Loss of Biodiversity, Food Chains Can Hamper Carbon Sequestration
Animal biodiversity—including strategies to preserve top predators to prevent over-grazing by herbivores—could be an overlooked tool in the effort to sequester carbon and control climate change.
In a post on Yale Environment 360, population and community ecology specialist Oswald J. Schmitz traces the wildfires and resulting net carbon emissions that swept East Africa’s Serengeti grassland in the mid-20th century, when disease and poaching almost wiped out the region’s majestic wildebeest population.
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“The wildebeest decline and recovery taught a valuable lesson, not only in how easy it is to lose an iconic animal species but, more importantly, how the loss of a single species can have far-reaching ramifications for ecosystems—and the climate,” Schmitz writes. With the wildebeest restored, thanks to efforts to eradicate disease and control poaching, “grazing now causes much of the carbon in grass to be released as animal dung, which is in turn incorporated by insects into soil reservoirs that are not prone to burning. The Serengeti ecosystem has now reverted to a carbon dioxide sink so large that it is estimated to offset all of East Africa’s current annual fossil fuel carbon emissions.”
The takeaway is not that any single species is essential to a region’s carbon budget, but that changes to food chains can have unexpected impacts.
“Recent studies have shown, for example, that the loss of important predators—from wolves in boreal forests to sharks in seagrass meadows—can lead to growing populations of terrestrial and marine herbivores, whose widespread grazing reduces the ability of ecosystems to absorb carbon,” Schmitz explains. Yet “the impact of biodiversity loss on the climate system is underappreciated, and reversing that loss is rarely considered as an effective tool to help slow the build-up of atmospheric carbon dioxide.”