Lessons from four global meta-analysis on biodiversity and ecosystem services restoration

Abstract

Ecological restoration is often carried out to recover biodiversity and ecosystem services (ES) of degraded ecosystems. In general, the outcomes of ecological restoration can be assessed as the recovery progress or the recovery completeness of indicators of ecological integrity in the restored state against the degraded or reference states, respectively. Here we present the results of four global meta-analyses previously published to assess these outcomes in a wide range of ecosystem types, wetlands, agroecosystems, and forests. For all ecosystem types, ecological restoration increased provision of biodiversity and ES by 58 and 59%, respectively; however, values of both remained lower in restored versus intact reference ecosystems (-10 and -8%, respectively). Levels of recovery varied among ecosystem types. Restored wetlands showed 19 and 43% higher levels of biodiversity and ES, respectively, than did degraded wetlands; however, their levels of ES were lower (-13%) than in reference wetlands. Restoration increased biodiversity and levels of supporting ES and regulating ES by an average of 68, 42, and 120%, respectively, relative to levels in the pre-restoration agroecosystem, and restored agroecosystems showed levels of biodiversity and these ES similar to those of reference ecosystems. Recovery was complete for all ES, whereas biodiversity, although it increased by 106% after restoration, was 21% lower than in reference forests. There is gap related to quantitative assessment of cultural ES provided by restored ecosystems in the scientific literature. Biodiversity and ES response ratios positively correlated in comparisons of restored and degraded ecosystems in all individual meta-analysis. We conclude that ecological restoration markedly enhances biodiversity and ES supply, but the attained levels are lower than those in the reference ecosystems and effectiveness is context dependent to a large extent.