Collaborative Research: Elucidating the chemical plasticity of fine roots in response to soil heterogeneities and developing a better parameter to forecast fine root decomposition

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Plants adapt to their soil environment through changes in patterns of root growth and chemical composition, which influence how plants take up nutrients and water. Poor understanding of how roots respond to stress is an obstacle to understanding plant responses to environmental change. In addition, how quickly roots decompose affects how nutrients are recycled from dead root tissues, which can further influence plant growth. However, current models of root decomposition are based on what is known about the breakdown of aboveground parts of plants, like leaves and stems. Furthermore, little is known about how root chemistry varies with local soil conditions which limits understanding of how plants respond to nutrient poor soils, or how this in turn influences soil nutrient recycling. This research will study how soil conditions and microbes influence root chemistry of important forest tree species in eastern North America. Results of this research will also improve models of root decomposition by incorporating root chemical composition. This project will also provide several benefits to society. It will create workshops for high school students and a summer course and curriculum development materials for K-12 teachers. It will also provide training for undergraduates, graduate students and a postdoctoral researcher.Fine roots (less than 2mm diameter) have a disproportionately large influence on plant adaptation and key ecosystem processes, yet they remain one of the least understood components of Terrestrial Biosphere Models. Commonly used parameters, such as element ratios, that predict decomposition of aboveground tissues fail to adequately predict the decomposition of fine roots. The central hypothesis of this proposal is that this disconnect is due to the unique chemical construction of roots, which is shaped by their immediate biotic and abiotic soil environments. The PIs propose to investigate the chemical plasticity in fine roots of different tree species developed under different soil resource availabilities and associations with different species of mycorrhizal fungi. The PIs will link observed chemical plasticity to decomposition dynamics of fine roots using decomposition experiments and by utilizing advanced imaging and spectroscopy techniques. The PIs propose to develop parameters that incorporate root chemistry to improve predictions of fine-root decomposition. The proposed project would be one of the first attempts to obtain a comprehensive understanding of the molecular-level chemical profile of fine-roots that facilitate plant stress adaptation, and to develop robust parameters to predict fine-root decomposition and soil organic matter formation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.