Novel forestry practices for mitigating global change: investigating effects of legacy trees on plant-soil microbial networks, carbon cycling and forest recovery

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Canada's forests are being disturbed at unprecedented rates because of harvesting and climate change. Clearcutting followed by reassembly with fast-growing, species-poor plantations dominates forest practices, but shortcomings are evident in plantation failures and altered disturbance regimes. While competition remains central to ecology and evolution, as well as resource management, a more holistic theory recognizing the multiplicity of interactions would improve our ability to regenerate forests with greater biodiversity, carbon storage, and adaptive capacity. Recognizing ecosystems as such dynamic networks of interactions, as framed by complex adaptive systems theory, has promise for improving how we view and steward forests. My program will continue to investigate plant-microbe-soil interactions in forests. A key discovery has been that mycorrhizal networks linking trees mediate interactions between residual trees and regenerating seedlings. This has been integral in the design of the Mother Tree Project, an NSERC-funded experiment that compares effects of legacy tree retention levels on forest recovery across a 900 km-long climatic gradient of Douglas-fir forests in British Columbia. The overall goal herein is to use the Mother Tree framework to investigate the role of competitive and facilitative interactions between legacy trees and regenerating seedlings in forest resilience as climate changes. The underlying premise is that resilience is rooted in the balance of interactions among species, in keeping with complex adaptive systems theory. Over the next five years, I will meet three objectives: 1. Determine how climate and harvesting regimes affect competitive and facilitative interactions between legacy trees and regenerating seedlings, and how these influence the assembly of plant, fungal and microbial communities; 2. Understand how the assembly of these communities affect carbon and nutrient cycling; 3. Integrate new understanding of interactions into harvesting and regeneration strategies to augment carbon storage, biodiversity and forest recovery under changing climatic conditions. To meet these objectives, I will train HQP at the undergraduate, MSc, PhD and PDF levels. This will involve not only training in scientific research, but also mentoring for cultural, professional and personal intelligences, including building collaborative relationships, problem solving, critical thinking, and communication. I will build on my strong track-record of HQP training as evidenced in my graduates, publications and earlier CREATE program. This research tests classic ecological theory, but has practical implications for forests in Canada and world-wide. My previous research has already started changing forest management as well as carbon and biodiversity conservation practices and policies in western Canada. I anticipate continued success over the next five years as new understandings emerging from this research and reach the public sphere.