Data from: Frost sensitivity of leaves and flowers of subalpine plants is related to tissue type and phenology

Harsh abiotic conditions–such as low temperatures that lead to spring and summer frost events in high-elevation and high-latitude ecosystems–can have strong negative consequences for plant growth, survival, and reproduction. Despite the predicted increase in episodic frost events under continued climate change in some ecosystems, our general understanding of the factors associated with frost sensitivity of reproductive and vegetative plant structures in natural plant communities is limited. The timing of growth and reproduction may be an important strategy by which plants can avoid frost. In this study, we experimentally investigated the frost sensitivity of eight long-lived perennial herbaceous plant species from a subalpine ecosystem in the Colorado Rocky Mountains, USA. The study taxa represent four congeneric pairs from four flowering plants families; within each pair is a species with early and late growth and reproductive phenology. Thus, we control for evolutionary history–and therefore additional traits shared through common ancestry– to some degree, while examining the influence of phenology on frost sensitivity. Specifically, we compared frost sensitivity of vegetative and reproductive structures for each species, and asked whether frost sensitivity was similar between species within congeneric pairs, or instead was related to phenology (i.e. differences in the timing of growth and reproduction). For most species (6 of 8), flowers were more sensitive to frost than leaves. Within most congeneric pairs (3 of 4), the leaves of species with later phenology were significantly more sensitive to frost than the leaves of species with earlier phenology. For flowers, the later-flowering species were more sensitive in two of the four congeneric pairs. Synthesis: This study contributes to our general understanding of factors related to interspecific differences in plant sensitivity to episodic frost events of naturally occurring species. The increased frost sensitivity of reproductive structures compared to vegetative structures may be a widespread pattern for long-lived perennial plants. Furthermore, we find evidence for a trade-off between phenology and frost sensitivity, whereby species with later phenology exhibit higher frost sensitivity compared to species with earlier phenology. These results have implications for plant populations, species interactions, and ecological communities.

严苛的非生物环境条件——比如高海拔与高纬度生态系统中，低温引发春夏季霜冻事件——会对植物的生长、存活与繁殖造成严重负面影响。尽管在部分生态系统中，持续气候变化下间歇性霜冻事件的发生频率预计会上升，但目前我们对自然植物群落中，植物繁殖结构与营养结构的霜冻敏感性相关影响因子的整体认知仍较为有限。生长与繁殖的物候（phenology）时序，或许是植物规避霜冻的重要策略之一。
本研究针对美国科罗拉多落基山脉亚高山生态系统中的8种多年生宿根草本植物，开展了霜冻敏感性的实验探究。本研究的研究类群涵盖来自4个显花植物科的4个同属物种对（congeneric pairs），每一对物种分别具有较早与较晚的生长及繁殖物候。借此，我们在探究物候对霜冻敏感性的影响时，可在一定程度上控制进化历史（即由共同祖先所共享的其他性状）这一变量。
具体而言，我们对比了各物种营养结构与繁殖结构的霜冻敏感性，并探讨了同属物种对内部的霜冻敏感性是否趋于一致，或是与物候相关（即生长与繁殖的时序差异）。针对多数物种（8种中的6种），其花部组织对霜冻的敏感性显著高于叶片。在多数同属物种对（4对中的3对）中，物候较晚的物种其叶片的霜冻敏感性显著高于物候较早的物种。就花部组织而言，4对同属物种对中有2对显示出开花更晚的物种敏感性更高。
综合分析：本研究有助于深化我们对自然物种间，植物对间歇性霜冻事件敏感性的种间差异相关影响因子的整体认知。相较于营养结构，繁殖结构的霜冻敏感性更高，这或许是多年生宿根植物的普遍规律。此外，本研究发现物候与霜冻敏感性之间存在权衡（trade-off）关系：物候较晚的物种，其霜冻敏感性相较于物候较早的物种更高。上述研究结果对植物种群、物种互作以及生态群落均具有重要启示意义。