Date of Award
Fall 2024
Project Type
Thesis
Program or Major
Natural Resources and Environmental Studies
Degree Name
Master of Science
First Advisor
Jessica G Ernakovich
Second Advisor
Susan M Natali
Third Advisor
William H McDowell
Abstract
Wildfires in the Arctic tundra are increasing in frequency in response to global warming.Under this changing fire regime, important components of permafrost ecosystems, such as soils and their microbial communities, are disturbed by the burning of vegetation, organic soils, and their nutrients. Previous studies of wildfires have documented significant changes in nutrient availability following wildfires, including an increase in inorganic nitrogen (N), which is a key nutrient component of soil organisms. Microbes are the main drivers of transformation of soil N, which is ultimately taken up by both microbes and plants as a nutrient source. However, due to the historical low occurrence of wildfires in tundra ecosystems, the effects of fire on microbial communities involved in N-cycling in tundra soils are underexplored. Peat plateau tundra soils from the Yukon Kuskokwim Delta, Alaska, with documented fire history from 1972 and 2015 were sampled to evaluate the postfire repercussions on soil microbial communities and gene expression involved in N cycling through 16S rRNA amplicon sequencing and metatranscriptomic analyses. A decrease in microbial species richness and changes in community composition were observed in the humic horizon 7- and 50-years post-fire. In mineral soils, total N stocks and dissolved N increased post-fire. However, no changes in N stocks or N-related gene expression were observed between burned and unburned soils in the humic horizon, indicating that despite changes in microbial community composition, ecological function is restored to promote nutrient recovery in tundra soils.
Recommended Citation
Hernandez, Alma Idali, "Evaluating the Effects of Wildfires on Microbial Communities and Gene Expression Involved in Nitrogen Cycling in Arctic Tundra Soils" (2024). Master's Theses and Capstones. 1884.
https://scholars.unh.edu/thesis/1884