【生物多様性】森林の林縁に生息する動物種の個体数減少傾向

Human-induced forest fragmentation is having a global impact on the abundance of vertebrate species that live in forest edges, reveals a paper published online in Nature this week. The findings may have policy implications and may help researchers to predict how biodiversity is likely to change in response to large-scale forest loss and fragmentation.

The ongoing fragmentation of the world’s forests is affecting biodiversity both directly, through the loss of core forest habitat, and indirectly, through the creation of edge areas. Today, approximately half of the world’s forest lies within 500 metres of a forest edge. Marion Pfeifer and colleagues assessed the impact of human-induced forest fragmentation on the abundance of 1,673 species of mammals, birds, reptiles and amphibians around the globe, and found that 85% of all vertebrate species are affected by forest edges. As a result, the community of animals that persists near edges bears little resemblance to that found in the forest core, and half of the world’s forests now house disrupted vertebrate populations. In particular, the researchers find that 11%, 30%, 41% and 57% of bird, reptilian, amphibian and mammalian species, respectively, show strong declines in abundance towards forest edges.

The authors use a new method, which accounts for the continuous changes in habitat quality across fragmented landscapes. This makes their analysis markedly different from previous global analyses of biodiversity responses to land-use changes, which did not incorporate these gradations of change.