Postdoctoral Research Scientist, Natural Resources Canada
Comparing soil microbial diversity and functions in reclaimed and natural benchmark sites in Alberta
The current research is comparing structural and functional diversities of soil microbial communities in reconstructed ecosystem following oil sands mining with that in natural boreal forests. Open pit oil sands mining in Alberta removes all the vegetation and soil materials upto 75 m to access the ore. Upon finishing ore extraction, the disturbed landscapes go through a systematic reconstruction process using the stockpiled materials and selectively salvaged boreal forest floor. Reclaiming disturbed ecosystem to land capabilities equivalent to pre-disturbance condition is a legal mandate in Alberta. The main objective of the current research is to evaluate the structural and functional similarities in soil microbial communities between reconstructed and natural ecosystems. Both fire disturbed and mature forests were used as natural analogues of the reconstructed system. DNA metabarcoding and microbial physiological responses are being used for characterizing microbial structure and functions, respectively. Vegetation composition, rhizosphere properties and abiotic conditions are all being measured to get a better insight of the processes involved in microbial community assemblages on different reclamation and natural soil types. Findings from this research will be useful in guiding future reclamation and managing the current sites in terms of soil health and fertility.
Abstract: Canadian Journal of Soil Science, e-First Articles. Comparing functional similarity in reconstructed ecosystems with natural benchmarks can provide ecologically meaningful information to measure reclamation success. We examined nutrient supply rate using ion-exchange resins as a measure of ecosystem function in two oil sands reclaimed soils, viz. peat mineral mix (PMM) and forest floor mineral mix (FFMM), and measured fertilization effect on nutrient supply rates in these soils for three consecutive years contrasted with young-fire-disturbed and mature forest stands. Results indicated that nutrient profiles of reclaimed soils were significantly different than natural benchmarks. Phosphorus and potassium supply rates in reclaimed soils were up to 91% lower, whereas S, Ca, and Mg were, respectively, up to 95%, 62%, and 74% higher than in benchmark soils. The expected nutrient flush postfertilization was only apparent in N and P, but the transient effect levelled off the year after fertilization in most cases. Fertilization aligned the temporal trajectory of the nutrient profile in PMM similar to benchmark conditions indicating greater ecological benefit of fertilization than in FFMM. The findings from this study suggest that fertilization focusing on P and K is likely more ecologically appropriate for establishing natural ecosystem function on reclaimed soils in this region of the boreal forest.
Pub.: 12 Oct '16, Pinned: 01 Sep '17
Abstract: Ecosystem recovery following disturbance requires the reestablishment of key soil biogeochemical processes. This long-term 7 year study describes effects of organic material, moisture, and vegetation on soil microbial community development in the Athabasca Oil Sands Region of Western Canada.Phospholipid fatty acid analysis was used to characterize and compare soil microbial community composition and development on reclaimed and natural forest sites. Additionally, we conducted a laboratory moisture manipulation experiment.The use of forest floor material as an organic amendment resulted in a greater percent cover of upland vegetation and placed the soil microbial community on a faster trajectory towards ecosystem recovery than did the use of a peat amendment. The soil microbial composition within the reclaimed sites exhibited a greater response to changes in moisture than did the soil microbial communities from natural sites.Our research shows that the use of native organic amendment (forest floor) on reclaimed sites, and the associated establishment of native vegetation promote the development of soil microbial communities more similar to those found on natural forest sites. Additionally, soil microbial communities from natural sites may be more resistant to changes in soil moisture than those found on reclaimed sites.
Pub.: 19 Jun '12, Pinned: 01 Sep '17
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