引种保护植物对西双版纳极端冷年的春季物候响应

气温被普遍认为是春季物候期最主要的控制因子之一, 然而低温对植物物候的影响效应一直都存在不同的观点。西双版纳由于地处热带地区的北缘, 其气温相对于赤道附近的热带地区较低。自1959年以来, 西双版纳热带植物园引入了来自世界各个热带地区的4万余种植物进行保护, 之前的研究证明西双版纳的低温对这些引种植物的生长有很大影响。因此,1974年西双版纳出现的极端低温势必对引种植物造成极大威胁, 同时也是对这些植物低温适应能力的一个考验。通过对比43种引种植物物候期(生长抽梢期与开花期)在1974年与常年的差异情况, 分析不同来源(热带亚洲、热带美洲与热带非洲)引种植物对西双版纳低温的适应性。结果表明, 经历西双版纳1974年初的极端低温之后, 使81%的引种植物生长抽梢期提前, 同时也造成35%的引种植物在该年没有开花; 而植物生长抽梢提前的主要原因则是极端低温以及低温过后气温迅速回升。引种植物均能顺利度过1974年的最冷时期, 并出现生长抽梢物候, 这意味着引种植物在经历极端低温之后都能够进行正常的生长活动, 但极端低温对引种植物繁殖活动的不利影响大于其对生长活动的影响; 引种植物对西双版纳极端低温的适应能力由大到小顺序依次为: 亚洲来源植物>美洲来源植物>非洲来源植物。因此在迁地保护植物的选择过程中, 应多选择亚洲热带植物, 其次为美洲热带植物, 而对非洲热带植物的引入则需谨慎考察。     

西双版纳热带植物园引种植物物候特征比较

迁地保护是生物多样性保护的重要手段之一, 前期的植物引种研究可为迁地保护提供必要的理论支持。通过对西双版纳热带植物园内不同来源的引种植物和本地植物的4个物候期(萌叶期、落叶期、开花期和果熟期)分布格局及其气候影响因子进行对比, 阐明引种植物对环境的适应性和对策。结果表明, 引种植物比本地植物萌叶生长盛期更长, 但对低温和干旱更加敏感的引种植物, 在旱季其落叶比例明显高于本地植物, 而3、4月由于气温的回升, 使引种植物和本地植物在雨季之前就进入了萌叶盛期。而在繁殖物候方面, 由于受气候因子影响较小, 引种植物和本地植物的开花期和果熟期格局季节性表现都不明显, 且规律性不强。总体上, 各来源地的引种植物能根据环境的改变形成相应的生长与繁殖适应对策, 可较好地适应西双版纳的环境。     

植物生长抽梢期和气候因子对株高生长影响

利用西双版纳热带植物园的热带植物物候观测资料和气候资料,通过对热带植物株高生长偏差、生长抽梢期和气候因子的分析,探讨了三者的关系。结果表明,热带植物生长抽梢期变长不一定影响株高生长,而且与株高生长偏差的关系也小于气候因子与株高生长偏差的关系。同时,热带植物生长抽梢期对气候因子和株高生长偏差之间关系的贡献很小。因此,可以认为热带植物的生长期对植被生产力的促进作用较弱。     

西双版纳热带植物园引种植物物候特征比较

迁地保护是生物多样性保护的重要手段之一,前期的植物引种研究呵为迁地保护提供必要的理论支持。通过对西双版纳热带植物园内不同来源的引种植物和本地植物的4个物候期（萌叶期、落叶期、开花期和果熟期）分布格局及其气候影响因子进行对比,阐明引种植物对环境的适应性和对策。结果表明,引种植物比本地植物萌叶生长盛期更长,但对低温和干旱更加敏感的引种植物,在旱季其落叶比例明显高于本地植物,而3、4月由于气温的回升,使引种植物和本地植物在雨季之前就进入了萌叶盛期。而在繁殖物候方面,由于受气候因子影响较小,引种植物和本地植物的开花期和果熟期格局季节性表现都不明显。且规律性不强。总体上,各来源地的引种植物能根据环境的改变形成相应的生长与繁殖适应对策,可较好地适应西双版纳的环境。     

西双版纳区域气候变化对植物生长趋势的影响

目前全球变暖已经致使地球上生物群系的格局发生了显著的变化。高纬度地区的植物生长由此变得更加活跃,而热带地区植物生长的趋势仍然是一个具有争论的问题。西双版纳热带植物园地处中国西南地区,20世纪70年代以来,这里气候发生了显著的变化,其气温以每10年0.18℃的速度上升。本研究利用西双版纳热带植物园中的48种热带植物（28科）的株高生长数据（1974～2003年）来分析其对西双版纳区域气候变化的长期变化响应,通过对株高与气候因子的相关分析选出对植物株高生长影响最大的气候因子。结果表明,植物在研究期间的株高生长年间波动比较强烈,但没有表现出明显的趋势;植物的株高生长主要受到干热季（3、4月份）的日照时数（负）与月均最低气温（正）所影响,而干热季正是这些植物每年开始萌叶的时期;另外,降雨并没有对引种植物株高生长产生显著的影响;从2个关键因子的长期变化趋势来看,西双版纳气候变化将有利于保护植物的生长,进而将有利于植物园内热带植物的保护与保存。     

