叶片的形态变异是研究植物响应气候变化的重要指标之一.叶片大小与形状影响着植物与外界环境的碳、水等物质交换和能量交换.然而,叶片大小与形状如何响应气候变化仍缺乏研究.此外,大多研究忽略了叶大小与形状在时间和空间上的种内变异,而只关注种间变异.我们收集了中国98年(1910-2008年)7个代表性双子叶植物的植物标本馆标本6000多份,并测量了它们叶片的叶长和宽度.我们探索了叶片大小(叶长、叶宽和长×宽乘积)的地理模式和时间趋势,(即研究了降水量和温度随时间和空间的变化对叶片大小和形状变化的影响.在控制了标本采集时间的影响后,全部物种的平均叶大小沿着纬度梯度的增加而减小,但这一关系在不同物种间存在差异.叶大小和形状的空间变异与温度和降水正相关.当控制了采集地点的影响后,全部物种的平均叶大小随着时间有变大的趋势.大多数物种叶大小的时间变化与降水正相关,而叶形状的时间变化则与温度正相关.我们的研究指出叶大小和形状在时空上的种内变异显著受气候的影响,同时说明植物标本可以为研究植物形态对气候变化的响应提供素材.“,”Aims Morphological variation of leaves is a key indicator of plant response to climatic change.Leaf size and shape are associated with carbon,water and energy exchange of plants with their environment.However,whether and how leaf size and shape responded to climate change over the past decades remains poorly studied.Moreover,many studies have only explored inter-but not intraspecific variation in leaf size and shape across space and time.Methods We collected＞6000 herbarium specimens spanning 98 years(1910-2008)in China for seven representative dicot species and measured their leaf length and width.We explored geographical patterns and temporal trends in leaf size(i.e.leaf length,leaf width and length x width product)and shape(i.e.length/width ratio),and investigated the effects of changes in precipitation and temperature over time and space on the variation in leaf size and shape.Important Findings After accounting for the effects of sampling time,leaf size decreased with latitude for all species combined,but the relationship varied among species.Leaf size and shape were positively correlated with temperature and precipitation across space.After accounting for the effects of sampling locations,leaf size of all species combined increased with time.Leaf size changes over time were mostly positively correlated with precipitation,whereas leaf shape changes were mostly correlated with temperature.Overall,our results indicate significant spatial and temporal intraspecific variation in leaf size and shape in response to climate.Our study also demonstrates that herbarium specimens collected over a considerable period of time provide a good resource to study the impacts of climate change on plant morphological traits.