Current Projects
Greater Yellowstone Ecosystem
Dr. Erica Smithwick
Little is known about post-fire soil nitrogen and microbial communities following severe fire in western U.S. forests (Smithwick et al. 2005, Ecosystems). In this set of research questions, we asked how microbial communities are patterned following fire, and whether this information can improve statistical models of post-fire soil nitrogen cycling (Smithwick et al. 2005, Soil Biology and Biochemistry). Using the Century ecosystem model to forecast changes in carbon and nitrogen cycles in Yellowstone National Park under climate change scenarios, we demonstrated that extensive disturbances create heterogeneity that modifies how forests will respond to altered climate change at landscape scales (Smithwick et al. Global Change Biology, in press).
(Funding from the Andrew Mellon Foundation to Monica Turner, Bill Romme, Daniel Tinker; Joint Fire Sciences Program to Michael Ryan, Monica Turner, Bill Romme and Dan Tinker).
The Effect of Wildfire Severity on Short-Term Post-Fire Boreal Vegetation Recovery in Interior Alaska
Jared Oyler
Wildfire is the dominant disturbance in the interior boreal region of Alaska and is predicted to increase with climate change. However, due to limited fine-scale studies, it is not known how increased fire severity (i.e.—amount of organic material consumed) alters post-fire recovery of vegetation productivity and biomass, nor how the relationship between severity and post-fire recovery varies across heterogeneous landscapes. Using remotely sensed data, this study will analyze the effect of fire severity (Normalized Burn Ratio) and related landscape variables (land cover, elevation, slope, aspect, etc.) on post-fire productivity and biomass recovery (MODIS NDVI/EVI) and determine how recovery varies within and among all fires that burned in Alaska in 2004. A stand-scale analysis of field-based measures of fire severity, pre-fire stand variables, and succession vegetation biomass and productivity at a subset of the 2004 fire sites will augment the remote sensing analysis. Understanding how increased fire severity alters boreal vegetation recovery and succession is critical in predicting associated feedbacks and effects on climate and global biogeochemical cycles.
Nitrogen Availability Along a Condition Gradient in Headwater Wetlands in the Upper Juniata Watershed, Pennsylvania
Misha Williams-Tober
Human activities have led to a large increase in nitrogen inputs to terrestrial and aquatic ecosystems. Elevated nitrogen levels in water are deleterious to both aquatic biota and humans. The reduction of nitrogen inputs to streams can be achieved through the protection and restoration of riparian zones, including headwater wetlands. Management of riparian zones for the function of nitrogen removal requires understanding the factors that control the process. In non-wetland riparian zones, vegetation uptake might be the primary source of nitrogen removal, while nitrogen removal in headwater wetlands might depend more upon oxic/anoxic conditions and denitrification. Through collaboration with the Penn State Cooperative Wetland Center, 12 headwater wetland sites within the Upper Juniata watershed were selected. Four condition categories were established, ranging from 0 (extremely poor condition) to 100 (excellent condition), and each category includes three sites. Readily available nitrogen at each site will be collected with free ion exchange resin bags and analyzed with a Lachat autoanalyzer for dissolved organic nitrogen, ammonium, and nitrate. Regression will be used to characterize the relationship between these nitrogen pools and soil moisture, condition category, pH, vegetation type, percent vegetation, and biomass of trees (by species). This will reveal the controls over nitrogen removal in headwater wetlands. Knowledge of these controls can be used to properly manage headwater wetlands for the function of nitrogen removal.
Climate Change Impacts on Forests along the Applachian Trail
Elizabeth Crisfield
I am interested in studying the interdependencies of species compositions shifts, disturbance, and climate change. I am also interested in the potential role of topography to facilitate or interfere in natural species migrations. The Appalachian Trail is oriented along a predicted migration path for animal and plant species and offers a relatively contiguous pathway for these migrations. In addition, micro-climate due to elevation also offers unique adaptation opportunities for species in the region.
(Funding from the National Park Service Centennial Challenge and the DOE NICCR Program).
Past Projects
Pacific Northwest
Erica Smithwick
I have developed (with Mark Harmon, Jimm Domingo) a model to predict how carbon storage changes under altered disturbance regimes (Smithwick et al. Landscape Ecology 2006). I also modeled how non-linear interactions across forest edges result in emergent behavior at broad scales, contributing to a greater understanding of scaling issues (Smithwick et al. Landscape Ecology 2003). Leading to a better valuation of ecosystem services, I also calculated that future carbon sequestration potential in the Pacific Northwest could be worth billions of dollars (Smithwick et al. Ecological Applications 2001).