By Heidi Toth
Two Northern Arizona University postdoctoral scholars authored a paper measuring how forest restoration in response to wildfires or climate change can benefit water quality.
Frances O’Donnell, now an assistant professor of civil engineering at Auburn University, and William Flatley, now an assistant professor of geography at the University of Central Arkansas, collaborated with hydrogeology and ecohydrology professor Abe Springer and forestry professor Peter Fulé for “Forest restoration as a strategy to mitigate climate change impacts on wildfire, vegetation and water in semi-arid forests,” published in Ecological Applications. They found the negative effects of climate change and wildfire, although significant and worrisome, could be mitigated by targeted forest restoration, thus reducing undesirable outcomes for multiple ecosystem services.
Both postdocs spent three years at NAU supported by the Bureau of Reclamation WaterSMART: Applied Science Grants for the Southern Rockies Landscape Conservation Cooperative and the Technology Research Initiative Fund; they studied the risks to forest and water health. The researchers modeled the different combinations of vegetation, fire, hydrology and sediment yields to assess the potential impacts of climate change and forest restoration on future water resources in Grand Canyon National Park.
The research used various models to predict the future loss of high elevation forest species, water yield declines and the potential for substantial sediment yield in the park, which is experiencing a similar trend as other mountainous regions—climate change and wildfire are interacting to cause lower elevation forests to replace higher elevation forests. If left unchecked, this could lead to a loss of biodiversity and ecosystem services and reduced water quantity and quality, as well as increasing the risk of destructive forest fires.
“Our research suggests that forest restoration will slow these losses,” O’Donnell, the first author on the paper, said. “If carbon emissions are curbed in the future, forest restoration done now could prevent the permanent loss of high elevation vegetation species and aquatic species that depend on clean, plentiful water for their habitat.”
Fulé, who studies ecological restoration and fire ecology in the southwestern United States, examined the significance of climate change on these ecosystems.
“It is increasingly clear that climate warming is affecting forests directly, by shifting the boundaries of where species can live, and indirectly, by influencing disturbances such as fire, insects and diseases,” Fulé said. “There is substantial uncertainty about how these factors will interact, but models that incorporate our best understanding of physical and biological factors are critical tools for testing the range of future possibilities.”
Springer, who studies the flow of water through the Grand Canyon, said the park derives all of its water supply from Roaring Springs, which discharges from the Redwall-Muav Aquifer of the Kaibab Plateau on the North Rim of the canyon. It recharges from melting snow and rainfall on the forests of the Kaibab Plateau.
“Roaring Springs and many other springs discharging from these snowmelt-sourced aquifers also support some of the most important ecosystems in the desert Southwest at springs and spring-fed streams,” he said. “As our research shows, forest restoration is critical to minimize the effects of climate change on the hydrology of the Kaibab Plateau and the associated springs. Without forest restoration, the conversion of the forests due to climate change will significantly reduce the amount of water available for springs and spring-fed streams, putting many plant and animal species at risk.”
Although this study did not recommend courses of action, there are suggestions for forest managers. Flatley said managers from the U.S. Forest Service and National Parks Service can use the study to help decide whether to allocate limited resources to frequent restoration of smaller areas or less frequent restoration of larger areas.
He and Fulé are collaborating on a follow-up project funded through the U.S. Department of Agriculture’s Institute of Food and Agriculture.
“In this new project, we will expand the forest simulation modeling to national forests in New Mexico, Colorado and Wyoming with the goal of designing forest management strategies that optimize ecosystem services under future climate change scenarios,” he said.