Environmental drivers of coarse woody debris and its role as a nutrient sink in a Caatinga dry forest

Coarse woody debris (CWD) plays a key role in carbon storage and nutrient cycling in tropical dry forests, yet its continuous removal as firewood may compromise ecosystem functioning in human-modified landscapes. Here, we quantified CWD stocks, nutrient concentrations, and nutrient exportation via firewood consumption across 34 forest stands in a Caatinga dry forest, Brazil. Forest successional status, precipitation, and chronic anthropogenic disturbance (CAD) were adopted as explanatory variables. CWD stocks were highly variable (12.5–4675 kg ha −1 ), averaging 794.3 ± 863.7 kg ha −1 and representing only 4–5% of aboveground biomass. Stocks increased with forest biomass and were higher in old-growth stands, while decreasing with precipitation. No detectable effect of CAD emerged. CWD Nutrient concentrations were consistently lower than in other forest compartments, particularly for phosphorus, but increased with forest biomass and during the rainy season, indicating a strong influence of forest structure and seasonality on nutrient retention. Overall, CWD stored a small fraction of ecosystem nutrients (∼1% of phosphorus relative to belowground biomass and other compartments). Monthly familiar firewood consumption removed approximately 22% of available CWD and resulted in monthly losses of 0.88 kg N and 0.017 kg P per household. Our findings indicate that CWD operates as a limited but dynamic nutrient pool, primarily regulated by vegetation structure and climate, while its continuous collection as a source of firewood probably contributes to the alarming rates of Caatinga forest degradation via soil impoverishment.