December 19, 2010
Examining ten forest fragments in Brazil's Atlantic Forest, researchers have undercut the theory that the climate of forest fragment' is driven by the edge-effect. Writing in mongabay.com's open source journal Tropical Conservation Science, researchers found that edge-effect was too simple to explain the microclimate of isolated forest fragments from 3 to 3,500 hectares large, each at least 80-years-old.
After a forest is fragmented heat and moisture are exchanged occur between the forest and the outlying area, causing the forest near the border to get warmer and drier. This impact, known as the edge-effect, in turn negatively impacts biodiversity and forest survival. However, it "is not sufficiently robust to explain the environmental changes faced by old-forest fragments, even in a highly homogeneous matrix consisting of sugar-cane fields," the researchers write.
Instead, measuring air temperature, humidity, vapor, and light, researchers found that other conditions play a bigger role in the microclimate, most importantly the percentage of forest cover and the size of the fragment.
"Each fragment appears to exhibit a particular or even idiosyncratic pattern of [its microclimate] in response to fragment size and percentage of forest cover around it," the researchers write.
Once the second greatest tropical forest of South America—after the Amazon—the Atlantic Forest is today one of the world's most endangered ecosystems. Less than 7 percent of the Atlantic Forest remains and most of what remains is degraded and fragmented. In addition, every year forest cover continues to fall.
According to the study Brazil should focus on "protecting large areas and preventing further fragmentation of continuous large patches" in the Atlantic Forest.