Water table depth modulates productivity and biomass across Amazonian forests

Aim Water availability is the major driver of tropical forest structure and dynamics. Most research has focused on impacts climatic water availability, whereas remarkably little known about influence table depth excess soil processes. Nevertheless, given that plants take up from soil, supply are likely to be modulated by conditions. Location Lowland Amazonian forests. Time period 1971–2019. Methods We used 344 long-term inventory plots distributed across Amazonia analyse effects edaphic functioning. modelled dynamics as a function climatic, soil-water properties. Results supplied both precipitation groundwater affects dynamics, but in different ways. Forests with shallow (depth <5 m) had 18% less above-ground woody productivity 23% biomass stock than forests deep table. drier climates (maximum cumulative deficit < −160 mm) 21% 24% those wetter climates. Productivity was affected interaction between depth. On average, lower table, this difference decreasing within wet climates, where confined very Main conclusions show two extremes (excess deficit) reduce Amazon upland (terra-firme) Biomass respond not simply regional climate, rather its conditions, exhibiting high local differentiation. Our study disentangles relative contribution factors, helping improve understanding functioning ecosystems how they climate change.