Forest Management and Warming Effects on a Century of Salt River Streamflow
Marcos D. Robles, Dale S. Turner, and Jeanmarie A. Haney
Colorado River Basin
Recent studies suggest that climate change has altered the flow and provision of water from western US rivers to downstream cities and natural communities, but fewer studies have examined hydrological influences related to a century of fire suppression. This study evaluated the effects of changing forest and temperature conditions on 20th century flow patterns in the Salt River in central Arizona. Seasonal and annual flows declined by 8-29% in the first half of the century which coincided with a 10-fold increase in ponderosa pine forest densities. Based on a scientific review, there is strong evidence that changes in forest structure contributed to these flow declines. In the 2nd half of the century, warmer temperatures led to earlier timing of peak spring flows of almost 2 weeks but had negligible direct effects on flow magnitudes. These results suggest that forest change had effects on flow well before anthropogenic warming and that large-scale restoration projects hold some promise of recovering seasonal flows.
Aerial view of the Parks West restoration site overseen by TNC. Taken March 16, 2020.
Conservancy staffers, Dale Turner and Amanda Rebore, helping to map the Sabn Pedro River in Arizona. They use a GPS unit to denote the end of the water flow on the LowerSan Pedro River. They hiked through the Conservancy’s San Pedro Preserve.
Our Approach to Science
The Nature Conservancy’s conservation science program in Arizona engages stakeholders and expertise in applied science and policy to develop new information, ideas, and tools that can help solve some of our most pressing challenges affecting people and nature
Explore Our Science
We are working with partners and stakeholders to accelerate the pace and scale of forest restoration for a healthy Arizona
Mapping the Status of River Streams
Wet/dry mapping provides a low-cost, river-wide snapshot of hydrologic conditions for rivers with interrupted perennial surface flows.
Lisa A. McCauley, John. B. Bradford, Marcos D. Robles, Robert K. Shriver, Travis J. Woolley, Caitlin A. Andrews
Landscape-scale forest restoration decreases vulnerability to drought mortality under climate change in southwest USA ponderosa forest
Drought is projected to increase tree mortality in many western US forests due to climate change and could result in large-scale tree die-offs, altering forest composition and ecosystem services. Tree mortality has also been found to be higher in forests with greater tree density. Southwestern US fo[…]
The Nature Conservancy, in collaboration with the Western Water Assessment and the USDA-Agricultural Research Service, has produced a snowtography handbook to support resource managers, researchers, and practitioners seeking to understand how the arrangement and density of trees, or the size and sev[…]
Climate Change, Forest Restoration Benefits
John. B. Bradford, Robert K. Shriver, Marcos D. Robles, Lisa A. McCauley, Travis J. Woolley, Caitlin A. Andrews, Michael Crimmins, David M. Bell
Tree mortality response to drought-density interactions suggests opportunities to enhance drought resistance
A future of hotter temperatures and less precipitation under climate change could increase tree mortality under drought conditions in dry forests across the western U.S., causing large-scale tree die offs. Restoration projects that reduce densities of overgrown forests can result in lower competit[…]