Simulation of the physiological and photosynthetic characteristics of C3 and C4 plants under elevated temperature and CO2 concentration

Presently, rapid global climate change, escalating atmospheric CO2 concentrations, and associated global warming, alongside other critical issues, are exacerbating, manifesting various impacts on the physiological and ecological traits of plants. This study initially established physiological models of photosynthesis in C3 and C4 plants based on the stomatal action, atmospheric CO2 transport process, and physiological process of photosynthesis. Additionally, we measured the photosynthetic physiological parameters for two typical C3 and C4 plants, Phragmites communis and Sporobolus alterniflorus, using a photosynthesizer to estimate the model parameters. Experimental and simulation results revealed that the stomatal conductance of C3 plants was increasingly influenced by rising temperature and CO2 concentration, with the optimal range being 25 °C to 30 °C, and stomatal closure observed at elevated temperatures. C4 plants demonstrate a more adaptable mechanism in regulating stomatal conductance, leveraging their CO2 concentrating mechanism to sustain lower levels of stomatal conductance, thereby enhancing water use efficiency and facilitating better adaptation to high-temperature stress on stomata. Moreover, the intercellular CO2 concentration of both C3 and C4 plants was influenced by stomatal conductance and atmospheric CO2 concentration, exhibiting distinct trends under varying conditions. Simulations of photosynthesis in C3 and C4 plants indicated that C4 plants were adept at coping with high temperatures and low CO2 concentrations, whereas C3 plants exhibited limited adaptation to high temperatures but experienced benefits from increased CO2 concentrations. The simulations demonstrated that temperature fluctuations exert a comparatively greater influence on plant physiological traits. If temperatures escalate beyond a certain threshold, the benefit of elevated CO2 concentrations for C3 plants may diminish. Consequently, C4 plants can sustain a higher net photosynthetic rate by employing their mechanisms to mitigate the stress induced by high temperatures. Against the backdrop of global environmental change, atmospheric CO2 concentrations and temperature invariably increase synergistically. Based on current trends, C3 plants are poised to maintain an advantage in cold regions at high latitudes for the foreseeable future, while C4 plants are likely to thrive in hot areas at low latitudes. However, in mid-latitude regions, the relative advantage of the simultaneous increase in temperature and CO2 concentration for either C3 or C4 plants is influenced by factors such as the local ambient temperature, the magnitude of CO2 elevation, the plant type, and its physiological characteristics. Consequently, heightened attention should be directed towards monitoring changes in plant communities within mid-latitudes.