New study by HUCE Environmental Fellow Elsa Ordway and co-author Greg Asner of ASU mapped and measured "edge effects" on rainforests
By Marina N. Bolotnikova
Last summer—seemingly a lifetime ago—the news was dominated by reports of the escalation of human-created fires in the Amazon rainforest. For many readers, the Amazon fires brought awareness not just of the immense suffering deforestation inflicts on the people and animals who live there, but also of tropical rainforests' role in maintaining a stable climate for the planet. Tropical forests hold about 25 percent of the world's carbon in their trees and other plant species; when they're burned, all of that carbon is emitted into the atmosphere—and all of the vegetation that acted as "carbon sinks" to absorb carbon disappears. Without rainforests, climate scientists warn, the global-warming consequences could be catastrophic.
Yet rainforest destruction continues unabated, not just in the South American Amazon, but also in Sub-Saharan Africa and Southeast Asia, to clear land for the cultivation of beef, timber, and oil crops like soy and oil palm. And deforestation doesn't just impact species on the tracts that are directly burned—it's also harmful to neighboring forestland still left standing in ways that scientists are only beginning to understand. In a study published this week in the Proceedings of the National Academy of Sciences, Elsa Ordway, a postdoctoral fellow at the Harvard University Center for the Environment, and co-author Greg Asner of Arizona State University mapped and measured these "edge effects" on rainforests that border oil-palm plantations in Malaysian Borneo. Forestland that was within about 100 meters of a boundary with a plantation, they found, showed a 22 percent decline in above-ground carbon compared to forest interiors, reflecting a reduced ability for trees there to store carbon.