NSF Award
2312514
Since the start of the industrial revolution, the burning of fossil fuels has led to nitrogen pollution of Eastern US forests. This created an inadvertent experiment by society that had two opposing consequences. Forests retained only a fraction of this added nitrogen. The rest washed downstream and reduced water quality. Nitrogen pollution also acted as a fertilizer which enhanced the ability of trees and soils to store carbon and slow climate change. However, it remains unknown whether these consequences will persist as nitrogen pollution declines due to the success of the Clean Air Act. Notably, there is a lack of long-term records that can be used to investigate how Eastern US forests recover from nitrogen pollution during the final chapter of society’s inadvertent experiment. The research addresses whether these consequences will persist, recover, or reach a new normal, through long-term records of forest responses to nitrogen pollution at the Fernow Experimental Forest in West Virginia. The project broadens participation in science by engaging local 8th grade students in rural Tucker County, WV through field trips and in-class activities. <br/><br/>This research couples one of the country’s longest stream water datasets with the cessation of one of its longest watershed nitrogen addition experiments at the Fernow Experimental Forest. Reductions in nitrogen are hypothesized to trigger ecosystem recovery, wherein trees will send more carbon below ground to roots and symbiotic fungi for nitrogen acquisition ultimately leading to reductions in ecosystem nitrogen losses and carbon storage. This hypothesis was tested by tracking the recovery of four watersheds experiencing declines in ambient nitrogen pollution as well as in an experimental watershed where nitrogen fertilization ceased in 2020. Across these watersheds, long-term records of stream water nitrogen and forest carbon storage are maintained and enhanced by new measurements of tree and microbial species composition as well as assessments of carbon investment by trees in roots and symbiotic fungi to reveal the mechanisms of ecosystem responses. The research refines and informs processes in an ecosystem model to improve our predictive understanding of forest recovery to declines in nitrogen pollution.<br/><br/>This project is jointly funded by Ecosystem Science and the Established Program to Stimulate Competitive Research (EPSCoR).<br/><br/>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.
