Important large-scale, ecosystem functions such as the flux of water and carbon dioxide across the ecosystem-atmosphere boundary are determined by physiological controls exerted by plants. Climate change is altering many of the environmental conditions that directly drive the stomatal control of plants. We investigated shifts in plant carbon and water dynamics, by measuring photosynthesis and transpiration rates for four common species of ‘old field’ plants (two forb species and two grass species) under twelve altered temperature and precipitation regimes at the Boston Area Climate Experiment (BACE). We took replicated photosynthesis and transpiration measurements using a LiCOR-6400 at early and late growing season time points over two consecutive years. We also measured the carbon and nitrogen content of leaf tissue. 

Results/Conclusions

Results show that warming reduced rates of photosynthesis of both forb species. Transpiration rates responded significantly to both warming and precipitation treatments. Species responded differently to the treatments and the responses differed across the growing season. Nitrogen tissue content of one of the forb species was significantly reduced by both the drought and wet precipitation treatments. Our results indicate the importance of understanding the response of different plant species at different time points and for considering both temperature and precipitation changes when measuring the impacts of climate change for plant communities.