西双版纳热带植物园引种植物个体适应性研究

本研究通过比较引种植物和本土植物的生长状况,主要是果熟现象,讨论了引种植物对引种目的地的适应性。中国科学院西双版纳热带植物园,引种和保存了国内外万种以上的热带和亚热带植物,并对多种引种植物进行了长期连续生长监测。本文统计分析了其中观测4年以上的569个编号的引种植物生长适应状况。结果表明：1）引种植物基本适应植物园的环境,但是不同气候区来源的植物适应性表现不同,不同地区来源植物适应性顺序为：热带亚洲植物〉亚热带和热带北缘植物／热带非洲植物〉热带澳洲植物〉热带美洲植物;2）不同科属植物个体适应表现也有差别,无患子科,蝶形花科,楝科和紫葳科等的植物个体适应性和本土植物比较相似,而大戟科植物个体适应性和本土植物差异最大;3）分析表明引种植物对植物园的适应受到来源地气候和区系起源两个因素的影响;4）紫蒇科,桃金娘科和含羞草科的一些引种植物个体果熟年比高于本土植物,其入侵性有待于进一步入评估。     

民勤荒漠区植物物候型特征及其与气温的关系

对民勤荒漠区34年的物候观测资料进行了物候型分析。结果表明：植物的萌动期有2种物候型,展叶期和开花期各有4种物候型,果熟期有2种物候型,1974年以来,当地年平均气温和2、3、6月月平均气温有较显著的增温趋势,与此同时,植物的春季物候期亦有明显的提前趋势,低温-短日照-早萌动物候型的芽膨大期34年提前了9.7 d;从萌动期→展叶期→开花期→果熟期,物候期的提前幅度逐渐减小;物候期提前主要与当月气温升高有关;萌动期2种物候型和展叶期4种物候型是植物对春季气温和秋末冬初气温适应性的分异,开花期4种物候型和果熟期2种物候型是植物花期多样性和果熟期多样性对当地干旱环境适应性的反应。     

观赏果树—西印度樱桃

西印度樱桃（Ｍａｌｐｉｇｈｉａ　ｇｌａｂｒａ）又名光果樱，金虎尾科金虎尾属植物，多年生常绿灌木。原产热带美洲，主要栽培在西印度群岛和南美北部。我国于二十世纪五十年代先后引种栽培在台湾、广东、海南、云南等省热带地区，中国科学院西双版纳热带植物园于１９６４年从非洲加纳引种栽培，并获成功。 据观测，西印度樱桃１０年生扦插树株高仅为４．２－４．５ｍ，冠幅５．８－６．７ｍ，树冠自然圆头形，茎枝灰褐色，分枝部位低，成枝能力强，分枝多，枝条柔软微下垂；单叶对生，绿色或浅绿色，椭圆形或卵圆形，长约２－３ｃｍ，宽…     

甘肃民勤荒漠区18种乔木物候与气温变化的关系

在全球气候变暖的大背景下, 荒漠地区的植物物候是怎样响应气候变暖的?为了弄清这个问题, 对甘肃民勤荒漠区沙生植物园内18种乔木34 a的物候观测资料进行了分析。分析结果表明: 自1974年以来, 甘肃民勤荒漠区气温抬升幅度高于全国和全球水平, 尤其在2、3月气温抬升最为明显, 春季物候期提前幅度明显大于国内外其它文献报道; 物候期发生当月的平均气温对该物候期的影响>物候期发生上月平均气温的影响>年平均气温的影响; 研究区春季气温升高较其它地区更为明显, 这就是当地春季物候期提前幅度相对较大的原因。荒漠植物物候变化既是植物对气候变化的综合反应过程, 又是植物适应气候变化的过程。     

