Trading water for carbon in the future: effects of elevated CO2 and warming on leaf hydraulic traits in a semiarid grassland

The effects of climate change on plants and ecosystems are mediated by plant hydraulic traits, including interspecific and intraspecific variability of trait phenotypes. Yet, integrative and realistic studies of hydraulic traits and climate change are rare. In a semiarid grassland, we assessed the response of several plant hydraulic traits to elevated CO2 (+200 ppm) and warming (+1.5 to 3℃; day to night). For leaves of five dominant species (three graminoids, two forbs), and in replicated plots exposed to seven years of elevated CO2, warming, or ambient climate, we measured: stomatal density and size, xylem vessel size, turgor loss point, and water potential (pre-dawn). Interspecific differences in hydraulic traits were larger than intraspecific shifts induced by elevated CO2 and/or warming. Effects of elevated CO2 were greater than effects of warming, and interactions between treatments were weak or not detected. The forbs showed little phenotypic plasticity. The graminoids had leaf wa...气候变化对植物与生态系统的影响由植物水力性状（plant hydraulic traits）介导，其中包含性状表型的种间与种内变异。然而，针对水力性状与气候变化的整合性、现实性研究仍较为匮乏。本研究在一处半干旱草原中，评估了多种植物水力性状对CO2浓度升高（提升200 ppm）与增温（1.5至3摄氏度，日间至夜间梯度）的响应。针对5种优势物种（3种禾本科草本、2种非禾本草本）的叶片，在历经7年CO2浓度升高、增温或自然气候处理的重复样地中，我们测定了以下指标：气孔密度与大小、木质部导管尺寸、膨压丧失点以及黎明前水势。水力性状的种间差异大于CO2浓度升高和/或增温所诱导的种内变化。CO2浓度升高的效应强于增温效应，且两种处理间的交互作用微弱或未被检测到。非禾本草本植物的表型可塑性极低。禾本科草本的叶片水……