Across the globe, forests cover about a quarter of all land and are important sources of clean water. A new book, edited by U.S. Forest Service Southern Research Station (SRS) scientist Devendra Amatya, examines the interactions between forests, water, climate, and management. The book, Forest Hydrology: Processes, Management and Assessment, was recently published by the Centre for Agriculture and Biosciences International (CABI).
Scientists have been investigating forest hydrology for decades, but until now, much of the information has been accumulating only in journals, proceedings papers, reports, and a few textbooks. The new book is unique because it represents the state of the science on forest hydrology, the study of how water and forests interact, and watershed management.
Several Forest Service scientists contributed to the book as lead authors, including SRS research hydrologist Ge Sun and SRS project leader Jim Vose. In addition to being the lead editor, Amatya contributed to several chapters both as lead and coauthor. Each chapter was written and edited by world-renowned scientists, managers, engineers, and others with extensive background in forest hydrology and management.
“Forests interact with and protect water and soil in a variety of ways,” says Amatya. For example, when rain falls on a forest canopy, some of it is intercepted by the leaves and branches in the canopy and evaporates back to the atmosphere. Trees also suck water out of the soil with their roots, eventually releasing it to the atmosphere via transpiration. Read Amatya’s chapter on the hydrological processes of reference watersheds in U.S. experimental forests.
The scientists also summarize recent findings about evapotranspiration (plant transpiration plus evaporation) and techniques for measuring it. “Evapotranspiration links climate, hydrology, and ecosystem services such as carbon sequestration – especially in the context of trees’ ability to fix atmospheric carbon dioxide,” says Sun, who was lead author of the chapter. “Evapotranspiration is a large component of the water budget and one key aspect of forest hydrology that is rapidly developing.”
Climate change directly affects forest hydrology. When air temperatures increase, the amount of water lost to the atmosphere will potentially increase, causing a decrease in the amount of water that seeps into the earth, eventually depleting groundwater, and potentially streamflow. Several chapters address the potential impacts of climate-related disturbances such as extreme floods, drought, disease, and fire.
The rate of disturbances has increased to unprecedented levels. “It is not clear if the past alone will serve as an adequate model of the future,” says Vose, who was lead author of the chapter on future challenges. “Hydrological cycles have already been altered and changes will continue as climate change, population growth, water diversion, and numerous other environmental changes continue.”
The Forest Service has a long history of studying forest hydrology and maintains premier research facilities. “The long-term research conducted on Forest Service Experimental Forest watersheds has contributed substantially to our understanding of relationships between forests and streamflow,” says Amatya. Amatya and his coauthors discuss the characteristics of 10 relatively undisturbed watersheds across the country, including those at Coweeta Hydrological Laboratory and the Santee Experimental Forest. Their analyses will be useful for assessing the impacts of forest disturbance and restoration projects, and testing models used elsewhere for ecohydrologic studies.
“The book covers almost all aspects of forest hydrology, in multiple environments – from tundra to the tropics,” says Amatya. “It will be useful for graduate students, professionals, land managers, practitioners, and researchers.”
For more information, email Devendra Amatya at firstname.lastname@example.org.