【作者】 勾昕；

【导师】 王刚；

【作者基本信息】 兰州大学 ， 生态学， 2009， 博士

【摘要】 群落演替是一个动态的过程，随着演替的进行一些个体被另一些个体所取代，一个植物群落取代另一个群落。关于群落演替的研究已经持续了一个多世纪，对于群落演替的形成；演替过程中植物群落的变化；演替过程中植物与环境因子间的相互作用以及演替系列的顶极提出了许多理论与机制。但是迄今为止还没有一个关于演替的统一的理论能适用于所有的生态系统、生境甚至同一个演替的不同阶段。生态化学计量学和生态代谢理论都是最近两年新兴的理论。生态化学计量学是研究植物与环境间元素平衡的一门学科，因此它能够为群落演替的研究提供一个关于元素间的平衡系统，为研究演替过程中植被与环境因子间的相互关系提供理论基础。生态代谢理论是以个体代谢速率与有机体个体大小以及环境温度间的相互关系为基础，将有机体的生长以及繁殖速率与有机体的代谢速率相统一，从而使得从有机体个体到生物圈的各个水平的生态学过程都统一到单个有机体的个体代谢过程。它提供了从个体大小角度出发研究演替过程中群落的变化规律的方法。因此本文以一个位于青藏高原的高寒草甸演替系列为例，分析了这个演替系列的物种多样性和植物氮磷含量及其比值的变化规律，并以生态化学计量学以及代谢理论为方法，试图总结出演替过程植物氮磷含量及其比值的变化与土壤养分变化间的关系、沿演替梯度植物个体大小的变化规律以及物种多样性与植物个体大小产的关系等。以下是本文的主要研究结果：1．来自不同科属的植物种数及其在群落中的作用随着演替的进行而变化。菊科植物在演替的早期其重要值为演替三个时期中最大的。在演替早期菊科植物主要是细叶亚菊（Ajania tenuifolium（Tacquem）Tzvel，）；演替中期的菊科植物以火绒草（Leontopodium leontopodiaoides（Willd）Beauv．）为主；演替后期则以甘青蒿（Artemisia tangutica Pamp）为主。沿着演替梯度，生活型组成趋于多样化，一年生草本植物的重要值逐渐下降，而多年生草本植物和半灌木的重要值逐渐上升。2．从整个演替系列来看，多样性指数与土壤中全氮、全磷和有机质的相关性显著；而优势度和均匀度均只与土壤全磷显著相关；而地上生物量与土壤中这几个参数的相关性都达到了显著。由于演替中期的优势种为披针叶黄华（Thermopsis lanceolata R．Br．）并且由于土壤磷的可利用性可以控制微生物的固氮作用，从而使得演替中期多样性指数、优势度和均匀度与土壤中的全磷和有效磷显著相关。3．通过RDA分析，得出了土壤速效N和速效P含量与植物化学计量学问的关系。在演替初期土壤中速效P对植物化学计量学没有影响或者影响极其微弱。土壤速效N与植物化学计量学呈正相关，和植物化学计量学中与N元素有关的变量是正相关而与植物中P的含量则为负相关性。在演替的中期，土壤中的速效N和速效P对植物化学计量学都有一定的影响，而且土壤速效N对植物化学计量学的影响要大于土壤速效P对植物化学计量学的影响；演替后期中土壤速效N，速效P与植物化学计量学的影响中，土壤速效P对植物化学计量学影响较大。沿着演替梯度，所有典范轴特征值所解释变量的总和逐渐增大，土壤中速效N和速效P对植物化学计量学的影响沿着演替梯度逐渐增大。4．以代谢理论的基本结论和能量平衡规律为基础推导出了种群平均个体大小与演替时间的相互关系：ln（（?）_t）)=ln（（?）₀）-4／3ln（（ln（R₀））／t_B）t（其中（?）_t，（?）₀，R₀，t_B分别表示t时刻的种群平均个体大小，种群进入演替系列时的平均个体大小，该种群的世代净繁殖率，该种群的世代时间）。这一个方程表明随着演替的进行种群的平均个体大小逐渐减小。当种群平均个体大小降低到一个临界值时，个体将不能在繁殖，因此该种群将会被排除演替系列。5．由于有机体是一个四维的分形几何体，所以能够推导出叶面积与个体大小间的关系为A_i=ρ_i^-3／4m_i^3／4，进一步可以推导出群落的表观叶面积指数为LAI=(sum from i=0 to J（m_i）^3／4)ρ₀／A=ρ₀J／A〈M^3／4〉_J=ρ₀，这样对于冠层密集的群落来说表观叶面积指数为一个常数。由于演替过程中群落中能量流为一个常数值以及个体大小沿着演替时间梯度逐渐降低，可以推导出一定时间段内群落中物种丰富度和多度与时间的关系为：lnS_t2=lnS_t1+ln(（ln R₀）／t_Bm)t，lnJ_t2=lnJ_t1+ln(（ln R₀）／t_Rm)t。更多还原

