Aboveground and soil carbon, nitrogen, and phosphorus concentrations and stocks and their responses to environmental and human-related drivers in a tropical dry forest

Abstract

Nutrient dynamics directly influence forest productivity, yet their exploration in tropical dry forests, particularly in human-modified landscapes, is limited. We examine aboveground and soil carbon, nitrogen, and phosphorus concentrations and stocks in 19 stands across gradients of rainfall, chronic anthropogenic disturbances (CAD), aboveground biomass (AGB), and soil fertility in a Caatinga dry forest. Leaves exhibit three times higher N and P concentrations than twigs but a 20% lower C concentration. Conversely, the soil compartment presented the lowest concentration scores across all nutrients. Stoichiometric N ratios exceed 20 in all compartments. Soil C, N, and P stocks are approximately two, seventeen, and twelve times greater than aboveground biomass. Rainfall, CAD, and AGB exert both positive and negative effects on C and N concentrations and stoichiometric ratios in twigs and soil. Our results suggest that the Caatinga dry forest in human-modified landscapes supports woody plant assemblages with high nutrient concentration but reduced stocks across all compartments. Both environmental and human-related disturbances play specific roles by affecting nutrient availability. In this P-limited system, reduced nutrient stocks and the prevalence of disturbance-adapted plant species apparently dependent on biotic associations for nutrient uptake render Caatinga forest productivity and resilience highly susceptible to human disturbances.