Landscape effects on pollinator communities and pollination services in small-holder agroecosystems
van der Werf, W
Agriculture, Ecosystems and Environment
Reason for embargo
Pollination by insects is key for the productivity of many fruit and non-graminous seed crops, but little is known about the response of pollinators to landscapes dominated by small-holder agriculture. Here we assess the relationships between landscape context, pollinator communities (density and diversity) and pollination of oilseed rape in 18 landscapes with proportions of small-holder farming ranging from 10% to 70% in southern China. To quantify the contribution of pollinators to oilseed rape yield, we manipulated pollinator access in a focal oilseed rape field in each landscape using open and closed cages. The pollinator communities in the focal fields were sampled using pan traps. The abundance of wild pollinators increased significantly with the proportion of cultivated land, but the diversity of the wild pollinator communities declined. The responses of pollinator abundance and diversity to cultivated land were best explained at scales of around 1000 m. The abundance of the unmanaged honey bee Apis cerana was positively associated with the proportion of cultivated land, whereas the abundance of the managed A. mellifera was not. A pollination services index (PSI) was calculated by comparing the reproductive investment in seeds between plants with or without pollinator access. PSI was positively correlated with wild pollinator abundance, but not with the abundance of honeybee species. PSI was also not significantly correlated with the area proportion of cultivated land. Our results indicate that crop dominated landscapes with numerous small fields supported an abundant, but relatively species poor bee community that delivered pollination services to oilseed rape. Conservation of (semi-)natural habitats, however, is important for maintaining the diversity of wild pollinators.
This study was financially supported by the Division for Earth and Life Sciences of the Netherlands Organization for Scientific Research (grant 833.13.004), the National Natural Science Foundation of P.R. China (31660539), the Agricultural Science and Technology Innovation Program (CAAS-ASTIP-2015-IAR), the Cultivation Plan for Young Scientists of Jiangxi Province (20153BCB23014) and External Cooperation Program of the Chinese Academy of Sciences (GJHZ1312).
This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.
Vol. 246, pp. 109 - 116