Inter- and intraspecific variability in the responses of grassland plants to winter climate change

气候变暖预计将缩短冬季的持续时间。然而，在温带草原，温度变异性的增加和冷驯化信号的变化可能会对植物构成挑战，因为它们在没有完全冷驯化的时候暴露在霜冻中。特别是，如果积雪减少，土壤表面牧草的基本分生组织很容易受到极端气温的影响，而后者预计适用于气候变暖的温带地区。当受到极端气候的挑战时，种群内的遗传变异或来自其他种群的扩散使物种能够在特定地点持续存在。如果耐霜性生态型的扩散受到限制，耐霜性的种间高度变异可能会改变物种组成。因此，未来温带草原的组成将取决于气候变化时耐霜性的种间差异和种内差异之间的平衡，但关于这一主题的数据很少。在这里，我们建议比较草原植物对冬季气候变化的反应的种间差异和种内差异。具体地说，我们将在受控环境室内实验中检查(1)植物对土壤冻融循环频率和强度变化的反应，(2)对持续时间较短的温暖冬季的冷驯化反应，以及(3)对仲冬融化事件的脱驯化和霜冻脆弱性的反应。我们将把重点放在德国草原物种内的种间变异和大陆范围内单一物种内的生态变异上。

Climate warming is expected to shorten the duration of winter. However, in temperate grasslands, increased temperature variability and changes to cold acclimation cues could challenge plants by exposing them to frost at times when they are not fully cold acclimated. In particular, basal meristems of grasses at the soil surface are vulnerable to air temperature extremes if there is reduced snow cover, and the latter is predicted for temperate regions with climate warming. When challenged by climate extremes, genetic variation within populations or dispersal from other populations enables species to persist at a specific location. High inter-specific variation in frost tolerance can alter species composition if dispersal of frost tolerant ecotypes is limited. Therefore, the future composition of temperate grasslands will depend on the balance between inter- versus intraspecific variation in frost tolerance in an altered climate, yet very little data are available on this topic. Here, we propose to compare inter- versus intraspecific variation in the responses of grassland plants to winter climate change. Specifically, we will examine (1) plant responses to variation in the frequency and intensity of soil freeze thaw cycles, (2) cold acclimation responses to warmer winters of shorter duration, and (3) deacclimation and frost vulnerability in response to mid-winter thaw events, in controlled- environment chamber experiments. We will focus on inter-specific variation within German grassland species as compared to ecotypic variation within a single species on a continental scale.