IMHE OpenIR  > 山地表生过程与生态调控重点实验室
高山草地植物群落对气候变化的响应研究
Alternative TitleStudy on the response of plant community in alpine grassland to climate change
Language中文
崔海军
Thesis Advisor王根绪
2016
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Name博士
Degree Discipline自然地理学
Keyword气候变化 高山草地 种群动态 圆叶小堇菜 开花物候
Other Abstract

在过去的100年地球增温大约0.74 °C,预测到2100年全球平均温度将再增加4.3 ± 0.7 °C。高山生态系统由于短距离栖息地限制和短距离决定植物生命关键环境因子改变等特点,易受气候变化影响。高山生态系统无论就蕴含的生物多样性而言,还是提供的生态系统服务,均是无价的资源。高山生态系统短距离快速变化的环境梯度又是优良的生物学天然实验室。雅家埂高山带地处青藏高原东缘,属于高寒湿润区,分布有放牧形成的亚高山草甸和高山草甸,是研究气候变暖的理想梯度带谱。我们以雅家埂高山草地带谱为依托,通过在4个不同海拔设立样地,首先研究了自然梯度下高山草地植物群落特征和土壤微生物群落组成的分布规律及其影响因素。再次我们结合模拟试验研究了典型高山种种群动态和典型植物群落开花物候对气候变化的响应。主要成果如下:1)植物群落特征沿海拔梯度具有明显分异。随海拔升高地上生物量呈现显著降低,而地下生物量和群落的根冠比呈现显著增加。群落多样性指数在较低海拔样地间呈现显著变化,而在较高海拔样地间变化不明显,总体而言随海拔升高群落多样性增大,均匀度增大。不同海拔群落特征差异主要由气象因子控制,且温度起主导作用,土壤的解释度可忽略。其他未考虑因子如放牧、种间关系等也可能对植物群落特征起重要作用。整个海拔梯度地上生物量与群落多样性指数呈负相关关系,支持根竞争和光竞争假说。2)沿海拔梯度土壤微生物群落有明显的分异,但微生物量和各种微生物类群基本未呈现明显的海拔趋势。豆科植物盖度和土壤TN对土壤微生物群落有重要影响,其他因子可能通过与二者的相互作用影响土壤微生物群落。植物功能群组成和土壤化学分别影响土壤微生物群落的不同方面,长期的放牧可能通过减少凋落物形成而极大降低了二者相互作用对土壤微生物群落的影响。3)高山种圆叶小堇菜尽管为矮小植物,但其表型塑性具有明显的对光竞争的适应策略,在光竞争激烈的群落它增加对茎生长和单个叶面积的投入,而减少叶片数量方面的投入,反之亦然,这就保证了生物量的投入对光的有效获取。这种适应不但体现在长期形成的自然梯度格局,且体现在短期环境改变中。圆叶小堇菜对光竞争敏感,表型塑性的适应调整跟光竞争的激烈程度密切相关。4)圆叶小堇菜在完全的草皮主要靠克隆繁殖扩大种群。移植模拟的增温主要通过降低克隆和存活降低种群增长率,这些关键比率的降低应归因于增温条件下周围群落竞争力的增强。小幅增温处理对高海拔种群克隆影响程度更大,而对低海拔种群存活影响程度更大。高海拔种群在大幅增温处理前期种群增长率和克隆出现异常变化,可能与降水强度增加促使营养体休眠的再萌发有关;中后期种群增长率的大幅下降应该归因于外围种的入侵极大增加周围群落的竞争。圆叶小堇菜具有机会种的特征,竞争力低,但具有一定的定植和传播能力。在气候变化下,圆叶小堇菜的存留将更加的依赖于干扰,如放牧。 5)在增温条件下,高山草甸单个植物种物候的改变存在很大的多样性,假设物候起始代表全部物候变化可能导致对生态群落响应物种数量和响应程度的错误评估。物种水平物候改变的多样性最终导致了共开花类型的改变,花期的改变和群落水平开花丰富度的再分布。不同功能群植物(forb, graminoid)及不同生活史特征植物(开花早晚)开花物候和开花丰富度对增温的响应具有一定的规律性和差异性。植物生活史特征、表型塑性、对环境因子的敏感性均可能影响植物有性繁殖投入,影响植物种群变化和竞争力,进而影响群落水平开花丰富度的变化。气候变化引起的一系列物候改变很可能将增加强大的选择压力,不但对植物种本身,且可能对决定于这些植物的更高营养级也是如此。组成群落的物种在一个生长季相继开花形成一个不间断的过程,这种现象可能标志着物种繁殖物候的动态进化结果,和它们对环境资源可用性的长期适应。气候变化诱导的物候改变可能会破坏这种相继过程,可能随时间影响群落组织,进而可能对生态与进化有深远的影响。 

