How might previous land uses still affect restoration efforts today? Associate Editor, Gaowen Yang explores our latest Editor’s Choice research by Nash E. Turley and colleagues.  

Agricultural abandonment can result in many environmental benefits, such as reduction in soil loss, increase in soil nutrient, biodiversity conservation. However, agricultural history has long-lasting effects (also called land-use legacies) on ecosystem recovery. For instance, when compared with nearby remnant grasslands, only three quarters of plant species and half of primary productivity could recover 91 years after agricultural abandonment. What is less well-known is whether restoration practice can mitigate land-use legacies and therefore promote recovery.

In the Editor’s Choice article, Agricultural land-use history and restoration impact soil microbial biodiversity, Turley et al. conducted a large-scale restoration experiment with 126 1ha plots located in 27 sites to investigate the joint effect of agricultural history and restoration thinning on soil microbial diversity. Restoration thinning was implemented by mechanically thinning the overstory to open-canopy conditions in native longleaf pine savannas. They found that agricultural land use from over 60 years ago still increased soil bacterial diversity but decreased soil fungal diversity. Restoration thinning did not overcome land-use legacies in the recovery of soil microbes, although it increased both soil bacterial and fungal diversity.

These results indicate that the methods that recover plant communities (e.g. overstory thinning, reseeding, sowing) can also help to restore soil microbial diversity. The authors’ previous study in the same experimental system found that restoration thinning increased plant species diversity. The increase in plant diversity could promote soil microbial diversity by supporting more host-specific microbes.

However, compared with plant communities, belowground variables, for instance, soil texture, nutrient content, water holding capacity and pH may be more important for structuring soil microbial diversity. Former agricultural land use can alter these belowground variables, which could become limiting factors for restoring soil microbes. These findings indicate that soil improvement may have the potential to improve soil microbial restoration.

Land-use legacies in the recovery of soil microbes may also come from dispersal limitation. A recent study shows dispersal limitation governs soil microbes during reforestation. Therefore, the reintroduction of particular soil microbes (especially soil fungi, e.g. mycorrhizal fungi) or native soil biota as a whole, could be of great importance for soil microbial restoration.

In summary, comprehensive management, including revegetation, soil improvement, and reintroduction of soil microbes, might be a useful for rapid and successful restoration.

The full Editor’s Choice article, Agricultural land-use history and restoration impact soil microbial biodiversity is free to read for a limited time in Journal of Applied Ecology.