Showing papers on "Biodiversity published in 1990"

Indicators for Monitoring Biodiversity: A Hierarchical Approach

Abstract: Biodiversity is presently a minor consideration in environmental policy. It has been regarded as too broad and vague a concept to be applied to real-world regulatoy and managernentproblems. This problem can be corrected ifbio- diversity is recognized as an end in itsea and if measurable indicators can be selected to assess the status of biodiversity over time. Biodiversity, as presently understood, encom- passes multiple levels of biological organization. In thispa- per, I expand the three primay attributes of biodiversity recognized by Jerry Franklin - composition, structure, and function - into a nested hierarcby that incorporates ele- ments of each attribute at four levels of organization: re- gional landscape, community-ecosystem, population- species, andgenetic. Indicators of each attribute in terrestrial ecosystems, at the four levels of organization, are identified for environmental monitoring purposes. Projects to monitor biodiversity will benefit from a direct linkage to long-term ecological research and a commitment to test hypotheses relevant to biodiversity conservation. A general guideline is to proceed from the top down, beginning with a coarse-scale invent0 y of landscape pattern, vegetation, habitat structure, and species distributions, then overlaying data on stress lev- els to identiD biologically significant areas at high risk of impoverishment. Intensive research and monitoring can be directed to high-risk ecosystems and elements of biodiversity, while less intensive monitoring is directed to the total land- scape (or samples thereon. In any monitoringprogram, par- ticular attention should be paid to specifying the questions that monitoring is intended to answer and validating the relationships between indicators and the components of bio- diversity they represent

Changes and disturbances of forest ecosystems caused by human activities in the western part of the mediterranean basin

Abstract: The development of socio-economic activity over the past ten years in the Mediterranean region has induced severe changes in the main natural forest ecosystems. In the northern Mediterranean, rural depopulation has accelerated since the end of the second World War, particularly since the establishment of Common Market agricultural policies, and led to an under-utilization of species causing a strong biological resurgence of the forest, even at high altitudes. This means that, at the present time, the extension of expansion model coniferous forests is favored by their capacities for spatial, biological and ecological selection. Along with this, the under-utilization of sclerophyllous (resistance model) and deciduous (stabilization model) oak coppices has led to the establishment of new forest structures and architectures which are notably different from the main climatic groups defined up to now by phytosociological and synchronic methods. Two new forms of disturbances have appeared: In the southern Mediterranean, particularly in North Africa, demographic pressure and grazing have widely disturbed the main forest ecosystems which show a continual regression of their surface. Many forest tree species with a low spatial and biological selection, such as Mediterranean firs and black pines (Pinus nigra subsp. mauritanica), are threatened with extinction, as are the deciduous oak forests which, considering the climatic stress and edaphic constraints, are permanently in a state of imbalance. Human disturbances induce a complete modification of structures and architectures tending towards the installation of simplified forest models (trees-grasses) where tree regeneration is nearly impossible. The sclerophyllous coppices well-adapted to stress are also threatened by shorter and shorter cutting cycles and by the high usage of tree canopies for grazing. In all bioclimatic groups, the increase in grazing pressure throughout the southern Mediterranean ecosystems can even lead to the total disappearance of perennial species from the ecosystem with the exception of the dominant tree. Regardless of the altitude or ecosystem, invasive therophytes are then the only plants to occupy the understory and indicate hyperdegradation (forest therophytization).

Biodiversity Loss in the Temperate Zone: Decline of the Native Fish Fauna of California

Abstract: In proportion to the entire fauna, loss of species may be as great in temperate regions as in tropical regions. To test the validity of this statement we analyzed the status of the native fish fauna of California, using a methodology that quantifies expert knowledge. Of 113 native taxa, 6 percent are extinct, 12 percent are officially listed as threatened or endangered 6 percent deserve immediate listing I7 percent may need listing soon, 22 percent show declining populations but are not yet in serious trouble, and 36 percent appear to be secure. Much of the faunal decline has taken place in recent years; it has included unexpectedly rapid declines of once abundant species. Fish taxa in serious trouble are most likely to be (1) endemic to California, (2) restricted to a small area, (3) occupants of just one drainage basin, (4) part of a fish assemblage of less than five species, and (5) found in isolated springs, warm water streams, or big rivers. Water diversions and introduced species, acting in concert, seem to be the principal causes of the decline of the native fauna, although other types of habitat degradation have contributed as well. The situation in California, with its high degree of endemism (60 percent), may be regarded as extreme but fish faunas in other temperate regions show signs of being nearly as stressed. It is likely that the situation with fish reflects a more general decline of the biota of temperate regions of the world.

