Late to bed, late to rise—Warmer autumn temperatures delay spring phenology by delaying dormancy

Spring phenology of temperate forest trees has advanced substantially over the last decades due to climate warming, but this advancement is slowing down despite continuous temperature rise. The decline in spring advancement is often attributed to winter warming, which could reduce chilling and thus delay dormancy release. However, mechanistic evidence of a phenological response to warmer winter temperatures is missing. We aimed to understand the contrasting effects of warming on plants leaf phenology and to disentangle temperature effects during different seasons.

With a series of monthly experimental warming by ca. 2.4 °C from late summer until spring, we quantified phenological responses of forest tree to warming for each month separately, using seedlings of four common European tree species. To reveal the underlying mechanism, we tracked the development of dormancy depth under ambient conditions as well as directly after each experimental warming. In addition, we quantified the te...

近数十年来，受气候变暖影响，温带林木的春季物候（spring phenology）已显著提前，但尽管气温仍在持续升高，这种物候提前的速率却正在放缓。学界常将春季物候提前速率的放缓归咎于冬季升温——冬季变暖会降低冷积温（chilling）累积量，进而延迟休眠解除。然而，目前仍缺乏冬季升温对植物物候产生影响的机制性证据。本研究旨在阐明升温对植物叶片物候的差异化影响，并厘清不同季节温度变化的具体作用。
本研究通过一系列从夏末至春季的月度实验性升温（experimental warming），升温幅度约为2.4℃，以4种欧洲常见林木的幼苗为实验材料，分别量化了林木物候对各月度升温的响应。为揭示背后的调控机制，我们监测了自然环境条件下以及每次实验升温后，林木休眠深度的动态变化。此外，我们还量化了[原文未完结]