Long-term vs. Short-term Plant Responses to Warming and Nitrogen Addition in a Temperate Old Field
Abstract
Climate warming and atmospheric nitrogen (N) deposition are expected to have strong effects on plant productivity in temperate ecosystems over the next century. However, short-term experiments may not adequately address their potential effects because of lags in changes in species composition. I added new plots to a pre-existing field experiment to compare the short-term (1-2 year; new plots) vs. long-term (14-15 year; old plots) effects of warming and N addition on plant productivity, relative species abundances, plant tissue N content, and litter decomposition. In 2020, N addition increased aboveground plant productivity most in old plots and only increased belowground biomass in the old N plots. In 2021, N addition effects did not differ among old and new plots. There were no significant treatment effects on forb species composition. Overall, non-native C3 grasses appear to impede additional long-term responses of plant productivity to global change by suppressing changes in species composition.