模拟增温改变青藏高原植物繁殖物候及植株高度

气候变化显著影响了高寒植物物候期及生长模式, 从而改变了高寒生态系统功能。而高寒植物物候期和生长状况对气候变化的响应程度, 与其自身资源分配策略有关。为了更好地探究气候变化下高寒植物繁殖物候及生长的规律, 该研究以青藏高原高寒草甸为研究对象, 按生物量从高到低选取15种常见植物, 其生物量之和占样地总生物量80%以上, 采用红外辐射器模拟增温的方法, 利用同质园实验, 观测无种间竞争条件下, 增温2年间植物返青、现蕾、开花以及结实物候, 并监测了植株高度。研究结果表明: (1)在功能群水平上, 增温使豆科类植物的返青、现蕾和开花时间分别显著提前了(8.21 ± 1.81)、(9.14 ± 2.41)和(10.14 ± 2.05) d, 使其开花持续时间显著延长了(6.14 ± 1.52) d, 而增温对其他功能群物候事件无显著影响。增温对高寒植物物候的影响存在种间及年际间差异, 但总体上增温使大多数高寒植物繁殖物候提前并且开花持续时间延长, 将更多的资源更多地分配到繁殖生长上。(2)增温显著降低了杂类草植物的植株高度(平均降低(3.58 ± 0.96) cm), 但对豆科类、禾草类及莎草类功能群植株高度没有显著影响。 增温对高寒植物植株高度的影响存在显著的种间差异以及年际差异。综上所述, 未来气候变暖背景下, 青藏高原高寒植物群落可能更早进入繁殖阶段, 从而降低在营养生长上的资源分配。另外, 由于各物种繁殖能力和营养生长对温度变化响应的差异, 气候变暖将导致高寒植物群落中各物种盖度的变化, 进而改变群落物种组成, 从而影响高寒生态系统的功能。     

大学校园植物物候格局及其气候驱动因子研究——以海南大学为例

植物的物候格局通常随时间而变化,展叶、开花和结实的出现时间和数量因年而异,或因事件而异,然而,热带地区的物候格局在很大程度上仍然是未知的。该研究利用海南岛海口市海南大学校园3年的物候监测数据,分析植物的展叶、开花、结实物候格局。对物候期与环境变量进行多重回归分析影响热带地区植物物候的主要气候因子。结果表明, 热带地区植物物候格局具有明显的季节性,展叶、开花和结实分别集中在4月—6月、4月—8月、5月—11月;影响展叶和开花物候格局的气候因子均为月均日照时长,每月结实物种数与气温相关,尤其是每月果实成熟物种数与月最低气温呈显著相关。不同功能群之间物候期存在差异,灌木展叶早于草本和乔木,风媒植物展叶早于虫媒植物,肉质果型植物展叶和果实成熟时间早于非肉质果型植物。乔木开花比草本和灌木早,非肉质果型植物开花时间比肉质果型植物早,风媒植物果实成熟早于虫媒植物。这些对将来预测热带物候事件具有重要意义。     

南亚热带阔叶林展叶物候及其种内种间差异探讨

植物的展叶物候与植物的生长和生存密切相关,但未见有定性的研究植物展叶物候的种间和种内差异与验证亚热带常绿阔叶林植物展叶物候系统发育关系的报道。为了更好地理解南亚热带常绿阔叶林物种共存机制和预测不同物种对气候变化的响应,该研究于2013年1月至2014年12月期间,在中国科学院华南植物园鼎湖山自然保护区内对44个树种的展叶物候进行了连续观测,利用变异系数定性分析了气候因子、系统发育关系对展叶始期及其种内和种间差异和展叶期的影响。结果表明:鼎湖山自然保护区植物展叶始期主要集中在3-5月,植物展叶物候受气候因子影响不显著;不同物种的展叶物候种内变异差别较大,其中种内差异最大的是红皮紫棱(Craibiodendron kwangtungense)(变异系数为0.74),最小的是广东润楠(Machilus kwangtungensis)(变异系数为0.09);基于APGⅢ物种数据库构建谱系树,发现植物间的系统发育关系对展叶物候无显著影响,即亲缘关系近的物种,展叶期并不相似。该研究结果对于理解生态系统过程,如碳循环、物质能量流动,以及展叶物候对气候变化的适应性具有重要意义。     

