Leaf-Level Gas Exchange and Foliar Chemistry of Common Old-Field Species Responding to Warming and Precipitation Treatments

Abstract

We investigated the shifts in plant carbon (C) and water dynamics by measuring rates of photosynthesis, transpiration, and instantaneous water use efficiency (WUE) in three common species of ''old-field'' plants-two C 3 forb species (Plantago lanceolata and Taraxacum officinale) and one C 3 grass species (Elymus repens)-under 12 experimentally altered temperature and precipitation regimes at the Boston Area Climate Experiment (BACE) in Waltham, Massachusetts. We also measured shifts in foliar C and nitrogen (N) content to determine possible changes in plant C/nutrient balance. We hypothesized that the warming treatment would cause an increase in photosynthesis rates, unless water was limiting; therefore, we expected an interactive effect of warming and precipitation treatments. We found that warming and drought reduced leaf-level photosynthesis most dramatically when environmental or seasonal conditions produced soils that were already dry. In general, the plants transpired fastest when soils were wet and slowest when soils were dry. Drought treatments increased WUE relative to plants in the ambient and wet treatments but only during the driest and warmest background conditions. Leaf N concentration increased with warming, thereby indicating that future warming may cause some plants to take up more soil N and/or allocate more N to their leaves, possibly as consequences of increased nutrient availability. There were no significant interactive effects of the warming and precipitation treatments together across all seasons, indicating that responses were not synergistic or ameliorative.

Net primary productivity and rain‐use efficiency as affected by warming, altered precipitation, and clipping in a mixed‐grass prairie

“…The increases in NPP may be attributed to prolonged growing seasons with earlier beginnings and later endings under continuous warming (Wan et al ., ), increased soil nutrient mineralization and plant nutrient uptake (Rustad et al ., ; Sardans et al ., ), and also stimulated photosynthetic rates at higher temperatures (Rustad et al ., ; Luo et al ., ; Wu et al ., ). However, stimulated photosynthesis may be a minor cause of the increase in NPP since warming had no significant effect on photosynthesis according to previous studies (Stirling et al ., ; Zhou et al ., ; Rogers et al ., ). The non‐significant warming effect on ANPP probably resulted from the translocation of photosynthates from aboveground biomass to roots under warming, which was evidenced by the increased BNPP as well as f BNPP under warming (all P < 0.05, Table ; Figs b, d and a, b).…”

Warming increases the sensitivity of seedling growth capacity to rainfall in six temperate deciduous tree species

“…If photosynthetic carbon gain responds differently to these environmental changes than nitrogen uptake or allocation, leaf tissue chemistry could change. Interestingly, previous studies have found that warming can either increase ( Nijs et al 1996 ; Oleksyn et al 2003 ; Rodgers et al 2012 ) or decrease ( Yin 1993 ; Dormann and Woodin 2002 ; Reich and Oleksyn 2004 ; Suseela et al 2015 ) a plant species’ foliar nitrogen concentration. Altered foliar carbon and nitrogen concentrations can affect ecosystem-scale processes by influencing rates of photosynthesis, herbivore forage quality, plant litter chemistry and ultimately carbon and nutrient pathways ( Shaver et al 2001 ; Aerts et al 2009 ).…”

Increased water supply promotes photosynthesis, C/N ratio, and plantamajoside accumulation in the medicinal plant Plantago depressa Willd

“…Previous studies have suggested that drought treatment significantly reduced E and g s of plants than wet treatment in greenhouses (Miyashita et al 2005, Miao et al 2015. Nevertheless, Rodgers et al (2012) found that a 50% increased rainfall treatment did not cause a significant shift in E of P. lanceolata compared to a 50% reduced rainfall treatment.…”