A belowground framework for predicting how plant-microbe interactions couple carbon and nutrient economies of forests

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Temperate deciduous forests occupy millions of acres across the Eastern and Midwestern US and perform vital ecosystem services by storing carbon (C), improving water quality and mediating climate. These forests have undergone and are currently undergoing dramatic changes in forest composition owing to human activities. The goal of this research is to develop a predictive framework for examining how tree species and their associated soil microbes influence C and nutrient cycles in central hardwood forests. Much of what is known about the role of tree species in influencing C and nutrient cycling is based on measurements of processes occurring in the forest canopy, despite the fact that roots and other belowground processes play a vital role in storing C and releasing nutrients. This project will integrate observational and experimental plot-level data with models and satellite imagery to examine how trees with different symbiotic fungal associations influence C and nutrient dynamics. To determine the importance of belowground processes to C and nutrient cycling, trees will be experimentally girdled, a process which physically blocks the flow of sugars to roots. A predictive framework for scaling plot-level data of C-nutrient cycling to ecosystem, regional and global scales will be developed by updating a nutrient uptake model and developing a land cover classification from remotely sensed data. Collectively, these approaches will enable the incorporation of plant-soil interactions into C cycle-climate models, and result in novel insights into how shifts in forest composition may influence ecosystem functioning.This multidisciplinary project will provide integrative training of undergraduate and graduate students in ecology, ecosystem modeling, and remote sensing. Moreover, the results of this research will be disseminated through reports developed for public land managers (state and federal forests). Reports designed for private landowners will also be produced to disseminate this information. Knowledge about C and nutrient dynamics in forests containing different tree species will enable private landowners, state extension offices and NGOs to make management decisions that enhance ecosystem services such as C storage. Importantly, this knowledge will enable the incorporation of critical plant-soil interactions into regional scale models of C cycling, and address a critical knowledge gap in the ability of policy makers to predict climate change impacts.