Hundreds of millions of acres of land are now being abandoned throughout the world as a result of “rural outmigration,” or people moving to urban areas.
Some people leave in pursuit of a better life financially. Others are displaced as a result of conflict or climate change. These demographic movements, combined with globalization and mechanization, are affecting the economics of farming in these places, forcing less productive land to be abandoned.
Some of these croplands ultimately regenerate into natural ecosystems, increasing biodiversity and absorbing carbon from the atmosphere. While environmentalists had hoped that this process would give the opportunity to restore ecosystems and capture carbon, a recent study published in Science Advances indicates that much of the land is eventually recultivated, indicating that this is unlikely to happen without governmental interventions.
As people move from rural areas into cities, there is a chance for wildlife and the climate to gain ground—literally—as abandoned farms and pastures revert back to forests and grasslands. Our work shows that this is not happening because the ‘abandoned’ lands are being rapidly recultivated.
David Wilcove, Study Co-Author and Professor, Ecology and Evolutionary Biology and Public Affairs, High Meadows Environmental Institute, Princeton University
The degree to which agricultural abandonment provides environmental benefits is determined by how much land is abandoned and how long it remains abandoned. Unfortunately, the researchers discovered that a significant portion of the land they surveyed was finally recultivated after tracking abandonment year by year.
Land in the former Soviet Union had the highest levels of recultivation, although it varied by site. Meanwhile, the land was left abandoned for a little longer in China’s Shaanxi and Shanxi provinces, possibly due to the central government’s “Grain for Green Program,” which gives financial incentives to reforest crops.
Overall, most of the crops included in the study were abandoned for just 14 years on average, according to the researchers, which is not long enough to offset significant quantities of carbon or provide high-quality habitat for wildlife.
Their calculations project that about half of all abandoned croplands will be recultivated in the next 30 years. Important environmental benefits will be lost in the process.
By 2017, the re-cultivation of abandoned crops at these sites resulted in more than 30% less land abandoned and 35% less carbon stored.
The data shows that incentive schemes can be successful.
The researchers also suggested that abandoned fields, particularly those in non-food-producing agriculture, can be transformed into protected zones. Landowners might be compensated for abandoning their croplands under ecosystem service schemes. Alternatively, initiatives might be done to encourage long-term cultivation of selected areas, resulting in decreased field turnover.
Without incentives for restoration, cropland abandonment rarely lasts long enough to yield benefits for biodiversity or carbon sequestration. For abandoned croplands to reach levels of carbon stocks and biodiversity comparable to more intact natural ecosystems, they typically need at least 50 years of regeneration.
Christopher Crawford, PhD Candidate, Princeton School of Public and International Affairs, Princeton University
The study’s co-authors include Kent State University’s He Yin and University of Wisconsin-Volker Madison’s C. Radeloff.
Crawford, C. L., et al. (2022) Rural land abandonment is too ephemeral to provide major benefits for biodiversity and climate. Science Advances. doi.org/10.1126/sciadv.abm8999.