Data from: Climate warming drives Himalayan alpine plant growth and recruitment dynamics

Understanding how climate influences plant reproduction and growth at
contrasting range limits is crucial for predicting how species‘ ranges may
shift in response to ongoing climate change. Trees and shrubs have shown
warming-induced increases in performance at upper elevation limits but
reduced performance at lower distributional limits due to warming-driven
drought limitation. Whether these differential responses are also valid
for alpine forbs exposed to accelerated warming remains largely unknown.
We examined climate signal recorded in annual growth and recruitment over
the past sixty years in the alpine forb Potentilla pamirica in Western
Himalayas, and tested whether the responses to recent climate warming
differ between dry steppe, wet alpine and cold subnival zone within the
species 5250-5900 m elevation range. We reconstructed recruitment and
growth chronologies from 1019 individuals spanning 1-73 years, and more
than 21,500 annual growth rings. We identified contrasting climatic
controls of recruitment and growth at opposite elevation range margins, as
well as contrasting demographic trends identified from age distributions.
In lower-elevation steppes, recruitment increased with high late-winter
snowfall and decreased with high summer temperatures, while growth
increased with high summer precipitation. Conversely, warm winters and
summers in higher-elevation alpine and subnival zones support growth and
recruitment, while snowy winters reduce them, especially at their upper
elevation limit. The age distribution revealed greater numbers of younger
individuals, indicating healthy growing populations, in the alpine
habitat, while evidence of ageing plant populations was observed in steppe
and subnival zones. Accelerated warming since the 1990s reduced growth and
recruitment in dry steppes while supporting plant performance in the
alpine habitat. The recruitment in the subnival zone did not peak during
the past warmest decade due to concomitant extreme snowfall
events.  Synthesis: Our results bring novel information on
population-specific climate dependency of plant recruitment, growth, and
population dynamics, suggesting a high vulnerability of high elevation
Himalayan ecosystems to climate change. This is partly balanced by high
species longevity and slow radial growth securing a long-term population
persistence. Continuing trends of extreme snowfall events at higher
elevations and droughts at lower elevations may lead to species range
contraction.

阐明气候如何在物种分布的对立边界处调控植物繁殖与生长，对于预测物种分布范围如何响应持续气候变化发生迁移至关重要。乔木与灌木在高海拔分布上限处表现出增温诱导的种群表现提升，但在低海拔分布下限处，由于增温引发的干旱胁迫，其种群表现出现下降。这类差异化响应是否同样适用于经历加速增温的高山非禾本科草本植物（alpine forbs），目前仍未明确。本研究以喜马拉雅西部海拔5250-5900米范围内的帕米尔委陵菜（Potentilla pamirica）为研究对象，分析了过去60年间其年生长与种群补充记录的气候信号，并检验了该物种在干旱草原带、湿润高山带与寒冷亚雪带（subnival zone）中对近期气候增温的响应是否存在差异。研究团队基于1019株树龄跨度1至73年的个体，以及超过21500个年轮，重建了该物种的种群补充与生长年表。我们发现，在海拔分布边界的两端，种群补充与生长受到的气候调控机制存在显著差异；同时基于年龄结构分析得到的种群动态趋势也截然不同。在低海拔草原带，种群补充量随冬末降雪量增加而升高，随夏季气温升高而降低；而植株生长则随夏季降水量增加而提升。与之相反，高海拔湿润高山带与寒冷亚雪带中的暖冬与暖夏可促进植株生长与种群补充，而多雪的冬季则会抑制这两个过程，尤其是在该生境的海拔上限处。年龄结构分析显示，高山生境中幼龄个体占比更高，表明种群生长状况良好；而草原带与亚雪带则呈现出种群老龄化的特征。自20世纪90年代以来的加速增温，对干旱草原带的植株生长与种群补充产生了抑制作用，却提升了高山生境中植物的种群表现。亚雪带的种群补充量在过去最温暖的十年间并未达到峰值，这与同期频发的极端降雪事件有关。综合分析：本研究结果揭示了植物种群补充、生长以及种群动态的种群特异性气候依赖性，表明高海拔喜马拉雅生态系统对气候变化具有较高的脆弱性。物种较长的寿命与缓慢的径向生长，在一定程度上缓冲了这一风险，保障了种群的长期存续。高海拔地区极端降雪事件频发、低海拔地区干旱加剧的持续趋势，可能会导致该物种的分布范围收缩。