Rainwater harvesting and arthropod biodiversity within an arid agro-ecosystem

Abstract

The Bedouin of South Sinai, Egypt, use a technique known as runoff agroforestry to capture rainwater and increase the agricultural potential of the arid landscape. Utilising water that would otherwise be lost from the vicinity allows the creation of multi-strata orchards with higher plant densities than the surrounding environment. We used pitfall traps to compare ground arthropod communities within 15 agricultural gardens to those in the external habitat. Total arthropod abundance and species richness were significantly higher inside the gardens, with no loss of alpha-diversity. Species level analysis of ants revealed that six out of seven recorded species were more abundance inside the gardens. There were significant differences in the responses of Coleopteran functional groups, with scavengers occurring in higher numbers inside, predators higher outside, and herbivores showing no difference. There was a high presence of the ant Monomorium venustum and the scavenger beetle Lagria sp. inside the gardens, but no negative impacts on species accumulation rates or alpha-diversity. In conclusion, runoff agroforestry seems to enhance local arthropod abundance, without a strong negative affect on biodiversity.