Land use and multidimensional diversity jointly shape carbon stocks in an Indonesian seasonally dry ecosystem.

Dry ecosystems are critical to the global carbon cycle. Seasonally dry tropical ecosystems as a whole are botanically megadiverse, yet we have little understanding of how diversity impacts aboveground carbon, which is particularly noticeable for insular Asia. Across 133 vegetation plots on the seasonally dry tropical island of Flores, we used spatially explicit models to determine how land use impacts aboveground carbon stocks and whether this is dependent upon multidimensional diversity. Carbon is greatest in primary forests and least in agricultural landscapes. However, we find that land use interacts with phylogenetic and species diversity to shape carbon stocks. Across almost all models, quadratic effects of diversity were better predictors of carbon, indicating that whilst the initial build-up of diversity increases carbon, greater diversity causes carbon decline. Results suggest that future conservation plans will be needed to balance carbon storage with multidimensional diversity, which may offer distinct benefits for ecosystem resilience and services.