Drought responses in floodplain forests obtained by remotely sensed and tree‐ring data

Abstract

AbstractForest and water‐resources management in floodplains requires an understanding of the nature of drought specific to ecosystems there. The complex relationships among floodplain vegetation, topography and hydrology affect water availability. This paper investigated whether hydrological assumptions within meteorological drought indicators and ecophysiological assumptions within remote‐sensing drought indicators reflect drought deficits as they occur in floodplain forests. We compared the performance of widely used meteorological and remote‐sensing drought indicators in floodplain forests to tree‐ring validation using five species at three floodplains in eastern Texas, USA. We found that the water balance in the Standardized Precipitation Evapotranspiration Index and the water loss estimated by the Evaporative Stress Index were useful models of water deficits in floodplain forests at the site and sub‐site scales, respectively. Hydrological and stand conditions varied among sites enough to affect the specific patterns of tree‐species responded to drought. However, of the species we examined, tree rings in green ash were the most consistently affected by drought across floodplains and were the most closely correlated with both meteorological and remotely sensed drought indicators. Finally, drought effects varied by species and among and within floodplains, but generally, growth of trees in topographically drier sites was more closely correlated with drought indicators.