Deforestation: 70 percent of remaining forests less than 800m deep
Seventy percent of forests left on the planet are within 800 meters (0.5 mile) of a forest edge due to land use changes, especially encroaching urban, suburban developments and agriculture, which are causing global declines in biodiversity, according to a new study lead by North Carolina University.
The researchers discovered that very few forest lands are unaffected by some kind of human development.
“The loss of area, increase in isolation, and greater exposure to human land uses along fragment edges initiate long-term changes to the structure and function of the remaining fragments.”
They also conducted major experiments across five continents examining the effects of habitat fragmentation. They found that fragmented habitats reduce the diversity of plants and animals by up to 75 percent, with the smallest, most isolated patches causing the most impact.
“The initial negative effects were unsurprising,” said the corresponding author of the paper, a professor at NC State University. “But I was blown away by the fact that these negative effects became even more negative with time. Some results showed a 50 percent or higher decline in plant and animals species over an average of just 20 years, for example. And the trajectory is still spiraling downward.”
“Data from 76 different studies across the five longest-running experiments were drawn from published and unpublished sources (table S1). We synthesized results according to three fragmentation treatments: reduced fragment area [the focus of Biological Dynamics of Forest Fragments Project (BDFFP), Wog Wog, and Kansas; see Fig. 2 for identifiers of experiments], increased fragment isolation [Savannah River Site (SRS) and Moss], and increased proportion of edge (all experiments). Fragmented treatments were compared directly to non- or less-fragmented habitats that were either larger or connected via structural corridors (table S1).”
“The results were astounding,” said the author. “Nearly 20 percent of the world’s remaining forest is the distance of a football field—or about 100 meters—away from a forest edge. Seventy percent of forest lands are within a half-mile of a forest edge. That means almost no forest can really be considered wilderness.”
Research Article: Habitat fragmentation and its lasting impact on Earth’s ecosystems http://advances.sciencemag.org/content/1/2/e1500052
Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/1/2/e1500052/DC1