开花时间与伴生种对鹤首马先蒿传粉和生殖成功的影响

开花物候是物种间相互作用的重要生活史特征和适合度因子,在全球气候变化的背景下而备受关注.为探讨开花时间如何存种内和种间水平上影响植物的传粉和生殖成功,我们连续3年(2003-2005)对不同花期和伴生种存在情况下的鹤首马先蒿(Pedicularis gruina)的传粉者访花忠实度、受粉率、坐果率、单果种子产量和果实被啃食频率进行了比较研究.结果表明鹤首马先蒿的坐果率主要受其传粉环境的影响:在没有伴生种时,不同时期鹤首马先蒿的坐果率没有显著差异,34-38％的花可以坐果;在有伴生种存在时既可以显著提高其坐果率,也可显著降低其坐果率,这取决于传粉者类型以及伴生种密穗马先蒿(P.densispica)花期的差异.密穗马先蒿具有花蜜和花粉双重报酬,在群落中可以作为主体物种吸引传粉者并间接促进与其伴生的鹤首马先蒿的传粉和生殖成功.同样无蜜的管花马先蒿(P.siphonantha)和鹤首马先蒿伴生,则是通过提高群落水平对传粉者的吸引力进而直接促进鹤首马先蒿的传粉和生殖成功.此外,研究结果也表明开花时间对坐果率没有显著影响,但是显著影响单果种子产量和果实被啃食的频率.在相同的传粉条件下早花期植株单果种子产量显著高于晚花期的种子产量,同时早花期的果实被啃食的频率显著增加.     

亚热带植物春季和秋季物候格局及其对气候变化的响应

全球变暖导致的物候变化已经对生物多样性和生态系统产生了重要影响,与温带和寒带相比,亚热带物候学的研究相对较少,秋季物候的研究也十分缺乏,不同功能群植物的物候对气候变化的响应是否存在差别,都有待进一步研究。为了研究亚热带植物春季和秋季物候对气候变化的响应以及不同功能群间的差异性,该研究利用湖南省长沙植物园25种木本植物20 a的物候观测数据,根据AIC信息标准,先筛选各物种最佳温度和降水模型,并利用Wilcoxon秩和检验分析不同功能群的物种对温度的响应是否一致。结果表明:(1)大多数物种的春季物候和秋季物候都对温度变化响应显著,展叶与开花的提前速率分别是3.76 d·℃^-1和6.53 d·℃^-1,叶变色与落叶的推迟速率分别是16.66 d·℃^-1和3.50 d·℃^-1。(2)部分物种的春季(展叶物候:60%,开花物候:35%)和秋季(叶变色物候:25%,落叶物候:13%)对降水显著响应。(3)除不同落叶性物种(常绿和落叶之间)的展叶物候表现出对气候的响应有显著差异外,其他不同功能群的物种对气候的响应均无显著差异。该研究认为,亚热带地区植物春季物候显著提前,秋季物候显著推迟,且亚热带地区不同功能群的物种对温度的响应大部分无显著差异,表明气候变化对亚热带地区不同功能群的影响程度大部分趋同。     

