Looking below: climate change and microbial communities in the rhizosphere of boreal forest soils
Climate change threatens the boreal forest, one of Canada’s greatest natural resources and the largest terrestrial store of carbon on Earth (Watson et al., 2000). Given continued increases in mean annual temperature, will the boreal forest—currently a global carbon sink—continue to sequester carbon or become a carbon source and further exacerbate climate change?
This research attempts to elucidate the effects of climate change on carbon stability in boreal forest soils. It focuses on the rhizosphere, soil characterized by root influence, which can host 19 to 32 times more microorganisms than bulk soil (Bodelier et al., 1997).
The main objectives are to determine: (1) if rhizosphere microbial communities differ in (a) natural aspen versus natural spruce stands, to investigate vegetation shifts, and (b) clear-cut aspen versus clear-cut spruce stands, to investigate management effects; and (2) whether rhizosphere microbial community composition differs from bulk soil.
Soil sampling was conducted in the boreal forest at the Ecosystem Management Emulating Natural Disturbance (EMEND) project in northern Alberta (Figure 1) in compartments under two stand types: deciduous dominated (more than 70% deciduous species) and conifer dominated (greater than 70% white spruce). Phospholipid fatty acid (PLFA) analysis was used to characterize microbial community composition.
Non-parametric statistics were used to assess significance in PLFAs and environmental variables. Clear-cutting affected rhizosphere microbial communities of conifer dominated sites only. Rhizosphere and bulk soil communities were not significantly different in natural stands. Microbial group and total PLFA data suggest vegetation shifts with climate change are unlikely to greatly affect rhizosphere carbon flux. However, overall microbial community composition under white spruce and aspen canopies differed significantly, and the effect of this difference on rhizosphere carbon remains unclear.
This research attempts to elucidate the effects of climate change on carbon stability in boreal forest soils. It focuses on the rhizosphere, soil characterized by root influence, which can host 19 to 32 times more microorganisms than bulk soil (Bodelier et al., 1997).
The main objectives are to determine: (1) if rhizosphere microbial communities differ in (a) natural aspen versus natural spruce stands, to investigate vegetation shifts, and (b) clear-cut aspen versus clear-cut spruce stands, to investigate management effects; and (2) whether rhizosphere microbial community composition differs from bulk soil.
Soil sampling was conducted in the boreal forest at the Ecosystem Management Emulating Natural Disturbance (EMEND) project in northern Alberta (Figure 1) in compartments under two stand types: deciduous dominated (more than 70% deciduous species) and conifer dominated (greater than 70% white spruce). Phospholipid fatty acid (PLFA) analysis was used to characterize microbial community composition.
Non-parametric statistics were used to assess significance in PLFAs and environmental variables. Clear-cutting affected rhizosphere microbial communities of conifer dominated sites only. Rhizosphere and bulk soil communities were not significantly different in natural stands. Microbial group and total PLFA data suggest vegetation shifts with climate change are unlikely to greatly affect rhizosphere carbon flux. However, overall microbial community composition under white spruce and aspen canopies differed significantly, and the effect of this difference on rhizosphere carbon remains unclear.
Disclaimer: The results presented on this website are preliminary and part of a Master's thesis. These may not represent the final results used in completion of the MSc degree.