【作者】 巴雅尔塔；

【导师】 杜国祯；

【作者基本信息】 兰州大学 ， 生态学， 2010， 博士

【摘要】 物候学是研究生命周期随季节变化的一门基础学科。对植物群落物候的翔实观测研究有助于人们认识群落结构及其功能在时间梯度上的变化规律。青藏高原高寒草甸生态系统是陆地生态系统的重要组成部分,其变化能够预示陆地生态系统变化动态。在全球变化背景下,对青藏高原草地群落物候学研究不仅有助于深入认识草地群落构建机制,并有助于对其功能属性的深入探究,更重要的是为青藏高原高寒草甸生态系统的预测和评估提供基础研究。本研究以青藏高原东缘兰州大学高寒草甸与湿地生态系统定点研究站—瓦拉卡实验点的天然草甸为研究对象,在2006年和2007年通过对高寒草甸封育群落中53种植物,施肥群落18种植物和放牧群落28种植物的物候观测及其群落结构分析,得出如下结果：1.高寒草甸群落气候因素具有明显的季节分布性,气候因素的季节性变化影响群落花期物候分布。对气候因素主成分(PCA)分析表明,日平均温度、生长时间和降水量是高寒草甸群落主要气候因子,其信息贡献率为97.11%。在2006年和2007年降水量从5月下旬到8月中旬集中分布,年度日均最高温度在7月中旬出现,在一年中日最低温度大于0℃天数大约100d。随着群落盖度和高度的增加,群落光合有效辐射(PAR)在各处理中都减小,在施肥群落冠层中60cm以下PAR减弱率显著大于封育群落冠层中PAR减弱率,放牧群落冠层中30cm以下PAR减弱率显著低于封育群落冠层中PAR减弱率,这一结果显示群落冠层差异显著改变PAR在群落中的分布。2.高寒草甸群落花期峰值期呈集中分布。本研究对群落种间花期峰值期分布模式检验结果表明,封育群落53个种,放牧群落28个种和施肥群落18个种的种间花期峰值期均为集中分布。根据科内种间花期峰值期分布检验结果,在封育群落和放牧群落中科内种间开花峰值期为随机分布；在施肥群落中禾草类种间开花峰值期为集中分布,其它科内种间开花峰值期为随机分布。根据群落中物种开花期在生长季节内分布比率,封育群落、放牧群落和施肥群落中多数植物种在群落生长中期集中开花。3.高寒草甸群落中种间选择不同花期物候对策。在物种水平上对花期物候变化分析表明,群落生长早期进入花期的多数种,如匙叶龙胆(Gentiana spathulifolia)、银叶火绒草(Leontopodium souliei)、矮藨草(Scirpus distigmaticus)等其始花期和终花期年际变化差异显著,在群落生长中期和后期进入花期的多数种其始花期和终花期年际变化差异不显著,其种内花期物候年际差异表现在花期持续期和花期同步性上。4.在封育群落中53个种的平均花期持续期为8.1±3.22d,在群落水平上花期持续期和花期同步性分别与始花期负相关。在群落生长早期开花植物其花期持续期短,同步性高,在群落生长中期开花植物其花期持续期长,花期同步性低。5.物种性状差异影响生长型间花期物候分离。在高寒草甸群落中,植物生长类型间花期峰值期分离明显。垫状类植物在群落返青期进入花期,花期持续期短,种内花期同步性低,开花峰值期在生长季节内随机分布,种内花期年际变化差异显著,花期持续期与始花期正相关,花期同步性与始花期负相关。莎草类在群落生长早期进入花期,先开花种花期持续期短,花期同步性高,花期物候年际变化差异显著；后开花中花期持续长,花期同步性低,种内花期物候年际变化相对稳定；莎草类花期持续期与始花期正相关,花期同步性与始花期负相关。匍匐类植物在群落生长中期进入花期,花期持续期与始花期负相关,花期同步性和始花期负相关。莲座类植物从群落生长中期到末期进入花期,花期持续期与始花期负相关。禾草类在群落生长中期进入花期,花期持续期与始花期负相关,花期同步性和始花期负相关。丛生类从群落生长中期到后期进入花期,花期持续期与始花期负相关。6.在不同传粉方式的植物之间花期物候存在差异。风媒花植物种始花期显著早于虫媒花植物始花期,风媒花花期持续期显著短于虫媒花花期持续期。多数风媒花植物在群落生长早期进入花期,多数虫媒花植物在群落生长中期进入花期。在群落生长早期花冠颜色以白色花和黄色花为主,在群落生长中期群落花冠颜色组成除了白色花和黄色花外,蓝色花和紫色花比例增加。群落生长中期花冠颜色多样性和均匀度高于群落生长早期和后期花冠颜色的多样性和均匀度。7.群落开花期与生物量和高度相关,在生长型间资源利用对策存在差异。根据对封育群落38个常见种花期生物量PCA分析结果,总生物量、茎生物量、叶生物量和高度是群落开花期相关的主要因子,其信息贡献率为83.03%。群落开花期与花期生物量和高度相关。根据各生长型开花期与生物量相关性,匍匐类开花期与叶生物量正相关,与花生物量和高度负相关；莲座状类开花期与高度负相关；丛生类开花期与花生物量和高度正相关,莎草类开花期与高度和总生物量正相关；禾草类开花期与高度和茎生物量正相关。在生长季节内群落水平上叶分配比率与始花期负相关,茎生物量分配比率与始花期正相关,花生物量分配比率在群落生长早期和后期高,群落生长中期低。8.群落生长型间花期物候对施肥响应存在差异。在施肥群落中丛生类、莲座类、匍匐类和莎草类始花期、开花峰值期和终花期轻度推迟或提前,花期持续期轻度延长或缩短；禾草类始花期、开花峰值期、终花期显著推迟,花期持续期未发生显著变化。9.根据放牧群落28个种花期物候分布,在放牧条件下垫状类、莎草类和匍匐类始花期显著提前,终花期显著推迟,花期持续期显著延长,而禾草类和丛生类花期物候无显著变化。总之,高寒草甸群落开花期受系统发育、环境胁迫和种间作用影响在生长季节内集中分布。群落组分种通过物候补偿机制实现生态位分化,植物种性状差异是生态位分化的基础。更多还原

【Abstract】 Phenology studies the seasonal timing of life cycle events, it is the fundamental of ecology, and affects nearly all aspects of ecology and evolution, an exhaustive research of phenolgy is crucial to the understanding of plant community assembly and its functions in variable environments. The Qinghai-Tibet grassland ecosystem is the integrate part of terrestrial ecosystems in China, due to unique ecogeography of the ecosystems, study of phenology of Qinghai-Tibetan grassland can be use to infer the phonological trends of other terrestrial ecosystem in global changes. Moreover, studying on the grassland phenology in the Qinghai-Tibetan plateau can be use to address many fundamental topics, e.g species coexist and community assembly, as well as exploring the relationship between vegetation process and ecosystem functioning in rapidly changing environment. We carried out during 2006 and 2007 two years intensively