Researchers have advocated restoration of abandoned farms to mitigate the effects of climate change.
Rural outmigration leads to abandonment of hundreds of millions of acres of land around the world and this globalization and mechanization is causing less productive lands to be abandoned. While some of these lands may regenerate into natural habitats, helping both to increase biodiversity and absorb atmospheric carbon there are those that do not regenerate without intervention and hence causes loss of possible fertile land resources.
While environmentalists have been optimistic for this process to provide opportunities to restore habitats and sequester carbon, this is unlikely to happen without policy interventions, according to a new study in Science Advances, which shows that much of the land is eventually recultivated.
To see where croplands were being regenerated — and how long the process lasted — the researchers used cutting-edge annual land-cover maps developed from satellite imagery covering 1987 to 2017. Abandonment and recultivation were estimated by tracking individual parcels of cropland through time.
The research team studied images from 11 sites across four continents, including locations in the United States, Brazil, Bosnia and Herzegovina, China, Iraq, Kazakhstan, Belarus, and Russia. Across these regions, cropland was abandoned for reasons ranging from war and conflict to socioeconomic and environmental factors.
Some of the sites were located in the former Soviet Union and abandoned following the geopolitical upheaval of the union’s collapse. Meanwhile, China has active reforestation programs that incentivize the regrowth of forests on marginal agricultural land and is experiencing increasing amounts of rural emigration, like other countries included in the study.
The degree to which cropland abandonment offers environmental opportunities depends on how much is abandoned and how long it stays that way. Unfortunately, after tracking abandonment year by year, the researchers found that a substantial amount of the land they studied was eventually recultivated.
While it varied across sites, land in the former Soviet Union experienced the highest levels of recultivation. Meanwhile, in China’s Shaanxi and Shanxi provinces, land was left abandoned a bit longer, perhaps thanks to the central government’s “Grain for Green Program” that provides financial incentives to reforest cropland.
Overall, most cropland reviewed in the study was left abandoned for only about 14 years on average, which is not long enough to offset substantial amounts of carbon, or become high-quality habitat for wildlife, the researchers said. Within 30 years, their models predict that around 50% of abandoned croplands will be recultivated. In the process, significant environmental benefits will be lost. The recultivation of abandoned croplands at these sites resulted in more than 30% less area abandoned and 35% less carbon sequestered by 2017.
The findings from the Shaanxi and Shanxi provinces, however, provide evidence that incentive programs can succeed. The researchers also proposed that abandoned fields, especially on cropland not necessary for food production, should be turned into protected areas. Ecosystem service programs could provide payments to landowners to abandon their croplands. Or steps could be taken to support sustainable long-term cultivation of certain sites so there is less turnover among fields.