How can we predict drought-induced forest mortality?

Drought-induced tree mortality has major impacts on ecosystem carbon and water cycles, and is expected to increase in forests across the globe with climate change. A large body of research in the past decade has advanced our understanding of plant water and carbon relations under drought. However, despite intense research, we still lack generalizable, cross-scale indicators of mortality risk. I will review recent progress in mortality prediction, focusing on the reasons why progress has been limited. I will also propose that a more explicit consideration of water pools (e.g., the relative water content, RWC) could improve our ability to monitor and anticipate mortality risk.
Measures of plant water content are likely to have a strong mechanistic link with mortality and to be integrative, threshold-prone and relatively easy to measure and monitor at large spatial scales, and may complement current mortality metrics based on water potential, loss of hydraulic conductivity and nonstructural carbohydrates.