Presented June 29, 2017- Presentation Slides
Abstract
“Identifying Indicators of State Change and Forecasting Future Vulnerability in Alaskan Boreal Forest” by Dr. Michelle Mack
The boreal region of Interior Alaska is changing. Greater occurrence of high severity fires is shifting forests from black spruce to deciduous and mixed forest ecosystems. This shift is altering the relationships between vegetation, soils and permafrost stability. Primary project objectives included (1) determining links among fire, soils, permafrost and vegetation succession and (2) forecasting landscape change in response to projected changes in climate, fire regime and fire management. Field measurements of ecosystem structure and function were used to modify the Terrestrial Ecosystem Model linked with the Alaska Frame-Based Ecosystem Code. The combined model was used to investigate how changing fire management planning options would influence the future fire regime and concurrent vegetation dynamics. These results support the understanding that increased wildfire severity increases permafrost thaw in the shorter-term and influences seedling establishment and successional trajectories, shifting forest composition from black spruce to deciduous-tree dominated ecosystems. In the longer-term, this shift has consequences for understory moss growth and organic layer re-accumulation, thereby directly influencing permafrost recovery post-fire. Change in tree species composition alters carbon partitioning into above and belowground pools and nutrient cycling rates. Finally, forest management approaches employed will further impact successional trajectories and vulnerability of permafrost to thaw.
"Subsurface Geophysical Mapping of Permafrost for Infrastructure Projects" by Mr. Kevin Bjella
The U.S. Department of Defense (DoD) and other federal agencies operate extensive infrastructure across Arctic North America and Greenland. The soil and rock of these high latitude regions is perennially frozen, and generally contains excess volumes of ground ice, which upon thawing often causes facility damage or failure. Under the Resource Conservation and Resiliency Program of SERDP, this project investigated geotechnical methods and tools that potentially would provide more resilient infrastructure for these sensitive conditions. A class of geophysical techniques was found to be very useful and accurate in identifying contrasts in ice-rich versus ice-poor, and frozen versus thawed conditions. In particular, capacitive-coupled resistivity (CCR) was demonstrated to effectively map these contrasting boundaries, while also identifying expansive regions of nearly continuous ground ice and soil class conditions. This project compared the results of resistivity surveys conducted over multiple transects where closely spaced sampling, vertically and horizontally, was conducted for moisture (ice) content and soil class determination. It was found that when geophysical surveys are conducted prior to geotechnical borehole drilling, anomalous locations can be pin-pointed for more detailed borehole investigation, and drilling efforts can be reduced at the large, seemingly homogenous stretches. The end result allows planners and engineers to better avoid problematic permafrost conditions, while optimizing the use of the ice-poor conditions. Overall, this reduces long term risk when constructing on permafrost in a warming climate.
Speaker Biographies
Dr. Michelle Mack is a Professor in the Center for Ecosystem Science and Society and the Department of Biological Sciences at Northern Arizona University in Flagstaff, AZ. She is an ecologist who studies the impacts of climate-sensitive disturbances, such as wildfire and abrupt permafrost thaw, on the dynamics of arctic and boreal ecosystems. Her work includes two decades of field research at the National Science Foundation (NSF)-funded Boreal and Arctic Longterm Ecological Research sites. She has produced more than 150 peer-reviewed publications in high-profile journals such as Nature and Science. She graduated from the Evergreen State College in Olympia, Washington, with a concurrent Bachelor of Science in Biology and Bachelor of Arts in Literature (1990). She received a doctorate in Integrative Biology (1998) from the University of California at Berkeley. Her experience in the Arctic started when she held an NSF postdoctoral-fellowship at the University of Alaska Fairbanks. She spent 12 years on the Biology faculty at the University of Florida before moving to Northern Arizona University.
Mr. Kevin Bjella is a Research Civil Engineer working with the Cold Regions Research and Engineering Laboratory (CRREL) of the U.S. Army Corps of Engineers (USACE), in Fairbanks, Alaska. He is the Technical POC for the CRREL Permafrost Tunnel in Fox, Alaska, and is the Project Engineer for the Permafrost Tunnel Expansion Project. His areas of research focus on improving methods for permafrost geotechnical investigations, and the interplay between degrading permafrost and built infrastructure. He has served as the Principal Investigator on several research projects, primarily focusing on improving methods for ground-ice delineation, but also investigation and mitigation of vertical and linear infrastructure failures related to permafrost degradation. His projects range across Alaska, Greenland, and Antarctica working with the Department of Defense and other Federal agencies, Alaska State Department of Transportation, academia and industry. He is a practicing Professional Engineer in the state of Alaska working with various USACE Districts on military construction (MILCON) projects in cold regions. Kevin has authored numerous peer reviewed articles and engineering guidance documents. He earned a Bachelor’s degree in Geological Engineering from the University of Alaska, Fairbanks in 1996, and a Master’s degree in Civil Engineering (Arctic Engineering) in 2008 from the University of Alaska, Anchorage.