comparative experiment in the field grassland of the Research Station for Alpine Meadow and Wetland Ecosystems of Lanzhou university in East Qinghai-Tibetan Plateau, namely Walaka site. By monitoring the phenology and species abundance of 53,28 and 18 comonpent species in enclosed (Ck), nomadic grazed communities (Gr) and fertilized community(Fr), respectively, we gained the following results:1.The environmental cues seasonally distribute in the alpine habitats, which influence the distributions of community flowering phenology.The daily average temperature, date and precipitations are the most important climate factors in determining to plant phonology, with cumulative proportion is 97.11% under the principal component analysis (PCA). The precipitations concentrated from the end of May to early August, the daily maximum temperatures occurred in the mid July, the days of annual daily minimum temperatures above 0℃were 100d during 2006 and 2007.With the increases in canopy covers and heights from mid to end of growing periods, photosynthetic active radiation (PAR)decreased dramatically from top to bottom, in Fr canopy PAR reduced more significantly under 60cm than Ck canopy, in Gr canopy PAR reduced less significantly under 30cm than Ck canopy, the PAR distributions significantly varied across canopies.2. The distributions of the peak flowering days are aggregated in the alpine meadow communities. The tests for 53 species in Ck,28 species in Gr and 18 species in Fr support that distributions of the peak flowering days(PFD) in communities are aggregated, PFDs within families are randomly distributed in Ck and Gr communities, whereas graminoids are aggregated, the other families are randomly distributed in Fr community. In the light of flowering species seasonal distribution rates, the most species bloom at the mid of growing season in Ck, Gr and Fr habitats.3. Species adapt the different flowering strategies. In view of annual variances of species flowering phases, the first flowering days (FFD) and last flowering days(LFD) of the early flowering species such as Gentiana spathulifolia, Leontopodium souliei and Scirpus distigmaticus, inter-annually varied significantly, where as FFDs and LFDs of the mid and late flowering species inter-annually changed insignificantly, only their flowering duration days(FDD) and flowering synchronies shifted inter-annually.4.In Ck community, the average FDDs the 53 observed species are 8.1±3.22d, both FDDs and flowering synchronies are negatively correlated with FFDs. Generally, the early flowering species manifest short FDDs and high flowering synchronies, the late flowering species do long FDDs and low flowering synchronies.5. The species trait influences the flowering phenology across growth forms. In the alpine meadows, the peak flowering phases across growth forms are separated. The most cushions bloom in early spring with short FDDs and low synchrony, usually the PFDs are randomly distributed, flowering phases inter-annually vary significantly, the FDDs are positively correlated with the FFDs, the synchronies are negatively correlated with FFDs. Sedges bloom in early growing periods, among them the early blooming species have short FDDs and high synchronies, flowering phases inter-annually vary significantly; the late blooming species have