Age-driven structural characteristics relate to epigeal arthropod communities in olive agroecosystems of the Atacama Desert

Abstract

Intensive agriculture has led to a significant global decline of biodiversity. However, agroecosystems like olive groves can serve as biodiversity refuges, especially in arid environments, by acting as resource islands that promote the persistence of multiple species, including arthropods. The structural complexity and productivity of olive groves typically increase with age, enhancing their ability to sustain high biodiversity. In this study, we examined how epigeal arthropod diversity patterns vary across olive orchards of different ages in the Huasco Valley of Chile's Atacama Desert. We hypothesized that older olive orchards, with greater structural complexity and productivity, would harbor higher arthropod abundance, diversity, and distinct community compositions than a younger olive orchard. To test this hypothesis, we sampled epigeal arthropods in three olive orchards of different ages (young, intermediate, and centennial) using pitfall traps and characterized each orchard's structure and productivity (NDVI). Our findings indicate that olive orchard age is related to arthropod composition and abundance but not diversity. Young and intermediate olive orchards had higher arthropod abundance, dominated by isopods and hymenopterans, while entomophthorans and mites predominated in the centennial orchard. Each orchard harbored a unique arthropod community, with NDVI being a key factor in the centennial orchard, dry weed biomass in intermediate orchards, and leaf litter in young groves. These results suggest that the structural characteristics associated with olive orchard age play a crucial role in shaping arthropod communities in arid environments, highlighting the importance of habitat management within agroecosystems for promoting biodiversity.