A Meta-Analysis on the Productive Value of Crop Biodiversity

Biodiversity contributes to the provision of numerous ecosystem services. Several studies have econometrically measured the impact of crop biodiversity using observational data to assess the "productive value" of biodiversity for agriculture. We propose the first meta-analysis of this literature, based on 120 estimates from 32 studies published between 1998 and 2022. We find that the literature reports positive and significant producitve effects of crop biodiversity on agriculture. Our meta-estimate indicates that previous studies found on average that a one percent increase in crop biodiversity increases agricultural production by 0.59%. This average effect, however, hides a large heterogeneity across studies. The variation among estimates can be explained by the presence of structural heterogeneity such as the country of analysis or the use of micro-level data, but also by heterogeneity in research settings. In particular, we find that the choice of the biodiversity indicator is not neutral, with settings using the Shannon index usually finding smaller beneficial productive impacts of biodiversity. We find that, compared to inter-specfic diversity, measurements of intra-specific diversity provide globally higher estimates of the value of biodiversity. Our results also suggest that biodiversity allows farmers to reduce variable costs in addition to its effects on crop production