WATERING THE FOREST FOR THE TREES: NEW PRIORITIES AND STRATEGIES FOR MANAGING WATER ON FOREST LANDS

Widespread threats to forests resulting from drought stress are prompting a re-evaluation of priorities for water management on forest lands. Many of the disturbance processes imperiling the world’s forests, including fire, insects, pathogens, and dieback, are related to water stress; such disturbances, and the frequency and magnitude of drought, are likely to increase as climate warms. Increased water stress in forests challenges our current paradigm– namely, forests are the “source” of water for downstream users – that often ignores the importance of water for the forest itself to maintain productivity and resilience. We argue that maintaining forest health in the context of a changing climate may require focusing on the forests themselves and on strategies to reduce their vulnerability to increasing water stress. Management strategies need to be tailored to specific landscapes but could include thinning, planting and selecting for drought-tolerant species, irrigating, and making more water available to plants for transpiration. Hydrologic modeling reveals that specific management actions could reduce tree mortality due to drought stress. Adopting water conservation for vegetation as a priority for managing water on forested lands would represent a fundamental change in perspective and potentially involve trade-offs with other downstream uses of water.