Replication Data for: Potassium and phosphorus limitations linked to drought responses in an Afrotropical forest

Abstract: Tropical forest productivity situated on highly weathered soils is increasingly reported to be nutrient-limited. Yet experimental evidence, particularly from Afrotropical forests remains rare. We conducted an ecosystem-scale, full factorial N-P-K addition experiment in a moist forest in Uganda to investigate nutrient controls on fine litter biomass production as well as changes in foliar and litter chemistry. We established 32 (eight treatments (control, N, P, K, NP, NK, PK, NPK) × four replicates) 40 × 40 m plots, and nutrients were added at 125 kg N ha−1year−1, 50 kg P ha−1year−1 and 50 kg K ha−1year−1. After three years, we found K and P limitations on leaf litter production, exhibiting strong links to drought responses in this ecosystem. Specifically, leaf litterfall reduced consistently during dry seasons with K additions but with P additions only following prolonged drought in the first year of the experiment. Furthermore, K additions delayed the timing of leaf litterfall peak, highlighting the key role of K in regulating stomatal aperture and signalling in leaves during water stress conditions, thereby delaying leaf-shedding and enhancing leaf lifespan. We conclude that the productivity and resilience of tropical forests, under extreme drought conditions, may depend on terrestrial K and P availability.