Michelle Mausolf | ALES Graduate Seminar

A graduate exam seminar is a presentation of the student’s final research project for their degree.
This is an ALES MSc Final Exam Seminar by Michelle Mausolf. This seminar is open to the general public to attend.

Thesis Topic: A survey of pyrogenic carbon in Kootenay National Park burned soils, and its positive effect on the establishment of pine-fungal ectomycorrhizal symbiosis

MSc with Drs. Derek MacKenzie and Mike Flannigan.

Seminar Abstract:

Wildfire is a natural disturbance in Rocky Mountain forest landscapes. Fire plays an important role in maintaining stand structure, woody debris consumption, and soil nutrient cycling. Fire exclusion in these ecosystems has expanded forest cover, altered stand structures, and allowed accumulations of duff, litter, and organic materials at the soil surface. Wildfire management and prescribed burning are two strategies currently used in Canadian National Parks to restore fire to Rocky Mountain ecosystems. This thesis examines the long-term influence of wildfire and prescribed burning on soil pyrogenic carbon (PyC), organic matter quality, and microorganisms at fire sites in Kootenay National Park as well as the impact of PyC on mycorrhizal colonization of pine seedling roots in a lab-based experiment. Mycorrhizal fungi form mutualistic symbioses with vascular plants wherein nutrients from the soil are exchanged for photosynthetically derived carbohydrates. Mycorrhizal fungi in forest soils have been shown to increase tree survival in harsh conditions created after fire. Soil samples from LFH and mineral horizons were taken from transects on four sites including: wildfires that occurred in 1968 and 2003, a fireguard burned in 2003, and a prescribed burn conducted in 2008. PyC was quantified in soils using chromatography following oxidation, and organic matter quality was characterized using simultaneous thermal analysis. Prescribed burn mineral soil contained the lowest quantity of PyC of the sites studied. Prescribed burn soil also contained the highest total organic carbon, which had a greater influence on their organic matter quality, (thermal stability), than PyC. The microbial community in the prescribed fire soils was distinct from the wildfire and fireguard sites. Results of this survey demonstrate that a single prescribed burn was not adequate to replicate wildfire in stands with heavy fuel loading resulting from fire exclusion. To investigate the effect of PyC (simulating restoration with fire) on soil fungi that form ectomycorrhizal symbioses with pine, microcosms containing Pinus banksiana and Suillus tomentosus were amended with biochar quantities representative of high and low severity fire. Biochar had no effect on the growth of non-mycorrhizal pine, and a negative effect on the growth of non-mycorrhizal S. tomentosus. However, in microcosms amended with biochar consistent with moderate-low severity wildfires, growth of pine seedlings and fungal hyphae was higher than in microcosms without biochar amendment. These results demonstrate that low to moderate severity prescribed fires may be beneficial to establishing mycorrhizal pine seedlings and play an important role in fire restoration in Rocky Mountain ecosystems.