Evaluation of pollination service supply and demand of agricultural landscape in Changping District, Beijing

The diversity of bees has declined in recent years around the world. This has raised concerns about pollination service, which is closely linked with sustainable agricultural production. To understand the supply and demand of regional pollination service and laid the basis for developing a regional pollination management strategy, we investigated seven common habitat types, which were forest, woodland, grassland, orchard, greenhouse, road boundary, field margin, and one non-habitat land in Changping District of Beijing in 2016. The data including bee (species, flying distance, nesting preference and active season), vegetation (vegetation composition, flowering season, nectar/pollen resources), nesting suitability (soil compaction) and crop area were collected. The supply of pollination service in the study area was evaluated by using the InVEST model, which was based on species composition, flight distance, nesting preference and activity season of wild bees. The model also used data of plant resources and nesting suitability in the habitat to estimate the dependent degree of crops on pollination. The demand for pollination service was evaluated based on planting area and dependence on pollination service of crops. Furthermore, the match between pollination service supply and demand was studies by stacking the levels of supply and demand. The results showed that natural forests were the most suitable habitat for wild bee production, followed by woodlands, grasslands and border habitats. Orchards too were wild bee habitats and also had high demand for pollination service. Greenhouse barely provided pollination service, but had a high demand for it. The supply and demand match results showed that in Changping area, pollination service supply exceeded demand. The areas where supply level was higher than demand level accounted for 34.2%, mostly distributed in mountain areas. The areas with the highest supply and lower demand for pollination service was worthy for protection. The areas with lower supply than demand accounted for 13.9% and were distributed in plain regions near mountains. Although such areas had a relatively high supply, demand was the highest. Areas with the same supply-demand accounted for 51.9%, distributed in plain areas far from mountains. In these areas, the supply and demand for pollination service were basically in balanced match because of the high proportion of semi-natural habitats. Finally, some management strategies were suggested to improve pollination service in the study area. For the areas with higher supply and medium/lower demand (key protected region), it was suggested to develop organic agricultural with less management to protect habitat. For medium/lower supply and higher demand areas (key improved and generally improved regions), it was necessary to improve pollination service by breeding bee and increase nat-ural/semi-natural habitat, and strengthen connectivity among habitats through ecological corridor construction. For the area with balanced supply and demand (key maintained, and generally maintained regions), decreasing management intensity of agricultural area and increasing connectivity among habitats were important for keeping sustainable pollination service supply.