Biodiversity in Organic Farmland – How Does Landscape Context Influence Species Diversity in Organic Vs. Conventional Agricultural Fields?

Abstract:

The most important current driver of biodiversity loss is the conversion of natural habitats for human land uses, mostly for the purpose of food production. However, by causing this biodiversity loss, food production is eroding the very same ecosystem services (e.g. pollination and soil fertility) that it depends on. We therefore need to adopt more wildlife-friendly agricultural practices that can contribute to preserving biodiversity. Organic farming has been shown to typically host higher biodiversity than conventional farming. But how is the biodiversity benefit of organic management dependent on the landscape context farms are situated in? To implement organic farming as an effective means for protecting biodiversity and enhancing ecosystem services we need to understand better under what conditions organic management is most beneficial for species.

We conducted a meta-analysis of the literature to answer this question, compiling the most comprehensive database to date of studies that monitored biodiversity in organic vs. conventional fields. We also collected information about the landscape surrounding these fields from remote sensing products. Our database consists of 348 study sites across North America and Europe.

Our analysis shows that organic management can improve biodiversity in agricultural fields substantially. It is especially effective at preserving biodiversity in homogeneous landscapes that are structurally simplified and dominated by either cropland or pasture. In heterogeneous landscapes conventional agriculture might instead already hold high biodiversity, and organic management does not appear to provide as much of a benefit for species richness as in simplified landscapes.

Our results suggest that strategies to maintain biodiversity-dependent ecosystem services should include a combination of pristine natural habitats, wildlife-friendly farming systems like organic farming, and high-yielding conventional systems, interspersed in structurally diverse, heterogeneous landscapes.