Changes in climate and grazing intensity influence plant-community compositions and their functional structure. Yet, little is known about their possible interactive effects when climate change mainly has consequences during the growing season and grazing occurs off growing season (dormant season grazing). We examined the contribution of trait plasticity to the immediate responses in the functional structure of plant community due to the interplay between these two temporally disjunct drivers. We conducted a field experiment in the northern Mongolian steppe, where climate was manipulated by open-top chambers (OTCs) for two growing seasons, increasing temperature and decreasing soil moisture (i.e., increased aridity), and grazing was excluded for one dormant season between these two growing seasons. We calculated the community-weighted mean (CWM) and the functional diversity (FD) of six leaf traits. Based on a variance partitioning approach, we evaluated how much of the responses in CWM and FD to OTCs and dormant season grazing occur through plasticity. The interactive effect of OTCs and the dormant season grazing were detected only after considering the role of trait plasticity. Overall, OTCs influenced the responses in CWM more than in FD, but the effects of OTCs were much less pronounced where dormant season grazing occurred. Thus, warming (together with decreased soil moisture) and the elimination of dormant season grazing could interact to impact the functional trait structure of plant communities through trait plasticity. Climate change effects should be considered in the context of altered land use, even if temporally disjunct.

气候和放牧强度的变化影响植物群落的组成及其功能结构。然而，当气候变化主要在生长季节产生影响而放牧发生在生长季节之外（休眠季节放牧）时，人们对它们可能的相互作用影响知之甚少。由于这两个暂时分离的驱动因素之间的相互作用，我们研究了性状可塑性对植物群落功能结构即时反应的贡献。我们在蒙古北部草原进行了一项田间实验，其中两个生长季节的气候由敞篷室（OTC）控制，增加温度并降低土壤湿度（即增加干旱），并且在两个生长季节之间的一个休眠季节排除放牧。这两个生长季节。我们计算了六个叶子性状的群落加权平均值（CWM）和功能多样性（FD）。基于方差划分方法，我们评估了 CWM 和 FD 对 OTC 和休眠季节放牧的响应有多少是通过可塑性发生的。只有考虑性状可塑性的作用后，才能检测OTCs和休眠季节放牧的交互作用。总体而言，OTC 对 CWM 反应的影响比对 FD 的影响更大，但在休眠季节放牧时，OTC 的影响不太明显。因此，变暖（连同土壤湿度下降）和休眠季节放牧的取消可能相互作用，通过性状可塑性影响植物群落的功能性状结构。应在土地利用改变的背景下考虑气候变化的影响，即使在时间上是不连续的。