浙江古田山亚热带常绿阔叶林开花和结实物候的种间种内差异

植物物候学主要研究植物的生活史事件发生时间和环境因子之间的关系.物候作为植物重要的功能性状,却未见有在群落水平上将植物物候变异和群落结构特征(多度)联系起来探究植物物候变异规律的报道.为了探索物候性状的种间种内变异规律,2012年4月~2015年8月在中国东部地区浙江省古田山国家级自然保护区亚热带常绿阔叶林24hm~2大样地(GTS;29°10′19.4″~29°17′41.4″N,118°03′49.7″~118°11′12.2″E)内,对106种植物的物候进行连续观测,用标准差定性分析物候的种间和种内差异.结果表明,影响开花物候的气候因子为降水,群落开花高峰集中在5月,结实成熟高峰集中在10月.群落结实物候种间差异小于开花物候,其中结实物候种间差异为41天,开花物候种间差异为52天;群落水平植物开花和结实物候的种内变异小于种间;大部分物种开花物候的种内变异小于结实物候.本研究首次探讨了物候期种内变异系数和物种多度的关系,也是首次研究物候种内变异系数与物候期早晚的关系,发现群落物候种内变异与物种的多度不相关,群落开花物候种内变异与物候期的关系不显著,群落结实物候的种内变异和物候期具有显著负相关关系,即物候期早的结实物候种内变异大,物候期晚的结实物候种内变异小.将植物物候变异和群落结构特征(多度)联系起来探究植物物候变异规律,有利于理解物候的改变是怎样影响物种的相互作用和适合度,这对于在气候变化大背景下理解植物性状变异及物种分化和群落动态变化具有重要意义.     

西安和宝鸡木本植物花期物候变化及温度敏感度对比

植物物候是指示生态系统对气候变化响应的重要证据。已有研究多基于代表性站点的物候观测数据研究物候特征及其对气候变化的响应规律。同一气候区内,不同站点的物候变化及对温度变化响应的敏感度是否一致仍需深入探讨。本文选择同属于暖温带湿润区汾渭平原气候区的西安和宝鸡为研究区,利用"中国物候观测网"在两个站点21个共有物种的开花始期和开花末期数据,比较了1987—2016年两站点各植物花期物候变化特征及其对温度变化响应的敏感度差异。结果表明,西安和宝鸡各物种的开花始期和开花末期均以提前趋势为主。大部分物种开花始期在西安的提前趋势(平均趋势-0.57 d/a)明显强于在宝鸡的提前趋势(平均趋势-0.29 d/a),但开花末期趋势差异不显著。除紫薇和迎春的敏感度差异较大外,其他物种开花始期和开花末期的温度敏感度在两站点间非常接近,无显著差异。由此可见,在同一气候区的不同站点,因增温幅度不同,植物的始花期变化存在较大差异,不能用单站点的物候变化反映整个气候区的物候变化。但同一植物在单站点的温度敏感度可以较好的反映同一气候区其他站点的植物物候-气候关系。本文研究结果可为利用有限站点的物候观测数据分析区域物候变化及对气候变化的响应提供科学依据。     

31种木本植物开花物候与系统发育的关系

植物物候通常被认为是由环境因素,如降水、温度和日照长度所决定,然而环境因素是否是物候唯一的决定因素仍然存在很大争议。谱系结构表征了植物在进化上的顺序,该发育时序是否对物候产生影响,当前仍然未知。在调查2016年春季新疆乌鲁木齐市最常见的31种木本植物的初始开花时间、败花时间和开花持续时间的基础上,通过分析植物开花物候的分布特征、开花物候在乔灌木间的差别、以及植物谱系距离与开花物候距离间的关系,试图揭示植物的开花物候和物种谱系(进化)顺序间的关系。结果表明:(1)新疆乌鲁木齐市31种木本植物的初始开花时间为4月18日±9d、败花时间为5月5日±12d、开花持续时间为(16±8)d;(2)乔木的初始开花时间和败花时间的标准差分别均低于灌木,乔木开花物候相对灌木更稳定;(3)乔木的初始开花和败花时间均显著早于灌木(P0.05),但开花持续时间在两者间未有显著性差异(P0.05);(3)31种木本植物间的初始开花时间距离、败花时间距离和开花持续时间距离均与物种谱系距离存在显著线性回归关系(P0.05)。综上可知:乔灌木在垂直空间上的分化使得木本植物的开花物候在植物生活型间存在不同。对植物的开花物候,除已被证明的降水、温度和日照长度等环境因素的影响外,物种进化顺序也可能造成了它在植物种间、时间和空间上的变异。     

