biodiversity is undisturbed rhithral streams in central Europe is high, with about 1000 resident metazoan species; over 600 insect species occur in the Fulda river (Germany) Longitudinal downstream shift of dominance from rheobiontic to rheophilous and finally to ubiquituos rheoxenic taxa in the potamal is described Present downstream importance of ubiquituous species probably results from replacement of original potamal communities, present faunas being surrogates Species losses through human impact are well documented for fish The case of Plecoptera (10 potamal species either altogether extinct, extinct in Central Europe or extremely endangered) suggests that potamal invertebrates suffered as severe losses as did fish

Neotropical Mammals and the Myth of Amazonian Biodiversity

Abstract: Data were compiled on the distribution of mammal taxa (883 species, 242 genera, 45 families, and 10 orders) among South America’s six major macrohabitats: lowland Amazon forest, western montane forests, Atlantic rain forest, upland semideciduous forest, southern mesophytic forest, and drylands. The drylands are the richest area in numbers of species supported and are more diverse than the other habitats, including the lowland Amazon rain forest, when endemics are considered. An analysis of number of endemic and nonendemic taxa versus size of area found a simple positive linear relationship: the drylands, almost twice as extensive as the Amazon lowlands, support more endemic taxa. Conservation plans that emphasize the wet tropics and fail to consider the drylands as special repositories of mammal diversity will be unable to preserve a significant number of novel taxa.

Vegetational and Climatic History of the Pacific Northwest during the Last 20,000 Years: Implications for Understanding Present-day Biodiversity

Abstract: Introduction During the last 20,000 years, the world climate system has moved from a glacial state into the present interglaciation, known as the Holocene. In the course of the transition, the vast continental ice sheets disappeared, sea level rose worldwide, land and ocean surfaces warmed, and moisture became redistributed (Ruddiman and Wright 1987). These global events also set in motion a series of adjustments to regional climate that caused changes in vegetational composition, the formation of new plant communities, and shifts in the biogeographic range of particular species. The legacy of these events is the present diversity—species richness or number of taxa—of plants and their distribution on the landscape. Thus, a knowledge of the environmental history of a region is important in understanding present and future landscape change. In the Pacific Northwest, the retreat of glacial ice created a landscape of stagnant ice and glacial meltwater debris in northern Washington, Idaho, and western Montana. This region was colonized by the biota that survived in the unglaciated region to the south, along the exposed coastal shelf, and in the highlands. What was the nature of vegetation in the unglaciated region? How did glacial-age communities respond as climates changed, deglaciated terrain became available, and new species entered the region? What environmental controls shaped the subsequent development of modern forests within both the glaciated and unglaciated regions? In what ways have present-day vegetation and plant communities in the Pacific Northwest been influenced by long-term changes in climate, substrate, biological interactions, and natural disturbance? Present patterns of biodiversity in the Pacific Northwest represent the culmination of

Biogeography, ecology and history of Mediterranean Quercus ilex ecosystems

Abstract: Quercus ilex sensu lato plays an important role in Western Mediterranean ecosystems, but is poorly developed in the Eastern Mediterranean where it is often replaced by Quercus calliprinos.

The response of some rain forest insect groups to logging and conversion to plantation.

Abstract: Data and analyses from pilot studies in the Danum area of Sabah, East Malaysia, and elsewhere in the Indo-Australian tropics are used to measure the effects of logging and other human disturbance, such as conversion to plantation, on insect diversity. The two insect groups studied have very different trophic requirements: moths, with floristically specific herbivory, and dung and carrion beetles, exploiting resources of much more uniform quality over different forest systems. Moths show significant loss of diversity and taxonomic quality with disturbance and conversion to plantation. The beetles show much less change in diversity and faunistic composition. The implications for conservation of biodiversity are discussed, and suggestions for further work are made.

Biological Diversity and Biological Integrity: Current Concerns for Lakes and Streams

Abstract: In discussing various concepts of biological diversity and biological integrity, we trace development of the terms from a focus on species to a consideration of ecosystems. We urge the public to extend its concern with species extinction and tropical rain forests to include temperate aquatic assemblages. Examples of losses in biological diversity and biological integrity are given for the genetic, species, assemblage, fauna, ecosystem, and landscape levels of biological organization. After discussing the recent recognition of biological diversity concepts by the U.S. Environmental Protection Agency in its surface water assessment and regulation programs, we conclude that a broadening of environmental ethics is needed to protect ecosystems and species before they become endangered.

Best Management Practices, Cumulative Effects, and Long-Term Trends in Fish Abundance in Pacific Northwest River Systems

Abstract: Although it is widely believed that forest management has degraded streams and rivers, quantitative relationships between long-term trends in fish abundance and forestry operations have not been successfully defined. In this article we review the difficulties in describing cumulative effects of forest management on fishes of the Pacific Northwest. Despite uncertainties in interpreting long-term trends from catch and escapement statistics as well as widespread programs of hatchery production, many local fish populations are declining. We suggest that trends in the abundance of individual populations are often of limited use in identifying the cumulative effects of forest management within a river system. Shifts in the composition and organization of fish communities may provide more comprehensive evidence of the extent of environmental alteration. Reduced stream habitat complexity has been one of the most pervasive cumulative effects of past forest practices and probably has contributed to significant changes in fish communities, particularly when accompanied by other land use activities that have led to straightened, confined channels. In simplified streams a few fish species have characteristically been favored while others have declined or disappeared completely. Likewise, fish culture practices have resulted in overall losses of genetic diversity among species. In order to protect channel complexity and biodiversity, best management practices (BMPs) should include measures to preserve physical and biological linkages between streams, riparian zones, and upland areas. Connections must include transfer processes that deliver woody debris, coarse sediment, and organic matter to streams, as these materials are largely responsible for creating and maintaining channel complexity and trophic diversity. Past forest practice regulations have required attainment of individual water quality standards, such as temperature or dissolved oxygen, and have been aimed at protecting certain life history stages of single species (e.g., salmon eggs in spawning gravels). This approach is inadequate to achieve the goal of restoring and maintaining natural levels of complexity at the level of a stream ecosystem. New BMPs are beginning to address this issue by prescribing riparian management zones with a greater range of vegetative species and structural diversity, thus providing for future sources of large woody debris, floodplain connections, and other linkages important to ecosystem function. Benefits of new BMPs in terms of improved habitat complexity and increased diversity of fishes on the scale of a river basin will require coordinated planning and extensive application, and will take years—perhaps decades—to become apparent.