Biodiversity Loss Seen as Harmful as Pollution
Washington - When species in an ecosystem die off, the productivity of the system declines, and the damage done ranks with the harm caused by climate change, pollution or other major forms of environmental stress, according to new research.
This work, made public May 2, is the first comprehensive examination of biodiversity loss as it compares to other forms of environmental decline.
"Some people have assumed that biodiversity effects are relatively minor compared to other environmental stressors," said biologist David Hooper of Western Washington University, the lead author of the paper. "Our results show that future loss of species has the potential to reduce plant production just as much as global warming and pollution.
Previous work has shown that the more biological diversity present in a given system, the greater is the system's productivity. Funded by the Division of Environmental Biology of the National Science Foundation (NSF), this work sought to discover if the corollary would be true - the less the diversity, the less productivity.
"Loss of biological diversity due to species extinctions is going to have major effects on our planet, and we need to prepare ourselves to deal with them," said ecologist Bradley Cardinale of the University of Michigan, another co-author. "These extinctions may well rank as one of the top five drivers of global change."
Hooper, Cardinale and researchers from other institutions in the United States, Canada and Sweden combined ecosystem data from a large number of previously published studies and focused on two system processes - plant growth and the decomposition of dead plants by bacteria and fungi. They built a database from existing research, drawing on almost 200 experiments that examined these processes.
"Within the range of expected species losses, we saw average declines in plant growth that were as large as changes in experiments simulating several other major environmental changes caused by humans," Hooper said. "Several of us working on this study were surprised by the comparative strength of those effects."
For example, plant growth could decline by 5 percent to 10 percent in ecosystems where species loss fell within 21 percent to 40 percent of the species. Where species loss rises over 41 percent, the ecosystem effect became comparable to the effects of climate warming or increased ultraviolet radiation.
The study authors say the findings are strong enough that policymakers should begin to take heed of how adverse effects on biodiversity could have broader consequences, but more research must be done to understand how the combined effects of the environmental problems might alter ecosystems.
The NSF supported the work through the National Center for Ecological Analysis and Synthesis, a research center at the University of California, Santa Barbara, where researchers use existing data to better understand fundamental issues in ecology and allied fields.
(Distributed by the Bureau of International Information Programs, U.S. Department of State.)