Shapotou Desert Research and Experiment Station, Northwest Institute of Eco-environment and Resource Research, Chinese Academy of Sciences, Lanzhou, China; University of Chinese Academy of Sciences, Beijing, China.
Shapotou Desert Research and Experiment Station, Northwest Institute of Eco-environment and Resource Research, Chinese Academy of Sciences, Lanzhou, China; University of Chinese Academy of Sciences, Beijing, China.
Sci Total Environ. 2024 Nov 20;952:175899. doi: 10.1016/j.scitotenv.2024.175899. Epub 2024 Aug 31.
Ongoing warming will influence plant photosynthesis via thermal effects and by enhancing water deficit. As the primary limiting factor for the growth and development of plants in arid deserts, water may alter the potential warming effects on plant photosynthesis and lead to increased uncertainty in plant dynamics. Here, we used open-top chambers (OTCs) to evaluate the impacts of in situ warming (+0.5 and +1.5 °C) on the photosynthesis and growth of two representative desert plants, Artemisia ordosica and Grubovia dasyphylla, from wet to dry spells. The plant traits associated with photosynthetic diffusive and biochemical processes were also measured to explore the underlying mechanisms involved. We found that warming significantly increased the net photosynthetic rate (A) during wet spells under 1.5 °C warming in both plants, while only increased that of A. ordosica under 0.5 °C warming. During dry spells, A decreased both in A. ordosica and G. dasyphylla, with the rates of declining being 48 % and 41 %, respectively, higher than control under warming. Consequently, warming significantly amplified photosynthetic responses to drought events, which offset the positive warming effects during wet spells and led to unchanged plant biomass in both species. Besides, alterations in plant traits tended to be associated with positive warming effects during wet spells, and the negative effects of drought were mainly due to stomatal limitation. Our results emphasised that the potential benefits of warming during wet spells may be reversed during drought events. Thus, the adverse effects of ongoing warming on desert productivity may increase during dry spells in growing seasons and during dry years.
持续变暖将通过热效应和加剧水分亏缺来影响植物光合作用。水分作为干旱荒漠地区植物生长和发育的主要限制因素，可能会改变潜在的变暖对植物光合作用的影响，导致植物动态的不确定性增加。在这里，我们使用开顶式气室（OTCs）来评估原位增温（+0.5 和+1.5°C）对两种典型荒漠植物，油蒿和沙木蓼在湿润到干旱期的光合作用和生长的影响。还测量了与光合作用扩散和生化过程相关的植物性状，以探讨所涉及的潜在机制。我们发现，在 1.5°C 升温下，湿润期的净光合速率（A）在两种植物中都显著增加，而在 0.5°C 升温下仅增加了油蒿的 A。在干旱期，A 在油蒿和沙木蓼中均下降，升温下下降率分别比对照高 48%和 41%。因此，变暖显著放大了光合作用对干旱事件的响应，抵消了湿润期的正向增温效应，导致两种植物的生物量不变。此外，植物性状的改变往往与湿润期的正向增温效应有关，干旱的负面影响主要是由于气孔限制。我们的结果强调，湿润期变暖的潜在好处可能会在干旱事件中逆转。因此，在生长季和干旱年份，持续变暖对荒漠生产力的不利影响可能会在干旱期增加。
