【作者】 何俊龄；

【导师】 张卫国；

【作者基本信息】 兰州大学 ， 草业科学， 2007， 硕士

【摘要】 土壤种子库是植被自然演替和自我修复机制的重要组成部分，在很大程度上代表了植被的演化历史、现状及未来的走向，对地上植被的恢复和重建有重要的作用。高原鼢鼠作为高寒草甸生态系统中的重要成员，以其终身营地下生活和掘土造丘的特殊方式，对高寒草甸土壤种子库的性质和功能，以及鼠丘植被的恢复产生着独到而重要的影响。为了深入探讨高原鼢鼠与土壤种子库以及鼠丘植被恢复的关系和作用机理，2004年至2006年间，以玛曲县境内的典型高原鼢鼠分布地为研究地，分别就鼠丘分布格局、植被群落、种子雨、土壤种子库和鼠丘种子库的基本特征及其相互关系进了研究。主要研究结果如下：1．高原鼢鼠的土丘可依据其形成时间大致分为当年龄、1-2年龄和3年龄以上3种类型。研究期内，这3类土丘的数量关系基本维持在1:1:1，说明种群密度较为稳定。利用这一特性，可通过对3类土丘比例关系对鼠群数量的消长趋势作出预测。由于当年8月前形成的土丘数具有易于定性、现实意义较大的特点，因而，更适宜于作为高原鼢鼠相对密度的指标。2．典型亚高山草甸的高原鼢鼠栖息地，土壤种子库的平均密度为4836粒／m~2，物种数为38种，分布在19个科。其中多年生物种占有绝对优势，占物种总数85％以上。3．植被物种数为46种，其中一年生物种约占10％左右，显著高于无鼠分布地(P＜0.01)。植被物种数显著高于土壤种子库的物种数(P＜0.05)，且科间分布更加广泛，二者间的相似性约为68％。4．鼠丘种子库密度、物种数和种子活力均表现为随丘龄增加而增大的显著趋势。当年龄鼠丘与其它龄级鼠丘相比，种子库密度和物种数间的差异均极为显著(P＜0.01)，而2年龄和3年龄间的差异显著性则为显著极水平(P＜0.05)；新鼠丘种子库的种子活力显著低于2年龄和3年龄鼠丘(P＜0.05)，3年龄鼠丘的种子活力虽也高于2年龄鼠丘，但无显著性差异(P＞0.05)。5．种子雨与鼠丘种子库组成存在一定的差异，但它与植被的物种组成却较为类似。鼠丘种子库的物种数占种子雨物种数的82.05％，占植被物种数的69.57％。可见，种子雨是鼠丘种子库补充更新的物质基础，是鼠丘植被恢复的重要种源，是维持植被物种多样性的机制之一。6．鼠丘密度是影响植被性状的重要因素。在鼠丘密度的各梯度水平上，物种丰富度、地上生物量、香农-威纳多样性指数的最高值均出现于中等密度样地，一定数量高原鼢鼠的存在，有助于群落结构的优化，并对物种多样性和地上生物量的提高具有明显的促进作用。7．鼠丘种子库与鼠丘植被物种组成的相似性随鼠丘形成时间的延长而增加。经过三次越冬以后，新鼠丘、当年、1-2年和3年龄鼠丘物种组成与对应植被的相似性依次为60.07％、65.82％、70.41％和76.57％，与此同时，植被盖度、物种组成等性状指标也表现为与背景植被逐次趋同的变化。据此推断，鼠丘植被恢复周期应当在4-5年。更多还原

【Abstract】 Soil seed bank is an important component of natural vegetation succession and self-repair mechanism, largely represents evolutionary history, current status and future trend of vegetation, and plays an important role in the recovery and regeneration of aboveground vegetation. Plateau zokors are important members of alpine meadow ecosystem and have unique and important effects on soil seed bank traits and function in alpine meadow, and recovery of mound vegetation with the special way of subterranean existence for life and mounding by excavating. In order to probe into the relationship and mechanism between plateau zokor, soil seed bank and recovery of mound vegetation, the research was conducted in a typical distribution site of plateau zokors in Maqu county from 2004 to 2006, studying essential characteristics and correlations among mound distribution pattern, plant community, seed rain, soil seed bank and mound seed bank. The main results are as follows:1.Plateau zokor mounds can be separated into three age categories: new or less than 1 year old, intermediate or 2 years old and old or 3 years old, according to their formation time. During the study, the quantitative relationship among three kinds of mounds has been maintained 1:1:1, indicating that the population density is relatively stable. Thus, we could make prediction on ebb and flow trend of population quantity with the proportional relationship among three kinds of mounds. Since the number of mounds formed before August is easily to determine the nature and has larger practical significance, consequently, it is more suitable to be used as relative density index of plateau zokor.2.In typical plateau zokor habitats of sub-alpine meadow, the average density of soil seed bank is 4836 seeds/m~2 , species number is 38, distributed among 19 families, and perennial plants are absolutely predominant, accounting for 85% of the total species number.3.Species number of vegetation is 46, and annuals approximately account for 10%, significantly higher than that in sites of no plateau zokor. Species number of vegetation is significantly higher than that in soil seed bank (38), and they are distributed more extensively among families, similarity indices between the two are around 68%.4.Seed bank density of mound, species number and seed viability all increase markedly with the increased mound age. There are extremely significant differences between new mounds and other kinds of mounds in seed bank density and species number (P < 0.01), while the differences between 2 years old and 3 years old mounds are significant (P < 0.05); seed viability of new mound seed bank is significantly lower than that of 2 and 3 years old mounds (P < 0.05), and seed viability of 3 years old mounds is higher than that of 2 years old mounds, but not statistically significant (P > 0.05). 5.Components of seed rain are different than that of mound seed bank, but species components of seed rain and vegetation are relatively similar. Species number in mound seed bank occupies 82.05% of that in seed rain, and 69.57% of that in vegetation. Obviously, seed rain is material base of recruitment and renewal of mound seed bank, important seed sources of mound vegetation recovery, and one of the important mechanisms to maintain plant diversity.6.Mound density is an important factor affecting vegetation traits. Species richness, aboveground biomass and Shannon-Winner index all peak in intermediate density plots across mound density gradients, thus, certain number of plateau zokor in alpine meadow contributes to optimization of community structure, and promotes markedly the enhancement of species diversity and aboveground biomass.7.Similarities of species components between mound seed bank and mound vegetation increase with the time of mound formation. Similarity indices between species components of new, 1 year old ,2 years old and 3 years old mound send bank and corresponding mound vegetation are 60.07%、65.82%、70.41% and 76.57% respectively; while vegetation cover, species components and other property indices also showed increasing convergence to that of background vegetation. Accordingly, recovery cycle of mound vegetation should be between 4 to 5 years.更多还原