Crop species and climate shape amphibian communities and conservation significance of coffee agroforests in the Western Ghats

Vijay Karthick , Siva Dass, Vishal Gopal Sadekar, Rohit Naniwadekar, Anand M Osuri

Shade coffee agroforests are recognized as refuges for biodiversity and potential allies in conservation across the human-modified tropics. However, biodiversity is strongly influenced by coffee cultivation methods and climates, both of which vary widely and are increasingly dynamic. In this context, one significant but understudied change is the shift in cultivated species from arabica (Coffea arabica) to robusta (C. canephora) coffee, which alongside continued deforestation and climate change, is reshaping present and future coffee landscapes globally. We examined the effects of land use (rainforest, arabica coffee, robusta coffee) and climate (coffee in wet vs. dry zones) on amphibian abundance, community composition, multidimensional diversity (taxonomic, functional, phylogenetic), and ecologically-sensitive and conservation-priority species in India’s Western Ghats mountains—a global biodiversity hotspot and threatened amphibian landscape. We sampled amphibians along line transects (total 12.9 km), collected primary and secondary data on species functional traits (12 traits), geographic distributions, conservation threat status, and phylogenies, and estimated multidimensional diversity (Hill numbers q = 0-2) and species occurrence probabilities using joint species distribution models across land uses and climate zones. While overall abundance and richness (q = 0) were roughly similar across land uses and climates, the rainforest had distinct amphibian community composition, higher multidimensional diversity (q = 1 and 2), and higher occurrence probabilities of lotic (stream-breeding) and conservation-priority (threatened and endemic) species. Amphibian multidimensional diversity (q = 1 and 2) was generally higher in arabica compared to robusta coffee in both climate zones, and decreased alongside lotic and conservation-priority species from wet to dry zones. Our results highlight that while coffee agroforests can sustain substantial numbers and varieties of amphibians, arabica-to-robusta conversions and climate drying can diminish multidimensional diversity, and securing and restoring remnant forests and streams is essential for conserving threatened, endemic, and ecologically-sensitive amphibian species in changing coffee landscapes.