海南岛尖峰岭12种热带常绿阔叶乔木展叶期与开花期对气候变化的响应

为了探讨我国热带地区植物物候与气候变化的关系, 利用海南岛尖峰岭热带树木园12种热带常绿阔叶乔木植物2003-2011年物候观测资料结合同期月平均气温和降水数据, 运用积分回归分析方法, 筛选出影响海南岛12种乔木(8种本地种、4种引入种)展叶始期与开花始期的气象因素以及不同气象因素月值变化(月平均气温和月降水量)综合作用对这些树种物候期的动态影响, 最终建立积分回归-物候预测模型, 对气候变化背景下我国热带地区植物物候变化趋势进行了预测。结果表明: 海南岛12种热带常绿阔叶乔木展叶始期与开花始期均对气候变化做出较明显的响应, 几乎所有的树种展叶始期与开花始期的发生都受到气温和降水的共同影响。多数树种展叶始期受展叶前冬季及春季气温影响显著, 且在临近展叶始期的月份, 气温的影响更显著。上一年秋季月降水量对各树种开花始期的影响比其他时段显著, 这验证了降水的滞后性假说。本地种展叶始期对气候变化的响应比其开花始期对气候变化的响应更敏感, 引入种则相反。各树种展叶和开花在受气温和降水综合影响最明显的月份(假设其余11个月份月平均气温和月降水量不变), 月平均气温升高0.1 ℃、月降水量增加10 mm可使展叶始期和开花始期提前或推迟1-3天。积分回归分析方法为解释海南岛热带常绿阔叶乔木物候与气温和降水的动态关系提供了有效的途径, 基于气温和降水与物候资料建立的积分回归-物候预测模型具有对气温和降水变化影响下物候响应的解释率和预测精度高(R²≥ 0.943)的优点, 对于预测气候变化影响下的植物物候变化趋势有一定的适用性。     

Factors Influencing Tree Phenology in Taï National Park,Côte d'Ivoire1

Entrained phenology patterns of tropical trees are expected to be sensitive to short‐term fluctuations in typical rainfall and temperature. We examined 47 mo of data on the flowering, fruiting, and new leaf phenology for 797 trees from 38 species in the Taï National Park, Côte d'Ivoire. We determined the timing of the phenology cycles in relation to seasonal rainfall, temperature, and solar radiation. Regression analysis was used to examine how variations in rainfall and temperature influenced deviations in the peaks and troughs of phenology cycles. We also investigated whether populations that fruit during periods of community‐wide fruit scarcity were those populations with relatively long‐ or short‐fruiting duration. Flower, fruit, and leaf‐flushing phenophases all exhibited 12‐mo cycles. The broad peak in flowering began with the northward zenithal passing in April and ended with the southward zenithal passing in September. Fruiting peaks occurred in the long dry season, and leaf flushing peaked in the long dry season but continued into the wet season. Deviations from phenology cycles were largely attributable to short‐term fluctuations in rainfall and/or temperature. Fruiting durations of species were related to the mean diameter at breast height. Species with long‐ and short‐fruiting durations contributed equally to fruit abundance during periods of community‐wide fruit scarcity.     

Exploring the causes of variation in phenology and morphology in Mediterranean geophytes: a genus-wide study of Cyclamen

The phenology and morphology of Mediterranean plants are constrained by drought in summer and cold temperatures in winter. In this study we examine how climatic factors and phylogenetic constraints have shaped variation in the phenology and morphology of 17 species of the genus Cyclamen cultivated in uniform garden conditions. We quantify the extent to which traits differ among subgenera and thus represent conserved traits within evolutionary lineages. We also explore whether leaf, flowering and seed-release phenology are correlated among species, and thus whether variation in flowering phenology results from selection on dispersal phenology. Our results show a significant influence of subgenus membership on leaf and flowering phenology but not on morphological traits or the timing of seed release. Among-species variation in foliage height, leaf size and seed mass (but not in floral traits) is correlated with chromosome number. Leaf traits show that species with a shorter vegetative period have a higher capacity for resource acquisition. Major phenological shifts, i.e. spring vs. autumn flowering and a decoupling of leaf and flower phenology in autumnal flowering species, thus occurred prior to the diversification of species in each subgenus and not as a response to selection on dispersal timing. Leaf and flowering phenology illustrate a gradient of strategies from autumn flowering in the absence of leaves (hysteranthous species) to spring flowering with fully developed foliage (synanthous species). In the former, flowering is uncoupled from resource acquisition by simultaneous photosynthesis, indicative that hysteranthy is a response to temporal unpredictability in the onset of rain after the summer drought. Our results support the idea that whereas leaf development is controlled primarily by moisture availability and secondarily by temperature, flowering is temperature dependent, above a minimum moisture threshold. © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society, 2004, 145 , 469–484.     

