Biodiversity-mediated demographic trade-offs sustain resistance to pulse and press disturbances across United States forests with implications for management

Understanding the biological mechanisms sustaining forest productivity under intensifying climate-driven disturbances is a central challenge in ecology. While biodiversity enhances ecosystem functioning, its role in modulating recovery under contrasting disturbance regimes, including acute (pulse) versus chronic (press), remains unclear. Clarifying these demographic pathways is essential for predicting forest stability and informing resilience-based management strategies. Here, we utilized the USDA Forest Inventory and Analysis (FIA) database to analyze post-disturbance recovery across the contiguous United States. We investigated the variation in demographic recovery, including ingrowth (i.e., as new tree recruitment), growth, and mortality, under the interactive effects of structural, species, and functional diversity within distinct disturbance regimes using a bootstrap-based analysis framework. Specifically, we modeled these relationships while controlling for stand attributes as well as topographic, edaphic, and climatic conditions. We found that: 1) net productivity exhibited ecological resistance, remaining statistically indistinguishable from undisturbed baselines as all diversity effect sizes fell within the 95% confidence intervals of the null distribution with absolute deviations below 0.2 standard units; 2) Under pulse disturbance, this resistance relied on a direct demographic balance where structural complexity reduced tree mortality while new tree recruitment increased rapidly driven by acquisitive functional traits; and 3) Under press disturbances, conservative traits increased vulnerability to mortality although structural diversity facilitated the growth of survivors. These results demonstrate that forest resistance is maintained by regime-specific between mortality and recruitment rather than static persistence. Consequently, acknowledging the constraints of observational data management strategies could potentially support intrinsic recovery mechanisms by exploring competition control for pulse events and enhancing structural complexity for press stressors. • Net forest productivity resists pulse and press disturbances across the US. • Stable net growth masks active demographic trade-offs in recovery. • Structural complexity buffers tree mortality during pulse events. • Functional traits drive mortality under chronic press stress. • Management must target recovery mechanisms, not just net growth.