Date Published: 3 November 2017
Fragmenting forest landscapes reduces the extent of deep forest while creating more forest edges. There are 'winner' and 'loser' species ...
When human activity splits areas of rainforest into ever-smaller regions separated by areas of land managed for agricultural, commercial or other purposes, more forest-dwelling species tend to live at the edge of the areas of forest. Forest edges differ from the deep core of the forest in various ways e.g. there is more light, less moisture and often higher temperatures. As forests are fragmented the deep forest becomes a smaller proportion of the total. Recent research1 indicates that such fragmentation of landscape changes the biodiversity of valuable natural spaces, threatening some species with extinction while others thrive at the increasing extent of forest edges. (For a short simple overview of this important issue see the animation at the bottom of this page.)
Dr Marion Pfeifer, lead author of the recent research study, now based at Newcastle University (England), explained2 :
" Tropical forests, and the animals they harbour, are being lost at alarming rates but in order to protect them we need to know exactly how fragmentation of the land is impacting on the animals that live there.
_ This is critical for the hundreds of species that we identified as being clearly dependent on intact forest core areas - that is forest which is at least 200-400m from the edge.
_ These include species such as the Sunda pangolin (Manis javanica), the Bahia Tapaculo (Eleoscytalopus psychopompus), the Long-billed Black Cockatoo (Zanda baudinii) and Baird's tapir (Tapirus bairdii).
_ These species were highly sensitive to the changing habitat and therefore more likely to disappear in landscapes that encompass only a small proportion of intact forest."
The researchers, whose affiliations include universities and other organizations in the UK, Sweden, Mexico, Guatemala, USA, Brazil, Belgium, Colombia, South Africa, Canada, Germany and France, collected species' abundance data from 22 fragmented landscapes in seven major biogeographic realms, including tropical and temperate forests. They analyzed over 1,500 species of mammals, birds, reptiles and amphibians. The study found that 85% of species are being impacted by this forest fragmentation.
When describing their findings the researchers identified some species as 'winners'. They are the ones that seek out, hence seem to prefer, the forest edge and therefore benefit from increased space as a result of forest fragmentation. They identified other species as 'losers', those being the ones that inhabit the core of the forest ('deep forest') and whose habitat is being sadly being reduced by human activity. The scientists hope to use information about which species are most at risk from changing forest habitats to inform conservation and forest restoration work.
Prof Robert Ewers of Imperial College London, a co-author of the study, explained2:
" About half of species win from the forest change; they like the edges and so avoid the deep forest, preferring instead to live near forest edges.
_ The other half lose; they don't like the edges and instead hide away in the deep forest. The winners and losers aren't equal though. Some of the species that like edges are invasive like the boa constrictor, while the ones huddled into the deep forest are more likely to be threatened with extinction – like the Sunda pangolin."