Over the last three decades, forest vegetation has begun using significantly more water, as long-term climate and streamflow data reveal.
USDA Forest Service scientists Jim Vose and Dave Wear contributed to the study, which was led by Taehee Hwang, an assistant professor at the University of Indiana.
The findings were published in the journal Water Resources Research and recently received the Water Resources Research Editor’s Choice Award.
Editors’ Choice Awards are given to only about one percent of published articles in any calendar year. The selection is made by the Editors of Water Resources Research and is based on technical significance, novelty, originality, presentation, and broader implications of the publication. The award provides recognition for outstanding work.
“It is quite an honor to receive this award, and it reflects the strength of the multidisciplinary team that worked on the research,” says Vose.
The study used a combination of remote sensing, gauged watersheds, climate measurements, and modeling to understand changes in climate, vegetation, and streamflow.
“This paper addresses the complex nature of interactions between climate change and water resources that can’t be fully understood with simple models and empirical approaches,” says Vose.
The increase in forest water use was significantly correlated with longer growing seasons.
Longer growing seasons and faster tree growth are primarily attributed to increases in minimum temperatures – the coldest days of the year are not as cold as they once were.
Minimum temperatures are increasing faster and more consistently than changes in maximum temperatures. The study suggests that minimum temperatures in spring and autumn are particularly important drivers of a longer growing season.
Most modeling studies do not account for co-occurring changes in forest vegetation structure and dynamics that influence water use and impact streamflow.
Forested watersheds provide important ecosystem services such as high quality freshwater, flood mitigation, and maintenance of base flows. However, climate change could dramatically alter such ecosystem services.
Accounting for changes in temperature-driven phenology and vegetation growth responses in a process-based model improved predictions of streamflow.
The findings will help watershed managers plan for changes in future water supply.
Read the full text of the study.
For more information, email Jim Vose at james.m.vose@usda.gov.