Grasslands Take 300+ Years to Recover Original Plant Communities After Farming

A grassland can look green and alive again within years of being abandoned by farmers. But beneath that surface recovery lies a stubborn problem: the plants that come back are often not the plants that were there before. A global analysis of 742 plant species, published this month in the Proceedings of the National Academy of Sciences, found that grasslands regrowing after farming remain fundamentally different from ancient grasslands that were never plowed—and this difference can persist for more than three centuries.

The study compared old-growth grasslands across six continents with secondary grasslands at various stages of recovery. The pattern was consistent everywhere: recovering grasslands fill with tall, fast-growing plants that reproduce quickly and capture resources efficiently. Ancient grasslands, by contrast, are dominated by slow-growing perennials with tough, leathery leaves—plants built to endure drought, fire, and grazing. When land is plowed, those hardy species disappear. The survival traits that made them resilient in undisturbed grasslands become a liability in the scramble to recolonize bare ground. They cannot compete with the speed of aggressive annuals and fast-reproducing species that flood in after disturbance.

The difference shows up in specific plants. Wiregrass, a drought-tolerant perennial that characterizes pine savannas in the southeastern United States, is not a defining feature of secondary grasslands. Instead, regrowing sites are dominated by fast-reproducing annuals like white goosefoot, which outcompete for water and nutrients. Plants in recovering grasslands also tend to grow taller, giving them an edge in the race for sunlight. Once established, this advantage compounds: each generation reproduces the same way, and the fast-growing species quickly take over.

What makes this finding significant is its persistence. In one documented case, plants in secondary grasslands remained taller than their old-growth counterparts even after 300 years of recovery. This matters because grasslands are not merely open land without trees. Their root systems reduce runoff and erosion. They store roughly a third of Earth's terrestrial carbon. They support livestock and distinctive wildlife—from American bison to African wildebeests to Asia's great bustards. Nearly a quarter of Earth's land is grassland, and more than a billion people depend on grasslands for their livelihoods. The Eurasian steppe stretches roughly 5,000 miles from Hungary to China. North America's Great Plains and the African savanna represent some of the planet's most expansive ecosystems.

Yet many ancient grasslands have vanished in the past two centuries. Brazil's Cerrado, one of the world's most biodiverse grasslands, loses an area the size of London every three months. India's savannas shrank from 100 million acres in 1880 to 60 million acres by 2010. Less than half of North America's historical grassland acreage remains. At the same time, millions of acres of farmland are being abandoned worldwide, creating opportunities for grasslands to regrow. This raises a pressing question: if grass returns, does the original ecosystem return with it?

The research suggests the answer is often no—at least when measured by the plants that characterize the landscape. Ashish Nerlekar, the study's lead author and a postdoctoral researcher at Michigan State University, noted that secondary grasslands can take decades to regain the biodiversity of ancient grasslands, and even after centuries of regrowth, some plant species remain missing. The researchers do not yet know what these lasting shifts mean for ecosystem functions like carbon storage or nutrient cycling. More work is needed to determine whether secondary grasslands perform those functions differently from old-growth systems.

The findings have immediate practical implications for restoration. Allowing previously cultivated land to recover on its own may not recreate the plant community that existed before farming. Lars Brudvig, a Michigan State professor and co-author of the study, said that active intervention—sowing seeds and transplanting species—may be necessary if the goal is to restore secondary grasslands to function like old-growth ones. The research also underscores a harder truth: preserving and conserving existing ancient grasslands matters because what is lost does not quickly return.