Carol A. Wessman
Ph.D. University of Wisconsin, 1987
Professor, Ecology and Evolutionary Biology Department
Earth Science and Observation Center
E-mail: carol.wessman@colorado.edu
Office: Ekeley W265B
Phone: 303-492-1139
Web: Wessman Research Group
Research Interests
Ecosystem ecology, landscape ecology, regional and global biogeochemical cycling, ecological applications of remote sensing and geographic information systems. Current research includes studies of ecosystem controls over biophysical fluxes (CO2, water and energy) within global grasslands and semiarid lands utilizing remotely sensed spectral data in conjunction with simulation models; scaling site-level ecology to landscape and regional scales in the alpine; quantitative methods that link spatial patterns and ecological processes at broad spatial and temporal scales.
Current Research: Impacts of Multiple Disturbances and Their Interactions in Subalpine Landscapes -- Blowdown, Logging, Fire, and Beetle Kill
— with graduate student Kendra Morliengo-Bredlau and honors students Kerry Kemp and Julie Hayes
CIRES Ph.D. student Brian Buma in a burned blowdown plot in the Routt National Forest.
Conifer recovery in a burned logged-blowdown site.
Forest ecosystems are vulnerable to a range of disturbances that shape their structure, composition, and function, and consequently affect issues ranging from climate change to economics and social stability. Climate change, as well as ongoing human-forest interactions (i.e., forest management), is expected to yield forest disturbances of greater frequency, extent, intensity, and variety. We have a poor understanding of forest responses (especially regeneration) to multiple disturbances. Under climate change, compounded interactions among multiple disturbances may be unprecedented and unpredictable. We are studying the roles of large-scale disturbance interactions, historical contingencies, and ecological resilience in ecosystem dynamics in a long-term study of a subalpine ecosystem.
This study focuses on important drivers of forest regeneration at two scales: landscape (e.g., recent disturbance history, disturbance pattern) and local (e.g., biotic competition, microenvironment). Our study area in northern Colorado’s Routt National Forest experienced several catastrophic, large-scale disturbances over a short period. The region, currently undergoing epidemic spruce and mountain pine beetle infestations, experienced a recordsetting windstorm in 1997 (causing blowdown) followed by salvage logging and a regional wildfire in 2002. Historical records of such disturbance complexes are rare, and lack information on the processes important to ecosystem recovery.
This year, we found that successional processes are significantly different among disturbances, suggesting longer-term consequences for landscape structure. Areas that experienced a blowdown prior to fire are experiencing very little to no conifer regeneration, suggesting that fuels present in the blowdown contributed to increased fire severity. In contrast, blowdown areas that were logged are recovering well, comparable to forests that had no pre-fire disturbance. Our analyses show that pre-fire disturbance history interacted with both burn severity and time, implying that patterns of disturbances on the landscape may be affected spatially by previous disturbances, and have lasting temporal effects through seedling recruitment. This year we also examined Normalized Difference Vegetation Index (NDVI) time-series data from NASA’s MODerate Resolution Imaging Spectrometer (MODIS) sensor to determine whether 250-m resolution NDVI can be used to identify landscapes with drastically different recovery patterns. Results indicate that spring data can differentiate among recovery patterns in forest recovery, suggesting that MODIS NDVI can provide regional information on forest response to disturbance.
Publications
Click here for a complete list of published works »
Dr. Wessman is a member of the CIRES Professor.
