Control of Boreal Forest Soil Decomposition Processes by Plant Secondary Compounds

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Plants produce a vast and variable array of secondary chemicals that are not essential for basic metabolism, yet play important roles in defense, competition, and reproduction. Considerably less is known about the role of secondary plant metabolites in ecosystem processes like carbon cycling and the breakdown of environmental pollutants. Phenolics, flavonoids, and tannins can inhibit the decomposition of plant matter. Some of these same compounds have been shown to enhance the microbial degradation of aromatic contaminants in soil. Interestingly, boreal forest trees in Alaska possess remarkably high concentrations of secondary compounds. The boreal forest is also a critical component of the global carbon budget, housing nearly one third of the World's vegetation carbon and soil carbon. This study will make use of long-term study boreal forest sites in Alaska and Finland, including some petroleum-contaminated field plots, to test the hypothesis that certain plant secondary chemicals inhibit plant litter decomposition, while at the same time promoting pollutant degradation by microorganisms. Comprehensive analyses of plant secondary chemistry, litter decomposition, and contaminant degradation will be integrated with cutting-edge molecular approaches for characterizing microbial community composition and function in soils associated with an array of different boreal forest trees.This study will generate valuable information about the chemical interactions between plants and microbes and the ramifications for ecosystem processes and global carbon cycling. New insights into plant-chemical-microbial interactions that promote organic contaminant degradation will also provide insight into the resilience of boreal forest soils to organic contaminants, and may lead to affordable methods for mitigating contamination in remote, cold regions using native plants. Opportunities for advanced research training will be provided to Alaska Native high school students as well as undergraduate and graduate students and a postdoctoral researcher. The public will be engaged with the themes and findings of this project through novel arts events resulting from collaborative interactions between artists and scientists.