Conservation of wildlife. A bio-economic model of a wildlife reserve under the pressure of habitat destruction and harvesting outside the reserve.

Biodiversity is today threatened by many factors of which destruction and reduction of habitats are considered most important for terrestrial species. One way to counteract these threats is to establish reserves with restrictions on land-use and exploitation. However, very few reserves can be considered islands, wildlife species roam over large expanses, often via some density dependent dispersal process. As a consequence, habitat destruction, and exploitation, taking place outside will influence the species abundance inside the conservation area. The paper presents a theoretical model for analysing this type of management problem. The model presented allows for both the common symmetric dispersal as well as what is called asymmetric dispersal between reserve and outside area. The main finding is that habitat destruction outside may not necessarily have negative impact upon the species abundance in the reserve. As a consequence, economic forces working in the direction of reducing the surrounding habitat have unclear effects on the species abundance within the protected area. We also find that harvesting outside the reserve may have quite modest effect on the species abundance in the reserve. This underlines the attractiveness of reserves from a conservation viewpoint.

Fact sheet: Conserving rare plants in national parks and protected areas

Plant species are typically rare due to human activities such as habitat destruction, overharvesting, and introduction of exotic species. These specialized habitat requirements restrict the species to small portions of the landscape or combinations of both (Kruckeberg and Rabinowitz 1985). Protected areas such as national parks frequently are refugia for rare species. However, even when protected from wholesale habitat destruction due to construction or land development, habitat in these protected areas is threatened by many of the same factors such as climate change, fire-regime disruption, and exotic species encroachment (Falk et al. 1996)

Extinction Debt in Source-Sink Metacommunities

In an increasingly modified world, understanding and predicting the consequences of landscape alteration on biodiversity is a challenge for ecologists. To this end, metacommunity theory has developed to better understand the complexity of local and regional interactions that occur across larger landscapes. While metacommunity ecology has now provided several alternative models of species coexistence at different spatial scales, predictions regarding the consequences of landscape alteration have been done exclusively for the competition-colonization trade off model (CC). In this paper we investigate the effects of landscape perturbation on source-sink metacommunities. We show that habitat destruction perturbs the equilibria among species competitive effects within the metacommunity, driving both direct extinctions and an indirect extinction debt. As in CC models, we found a time lag for extinction following habitat destruction that varied in length depending upon the relative importance of direct and indirect effects. However, in contrast to CC models, we found that the less competitive species are more affected by habitat destruction. The best competitors can sometimes even be positively affected by habitat destruction, which corresponds well with the results of field studies. Our results are complementary to those results found in CC models of metacommunity dynamics. From a conservation perspective, our results illustrate that landscape alteration jeopardizes species coexistence in patchy landscapes through complex indirect effects and delayed extinctions patterns

Managing soil biodiversity: The New Zealand experience

Species diversity is a very important component of a healthy soil ecosystem, and a necessary condition for long-term sustainable development. However, it is widely recognised that soil degradation and species extinction are on the increase in New Zealand, as land resources come under pressure from urban expansion and modern agribusiness. New Zealand's soils, flora and fauna have evolved many unique elements during their long isolation from other land masses. Habitat destruction and introduced plants and animals have, therefore, had increasingly detrimental effects on indigenous biodiversity. New Zealand must conserve what remains

The role of asymmetric interactions on the effect of habitat destruction in mutualistic networks

Plant-pollinator mutualistic networks are asymmetric in their interactions: specialist plants are pollinated by generalist animals, while generalist plants are pollinated by a broad involving specialists and generalists. It has been suggested that this asymmetric ---or disassortative--- assemblage could play an important role in determining the equal susceptibility of specialist and generalist plants under habitat destruction. At the core of the argument lies the observation that specialist plants, otherwise candidates to extinction, could cope with the disruption thanks to their interaction with generalist pollinators. We present a theoretical framework that supports this thesis. We analyze a dynamical model of a system of mutualistic plants and pollinators, subject to the destruction of their habitat. We analyze and compare two families of interaction topologies, ranging from highly assortative to highly disassortative ones, as well as real pollination networks. We found that several features observed in natural systems are predicted by the mathematical model. First, there is a tendency to increase the asymmetry of the network as a result of the extinctions. Second, an entropy measure of the differential susceptibility to extinction of specialist and generalist species show that they tend to balance when the network is disassortative. Finally, the disappearance of links in the network, as a result of extinctions, shows that specialist plants preserve more connections than the corresponding plants in an assortative system, enabling them to resist the disruption.Comment: 14 pages, 7 figure

Shipping Through Sea Ice: Impacts on Marine Habitats and Best Practices

As the result of Arctic climate change and an increase in shipping season length, there is a growing interest in Arctic shipping operations. Sea ice serves as an important habitat for marine mammals, therefore, shipping through sea ice could lead to increased negative interactions with ice-bound marine mammals. The following literature review discusses the impacts of icebreaking on marine mammals and habitats. These impacts include: avoidance of areas where icebreaking is occurring, behavioral and physiological impacts of increased anthropogenic noise, entrapment, habitat destruction and fragmentation, and oil spills

Extinctions of aculeate pollinators in Britain and the role of large-scale agricultural changes

Pollinators are fundamental to maintaining both biodiversity and agricultural productivity, but habitat destruction, loss of flower resources, and increased use of pesticides are causing declines in their abundance and diversity. Using historical records we assessed the rate of extinction of bee and flower-visiting wasp species in Britain, from the mid 19th century to the present. The most rapid phase of extinction appears to be related to changes in agricultural policy and practice beginning in the 1920s, before the agricultural intensification prompted by the Second World War, often cited as the most important driver of biodiversity loss in Britain. Slowing of the extinction rate from the 1960s onwards may be due to prior loss of the most sensitive species and/or effective conservation programs

Epilogue

The Environmental Responsibility Reader is a definitive collection of classic and contemporary environmental works that offers a comprehensive overview of the issues involved in environmental responsibility, steering the reader through each development in thought with a unifying and expert editorial voice. This essential text expertly explores seemingly intractable modern-day environmental dilemmas - including climate change, fossil fuel consumption, fresh water quality, industrial pollution, habitat destruction, and biodiversity loss. Starting with "Silent Spring" and moving through to more recent works the book draws on contemporary ideas of environmental ethics, corporate social responsibility, ecological justice, fair trade, global citizenship, and the connections between environmental and social justice; configuring these ideas into practical notions for responsible action with a unique global and integral focus on responsibility

A Creation Perspective on Economics, Ecology and Environment

This paper discusses the creation perspective on economics, ecology and the environment and looks at the problems of species extinction, habitat destruction, land degradation, and pollution of the waters and the atmosphere