Population viability analysis

About: Population viability analysis is a research topic. Over the lifetime, 976 publications have been published within this topic receiving 39572 citations. The topic is also known as: Population viability analyses.

Minimum Population Sizes for Species Conservation

Abstract: Many species cannot survive in mandominated habitats. Reserves of essentially undisturbed habitat are necessary if such species are to survive in the wild. Aside from increased efforts to accelerate habitat acquisition for such species, the most pressing need facing conservationists is development of a predictive understanding of the relationship between a population's size and its chances of extinction. Biologists have long known that the smaller the population, the more susceptible it is to extinction from various causes. During the current era of heightened competition for use of the world's remaining wildlands, this qualitative understanding is of limited utility to conservation and natural resource planners. The old adage that "the bigger the reserve, the better" must be replaced with more precise prescriptions for how much land is enough to achieve conservation objectives. Efforts at making such determinations have been clouded by inconsistencies in the focus on the unit to be preserved (population, species, community, ecosystem) and lack of an explicit definition of what constitutes successful preservation (persistence for 10, 100, 1000 years, etc.). The intricate interdependencies of living things dictate that conservation efforts be focused on the community and ecosystem level. Unfortunately, the very magnitude of complexity of these systems makes such efforts difficult. Moreover, certain species are more sensitive than others to changing conditions and begin to decline prior to any noticeable degradation of the community to which they belong. Consequently, conservation efforts have been and, in many cases, will continue to be at the singlespecies level. Many species currently in jeopardy are large-bodied and/or specialized, two characteristics that usually

Quantitative conservation biology : theory and practice of population viability analysis

Abstract: Preface - What Is PVA, and How Can It Be Used in Conservation Decision-making? - The Causes and Quantification of Population Vulnerability - Count-based PVA: Density-independent Models - Count-based PVA: Incorporating Density Dependence, Demographic Stochasticity, Correlated Environments, Catastrophes and Bonanzas - Accounting for Observation Error in Count-based PVAs - Demographic PVAs: Using Demographic Data to Build Stochastic Projection Matrix Models - Demographic PVAs: Using Projection Matrices to Assess Population Growth and Viability - Demographic PVAs Based on Vital Rates: Removing Sampling Variation and Incorporating Large Variance, Correlated Environments, Demographic Stochasticity, and Density Dependence into Matrix Models - Using Demographic PVA Models in Management: Sensitivity and Elasticity Analysis - Multi-site PVAs: The Interaction of Dispersal and Environmental Correlation - Multi-site PVAs: Methods of Analysis for Spatially Complex Populations - Critiques and Cautions: When to Perform (and When Not to Perform) a PVA - References

On the Use of Demographic Models of Population Viability in Endangered Species Management

Abstract: We examine why demographic models should be used cautiously in Population Viability Analysis (PVA) with endangered species. We review the structure, data requirements, and outputs of analytical, deterministic single-population, stochastic single-population, metapopulation, and spatially explicit models. We believe predictions from quantitative models for endangered species are unreliable due to poor quality of demographic data used in most applications, difficulties in estimating variance in demographic rates, and lack of information on dispersal (distances, ages, mortality, movement patterns). Unreliable estimates also arise because stochastic models are difficult to validate, environmental trends and periodic fluctuations are rarely considered, the form of density dependence is frequently unknown but greatly affects model outcomes, and alternative model structures can result in very different predicted effects of management regimes. We suggest that PVA (1) evaluate relative rather than absolute rates of extinction, (2) emphasize short-time periods for making projections, (3) start with simple models and choose an approach that data can support, (4) use models cautiously to diagnose causes of decline and examine potential routes to recovery, (5) evaluate cumulative ending functions and alternative reference points rather than extinction rates, (6) examine all feasible scenarios, and (7) mix genetic and demographic currencies sparingly. Links between recovery options and PVA models should be established by conducting field tests of model assumptions and field validation of secondary model predictions.

Population Viability Analysis

Abstract: The Northern spotted owl is a small, predatory bird native to the coniferous forests of the Pacific Northwest. Its preferred habitats are the old-growth forest communities of that region. These habitats have been extensively logged during the last century, reducing both the quantity of habitat available to this subspecies of owl and greatly increasing the fragmentation of remaining habitat. Population Viability Analysis (PVA) is intended to be a structured, systematic and comprehensive examination of the interacting factors that place a population at risk of chance extinction, especially as these relate to population size and distribution. The number of species listed as threatened or endangered is expected to grow rapidly in the coming decades, primarily because of loss of habitat. There are many habitat-limited species, such as narrowly endemic plants and some sedentary invertebrates that occur in low numbers or few sites that a PVA is superfluous.