Non cropped fragments as important spider reservoirs in a Pampean agroecosystem

Abstract

Agricultural landscapes include patches of cropped and non-cropped habitats. Non-cropped fragments are often source habitats for natural pest predators which colonize less suitable agricultural fields. The goals of the present study were: i) to evaluate the contribution of non-cropped fragments to agro-ecosystems as biodiversity reservoirs and ecosystem service providers, by assessing the abundance of spider species and their diversity; and ii) to quantify the spatial variation in spider communities across different non-cropped fragments and crops. We hypothesized that non-cropped fragments function as spider diversity reservoirs with better conditions for reproduction than crops. We collected spiders from 14 restored fragments having had no disturbance for 20 years, along a gradient inside the crop adjacent to each fragment. Overall, we collected 3591 spiders belonging to 49 species/morphospecies in14 families. Non-cropped fragments had a central role in the spider community, as estimated thought species-habitat networks. We found differences in the diversity and abundance of spiders between non-cropped and cropped fragments. However, these differences were only for immature spiders, whose abundance decreased from non-cropped fragments towards the inside of crops. Our results highlight the importance of non-cropped fragments in agro-ecosystems as important source habitat patches, reservoirs of biodiversity and sites where spider reproductive success is possibly higher.