ORAL PRESENTER CO-AUTHOR: Jeffrey Matthews (University of Illinois Urbana - Champaign) TITLE: When is restoration win-win? Evaluating plant diversity and carbon storage tradeoffs across restored floodplains ABSTRACT: The simultaneous recovery of plant diversity and carbon (C) storage in restored wetlands is uncertain due to tradeoffs among primary productivity, vegetation composition, and soil organic carbon (SOC) accrual. In this study, we compared these tradeoffs across eight Illinois wetland sites with paired restored and reference floodplain forests by conducting vegetation surveys and collecting soil cores. After analyzing cores for total C (TC) and SOC concentrations, we quantified C storage in multiple ecosystem pools along with tree and herbaceous layer species richness. To explain variation in SOC, we also measured two SOC fractions and multiple soil edaphic properties. Although inorganic and particulate organic C stocks were somewhat lower in restored than reference wetlands, high mineral-associated organic C stocks in restored wetlands led to TC and SOC stocks only marginally below reference levels. Despite having nearly recovered soil C storage, however, restored wetlands ultimately had much less ecosystem C storage due to their limited woody material. Conversely, plant species richness was only lower than reference levels at younger restored sites (<20 years), which had less canopy cover and more invasive species biomass than older restored sites (>20 years). Thus, beyond hydrology, tree density could be an important secondary factor influencing long-term plant diversity and ecosystem C storage in restored forested floodplains. BIO: Chelsea Peterson is a PhD candidate studying wetland ecology and restoration in the Department of Natural Resources and Environmental Sciences at the University of Illinois Urbana-Champaign. She earned her bachelor’s degree in environmental engineering at Cornell University and master’s degree in agricultural engineering at University of Illinois Urbana-Champaign.