Are Plants Able to Utilize Nitrogen Released from Thawing Permafrost? Implications for Carbon Cycling and Feedback with the Climate System
Climate warming in high-latitude regions triggers widespread permafrost thaw, releasing massive amounts of carbon and nitrogen that were previously frozen in soil organic matter, through increased microbial activity. Climate warming has motivated extensive research on permafrost carbon release; however, fewer studies have addressed whether plants can access new nitrogen sources, potentially increasing primary productivity. Two research questions were explored using Carex aquatilis in sites experiencing thaw and thermokarst in interior Alaska: 1) does C. aquatilis ammonium uptake vary with depth and time-since-thaw; 2) does variation in C. aquatilis growth characteristics and ammonium uptake correlate with aboveground primary production? An ammonium uptake experiment was conducted on C. aquatilis roots, determining that deep roots took up equal if not greater amounts of ammonium than shallow roots. I also found that rooting depth was positively correlated with aboveground biomass, providing a plausible mechanism for increased N uptake post-thaw to impact aboveground plant productivity.