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Forest and water on a changing planet

Photo: Low perspective of a river running through a forest.
Forests provide a reliable source of clean water over much of the world. Rivers, like this one in Pisgah National Forest, run through thousands of miles of National Forest System land. USDA photo courtesy Lance Cheung.


—A newly published report presents the current state of knowledge on the relationships between forests and water across the planet. USDA Forest Service scientist Steven McNulty is among the report’s coauthors who assessed global forests’ capacity for supplying water resources to growing populations.

“All nations depend on a reliable source of clean water, and forests provide the resource over much of the world. However, increasing human demand and climate change and variability are making water shortages more common for billions of people,” said McNulty. “The objective of this study was to examine how adaptation, mitigation and governance could be used to more equitably share and use forest water resources.”

The eight-chapter report, “Forest and Water on a Changing Planet: Vulnerability, Adaptation and Governance Opportunities,” was prepared by members of the Global Forest Expert Panel on Forests and Water—an initiative of the Collaborative Partnership on Forests led by the International Union of Forest Research Organizations. McNulty, a research ecologist with the Forest Service Eastern Forest Environmental Threat Assessment Center and director of the USDA Southeast Regional Climate Hub, is an IUFRO deputy-coordinator who served as a panel member to develop the report. The panel included more than 50 internationally recognized scientists from 20 nations.

McNulty and Dr. Emma Archer of South Africa co-led the report’s chapter on determinants of the forest–water relationship, which highlights global trends within an interconnected social–ecological system. The chapter also discusses the factors driving changes to this system that ultimately impact water quantity and quality at various scales and timeframes.

“No single factor determines forest resources, but climatic changes are the most important factor that determines water supplies. We can no longer rely on historical patterns of seasonal weather to predict water availability,” said McNulty, who also contributed to five additional chapters in the report. “Managing forests such that they can adapt to these changes and stabilize water quantity and quality has never been more important.”

The report was released July 10 in New York at the 2018 United Nations High-Level Political Forum on Sustainable Development and is intended to inform policymakers and stakeholders in their efforts to support sustainable development and ensure access to clean water for all people around the world.