Erguna Forest-Steppe Ecotone Research Station, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
Erguna Forest-Steppe Ecotone Research Station, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China.
Sci Total Environ. 2022 May 20;822:153589. doi: 10.1016/j.scitotenv.2022.153589. Epub 2022 Feb 2.
Plant nonstructural carbohydrates (NSC) can reflect community and ecosystem responses to environmental changes such as water availability. Climate change is predicted to increase aridity and the frequency of extreme drought events in grasslands, but it is unclear how community-scale NSC will respond to drought or how such responses may vary along aridity gradients. We experimentally imposed a 4-year drought in six grasslands along a natural aridity gradient and measured the community-weighted mean of leaf soluble sugar (SS) and total leaf NSC (NSC) concentrations. We observed a bell-shape relationship across this gradient, where SS and total NSC concentrations were lowest at intermediate aridity, with this pattern driven primarily by species turnover. Drought manipulation increased both SS and total NSC concentrations at one moderately arid grassland but decreased total NSC concentrations at one moist site. These differential responses to experimental drought depended on the relative role of species turnover and intraspecific variation in driving shifts in SS and total NSC concentrations. Specifically, the synergistic effects of species turnover and intraspecific variation drove the responses of leaf NSC concentrations to drought, while their opposing effects diminished the effect of drought on plant SS and total NSC concentrations. Plant resource strategies were more acquisitive, via higher chlorophyll concentration, to offset reduced NSC concentrations and net aboveground primary productivity (ANPP) with increasing aridity at more mesic sites, but more conservative (i.e., decreased plant height and ANPP) to reduce NSC consumption at drier sites. The relationship between water availability and NSC concentrations may contribute to community drought resistance and improve plant viability and adaptation strategies to a changing climate.
植物非结构性碳水化合物（NSC）可以反映群落和生态系统对环境变化（如水分可用性）的响应。预计气候变化将增加草原的干旱程度和极端干旱事件的频率，但尚不清楚群落尺度的 NSC 将如何响应干旱，或者这种响应如何沿干旱梯度变化。我们在一个自然干旱梯度上的六个草原上进行了为期 4 年的干旱实验，并测量了叶片可溶性糖（SS）和总叶片 NSC（NSC）浓度的群落加权平均值。我们观察到了一个钟形关系，在这个梯度上，SS 和总 NSC 浓度在中等干旱度时最低，这种模式主要是由物种更替驱动的。干旱处理增加了一个中度干旱草原上的 SS 和总 NSC 浓度，但降低了一个湿润地点的总 NSC 浓度。对实验性干旱的这些差异响应取决于物种更替和种内变异在驱动 SS 和总 NSC 浓度变化中的相对作用。具体而言，物种更替和种内变异的协同作用驱动了叶片 NSC 浓度对干旱的响应，而它们的相反作用则减弱了干旱对植物 SS 和总 NSC 浓度的影响。随着干旱程度的增加，植物资源策略变得更加积极，通过增加叶绿素浓度来弥补 NSC 浓度的降低和净地上初级生产力（ANPP）的降低，在较湿润的地方，但在较干燥的地方则更加保守（即降低植物高度和 ANPP）以减少 NSC 消耗。水可用性与 NSC 浓度之间的关系可能有助于群落的耐旱性，并提高植物的生存能力和适应气候变化的策略。
