Land abandonment is common in the Mediterranean Basin, a global biodiversity hotspot, but little is known about its impacts on biodiversity. To upscale existing case-study insights to the Pan-Mediterranean level, we conducted a meta-analysis of the effects of land abandonment on plant and animal species richness and abundance in agroforestry, arable land, pastures, and permanent crops of the Mediterranean Basin. In particular, we investigated (1) which taxonomic groups (arthropods, birds, lichen, vascular plants) are more affected by land abandonment; (2) at which spatial and temporal scales the effect of land abandonment on species richness and abundance is pronounced; (3) whether previous land use and current protected area status affect the magnitude of changes in the number and abundance of species; and (4) how prevailing landforms and climate modify the impacts of land abandonment. After identifying 1240 potential studies, 154 cases from 51 studies that offered comparisons of species richness and abundance and had results relevant to our four areas of investigation were selected for meta-analysis. Results are that land abandonment showed slightly increased (effect size = 0.2109, P<0.0001) plant and animal species richness and abundance overall, though results were heterogeneous, with differences in effect size between taxa, spatial-temporal scales, land uses, landforms, and climate. In conclusion, there is no “one-size-fits-all” conservation approach that applies to the diverse contexts of land abandonment in the Mediterranean Basin. Instead, conservation policies should strive to increase awareness of this heterogeneity and the potential trade-offs after abandonment. The strong role of factors at the farm and landscape scales that was revealed by the analysis indicates that purposeful management at these scales can have a powerful impact on biodiversity.

Li, W., and L. Huntsinger. 2011. China’s grassland contract policy and its impacts on herder ability to benefit in Inner Mongolia: tragic feedbacks . Ecology and Society 16(2): 1. https://doi.org/10.5751/ES-03969-160201

Huntsinger, L., and J. L. Oviedo. 2014. Ecosystem services are social–ecological services in a traditional pastoral system: the case of California’s Mediterranean rangelands. Ecology and Society 19(1): 8.http://dx.doi.org/10.5751/ES-06143-190108

Plieninger, T., L. Flinzberger, M. Hetman, I. Horstmannshoff, M. Reinhard-Kolempas, E. Topp, G. Moreno, and L. Huntsinger. 2021. Dehesas as high nature value farming systems: a social-ecological synthesis of drivers, pressures, state, impacts, and responses. Ecology and Society 26(3):23. https://doi.org/10.5751/ES-12647-260323

California ranchers in urban Alameda and Contra Costa Counties, and in rural Tehama County, were surveyed to examine effects of increasing development, land use...