Ground-dwelling arthropods across human land use: Interpreting the spatial and temporal dimensions of beta diversity

Abstract

This study investigates beta diversity and its partitions to quantify the influence of different processes that drive spatial and temporal variation in ground-dwelling arthropod assemblages. First, ant assemblages across Goa, India, were studied to quantify how different species and functional groups, and human land use contribute to beta diversity over large spatial scales, and whether exotic species have a disproportionate influence on beta diversity. Human land use strongly influenced diversity and distribution of ant assemblages. Human land use spared local species richness, but not functional groups. A small number of exotic species exerted negative influence even in a very speciose community. Second, intra-annual variation in beta diversity and its partitions of ant communities was studied across three seasons in Bhagwan Mahaveer Wildlife Sanctuary, Goa, India, to quantify how loss and gain of species leads to functional redundancy. Ant community composition was highly variable at seasonal scales. But ecological roles were maintained across seasons by species with redundant functional traits. Third, effect of human altered land use on temporal beta diversity and its partitions of ground dwelling arthropods was quantified in the coupled human-natural Trans-Himalayan ecosystem in Spiti, northern India. Human land use altered seasonal trajectories of community dynamics and influenced beta diversity at the taxonomic level. But functional roles were spared due to species replacement and redundancy in traits. Together, the three chapters of this thesis show that community composition rather than species richness is a better indicator of how arthropods respond to human land use. They also establish functional redundancy to be an important feature of ecological resilience and resistance that can be affected by human land use.