Forests are often seen as the best stores of carbon. But due to logging, insect pests or fires, decades of carbon stored in the bark and leaves of trees can end up in the atmosphere in a matter of hours. And even in healthy forests, much of the carbon stored in terrestrial vegetation decomposes and returns to the atmosphere as a greenhouse gas in less than a century.
Meanwhile, the soil beneath savannahs and grasslands, where there are few trees but many herbivores, can store carbon for tens of thousands of years in hard-to-reach underground pools. So what’s the point?
A 2009 study found that when gnu antelopes returned to the Serengeti savannah in East Africa in the 1960s after an epidemic, catastrophic forest fires declined markedly. The animals began eating and trampling the vegetation cover that had fuelled the fires in their absence. The abundance of plants and trees in the burned areas gradually recovered to previous levels.
It may seem counterintuitive, but large herbivores and seasonal fires are natural elements of grassland ecosystems. Without antelope, elephants or zebras, small fires become natural disasters.