long FDDs and low synchronies, the variances of flowering phases are inter-annually stable; the FDDs are posivtively correlated with FFDs, the synchronies are negatively correlated with the FFDs. Creepers bloom in mid growing periods, the FDDs are negatively correlated with the FFDs, the synchronies are negatively correlated with the FFDs. Rosettes bloom from mid to end of growing periods, the FDDs are negatively correlated with FFDs. Graminoids bloom in mid growing periods, FDDs are negatively correlated with FFDs, the synchronies are negatively correlated with FFDs. Clusters bloom from mid to late growing periods, FDDs are negatively correlated with FFDs.6. The flowering phases differ among plants with different pollination modes. The FFDs of anemophilouos commence significantly earlier than entomophilouos, FDDs of anemophilouos continue significantly shorter than entomophilouos. The most anemophilouos species bloom in early growing periods, the most entomophilouos species bloom in mid growing periods. In the early growing periods the species with the white or yellow corollas bloom, in mid growing seasons besides species white and yellow corollas, the species with blue and purple corolla flower. The corolla color diversity and evenness in mid growing seasons are higher than those of both early and late growing seasons in alpine meadows.7. The community flowering times are correlated to biomass and height. PCA for Ck community 38 species biomass in flowering phase show that biomass, stem biomass, leaf biomass and height are the main components representing flowering time, their cumulative proportion is 83.03%.The community flowering days are positively correlated to biomass, and height. In the point of flowering time and biomass relationships across growth forms, creepers are positively correlated to biomass, negatively correlated to both flower biomass and height; rosettes are negatively correlated to height; clusters are positively correlated to flower biomass and height; sedges are positively correlated to height, and biomass, graminoids are positively correlated to height, and stem biomass. Within growing seasons, community level leaf biomass allocation rates are negatively correlated with FFDs, stem biomass allocation rates are positively correlated with FFDs, flower biomass allocation rates are high at early and late growing periods, which are low at mid growing season.8. Growth forms showed different responses to fertilization effects. In the fertilized community, the FFDs, PFDs and LFDs of sedges, rosettes and clusters are slightly accelerated or delayed, and the FDDs are truncated or prolonged in a small scale, whereas PFDs and LFDs of graminoids are significantly postponed, but their FDDs have no significant shifts.9. According to the flowering distributions of 28 species in Gr plots, under nomadic grazing the FFDs of cushions, sedges and creepers significantly accelerated, LFDs significantly retarded, FDDs significantly prolonged, whereas the flowering phases of clusters and graminoids are stable.In summary, under the influences of phylogeny, stress and biological interactions, the PFDs of alpine meadows are aggregated in growing seasons. The phonological complementarities promote niche differentiation in commuty, traits are the fundamentals of niche seperations.更多还原