Biodiversity in sub-saharan Africa and its islands : conservation, management and sustainable use

Abstract: A general overview is provided of biodiversity conservation in Africa which includes the current status and threats the action required for conservation and the priorities. Country profiles describe the status of biodiversity conservation in Angola Benin Botswana Burkina Faso Burundi Cameroon Cape Verde Central African Republic Chad Comoros Congo Djibouti Equatorial Guinea Ethiopia Gabon Gambia Ghana Guinea Guinea-Bissau the Ivory Coast Kenya Lesotho Liberia Madagascar Malawi Mali Mauritania Mauritius Mozambique Namibia Niger Nigeria Reunion Rwanda Sao Tome and Principe Senegal Seychelles Sierra Leone Somalia South Africa Sudan Swaziland Tanzania Togo Uganda Zaire Zambia and Zimbabwe. The aim is to highlight the seriousness of biodiversity loss in Africa. The target audience is decision makers concerned with wildlife and protected area management and nongovernmental organizations in Africa. The proposed biological diversity action plan is broad-based and multisectoral and targets priority areas. The conservation strategy can be compatibly linked to sectoral development and focuses on conservation of wild species and natural ecosystems. Plan limitations are that issues are constantly changing and coverage of some topics is limited. There is no attempt to present the strategy as a final solution. Strategy is identified for adopting sustainability as a goal of economic and development policy for completing the establishment of a representative network of protected areas for improving wildlife management for adopting land use practices around protected areas for adopting wider land use policies to promote conservation for sustaining harvest management for developing strong conservation agencies for running public awareness and education programs for developing legal support and for implementing research activities. The central African equatorial forests particularly to the east and west of the Zaire basin is identified as a priority area. The Afrotropical Realm is modeled as a series of seven regional centers of endemism with distinctive flora and fauna and two centers on Madagascar. There are also eight transition zone and regional mosaics. The least protected species are in the Guineo-Congolian Afromontane and Madagascan areas.

Land-Use, Forest Fragmentation and the Mammalian Fauna at Naringal, South-Western Victoria

Abstract: At Naringal in south-western Victoria, land use since European settlement has resulted in the loss of more than 90% of the original forest vegetation, and the progressive fragmentation and isolation of the remaining tracts. Surveys of mammals in remnant forest vegetation, together with information gleaned from historical sources, reveal that 33 species of native mammal are known to have occurred in this region. Six species (18%) are believed to be no longer present in the area, and four of these, Dasyurus maculatus, D. viverrinus, Vombatus ursinus, and Canis familiaris dingo, were persecuted as pests, and apparently disappeared before forest cover was greatly reduced. Six species of introduced mammal have established feral populations in the study area. The altered status of the mammalian fauna is discussed in relation to four factors associated with European land use: the loss and fragmentation of the forests; changes to the composition and structure of forest vegetation; destruction of mammals by humans; and, the introduction of exotic plants and animals. Four general recommendations are advanced as a basis for the management and conservation of the mammalian fauna: the importance of a regional perspective in conservation planning; the need to maintain a substantial total area of forest vegetation; the importance of maintaining and enhancing continuity between forest remnants; and, the protection and promotion of habitat components that are essential to native mammals.

The significance of the biological resources of New Zealand islands for ecological restoration

Abstract: Islands have historically played a significant role in New Zealand conservation because they contain such a disproportionately large amount of our biological wealth, including primary endemic species that never occurred on mainland New Zealand, pseudo-endemic species that once occurred on the mainland but survive now only on island refugia, and a kind of community structure seldom found outside the New Zealand region. Present knowledge significantly underestimates biodiversity on islands as measured by taxonomic, genetic, and community criteria. In the future, islands will play major roles as sites for ecological restoration programmes, nature sanctuaries, sources of knowledge for restoration goals and methodologies, sources of plant and animal species to be used for translocation to restoration sites, for monitoring of macro-environmental change, and examples to be used in conservation education programmes

INSECl' SPECIES DIVERSITY IN THE TROPICS: SAMPLING METHODS AND A CASE STUDY 1

Abstract: The tropical regions of the world generally have a richer store of biological diversity than other regions of the globe. But most tropical habitats face a significant threat of destruction. Yet, little is known about tropical biotic communities. Suspecting that at least part of the reason for the poor documentation of tropical insect communities is the lack of appropriate research methodology, we have endeavoured to standardize a package of methods for quantitative sampling of insects, suitable for tropical ecologists with modest research budgets. This methodology includes the use of a small light trap as well as net sweeps, pitfall traps and scented traps. The methods have been used to sample insect species diversity patterns in three replicate one hectare plots each in twelve selected sites in the Uttara Kannada district of Kamataka, India. During this case study, we have encountered 16,852 adult individuals belooging to 1,789 species. 219 families and 19 orders of insects. Here, we provide evidence that this methodology is adequate for sampling insects and differentiating habitats on the basis of the distribution of insect species. Some interesting biological problems that tropical ecologists can study with the data generated from the application of these methods are also briefIy illustrated.