New insights on plant phenological response to temperature revealed from long‐term widespread observations in China

Constraints of temperature on spring plant phenology are closely related to plant growth, vegetation dynamics, and ecosystem carbon cycle. However, the effects of temperature on leaf onset, especially for winter chilling, are still not well understood. Using long‐term, widespread in situ phenology observations collected over China for multiple plant species, this study analyzes the quantitative response of leaf onset to temperature, and compares empirical findings with existing theories and modeling approaches, as implemented in 18 phenology algorithms. Results show that the growing degree days (GDD) required for leaf onset vary distinctly among plant species and geographical locations as well as at organizational levels (species and community), pointing to diverse adaptation strategies. Chilling durations (CHD) needed for releasing bud dormancy decline monotonously from cold to warm areas with very limited interspecies variations. Results also reveal that winter chilling is a crucial component of phenology models, and its effect is better captured with an index that accounts for the inhomogeneous effectiveness of low temperature to chilling rate than with the conventional CHD index. The impact of spring warming on leaf onset is nonlinear, better represented by a logistical function of temperature than by the linear function currently implemented in biosphere models. The optimized base temperatures for thermal accumulation and the optimal chilling temperatures are species‐dependent and average at 6.9 and 0.2°C, respectively. Overall, plants’ chilling requirement is not a constant, and more chilling generally results in less requirement of thermal accumulation for leaf onset. Our results clearly demonstrate multiple deficiencies of the parameters (e.g., base temperature) and algorithms (e.g., method for calculating GDD) in conventional phenology models to represent leaf onset. Therefore, this study not only advances our mechanistic and quantitative understanding of temperature controls on leaf onset but also provides critical information for improving existing phenology models.     

Impact of tree leaf phenology on growth rates and reproduction in the spring flowering species Trillium erectum (Liliaceae)

We investigated the impact of overstory tree leaf phenology on growth rates, carbon allocation pattern, and fruit characteristics in the spring flowering species, Trillium erectum (Liliaceae). Air temperature, overstory canopy closure, and T. erectum phenology were monitored at three locations following a latitudinal gradient in Québec, Canada. Northern sugar maple trees leaf out at cooler temperatures than more southern populations, while Trillium development was initiated at the same soil temperature irrespective of the latitude. Therefore, in northern areas, the time between initiation of T. erectum leaf expansion and canopy closure was shorter than in southern areas, which left less time for northern plants to accumulate reserves before canopy closure. Differences in growth patterns were noted between T. erectum populations. From a south-north gradient, investment to reproduction, total plant biomass, and annual growth rate decreased, while specific leaf area and stem height increased, indicating shade acclimation. The length of the high light period in early spring seems to be a determinant for spring flowering plants' growth and reproduction and may explain the northern distribution limit of some of these species.     

Primary and secondary growth phenology of Schizolobium parahyba (Vell.) Blake at different time scales

Schizolobium parahyba is a tropical species that has expanded its distribution. However, little is known about its ecological performance beyond the tropics. Therefore, the objective of this research was to describe for this species, south of its original distribution, intra-annual variations in primary growth phenology (leaf flushing, leaf shedding, flowering and fruiting) and secondary growth (radial increase of the trunk), as well as secondary growth on an interannual scale (radial xylem increase) and to analyze the influences of climatic conditions on the evidenced phenological patterns. For this purpose, on an intra-annual scale, ten individuals had their phenophases observed fortnightly for 23 months and were described and correlated to climatic variables of photoperiod, temperature and precipitation. Inter-annual activity samples were obtained from the growth rings of 16 individuals, which were evaluated according to dendrochronological protocols and correlated to climatic variables of temperature and precipitation. South of its original distribution, S. parahyba trees presented seasonal growth rates in all observed scales and associations with variations in phenological rhythms and climatic conditions. Differences were found in the climatic response of the species in comparison to studies already performed in the tropics. In this study, on an intra-annual scale, this association is manifested by relationships with photoperiod, being positive for leaf flushing and fruiting and negative for leaf shedding. In the secondary growth, the intra-annual scale positive relationship was found with temperature, but on an inter-annual scale a positive influence of winter rainfall was found. The consistence of those patterns in broader spatial scales deserves further investigation.     

Unravelling proximate cues of mass flowering in the tropical forests of South‐East Asia from gene expression analyses

Elucidating the physiological mechanisms of the irregular yet concerted flowering rhythm of mass flowering tree species in the tropics requires long‐term monitoring of flowering phenology, exogenous and endogenous environmental factors, as well as identifying interactions and dependencies among these factors. To investigate the proximate factors for floral initiation of mast seeding trees in the tropics, we monitored the expression dynamics of two key flowering genes, meteorological conditions and endogenous resources over two flowering events of Shorea curtisii and Shorea leprosula in the Malay Peninsula. Comparisons of expression dynamics of genes studied indicated functional conservation of FLOWERING LOCUS T (FT) and LEAFY (LFY) in Shorea. The genes were highly expressed at least 1 month before anthesis for both species. A mathematical model considering the synergistic effect of cool temperature and drought on activation of the flowering gene was successful in predicting the observed gene expression patterns. Requirement of both cool temperature and drought for floral transition suggested by the model implies that flowering phenologies of these species are sensitive to climate change. Our molecular phenology approach in the tropics sheds light on the conserved role of flowering genes in plants inhabiting different climate zones and can be widely applied to dissect the flowering processes in other plant species.