Diversity and functional adaptation of mycorrhizal systems to extreme edaphic factors in British Columbia serpentine ecosystems

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Mycorrhizas are obligate symbioses between diverse fungi and the roots of most plants; they are critical to nutrient and energy exchange in belowground forest ecosystems. In part, the fungi facilitate plant nutrient and water uptake, and diminish toxic metal effects; in exchange, plants provide fungi with photosynthetic carbon (C). This proposal tests selection pressures related to physical, chemical, and biological properties of extreme soils on mycorrhizal fungi in serpentine landscapes. Globally, serpentine ecosystems support strikingly different, often unique, plant communities; however, we know little about the soil biology processes that support these systems, or how root-associated fungi may facilitate plant survival and adaptation. Using greenhouse and field studies, I will (1) assess root-fungal symbionts and seedling growth of conifers that are adapted to both serpentine and non-serpentine sites (including whitebark pine, a species that occurs only at high elevation and is 'endangered' in BC (COSEWIC), (2) assess the mycorrhizal structure, fungal identity and role of understory myco-heterotrophic plants that acquire all or part of their C via fungal links to other photosynthetic plants, such as conifers, on these sites, (3) examine the nutrient mobilization potential of extreme soils and the role of fungi on nutrient mobilization for plant use. The study will use advanced microscopy to characterize mycorrhizas, molecular techniques to directly amplify and analyze a portion of the fungal DNA from roots, and enzyme assays to measure nutrient mobilization activity. From this, we can identify fungi, calculate mycorrhizal abundance, estimate community diversity, and determine if the function and diversity of mycorrhizal fungi, and related growth adaptive traits of conifers, may be influenced by extreme soil factors. The study will provide fundamental information on rhizosphere processes in serpentine landscapes in western Canada. Results will address the importance of symbiotic associations in sustaining these ecosystems, the resilience and ability of mycorrhizal fungi to adapt to extreme soils, and their relevance in the conservation or re-establishment of biologically diverse plant habitats.