Ecology of Arctic Legumes in Upland Tundra Heath near Rankin Inlet, Nunavut
Date
2024-10-07
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Thesis
Degree Level
Masters
Abstract
Restoring mining sites in Arctic regions poses significant challenges due to slow natural ecosystem recovery, which can take decades or even centuries given the harsh environmental conditions. Compounding this challenge is the scarcity of native seeds and the reliance on fast-growing non-native species, which can disrupt ecosystem processes and become invasive. These studies focus on understanding the ecology of four native Arctic legumes and provide recommendations for their use in targeted restoration strategies.
In the first study, nodules from disturbed gravel areas and adjacent intact tundra near Rankin Inlet, Nunavut, Canada, were collected from four native legume species — Astragalus alpinus, Hedysarum americanum, Oxytropis arctica, and Oxytropis maydelliana. Next-generation sequencing of the 16S and nifH regions was used to characterize the nodule bacterial community composition and diversity. Despite large differences in substrate characteristics, no significant effects of soil environment were found on bacterial community composition within plant nodules, and few differences were observed in nodule communities between the plant species. These results suggest that the essential microbial propagules required for successful nodulation are present in disturbed substrates. Thus, restoration efforts to expedite ecological succession by planting native legumes may succeed without the need for commercial inoculants.
The second study aims to understand the belowground ecology of four native legume species near Rankin Inlet, Nunavut, Canada – Astragalus alpinus, Hedysarum americanum, Oxytropis arctica, and Oxytropis maydelliana. Entire plants, including intact root systems and surrounding soil, were collected and imaged using a positron emission tomography/ X-ray computed tomography (PET/CT) instrument. Experiments were conducted to adapt and optimize [11C]CO2 dosing and imaging procedures from recommended agricultural crop procedures. Oxytropis maydelliana was successfully exposed to [11C]CO2 tracer, and root structures were imaged using the GNEXT PET/CT imaging system. Non-invasive imaging technologies like PET provide insights into intact plant processes associated with belowground ecology, aiding in recommending better reclamation plans for Arctic sites.
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Keywords
arctic, legume, rhizobia, restoration, tundra, nodule
Citation
Degree
Master of Science (M.Sc.)
Department
Plant Sciences
Program
Plant Sciences