Semen Collection, Evaluation, and Cryopreservation in Exotic Animal Species: Maximizing Reproductive Potential

Abstract: In 1980, Thomas Lovejoy of the World Wildlife Fund stated that reduction in the biological diversity of the planet is the most basic issue of our time and that slowing this process of "bioa'c impoverishment" is a great challenge to the ingenuity of biologists. Extinction of a species represents the loss of a resource that has evolved through thousands, perhaps millions, of years of mutation and natural selection. The genetic diversity that now exists in captive exotic animals will steadily dwindle through random processes without continuous input from wild populations. The National Research Council (1978) has stressed the importance of conserving this genetic material and emphasized that if immediate action is not taken, much of this vital resource will be depleted in the near future. It is incumbent upon American zoos, as stewards of a large proportion of the earth's captive species, to maintain them in sufficient numbers to ensure that genetic variability is adequate for long-term genetic health. Notter and Foose (1985) have calculated that nearly 50,000 individuals would be required to maintain 99 percent of a species' genetic diversity for 1,000 generations. Because of severe space limitations in zoos and animal parks, this ideal genetic diversity will not likely be attainable for any of the species we are attempting to save from extinction. Perhaps a more realistic goal is to preserve 90 percent of a species' diversity for 1,000 generations with less than 5,000 individuals. Even that greatly reduced number of individuals is impossible to maintain in captivity. However, long-term germ plasm storage can minimize

Species diversity in relation to ultramafic substrate and to altitude in southwestern New Zealand

Abstract: Altitudinal trends in species diversity were examined on a New Zealand ultramafic mountain, and on nearby normal (schist) substrate. At lower altitudes, diversity is similar on the two substrates. On the ultramafic substrate, species diversity decreased with increasing altitude; on schist substrate the opposite trend was found. This difference was demonstrable in species richness, based on species presence/absence, and in indices of species diversity based on cover data (the ShannonH′ and the Simpson/Yule — InD). It is suggested that on ultramafics, altitudinal stress and soil conditions lead to a decrease in diversity with altitude. On schist, in contrast, the opening of the canopy with altitude is suggested to be the predominant influence, leading to an increase in diversity with altitude.

The institutional origins of deforestation in Latin America.

Abstract: Tropical deforestation has become the subject of considerable debate and concern. Experts disagree over how quickly tree-covered land near the equator is being cleared (Lanly, 1982) and deforestation's impacts on global climate (Detwiler and Hall, 1988). By contrast, the claim that land clearing threatens the world's stock of "biological information" is less controversial. Tropical forests' high biological diversity is indisputable; although they cover less than 10 percent of the Earth's land surface, they contain approximately half the world's plant and animal species (Wilson, 1988).

The institutional origins of deforestation in latin america

Abstract: Tropical deforestation has become the subject of considerable debate and concern. Experts disagree over how quickly tree-covered land near the equator is being cleared (Lanly, 1982) and deforestation's impacts on global climate (Detwiler and Hall, 1988). By contrast, the claim that land clearing threatens the world's stock of "biological information" is less controversial. Tropical forests' high biological diversity is indisputable; although they cover less than 10 percent of the Earth's land surface, they contain approximately half the world's plant and animal species (Wilson, 1988).