【Abstract】 Community succession is a dynamic procedure. Some species were replaced byothers, and one plant community took the place of another along communitysuccession. The sduties on dynamics of community succession went on more than onecentury. Some ecologists have posed a lot of theories and mechanisms concerningvariation of plant community, relationships between plant community and habitatfactor along the succession and climax community.But there have been a unifiedtheory which can be applicable to all ecosystems, habitat and even the different stagesin the same succession series. Ecological stoichiometry was knowledge about theelement balance between plant and the habitat. It could provide an equilibrium systemfor studies on succession, and the theoretical foundation for studies on therelationships between plant and their habitat factor. Metabolic theory predicts howmetabolic rate, by setting the rates of resource uptake fromg the environmet andresource allocation to survial, growth, and reproduction, controls ecological processesat all levels of organization from individuals to the biosphere. Therefore, it provid ameans to reveal the changes of community along succession series from body sizeviews.In this paper, we tried to summarize a model about variation of body size andbiodiversity by ecological stoichiometry and metabolic theory of ecology which couldbe applicable to all ecosystems, take a secondary succession series of alpinemeadow communities as an example. The conclusions were given as follows:1. The numbers of species in community and their effection could be changedalong successional gradients. For feverfew, Ajania tenuifolium Tzvel dominated inearly successional community, Leontopodium leontopodiaoides Beauv. dominated inmid-successional community, and Artemisia tangutica Pamp dominated in latesuccessional community. The results shown that Ajania tenuifolium Tzvel was used tothe harsh natural environment in early successional stage, and the important effect offeverfew on plant community successiom. Diversity of plant life-forms in communitywas increased along the successional series.Important value of annual herbs slowlydescenden, important value of perennial herbs and shrub slowly increased with the succession stages. It shown that stabilization of community structure and ecologicalfunction of community were strengthend.2. In all successional field, Shannon-Weiner indices was remarkably positivelyrelated to soil available N, available P, and organic matter.It explained that soilavailable N, P and organic matter observably promoted the restoration of speciesrichness along succession series. The Simpson indices were positively related to soilphysico-chemical properties. It shown that soil physico-chemical properties influncedstructure of community, reduced numbers of dominant species in community, reducedimportant value of dominat species, and weaken effection of dominat species oncommunity structure and ecological function.3. According to RDA, the relationships between soil available N and P and plantstoichiometry was revealed. Soil available P was not related to plant stoichiometryand soil available N was postively related to plant stoichiometry in early successionstages. Plant stoichiometry was influnced more heavly by soil available N than soilavailable P in mid-succession stages. But the complexion was reversed in latesuccession stages. The relationships between soil available P and N and plantstoichiometry were more and more significant along succession stages as a result ofmore variances explained by all canonical axis.4. Based on metabolic theory of ecology and energy equilibium rules, therelationships between body size and succession time were displayed asfollows: ln（（?）_t）=ln（（?）₀）-4/3（ln（R₀）/t_B）t. This equation explained that average bodysize of the population declined with the community succession. As average body sizeof the population reached the critical average body size, individual could notreproduce and the population would be removed from the community succession.5. For organisms were four-dimensional fractal geometry objects, therelationship between body size and leaf area was displayed asfollows: A_i∝m_i^3/4 .Further, apparent leaf area index was derived based on last equation:LAI=σ₀（?）（m_i）^3/4/A=（ρ₀J）/A〈M^3/4〉_J=ρ₀ρ₀ was density, and a constantacross all species. To sum up the above arguments, we reached an equation about therelationships between species richness and aboundance and succession time:ln S_t2=ln S_t1+ln(ln R₀/t_Bm)t,ln J_t2=ln J_t1-ln（ln R₀）/t_Bm)t.更多还原