Landscape effects on crop pollination services: are there general patterns?

Abstract

Pollination by bees and other animals increases the size, quality, or stability of harvests for 70% of leading global crops. Because native species pollinate many of these crops effectively, conserving habitats for wild pollinators within agricultural landscapes can help maintain pollination services. Using hierarchical Bayesian techniques, we synthesize the results of 23 studies - representing 16 crops on five continents - to estimate the general relationship between pollination services and distance from natural or semi-natural habitats. We find strong exponential declines in both pollinator richness and native visitation rate. Visitation rate declines more steeply, dropping to half of its maximum at 0.6 km from natural habitat, compared to 1.5 km for richness. Evidence of general decline in fruit and seed set - variables that directly affect yields - is less clear. Visitation rate drops more steeply in tropical compared with temperate regions, and slightly more steeply for social compared with solitary bees. Tropical crops pollinated primarily by social bees may therefore be most susceptible to pollination failure from habitat loss. Quantifying these general relationships can help predict consequences of land use change on pollinator communities and crop productivity, and can inform landscape conservation efforts that balance the needs of native species and people.

Negative effects of pesticides on wild bee communities can be buffered by landscape context

“…The risks to wild bees associated with habitat loss owing to agricultural intensification are well established [14][15][16][17][18]. By contrast, we know little about the response of wild bee communities to farm-level pesticide exposure within agroecosystems.…”

Indirect interactions between crops and natural vegetation through flower visitors: the importance of temporal as well as spatial spillover

“…A review of 23 studies performed on 16 crops found marked and exponential declines in pollinator visitation rate to crops with distance to natural vegetation (Ricketts et al, 2008).…”

Agroenergy Crops Influence the Diversity, Biomass, and Guild Structure of Terrestrial Arthropod Communities

“…Herbivore biomass was important in explaining predator biomass, and there was no effect of crop type on the relationship (ANOVA: herbivore biomass F 2,56 =20.2, P<0.001, crop type F 2,46 =0.9, P=0.38). These results suggest that the natural enemy community may be responding to the herbivore community in a numerical fashion tion of the surrounding landscape than has previously been recognized [9].…”

“…The historical focus on maximizing agricultural production without accounting for trade-offs with economically important ecosystem services [4] has resulted in degradation of water, soil quality, and biodiversity; increases in arthropod crop pests; and reductions in populations of pollinating insects [4][5][6][7][8][9]. Federal production mandates for next-generation, cellulosic biomass crops in the USA [10] are projected to impact over 100 million ha of land [11], particularly in the grassland biome [12] that has already sustained heavy biodiversity losses associated with conversion to agriculture [13].…”