Influence of landscape and plant community attributes on pollinators and pollination interactions in the Po Valley.

Abstract

Human activities have caused changes in biodiversity faster in the last 50 years than ever before, leading to changes in ecosystem functioning and services and the extinction of many species. Pollination is one of the most valuable ecosystem services and has received much international attention in recent years. Almost 90% of plant species worldwide are pollinated by animals, which has an economic value of $0.4 trillion. However, a decline in pollinator populations has been observed in recent decades, mainly due to landscape fragmentation and the decline of floral resources. In areas where these factors are more pronounced, such as the Po Valley, the loss of pollinators is even greater. To assess plant-pollinator interactions in the Venetian portion of the Po Valley, 39 georeferenced plots were placed and monitored in 2022, recording plant and pollinator species, number of visits and floral abundance. Plots were divided into two groups using a cluster analysis based on the buffers created around the sampling plots. Based on the landscape data, one cluster included agricultural sites and the other urban sites. For the agricultural sites, richness of pollinators and number of visits showed a positive relationship with richness of flowering species. For the urban sites, on the other hand, flowering species richness, number of floral displays, and number of visits were positively related to the surface of urban green space. Furthermore, pollinator richness showed a hump-shaped relationship with flowering species richness, and the same relationship was found between the number of visits and the number of floral displays. These results highlight the importance of green spaces within cities and how rural areas need to be improved.