Meta-analysis: Higher Plant Richness Supports Higher Pollinator Richness Across Many Land Use Types

Global biodiversity declines are attributed to many factors, including landscape fragmentation and vegetation homogenization. These patterns may be exacerbated by the intensification of management in agroecosystems, as management to meet the increasing demand for food, fuel, and fiber often comes at the cost of biodiversity and subsequent ecosystem functions and services. Conserving biodiversity will be necessary to create sustainable agroecosystems capable of optimizing both production and services such as pollination. We conducted a meta-analysis with 109 studies to examine the relationship between plant species richness and pollinator species richness to determine whether higher plant species richness supports higher pollinator species richness, especially in areas prone to biodiversity losses. We found most groups of insect pollinators, including bees, butterflies, flies, moths, and wasps, responded positively to increasing plant species richness, irrespective of location or land use, suggesting the capacity to increase pollinator richness through management strategies that increase plant species richness. However, we found pollinators in manipulated studies did not consistently respond to increasing plant species richness despite the overall positive relationships in observational and experimental studies, highlighting the importance of plant selection when making management decisions aiming to improve pollinator richness. Additional studies in regions such as Africa and South America will help fill in latitudinal gradients and provide greater coverage necessary to refine patterns. Increasing plant species richness through management changes or restorations will likely increase pollinator richness and be beneficial in agroecosystems to support biodiversity.