In seasonally dry Mediterranean regions, forest ecosystems are well adapted to water stress. However, extended droughts, or droughts that are warmer or more frequent than they have been in the past, can have large consequences on water availability, forest productivity, and forest mortality. Forest density reduction offers a strategy for potentially mitigating these effects and may not only improve forest health but also increase streamflow. While recent droughts have focused attention on forest density reduction strategies, there is great uncertainty in how changing forest structure alters water availability for both remaining trees and downslope water provision, particularly during droughts in semi‐arid and Mediterranean forests. To help to disentangle sometimes conflicting findings from case studies, we present a review from an eco‐hydrologic perspective that considers both how much water trees use (hydrology) but also how water availability affects forest ecophysiology and health (ecology). This eco‐hydrologic perspective helps to build a conceptual model of the mechanisms through which changes in forest structure and composition can influence water availability, forest productivity, and mortality patterns, particularly in Mediterranean‐climate regions, both during and after droughts. Ultimately, this eco‐hydrologic conceptual model offers a guide for assessing when and where density reduction will be likely to achieve desired management objectives.
TAGUE, C.L., MORITZ, M., HANAN, E (2019): The changing water cycle: The eco-hydrologic impacts of forest density reduction in Mediterranean (seasonally dry) regions. WIREs Water. DOI: 10.1002/wat2.1350