Areas formerly used for agriculture require decades for the biodiversity of the vegetation to recover. Without renaturation measures, this recovery can be delayed even further and often remains incomplete, reports a research team led by the German Center for Integrative Biodiversity Research (iDiv) in the Journal of Ecology.
Agriculture is considered to be one of the main disruptive factors in ecological systems. Land use, including the conversion of natural habitats into agricultural land, is the most important driver of biodiversity loss worldwide.
Species richness still lower after 80 years
The research team studied how biodiversity and species composition are recovering on 17 grasslands in the US state of Minnesota. These areas have historically been plowed and used for agriculture, but use ceased between 1927 and 2015. The researchers compared these set-aside areas with grassland that had never been cultivated.
The areas had not recovered even after 80 years. Compared to the untouched areas, the number of species was on average a third lower. Shortly after the decommissioning, mainly species that were less susceptible to disturbance settled on the old fields. Gradually, plants that were typically found on the untouched areas reappeared. However, there were also 63 native species found exclusively on pristine grasslands.
“By looking closely at how species composition is recovering at different scales, we can get a better understanding of which species might be the focus of restoration and how we can help ecosystems recover,” explains lead researcher Stan Harpole . This can be done, for example, by sowing or planting species that are known not to colonize the old fields by themselves. Land management could also reduce competition between exotic plants and native species.
The results could help to better classify the goals for renaturation, as discussed at international platforms such as the recent UN Biodiversity Conference. (tsp)
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