Zeta Diversity as a Tool for Sustainable Avian Conservation in the Eastern Himalayan Traditional Agricultural Landscapes

Biodiversity conservation in agricultural landscapes requires frameworks that move beyond species richness to address compositional dynamics and community structure. In this study, we apply a zeta diversity approach to explore the patterns of bird compositional turnover across five traditional agricultural systems in the Eastern Himalaya—agropastoral system (AP), farm-based agroforestry system (FAS), large cardamom-based agroforestry system (LCAS), terrace rice cultivation (TRC), and tea cultivation system (TCS). Zeta diversity, which quantifies species shared across multiple sites, enables a deeper understanding of the roles of both common and rare species in shaping community composition. Common, widespread species predominantly influenced compositional turnover within sites of FAS and LCAS, as indicated by higher retention rates across increasing zeta orders. In contrast, AP, TRC, and TCS exhibited greater turnover due to rare or site-specific species, reflected in lower retention rates across sites of the same system. Insectivores emerged as the dominant feeding guild across all systems, with turnover patterns varying significantly among landscapes. Key habitat and environmental drivers of turnover included shrub density, NDVI, temperature seasonality, precipitation seasonality, and elevation. Our findings highlight the critical role of traditional agricultural landscapes in maintaining avian biodiversity and underscore the importance of conserving habitat heterogeneity within agricultural matrices. By leveraging the zeta diversity framework, this study offers valuable insights for integrating biodiversity conservation into agricultural planning and land-use policy. As pressures from land-use change and climate variability intensify, such multidimensional biodiversity assessments are essential for designing resilient agroecosystems that support both ecological integrity, spatial connectivity and local livelihoods in mountain biodiversity hotspots.