Tropische Biodiversitat: Befunde und offene Probleme

Abstract: During the past 50 to over 100 million years communities evolved in the tropics which attained unprecedented levels of biodiversity, strikingly represented by evergreen lowland rain forests offering home to more than 50% of all the world's extant species. Within only some 30 years human action reduced the area covered with tropical rain forests to about half of its former size, thereby negatively affecting local and global functions of the biosphere and exterminating an unknown number of species. With an exponentially increasing rate we are throwing away our and all future generations' biological heritage. We destroy the most complicated, scientifically most interesting living systems before we have gained any knowledge of their structures ,and dynamics. To understand the particular structures and dynamics of tropical communities means in the first place to understand the causes and consequences of their ten- to more than hundredfold higher alphadiversity (as compared to temperate systems). This problem has a historical dimension and a functional side requiring answers as to the nature of the proximate mechanisms of its maintenance. My review is only concerned with the latter aspect, and its maIn emphasis is on the gaps in our knowledge. Two sets of hypotheses have been developed for explaining the high within-commUnIty diversity. (1) According to the classical concept interspecific niche competition and subsequent niche separation are the main forces determining the structure of the community. These so-called equilibrium models have been contrasted in recent times with (2) non-equilibrium models. These models do not attribute the decisive role to interspecific competition. Strong niche overlaps are presumed to be very common within species-rich communities. Continuous stochastic local disturbances are assumed to prevent the achievement of any long-term equilibrium (climax) state. Being on the right spot at the right time is regarded as most important. Whether oneor a combination of both models provide the best key for understanding the structure of a special section within a community will certainly depend on many properties of the species at debate (mobility, disr.ersal, fertility etc.). For the vast majority of tropical organisms all such information is at present unavailable. The principles governing the structure of communities is just one of the very ,basic open problems. Another very prominent question is how the qualitatively very rich, however quantitatively poor resources are distributed among the members of highly diverse guilds of consumers and decomposers. Does the scarcity rather favour generalists or specialists, are small species overrepresented, are resources more extensively used than in temperate communities? One important property is fairly well established: Populations of most tropical species seem to be very small. Since a) in very many' cases distribution range is obviously very limited, since b) predator pressure is generally assumed to be higher in the tropics and c) recent - perhaps unduely generalized - results claim abundance fluctuations in the tropics fully comparable in their dimensions to those in the temperate zone, the question arises as to how these small populations can persist for seemingly long periods of time and avoid rapid extinction. Additionally treated PoInts concern detritivore communities, plant animal Interactions, key stone groups. Saving biodiversity in general and the tropical species and community richness in particular is one of the most urgent tasks of our generation, and biologists have to play a still more prominent role in this extremely important endeavor than they have in the past decades.

Impact of Land Use on Biodiversity Preservation in Nigerian Natural Ecosystems: A Review

Abstract: This paper reviews the effect of rural land use in biodiversity preservation in Nigeria. It argues that the future of effective, biodiversity preservation in natural ecosystems is constrained byfactors arising from overharvesting of resources, population increase, unequal land tenure systems, reliance on wild biotic resources by rural economies, and a land extensive technique of agricultural production. The situation will remain unchanged unless the Nigeria government encourages public participation in natural resources conservation.

Vascular flora of the southern upland property of Paynes Prairie State Preserve, Alachua County, Florida.

Abstract: A taxonomic study of the vascular flora of Paynes Prairie State Preserve was conducted on the 1160 hectare southern upland property adjacent to the southern rim of the prairie basin. Plant communities of this area, forming a dynamic continuum and a changing vegetational mosaic, are typical of northcentral Florida and possess a moderately high degree of biological diversity. Collections of 573 species representing 123 families were made from January 1986 to December 1989 and are compiled in an annotated list. Voucher specimens have been placed in the University of Florida Vascular Plant Herbarium (FLAS). The species list and specimens will provide useful information for park personnel and other persons who are interested in the vascular flora and plant communities of northcentral Florida. INTRODUCTION It was from the uplands bordering the southern rim of Paynes Prairie that in 1774 William Bartram had his first glimpse of the "extensive Alachua savanna ... encircled with high, sloping hills, covered with waving forests and fragrant Orange groves, rising from an exuberantly fertile soil. The towering magnolia grandiflora and transcendent Palm stand conspicuous amongst them...." (W. Bartram 1791). The bluff where Bartram stood, with the vista of the savanna before him, is part of the northern border of the present study area, designated as the southern upland property of Paynes Prairie State Preserve. This property comprises some 1160 hectares of hammock, pine, hardwood-pine, meadow, swamp, and marshlands, as well as a small lake. Although the area has attracted human activity from prehistoric times, a comprehensive floristic investigation of the area has never been conducted, and is the objective of the present study. The study area is located in Alachua County, Florida, approximately eighteen kilometers south of Gainesville, on US highway 441. The area is delimited by the edge of the prairie basin, private property lines, SR 234, 1-75, and US 441 (Figure 1). CLIMATE Alachua County has a subtropical climate, with hot, humid summers and more or less mild, dry winters. Average annual temperature is 20?C, with an average maximum temperature of 33?C and an average minimum temperature 142 CASTANEA VOLUME 55 This content downloaded from 207.46.13.127 on Wed, 12 Oct 2016 04:37:55 UTC All use subject to http://about.jstor.org/terms

Toward a federal plan for biological diversity

Abstract: Recognizing that a wide variety of genes, species, communities and ecosystems are necessary to provide natural resources (food, medicines and shelter) for daily subsistence and the ecological services (climate moderation, nutrient cycling and breakdown of wastes) necessary for survival on earth, policies have been proposed which would conserve these biological resources. The author proposes a strategy that would proceed on four fronts: research, creation of protected areas, utilization of seminatural areas, and recovery of endangered species. He suggests that the United States must make a strong commitment to preserve our own biological diversity if we are to convince developing nations to put off short-term gains for long-term availability of natural resources.