Spider species richness in cocoa agroforestry systems, comparing vertical strata, local management and distance to forest

Abstract

Spiders are abundant and diverse in naturally shaded cocoa agroforestry systems and can be economically important predators, but surprisingly little is known on the determinants of spider communities in agroforests. Here, we use data from twelve differently managed cocoa agroforestry systems in Indonesia to investigate the abundance, diversity and composition of spider communities at three spatial scales: (i) stratum, i.e. litter, herb and cocoa canopy layer, (ii) plot-level shade, litter and weed management and (iii) landscape context, i.e. distance to natural forest. Spider communities of all three strata were positively affected by herb cover. High cocoa leaf litter density, which characterised high-intensity management, was accompanied by a decrease in spider abundance and species richness. On a community level, we did not find an effect of forest edge proximity on spider abundance or species richness, but with distance to forest a shift of species dominance in favour of generalists. Our results showed an impact of all three spatial scales, from the microhabitat and local plot management to the landscape context, which changed spider community composition, and suggest a focus beyond plot-level shade management to understand determinants of spider community in cocoa agroforestry systems.