The Science

A novel tree manipulation study shows the roles of hydraulic acclimation to both precipitation and temperature in two tree species and unravels their effects.

The Impact

Analysis of observations of a vast amount of tree-water dynamics shows juniper and piñon trees have different physiological responses to heat and drought stress including varying ability to acclimate. The scientists’ new framework allows separation of temperature and precipitation responses in these species and provides a path forward for better model representations of how trees will function within the evolving Earth system.

Summary

Previous findings suggested warming superimposed on drought would exacerbate drought stress and increase mortality. However, during this study’s five-year period of warmer and much drier conditions, no mortality was observed. The tree stomata adjusted to heat and drought even when other functions were drastically impaired by drought—stomata acclimation prevented tree death from the additive effects of warming and drying. Also, previous work had revealed that juniper trees can be highly resistant to drought, keeping their stomata open, while piñon shut down all functions that kept them alive. However, in this study, juniper was unable to significantly acclimate and showed strong reductions in function. Piñon, which suffered when exposed to drought, actually acclimated when warming was the only stressor, and it retained hydrological functions including sap production to repel invaders.

Principal Investigator

Charlotte Grossiord
Los Alamos National Laboratory
charlotte.grossiord@wsl.ch

Program Manager

Daniel Stover
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science
daniel.stover@science.doe.gov

Funding

The Los Alamos Survival-Mortality (SUMO) Experiment was funded by the Office of Biological and Environmental Research within the U.S. Department of Energy Office of Science.

References