PNNL

Abstract

Tropical forest resilience to climate change depends on the rate of vegetation biomass turnover, a key determinant of forest biomass storage potential. However, the large-scale patterns of tropical biomass turnover and their environmental drivers remain poorly understood. Here, we estimate kilometer-scale aboveground biomass turnover time (tAGB) across intact Amazonian forests by integrating satellite and field measurements. Our spatial analysis provides continent-scale evidence that tAGB exhibits strong nonlinear responses to climate. Convective storms, a major cause of tropical forest disturbance, are the dominant climatic driver of tAGB spatial variation, surpassing vapor pressure deficit and precipitation extremes. By the end of this century, projected increases in atmospheric dryness and storm activities are expected to reduce tAGB in the Amazon by ~3% (SSP126) to ~15% (SSP585), thereby accelerating biomass turnover. These findings highlight climatic sensitivities of biomass turnover critically shape tropical forest dynamics and carbon cycling.