气候变化下青藏高原全缘叶绿绒蒿的潜在分布变迁

青藏高原物种丰富且属于气候变化敏感区,研究气候变化对青藏高原物种的潜在分布影响,对于该区域物种多样性保护具有重要意义。该研究以一级濒危藏药植物全缘叶绿绒蒿为研究对象,利用加权平均算法(weighted average algorithm, WAA)构建随机森林(RF)、灵活判别分析(FDA)及人工神经网络(ANN)的集成模型,同时对比分析了WAA模型和不同生态位模型的预测精度。最后利用WAA模型预测了全缘叶绿绒蒿在当前(1970~2000年平均)和未来(2041~2060年平均)气候情景下的潜在分布,其中未来气候考虑了2种“共享社会经济路径”(SSP2-45和SSP5-85)。结果显示:(1) WAA模型的预测表明,基于RF、FDA和ANN的集成模型的AUC值为0.926,在AUC值最高RF模型的基础上提高了3%,在FDA和ANN模型的AUC值的基础上均提高了5%。(2) WAA模型确定,全缘叶绿绒蒿的潜在分布对年降水量和最暖季降水量最为敏感,其次是最热月份最高气温,同时对最湿月份降水量以及等温性表现出较低的敏感性。(3)当前全缘叶绿绒蒿潜在分布区主要分布在甘肃西南部、青海东部至南部、四川西部和西北部、云南西北部和东北部、西藏东部。(4)未来气候变化下青藏高原全缘叶绿绒蒿潜在分布预测表明,在2050年SSP2-45情景下,全缘叶绿绒蒿的潜在分布区大小与当前潜在分布区大小基本相同,但整体向西北方向高海拔高纬度地区迁移;在SSP5-85情景下,全缘叶绿绒蒿的潜在分布区明显收缩,且向西北高纬度高海拔地区延伸的趋势更加明显。     

非生长季降水对青藏高原高寒草甸优势种生物量稳定性的影响

受全球气候变化的影响,青藏高原在过去的几十年间整体上呈现暖湿化的趋势,相比于年际之间温度和降水的变化外,生长季和非生长季气候变化模式的差异可能会对生态系统产生更重要的影响,但相关的研究尚不充分。以青藏高原东部的高寒草甸为研究对象,基于2001年至2017年17年的野外观测数据,包括优势植物紫花针茅的高度、多度以及生物量、次优势物种洽草的生物量,结合生长季和非生长季平均温度和降水量的变化,通过线性回归以及结构方程模型,探究生长季/非生长季不对称气候变化对于青藏高原高寒草甸优势物种生物量稳定性的影响。研究结果表明：1)青藏高原东部年均温和年降水在过去的17年间显著增加,呈现暖湿化的趋势,但是非生长的降水却变化不明显;2)紫花针茅的高度、多度以及生物量在过去17年没有显著的趋势,但是洽草的生物量稳定性显著减少;3)非生长降水结合紫花针茅的高度、多度以及洽草的生物量稳定性促进了紫花针茅的生物量稳定性。研究结果可以为青藏高原高寒草甸在未来气候变化的背景下合理保护与利用提供科学依据。     

Herbarium records identify sensitivity of flowering phenology of eucalypts to climate: Implications for species response to climate change

