Historical Range of Variation for Potential Natural Vegetation Types of the Southwest
The Nature Conservancy Arizona
SW Forest Assessment
Descriptions of the Historical Range of Variation or Variability (HRV) characterize the change over time and space in the condition of the Southwest’s major vegetation types and the ecological processes that shape those types. HRVs enable land managers and the public to understand the drivers of change in our region’s major vegetation types.
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.
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[…]
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[…]
San Pedro River
Dale Turner, Holly Richter, Brooke Bushman
Wet/Dry Mapping Instructions and Data Forms
Example wet/dry mapping instructions and data forms used for the San Pedro wet/dry mapping effort. For more information, see our wet/dry mapping page.[…]