CSV Files

Altered seasonal cycles of precipitation and temperature due to climate change have disrupted historical patterns of plant phenology – the timing of developmental stages like flowering and fruiting. Despite growing evidence that plant phenology is changing globally due to ongoing climate change, little is known about how plants in highly endangered habitats, such as vernal pools, are responding to climate variation. Furthermore, it is unclear whether the degree of habitat specialization influences a species’ phenological responses to climatic, seasonal, and microhabitat variation. To determine the susceptibility of widespread and endemic vernal pool plants to climate change in the California Central Valley, we monitored bloom onset, floral duration and termination date of two dominant vernal pool species, rosey meadowfoam (Limnanthes douglasii ssp. rosea), a vernal pool endemic species, and whitetip clover (Trifolium variegatum), a vernal pool facultative species, over 7 years. We measured climate and microtopography of three vernal pools at the University of California, Merced Vernal Pool and Grassland Reserve to quantify the relationship between abiotic environmental factors and plant phenology. We found an advancing flowering schedule of 4.7 days/year for meadowfoam and 5.6 days/year for whitetip clover, respectively, with recent, rapidly changing climate. Early flowering advanced into months previously unrecorded for both species across California during the study period. Warmer and dryer environmental conditions occurring during early growth periods were strongly associated with advanced floral phenology later in the life cycle for both species. We found that the floral duration of the habitat specialist was influenced by microtopographic features of vernal pools whereas no change was observed for the habitat generalist. Finally, warmer and dryer conditions were associated with reduced occupancy rates of both focal species within vernal pools. To our knowledge, this is the first study linking current climate warming to vernal pool plant phenology and performance.

气候变化引发的降水与温度季节循环改变，已打破了植物物候的历史模式——即开花、结果等发育阶段的发生时序。尽管越来越多证据表明，全球范围内的植物物候正随持续的气候变化发生改变，但人们对春池（vernal pool）这类极度濒危生境中的植物如何响应气候变异，尚且所知甚少。此外，生境特化程度是否会影响物种对气候、季节及微生境变异的物候响应，目前仍不明确。
为探明加州中央谷地区广布与特有春池植物对气候变化的敏感性，我们在7年周期内，监测了两种优势春池物种的开花始期、花期持续时长与开花终止日期：其一为春池特有种粉花沼泽荠（rosey meadowfoam，*Limnanthes douglasii* ssp. *rosea*），其二为兼性春池物种杂色三叶草（whitetip clover，*Trifolium variegatum*）。我们在加州大学默塞德分校春池与草原保护区内的三个春池点位，测定了气候与微地形特征，以量化非生物环境因子与植物物候之间的关联。
研究发现，在近期快速变化的气候背景下，粉花沼泽荠的开花物候每年轻提前4.7天，杂色三叶草则每年轻提前5.6天；在本研究周期内，两个物种的开花始期均提前至加州地区此前未有记录的月份。两个物种在生长早期出现的暖干环境条件，均与其后续生活周期中开花物候的提前显著相关。我们还发现，生境专化种的花期持续时长受春池微地形特征的调控，而生境广适种则未表现出此类变化。最后，暖干环境条件与两个研究物种在春池内的占据率下降显著相关。据我们所知，本研究是首个将当前气候变暖与春池植物物候及生长表现建立关联的科研工作。