Contrasting Response of Mountain Plant-Pollinator Network to Fragmented Semi-Natural Grasslands

Abstract

The majority of the world's plants rely on animal pollinators for reproduction, making pollination a key ecosystem service for the maintenance of natural and cultivated plant communities. Mutual interactions between plants and pollinators, also called “plant-pollinator networks”, are becoming increasingly vulnerable due to the intensification of anthropogenic land use and climate change. Thus, due to the rapid decline of semi-natural grasslands in the Northern Apennines (Italy), we aimed at understanding how the fragmentation of these habitats, the spatial distribution, and the amount of semi- and natural areas surrounding them, could affect species diversity and plant-pollinator networks. Specifically, in the Northern Apennines, we monitored semi-natural grasslands belonging to the EU habitat type 6510 to evaluate the effect of fragmentation on plant and pollinator richness and on the plant-pollinator network. We carried out generalized linear models considering three taxonomical and six network descriptors as response variables and the combinations of grasslands size and isolation, as well as 10 other factors describing landscape composition as explanatory variables. We found a well-structured plant-pollinator network, characterized by a high diversity of both plants and pollinators, with mutual relations marginally specialized, highly affected by habitat fragmentation and the land use of surrounding grasslands. Moreover, large and neighboring patches increased pollinator richness and improved the overall network structure while the occurrence of meadows and shrubs around fragmented patches was important to ensure the continuity of floristic resources. Finally, extensive croplands and agricultural settlements significantly reduced plant and pollinator diversity, favoring generalist (probably invasive) species, which however increased the strength and stability of the network.

Ecology and abundance of a relict population of the bush cricket Saga pedo in the Northern Apennines, Italy

“…Seminatural grassland habitats are essential ecosystems for biodiversity conservation. The high diversity of animal and plants found in this habitat depends largely on traditional agro-pastoral practices, which limit the competition among plants and promote the coexistence of different plant species and favoring the surviving of many rare and sensitive insect species (Della Rocca et al, 2023;Sochera et al, 2013).…”

“…Seminatural grassland habitats are essential ecosystems for biodiversity conservation. The high diversity of animal and plants found in this habitat depends largely on traditional agro‐pastoral practices, which limit the competition among plants and promote the coexistence of different plant species and favoring the surviving of many rare and sensitive insect species (Della Rocca et al., 2023 ; Sochera et al., 2013 ). However, seminatural grasslands are in sharp decline in Europe (Bullock et al., 2011 ) due to their transformation into intensive crops or the abandonment of agro‐pastoral activities, which favors natural succession and forest invasion (Queiroz et al., 2014 ).…”

“…However, seminatural grasslands are in sharp decline in Europe (Bullock et al., 2011 ) due to their transformation into intensive crops or the abandonment of agro‐pastoral activities, which favors natural succession and forest invasion (Queiroz et al., 2014 ). This process has negative effects on species richness and the composition of communities (Della Rocca et al., 2023 ) leading to local extinctions and a reduction in the overall genetic diversity of populations, further exacerbating the impacts of habitat loss and fragmentation. Among the species that live in seminatural grasslands, the predatory bush cricket, Saga pedo (Pallas, 1771; S. pedo , hereafter), is a priority species for conservation.…”