Complex agricultural landscapes host more biodiversity than simple ones: A global meta-analysis

Significance

Agricultural land, the world’s largest human-managed ecosystem, forms the matrix that connects remnant and fragmented patches of natural vegetation where nondomesticated biodiversity struggles to survive. Increasing the resources that this matrix can offer to biodiversity is critical to halting biodiversity loss. Our comprehensive meta-analysis demonstrates the positive and significant effect on biodiversity of increasing landscape complexity in agricultural lands. We found more biodiversity in complex landscapes, potentially contributing to agriculture production, ecosystem resilience, and human well-being. Current biodiversity conservation strategies tend to focus on natural ecosystems, often ignoring opportunities to boost biodiversity in agricultural landscapes. Our findings provide a strong scientific evidence base for synergistically managing agriculture at the landscape level for biodiversity conservation and sustainable production.

Abstract

Managing agricultural landscapes to support biodiversity conservation requires profound structural changes worldwide. Often, discussions are centered on management at the field level. However, a wide and growing body of evidence calls for zooming out and targeting agricultural policies, research, and interventions at the landscape level to halt and reverse the decline in biodiversity, increase biodiversity-mediated ecosystem services in agricultural landscapes, and improve the resilience and adaptability of these ecosystems. We conducted the most comprehensive assessment to date on landscape complexity effects on nondomesticated terrestrial biodiversity through a meta-analysis of 1,134 effect sizes from 157 peer-reviewed articles. Increasing landscape complexity through changes in composition, configuration, or heterogeneity significatively and positively affects biodiversity. More complex landscapes host more biodiversity (richness, abundance, and evenness) with potential benefits to sustainable agricultural production and conservation, and effects are likely underestimated. The few articles that assessed the combined contribution of linear (e.g., hedgerows) and areal (e.g., woodlots) elements resulted in a near-doubling of the effect sizes (i.e., biodiversity level) compared to the dominant number of studies measuring these elements separately. Similarly, positive effects on biodiversity are stronger in articles monitoring biodiversity for at least 2 y compared to the dominant 1-y monitoring efforts. Besides, positive and stronger effects exist when monitoring occurs in nonoverlapping landscapes, highlighting the need for long-term and robustly designed monitoring efforts. Living in harmony with nature will require shifting paradigms toward valuing and promoting multifunctional agriculture at the farm and landscape levels with a research agenda that untangles complex agricultural landscapes’ contributions to people and nature under current and future conditions.