Influence of Precipitation, Vegetation Type, and Fire Severity on Post-Fire Vegetation Recovery in Colorado Ecosystems from 1985-2014
Abstract
Wildfire is an important disturbance in Southwestern US forests, and the frequency and severity of wildfire are predicted to increase with future climate change. During and immediately after a wildfire, forests shift to a source of carbon to the atmosphere. Whether a forest's carbon stocks return to their pre-fire state depends on the post-fire vegetation and soil recovery trajectories as well as the time between fires. If fires alter the long-term carbon balance in Southwestern US forests, it would represent a positive feedback to global climate change. This research aimed to elucidate the variables influencing vegetation recovery following wildfires in Colorado between 1985 and 2014. We analyzed the recovery of annual maximum NDVI and EVI following fire in relation to burn severity (MTBS), precipitation (PRISM), vegetation cover (USGS National GAP Analysis Program), elevation (USGS NED), slope (USGS NED), rock type (USDA NRCC), and soil organic carbon (USDA NRCC). We also examined long-term patterns of annual maximum NDVI (AVHRR: 1989-2015) and EVI (MODIS: 2000-2015) in unburned areas of Colorado's major natural ecosystem types (subalpine conifer forest, montane conifer forest, aspen forest, pinyon-juniper woodland, gamble oak woodland, saltbush and sagebrush steppes, semi-desert scrub steppe, and grassland). As expected, NDVI and EVI were correlated with precipitation and differed among vegetation types. In addition, severe burn areas were more likely to exhibit changes in NDVI than moderate burn or low burn areas. Pinyon-Juniper woodlands, montane forests, and subalpine forests showed significant drops in NDVI and EVI following severe fires. However, NDVI and EVI in grasslands, deciduous shrub ecosystems, and gambel oak woodlands showed minimal or no impact of fire and sometimes exhibited a small increase in the year following fire. NDVI and EVI in conifer ecosystems at higher elevation or with higher annual precipitation tended to recover more quickly than conifer ecosystems at lower elevation or with lower annual precipitation. This suggests that as fire frequency increases, the net ecosystem carbon balance of lower elevation, drier forested ecosystems is more likely to shift as compared higher elevation, wetter forests; leading to decreased carbon sequestration and/or a possible state shift.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.B53A0520W
- Keywords:
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- 0426 Biosphere/atmosphere interactions;
- BIOGEOSCIENCESDE: 0439 Ecosystems;
- structure and dynamics;
- BIOGEOSCIENCESDE: 1615 Biogeochemical cycles;
- processes;
- and modeling;
- GLOBAL CHANGEDE: 1616 Climate variability;
- GLOBAL CHANGE