Estimating the pollination supply of urban green spaces to determine suitable areas for urban agriculture in the city of Tehran

Identifying urban areas with a high potential for providing pollination is essential for the management of urban agriculture. Urban green spaces have a vital role in providing nesting and foraging habitats for pollinators, and they act as pollinator refuges in cities. Therefore, regions adjacent to green spaces can host agricultural products in dire need of pollinators for their produce. To determine the suitable areas for urban agriculture according to the proximity to urban green spaces, we used two models, the Lonsdorf and the graph theory models. The Lonsdorf model focuses more on the capacity of the patches to support pollinators but graph theory methods on the connectivity between the patches. According to graph theory, a set of patches with functional connectivity for pollinators can lead to the formation of clusters around them. Each of these clusters has a certain potential for supplying pollination for urban agricultural products. Both models estimate the capacity of patches in supplying pollination services based on the distances at which bees can fly. To test the robustness of the results of each model, we perform both models at distances of 500, 700, 1000, and 1500 m as maximum foraging distances of bees. Our results suggested that both models showed similar results in determining suitable areas for urban agriculture. Both models showed that the northern and northeastern regions of Tehran were the most suitable areas for urban agriculture and have a high potential to support the pollinator population. In contrast, the central regions had a low capacity to maintain pollinators for urban agriculture, and had little support from wild bees for pollination. Our results also showed that the conversion of bare lands into green spaces could significantly increase the pollination level in Tehran city.