Semi-natural habitats benefit maintaining the spider diversity in subtropical agroecosystems

Land use change has caused the loss of agricultural biodiversity. As major natural enemies of pests in agroecosystems, spiders have important ecological functions in improving agricultural productivity and thus deserve attention. However, few studies have considered their responses to land use changes. Here, we investigated the structure and diversity of the spider community in four land use types, that is, fallow land, woodland, orchard, and cropland in Pengzhou City, China. The differences in species richness, total abundance, community composition, and spider abundances with three foraging strategies and their correlations with environmental factors and agricultural intensity were compared between land use types. The results showed that the total abundance of spiders in fallow land was 71%, 157%, and 214% higher than that in orchard, cropland, and woodland, respectively. Similarly, fallow land maintained the highest species richness. Shannon-Wiener index, community structure heterogeneity, and number of spider species sampled in a single land use type were highest in woodland. Further, spiders with different foraging strategies showed distinctive responses to environmental factors and agricultural practices. The diversity of hunters was negatively correlated with the intensity of agricultural practices and canopy density, while web-builders were positively correlated with canopy density. The diversity of burrowers was positively correlated with the vertical complexity of vegetation structure. Our study emphasizes the vital role of semi-natural habitats, like fallow land and woodland, in maintaining spider diversity, and suggests optimizing land uses to provide wide-open spaces and mitigate the effects of intensified agricultural activities for natural enemies of pests in agriculture.