Flowering phenology of a widespread perennial herb shows contrasting responses to global warming between humid and non‐humid regions

Plant phenology was assessed as one of the most key Essential Biodiversity Variables on species functional traits, which underpins a variety of aspects of ecosystem function and is a vital determinant of species distribution. Flowering phenology is one of the most sensitive indicators of the effects of recent climatic change. Understanding of intraspecific variation in phenological responses to climate change can contribute to the accurate prediction of phenology and the assessment of potential impacts of climate change on organisms. However, this intraspecific variation in phenological sensitivity in natural systems is still unclear, especially at large spatial scales. Using the widespread perennial herb Spiranthes sinensis, we quantified intraspecific variation in phenological responses to warming among groups located along climatic gradients. Phenological data were derived from 1,681 collections of herbarium specimens and photographs across eastern Asia and southeastern Australia over the period 1902–2017 and spans eight humid and eight non‐humid regions. We found that peak flowering dates of Spiranthe sinensis (FLss) showed substantial intraspecific variation in temperature sensitivity, ranging from −5.16 ± 1.13 to 4.16 ± 0.90 days/°C. Across all 16 regions, FLss exhibited the strongest delayed response to warming in southeastern Australia. Temperature sensitivity of the FLss was significantly correlated with annual precipitation and aridity index of a region, suggesting a possible role of declined water availability in reducing temperature sensitivity. Notably, contrasting phenological responses to warming were found between collections with different humidity regimes: humid regions generally flowered earlier (M: −3.57 days/°C) and non‐humid regions exhibited slightly delayed flowering (M: 1.25 days/°C). These findings provide empirical evidence of substantial intraspecific variation in phenological sensitivity across large spatial scales, and highlights that soil water availability may play a key role in a warming planet, especially in non‐humid regions. 摘要 植物物候被认为是物种功能性状中最重要的基础生物多样性指标之一, 是构成生态系统功能各个方面的基础, 也是决定物种分布的重要因素。植物开花物候是气候变化影响生态系统的最敏感指示器之一。研究物候对气候变化的响应的种内变异性, 有助于准确预测物候和评估气候变化对生物的潜在影响。然而, 自然系统中物候对气候变化的响应在种内的变异性依然不清楚, 尤其是在大空间尺度上。 以分布广泛的多年生草本植物绶草(Spiranthes sinensis)为研究对象, 本研究量化了物候对气候变化的响应在沿气候梯度分布的群体之间的变异性。物候数据获取自1902–2017年期间在东亚和澳大利亚东南部采集或拍摄的1681份植物标本和野外照片, 覆盖了8个湿润区和8个非湿润区。 研究结果表明绶草盛花期在温度敏感性上表现出相当大的空间变异性, 敏感性从提前5.16 ± 1.13天/°C至推迟4.16 ± 0.90天/°C。其