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The Earth has warmed by about 0.74 °C in the last 100 years, and global mean temperatures are projected to increase fur-ther by 4.3 ± 0.7 °C by 2100. Alpine ecosystems are vulnerable to climate change due to specific characteristics, such as short-distance habitat limitations and alterations of environmental key factors determining plant life. Mountain ecosystems represent invaluable resources, both in terms of biodiversity and the ecosystem services they provide. Mountain ecosystems offering steep environmental gradients also represent exciting biological experiments of nature which have stimulated research for centuries. Mount Yajiageng is situated at the eastern fringe of the Tibetan Plateau and belongs to cold and wet area. It includes subalpine grasslands and alpine grasslands forming under grazing conditions along the elevational gradient, which is ideal to study the effects of climate warming on alpine grasslands. We selected four sites in the grasslands along its elevational gradient. Firstly we studied plant community characteristics of alpine grasslands and soil microbial community composition along elevation gradient, and their driving factors. Secondly we combing with experimental manipulation studied the influence of climate change on the population dynamics of a small alpine forb and the response of flowering phenology in an alpine meadow to climate warming. The main results are as follows:1)There were obvious differences in plant community characteristics along the elevation gradient. Aboveground biomass was significantly reduced with altitude increasing, while underground biomass and root-shoot ratios of community had significant increase. Community diversity indexes showed significant change between lower altitude sites, but did not change significantly between higher altitude sites. Overall community diversity and evenness increased with altitude increasing. Variation in community characteristic of different altitude was mainly controlled by meteorological factors, and the temperature played a leading role. The interpretation of the variance from soil factors can be ignored. Other factors not considered in this study, such as herding, interspecific interactions might also play important roles on characteristics of grassland community. Community diversity indexes showed negative correlation with aboveground biomass along the elevation gradient, which support root competition hypothesis and light competition hypothesis.2)There were obvious differences in soil microbial communities along the elevation gradient. However, microbial biomass and various microbial groups did not show elevational trend on the whole. Leguminous plant coverage and soil TN had important effects on soil microbial community composition. Other factors may influence the soil microbial community through interaction with leguminous plant coverage and soil TN. Soil chemistry and plant functional group composition respectively affect the different aspects of soil microbial community. The interaction between them had no impact on the soil microbial community maybe because long-term grazing greatly reduces litter.3)Though Viola biflora var. rockiana (Vio.bif) as alpine species is small, its phenotypic plastics has obvious adaptation strategy for light competition. In the community with intensive competition for light it increases investment in stem growth and single leaf area, and however decreases investment in increasing leaf number, and vice versa. This strategy ensures effective access into light per biomass.The adaptation is embodied not only in the natural gradient formating from the long time and in the short-term change of environment. Vio.bif is sensitive to competition for light and adaptive adjustment of phenotypic plasticity is closely related to the level of competition for light.4)Clonal reproduction is a main contributor to population growth of Vio.bif in closed vegetation. Survival and clonality were the most important vital rates contributing to reduce in population growth rate in warming treatment.The reduce of these two viato ratios should be attributed to the enhanced competition from the surrounding community. The population of higher altitude was affected by warming through greater impact on clonality, whereas the poputation of lower altitude was affected by warming through greater impact on survival. Population growth rate and clonality showed anomalous change at the early stage of greater warming treatment, which may be attributed to increased re-sprouting after vegetative dormancy in the environment with high precipitation pulse. Sharp decrease of population growth rate at the subsequent stages of greater warming treatment should be attributed to the dramatically increased competition from surrounding community with immigrating species. Vio.bif is similar to fugitive species with low competitive abilities and certain colonization and dispersal abilities. Persistence for Vio.bif may become increasingly dependent on management interventions (i.e. grazing, mowing) to reduce competition from surrounding community in a future climate.5)We find striking diversity in the phenological shifts of individual plant species under warming. Assuming that phenological firsts represent overall phenological change can lead to inaccurate assessments of the magnitude of change and the number of responsive species within an ecological community. This diversity of species-level shifts in phenology ultimately leads to altered patterns of coflowering, expansion of the flowering season, and community-level redistribution of floral abundance. The response of flowering phenology and flowering abundunce to warming showed a certain regularity and difference beween plants belonging to different functional groups (forb or graminoid ) or with different life history characteristics (flowering early or late). Life-history traits, phenotypic plasticity, sensitivity to environmental factors may affect the plant sexual reproduction investment, affect plant population and competitiveness, and thus affect the community-level floral abundance. The suite of changes in phenology caused by climate change will likely create powerful selection pressure not only on plant species themselves but possibly also on species at higher trophic levels that depend on these plants. A community pattern of blooming in which the flowering of various species is staggered in an unbroken progression over a growing season, which may indicate a dynamic evolutionary consequence of the reproductive phenology of the species and the resources available in the environments to which they have been adapted. The climate-induced disruption of phenological patterns potentially initiates changes that over time might affect community organization and have far-reaching consequences for ecology and evolution. 

Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/18919
Collection山地表生过程与生态调控重点实验室
Affiliation中国科学院成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
崔海军. 高山草地植物群落对气候变化的响应研究[D]. 北京. 中国科学院大学,2016.
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