Tropical Ant Communities Under Agroforestry Can Be Diverse but Lack Trait-and-Environment Associations

Abstract

Human land use often alters community composition that affects many related ecosystem functions. However, intermediate-intensity land use, such as agroforestry, can be a refuge for biodiversity and can maintain ecosystem functions and services in working landscapes. We quantified how the alpha and beta diversity of ants (Hymenoptera: Formicidae) vary with human land use in the Kodagu region of the Western Ghats, India, across four land use types (forests, forest fragments, and two types of coffee plantations with either native or non-native shade trees). We studied ants, as they perform a wide range of ecological functions such as predation, herbivory, seed dispersal, and decomposition, etc., in such landscapes. We also assessed the functional diversity of ants and estimated the interactions between their traits and the environment. We found that the plantations, on average, had 26% lower species richness than forests and forest fragments, and functional richness was 31% lower in non-native plantations. However, plantations showed higher beta diversity than forests at both taxonomic and functional levels. Interestingly, turnover was higher in non-native than native plantations by 32% and 24% at taxonomic and functional levels, respectively. Plantations also had weak and few ants' trait-and-environment interactions, suggesting that environmental filters may not be influential in structuring ant communities under human land use, compared to forests. Overall, while ant communities under human land use differ from those in forests, they can be heterogeneous and able to perform similar functions. Our findings highlight the importance of agroforestry as working landscapes which can maintain biodiversity and ecosystem functions.