A patchwork of intact forest and grazing lands in the Brazilian Amazon. Neil Palmer / CIAT
New research finds that even a few scattered trees on farmland can give a big boost to forest wildlife.
On the edges of the Amazon rainforest, there is a patchwork of farms, pastures, and the remnants of forest that harbor native wildlife. Until recently, experts believed that what mattered for conservation was the size of these arboreal “islands” and their nearness to other forest. But a new study shows that the quality of the surrounding landscape matters too.
For the study, researchers compared the diversity of birds in two settings: forest “islands” created by the spread of farms and actual forested islands in reservoirs that were created by damming rivers. The former hosted a far greater variety of birds when trees were found on surrounding farmland. And the more trees there were, the richer diversity of birds.
An illustration showing the relative number of bird species in forest fragments surrounded by pasture (left) and water (right). Matheus Gadelha.
The research looked not only at the Amazon but at fragmented landscapes in other parts of the Americas, Africa, and Asia. All told, 58 scientists took part in the effort, using on-the-ground surveys, sound monitoring, and satellite imagery to track close to 2,000 species of birds across more than 1,000 forest remnants. They found that a fragment of forest surrounded by farmland might host more than twice as many bird species as a reservoir island of the same size.
The study, published in the Proceedings of the National Academy of Sciences, calls for planting native trees, restoring degraded vegetation, and generally making farmland more hospitable to wildlife.
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