Flowering phenology is very sensitive to climate and with increasing global warming the flowering time of plants is shifting to earlier or later dates. Changes in flowering times may affect species reproductive success, associated phenological events, species synchrony, and community composition. Long‐term data on phenological events can provide key insights into the impacts of climate on phenology. For Australia, however, limited data availability restricts our ability to assess the impacts of climate change on plant phenology. To address this limitation other data sources must be explored such as the use of herbarium specimens to conduct studies on flowering phenology. This study uses herbarium specimens for investigating the flowering phenology of five dominant and commercially important Eucalyptus species of south‐eastern Australia and the consequences of climate variability and change on flowering phenology. Relative to precipitation and air humidity, mean temperature of the preceding 3 months was the most influential factor on the flowering time for all species. In response to a temperature increment of 1°C, a shift in the timing of flowering of 14.1–14.9 days was predicted for E. microcarpa and E. tricarpa while delays in flowering of 11.3–15.5 days were found for E. obliqua, E. radiata and E. polyanthemos. Eucalyptus polyanthemos exhibited the greatest sensitivity to climatic variables. The study demonstrates that herbarium data can be used to detect climatic signals on flowering phenology for species with a long flowering duration, such as eucalypts. The robust relationship identified between temperature and flowering phenology indicates that shifts in flowering times will occur under predicted climate change which may affect reproductive success, fitness, plant communities and ecosystems.     

Reproductive phenology of two Mimusops species in relation to climate,tree diameter and canopy position in Benin (West Africa)

Assessing species phenology provides useful understanding about their autecology, to contribute to management strategies. We monitored reproductive phenology of Mimusops andongensis and Mimusops kummel, and its relationship with climate, tree diameter and canopy position. We sampled trees in six diameter classes and noted their canopy position. For both species flowering began in the dry season through to the rainy season, but peaked in the dry season, whilst fruiting occurred in the rainy season and peaked during the most humid period. Flowering was positively correlated with temperature. Conversely, fruiting was negatively correlated with temperature and positively with rainfall, only in the Guineo‐Sudanian zone. For M. andongensis, flowering and fruiting prevalences were positively linked to stem diameter, while only flowering was significantly related to canopy position. For M. kummel, the relationship with stem diameter was significant for flowering prevalence only and in the Guineo‐Sudanian zone. Results suggest that phylogenetic membership is an important factor restricting Mimusops species phenology. Flowering and fruiting of both species are influenced by climate, and consequently climate change might shift their phenological patterns. Long‐term investigations, considering flowering and fruiting abortion, will help to better understand the species phenology and perhaps predict demographic dynamics.     

Beyond the usual climate? Factors determining flowering and fruiting phenology across a genus over 117 years

Premise

Although changes in plant phenology are largely attributed to changes in climate, the roles of other factors such as genetic constraints, competition, and self-compatibility are underexplored.

Methods

We compiled >900 herbarium records spanning 117 years for all eight nominal species of the winter-annual genus Leavenworthia (Brassicaceae). We used linear regression to determine the rate of phenological change across years and phenological sensitivity to climate. Using a variance partitioning analysis, we assessed the relative influence of climatic and nonclimatic factors (self-compatibility, range overlap, latitude, and year) on Leavenworthia reproductive phenology.

Results

Flowering advanced by ~2.0 days and fruiting by ~1.3 days per decade. For every 1°C increase in spring temperature, flowering advanced ~2.3 days and fruiting ~3.3 days. For every 100 mm decrease in spring precipitation, each advanced ~6–7 days. The best models explained 35.4% of flowering variance and 33.9% of fruiting. Spring precipitation accounted for 51.3% of explained variance in flowering date and 44.6% in fruiting. Mean spring temperature accounted for 10.6% and 19.3%, respectively. Year accounted for 16.6% of flowering variance and 5.4% of fruiting, and latitude for 2.3% and 15.1%, respectively. Nonclimatic variables combined accounted for <11% of the variance across phenophases.

Conclusions

Spring precipitation and other climate-related factors were dominant predictors of phenological variance. Our results emphasize the strong effect of precipitation on phenology, especially in the moisture-limited habitats preferred by Leavenworthia. Among the many factors that determine phenology, climate is the dominant influence, indicating that the effects of climate change on phenology are expected to increase.     

