COS 161-7 - Climate and burn severity effects on post-fire recovery of three ponderosa pine ecosystems

Thursday, August 10, 2017: 3:40 PM
B116, Oregon Convention Center
Beth A. Newingham, Great Basin Rangelands Research, USDA Agricultural Research Service, Reno, NV, Andrew Hudak, Rocky Mountain Research Station, USDA Forest Service, Moscow, ID, April G. Smith, Great Basin Rangelands Research Unit, USDA Agricultural Research Service, Reno, NV, Benjamin Bright, Rocky Mountain Research Station, USDA Forest Service and Azad H Khalyani, Ecosystem Science and Sustainability, Colorado State University, Fort Collins, CO

Climate change is predicted to affect plants at the margins of their distribution. Thus, ecosystem recovery after fire is likely to vary with climate and may be slowest in drier and hotter areas. However, fire regime characteristics, including burn severity, may also affect vegetation recovery. We assessed vegetation recovery one and 9-15 years post-fire in three North American ponderosa pine ecosystems (Oregon, Colorado, and South Dakota) distributed across climate and burn severity gradients. Using climate predictors derived from downscaled 1993-2011 climate normals, we predicted vegetation recovery as indicated by Normalized Burn Ratio derived from 1984-2012 Landsat image time series. Additionally, we measured vegetation cover and diversity in the field to examine local topographic controls on burn severity and post-fire vegetation recovery. At a regional scale, we hypothesized that warmer and drier sites would take longer to recover. At the local scale, we hypothesized southern aspects to recover more slowly than northern aspects. We also hypothesized higher burn severity would slow recovery.


A decade after fire, common species in ponderosa pine forests were influenced by climate, burn severity, and plant functional groups. Precipitation (r2 = 0.73) significantly influenced plant communities at the Colorado and South Dakota fires, while temperature affected the Colorado plant community (r2 = 0.68). Burn severity had significant effects at the most recent and driest fire in Oregon (r2 = 0.50). Several plant functional groups also influenced current plant communities at the Oregon and South Dakota sites. Species richness significantly changed over the ten-year period (P < 0.0001) and was affected by burn severity (P < 0.0001) at the Oregon fire. Likewise, time (P < 0.0001) and burn severity (P = 0.04) significantly affected species richness at the Colorado fire. Although plant communities were significantly different after ten years (P < 0.0001), they were not affected by burn severity (P = 0.65) at the South Dakota site. We concluded that ponderosa pine forest recovery after fire depends on locale climate, burn severity, and time since fire. Burn severity effects may lose their effect over time and also linger longer at drier ponderosa pine forests.