Division of Environmental Science and Ecological Engineering, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea.
Forest Technology and Management Research Center, National Institute of Forest Science, Pocheon, 11186, Republic of Korea.
Sci Rep. 2024 Mar 4;14(1):5250. doi: 10.1038/s41598-024-56120-3.
The frequency and intensity of summer extreme climate events are increasing over time, and have a substantial negative effect on plants, which may be evident in their impact on photosynthesis. Here, we examined the photosynthetic responses of Larix kaempferi and Pinus densiflora seedlings to extreme heat (+ 3 °C and + 6 °C), drought, and heavy rainfall by conducting an open-field multifactor experiment. Leaf gas exchange in L. kaempferi showed a decreasing trend under increasing temperature, showing a reduction in the stomatal conductance, transpiration rate, and net photosynthetic rate by 135.2%, 102.3%, and 24.8%, respectively, in the + 6 °C treatment compared to those in the control. In contrast, P. densiflora exhibited a peak function in the stomatal conductance and transpiration rate under + 3 °C treatment. Furthermore, both species exhibited increased total chlorophyll contents under extreme heat conditions. However, extreme precipitation had no marked effect on photosynthetic activities, given the overall favorable water availability for plants. These results indicate that while extreme heat generally reduces photosynthesis by triggering stomatal closure under high vapor pressure deficit, plants employ diverse stomatal strategies in response to increasing temperature, which vary among species. Our findings contribute to the understanding of mechanisms underlying the photosynthetic responses of conifer seedlings to summer extreme climate events.
随着时间的推移，夏季极端气候事件的频率和强度不断增加，对植物产生了实质性的负面影响，这可能在光合作用方面表现得尤为明显。在这里，我们通过野外多因素实验，研究了长白松和赤松幼苗对极端高温（+3°C 和+6°C）、干旱和强降雨的光合作用响应。长白松叶片气体交换在温度升高下呈现下降趋势，在+6°C 处理下，气孔导度、蒸腾速率和净光合速率分别比对照降低了 135.2%、102.3%和 24.8%。相比之下，赤松在+3°C 处理下表现出气孔导度和蒸腾速率的峰值功能。此外，两个物种在极端高温条件下总叶绿素含量增加。然而，由于植物整体具有良好的水分供应，极端降水对光合作用活动没有明显影响。这些结果表明，虽然极端高温通常通过在高水汽压亏缺下引发气孔关闭来降低光合作用，但植物在应对温度升高时采用了不同的气孔策略，这在物种间有所不同。我们的研究结果有助于理解针叶树幼苗对夏季极端气候事件的光合作用响应的机制。