Latitudinal cline of flowering and fruiting phenology in Fagaceae in Asia

The seasonal timing of flowering and fruiting is crucial for the reproductive success of plants and for resource availability to animals. Although plants synchronize their reproductive timing to coincide with appropriate seasons by responding to environmental cues, seasonal variations in temperature and precipitation vary minimally in very wet tropical environments. To explore the latitudinal cline in the reproductive phenology of the Fagaceae in Asia, we analyzed phenology data for a total of 94, 121, and 219 species from Thailand, Malesia, and China, respectively, in the three genera of Fagaceae, Quercus, Castanopsis, and Lithocarpus. We found that Quercus and Castanopsis showed flowering peaks in April in China. In Thailand, the peak shifted to an earlier month, and the peak disappeared in Malesia. The flowering period lengthened with decreasing latitude in the animal-pollinated genera Castanopsis and Lithocarpus. However, this was not the case for the wind-pollinated genus Quercus. The fruiting period lengthened with decreasing latitude in all three genera. We examined the relationship between reproductive phenology and climatic factors. The combination of monthly temperature and precipitation best explained the monthly change in the proportion of flowering and fruiting species in China in all three genera. However, climatic factors had almost no impact on the predictive ability of the model in Malesia. Our results on phenological shifts in the family Fagaceae, from the temperate climates and seasonal tropics to the humid tropics, provide valuable information for predicting phenological changes in future climate change.     

Phenological patterns among plant life-forms in a subtropical forest in southern Brazil

Phenological patterns in tropical plants usually are associated with the clear seasonality of rainfall associated with very different wet and dry seasons. In southern Brazil, in a subtropical forest with no pronounced dry season (average annual precipitation = 1389 mm, minimum monthly average c. 75 mm), plant phenology was studied to test for patterns (periodicity), to examine how phenological patterns vary among life-forms, and to test whether phenological cycles are associated with climatic variables. Thirty-seven plant species in four life-forms (trees, shrubs, lianas and epiphytes) were studied for 2 yr (1996-98) in an Araucaria forest remnant in southern Brazil, in the state of Paraná. Correlation and multiple regression methods established relationships between phenology and climate in terms of daylength, temperature and rainfall. In this Araucaria forest, plants showed seasonality in most life-forms and phenological phases. Leaf-fall, with its peak during the drier months (April to July), was the most seasonal. Flushing and flowering occurred during the wetter months (September to December), while fruiting occurred all year long. Phenologies varied among life-forms, and were strongly associated with daylength or temperature of preceding months, suggesting that plants receive their phenological cues well in advance of their phenological response. Phenologies in this Araucaria forest appear to be associated with the most predictable and highly correlated of the climatic variables, daylength and temperature and least so with rainfall, which is unpredictable.     

基于数字标本探究绿绒蒿属植物花期的变化

近年来,随着全球气温的明显升高,气候变化引起的全球变暖受到人们的广泛关注.气候变暖会使植物物候发生改变,花期的变化能够直观地反映出植物对周围环境的适应,尤其是高山植物对气候变化更为敏感,因此探究高山植物的花期更具有代表性.为了解植物在气候变暖背景下花期的变化特征,并制定出合理的植物保护措施,该文以典型的高山植物绿绒蒿属...     

内蒙古克氏针茅草原植物物候及其与气候因子关系

 植物物候作为气候变化敏感的生物圈指示计, 已经成为全球变化研究的热点。利用1985~2002年地面物候观测数据, 构建了内蒙古克氏针茅(Stipa krylovii)草原植物物候的时间序列谱, 并分析了植物物候的时间变异与气候因子之间的相关关系。结果表明: 1) 从1985~2002年内蒙古克氏针茅草原的气候朝着暖干趋势发展, 主要表现在春、夏气温的显著性增加与秋季(9月)降水的显著性减少; 2) 主要植物物候的变化整体呈返青期推后其它物候期提前趋势; 3) 植物生长盛期(7、8月)对气候变化最敏感; 4) 光照和温度是影响内蒙古克氏针茅草原植物物候格局的主要因素, 年内最寒冷的1月月均温和2、3月的光照对春季返青期具有负效应, 而其它物候期与7、8月的光照则呈显著的负相关关系, 6、7月的降水对发育盛期的花序形成、抽穗与开花具有显著的负效应, 8、9月的降水量能显著推后枯黄期的结束, 从而有利于生长季的延长。     

Impact of climate change on plant phenology in Mediterranean ecosystems

Plant phenology is strongly controlled by climate and has consequently become one of the most reliable bioindicators of ongoing climate change. We used a dataset of more than 200 000 records for six phenological events of 29 perennial plant species monitored from 1943 to 2003 for a comprehensive assessment of plant phenological responses to climate change in the Mediterranean region. Temperature, precipitation and North Atlantic Oscillation (NAO) were studied together during a complete annual cycle before phenological events to determine their relative importance and potential seasonal carry‐over effects. Warm and dry springs under a positive phase of NAO advance flowering, leaf unfolding and fruiting dates and lengthen the growing season. Spatial variability of dates (range among sites) was also reduced during warm and dry years, especially for spring events. Climate during previous weeks to phenophases occurrence had the greatest impact on plants, although all events were also affected by climate conditions several months before. Immediate along with delayed climate effects suggest dual triggers in plant phenology. Climatic models accounted for more than 80% of variability in flowering and leaf unfolding dates, and in length of the growing season, but for lower proportions in fruiting and leaf falling. Most part of year‐to‐year changes in dates was accounted for temperature, while precipitation and NAO accounted for <10% of dates' variability. In the case of flowering, insect‐pollinated species were better modelled by climate than wind‐pollinated species. Differences in temporal responses of plant phenology to recent climate change are due to differences in the sensitivity to climate among events and species. Spring events are changing more than autumn events as they are more sensitive to climate and are also undergoing the greatest alterations of climate relative to other seasons. In conclusion, climate change has shifted plant phenology in the Mediterranean region.     

Greater temperature sensitivity of plant phenology at colder sites: implications for convergence across northern latitudes

Warmer temperatures are accelerating the phenology of organisms around the world. Temperature sensitivity of phenology might be greater in colder, higher latitude sites than in warmer regions, in part because small changes in temperature constitute greater relative changes in thermal balance at colder sites. To test this hypothesis, we examined up to 20 years of phenology data for 47 tundra plant species at 18 high‐latitude sites along a climatic gradient. Across all species, the timing of leaf emergence and flowering was more sensitive to a given increase in summer temperature at colder than warmer high‐latitude locations. A similar pattern was seen over time for the flowering phenology of a widespread species, Cassiope tetragona. These are among the first results highlighting differential phenological responses of plants across a climatic gradient and suggest the possibility of convergence in flowering times and therefore an increase in gene flow across latitudes as the climate warms.     

Flowering phenology change and climate warming in southwestern Ohio

Global surface temperature has increased markedly over the last 100 years. This increase has a variety of implications for human societies, and for ecological systems. One of the most obvious ways ecosystems are affected by global climate change is through alteration of organisms’ developmental timing (phenology). We used annual botanical surveys that documented the first flowering for an array of species from 1976 to 2003 to examine the potential implications of climate change for plant development. The overall trend for these species was a progressively earlier flowering time. The two earliest flowering taxa (Galanthus and Crocus) also exhibited the strongest shift in first flowering. We detected a significant trend in climate suggesting higher temperatures in winter and spring over the sampling interval and found a significant relationship between warming temperatures and first flowering time for some species. Although 60% of the species in our study flowered earlier over the sampling interval, the remaining species exhibited no statistically detectable change. This variation in response is ostensibly associated with among-species variation in the role of climate cues in plant development. Future work is needed to isolate specific climate cues, and to link plant phenology to the physiological processes that trigger plant development.