【作者】 梁继业；

【导师】 慈龙骏； 杨晓晖；

【作者基本信息】 中国林业科学研究院 ， 水土保持与荒漠化防治， 2007， 博士

【摘要】 干旱生态系统是经过长期自然选择作用形成的一种动态平衡系统，尽管这种系统是波动的，但仍然能够在一定时空范围内维持系统的结构和功能。然而自然条件的变化和不合理的人为干预，会扰乱这种结构和功能，进而引发一系列的变化，如果干扰的强度超过系统的耐受阈值，就可能导致整个系统的变化，过度的干扰最终导致的就是荒漠化的发生。处于干旱、半干旱地区的沙漠与河岸过渡带，就是这种生态系统的典型代表，该区内植物资源的存在及其演替是维系生态系统正常运转的关键环节。因此它们的存在与合理配置，对区域脆弱的生态系统稳定与持续发展所起到的作用是不可替代的。本研究所选的唐古特白刺(Nitraria tangutorum Bobr．)，不仅在鄂尔多斯北缘地区库布齐沙漠和黄河河岸过渡带是一种广泛分布的植物，而且由于其本身耐盐碱和耐沙埋，所以在全国十几个省市自治区都有分布，其适生的范围很广。这种广泛分布于荒漠化地区的重要植物资源，在防治荒漠化、稳定区域生态系统都扮演着十分重要的角色。本文试图通过对白刺沙堆个体特征和空间分布格局的研究，为鄂尔多斯北缘地区的防治荒漠化提供一定的理论支持，也能为其他地区白刺资源的保护和利用提供参考。在研究的过程中除了采用常规方法对白刺沙堆个体进行了包括它的结构、土壤、动植物以及固碳特征的研究外，还尝试应用了地统计学和空间点格局的分析方法，配合Arcgis、GS+和surfer等软件，再现了白刺沙堆个体特征的空间分布规律，并进一步分析出了白刺沙堆对其它植物的影响。分析结果显示：(1)白刺个体沙堆土壤的粒径从沙堆顶部向下细粒物质有增加的趋势：土壤水分、土壤的养分含量从上至下有明显的增加，尤其以近地面以下0—10cm范围最为显著，而这层土壤对地面表层植物的生长是非常重要的：沙堆上和沙堆间空地的土壤粒径分布和养分含量有明显的差异性，白刺沙堆上土壤主要的粒径范围是0.05—0.25mm的细沙粒，而空地间的粒径范围是集中在0.05—0.25mm细砂粒和0.01—0.05mm粗粉粒，同一层次的土壤相比，沙堆内部粒径在0.001—0.005mm之间的细粉粒含量比间地明显增多，说明了沙堆对风沙土结构有改良作用；白刺沙堆上的动植物种类明显要比沙堆间地上多：白刺沙堆上从沙堆顶部向下0—30cm毛细根分布比较密集，对吸收养分、水分以及固持沙土有积极的作用；通过初步估算，在研究区1.33km~2范围内白刺与沙堆碳存储量可以达到356.134t。个体沙堆的研究结果证实了白刺沙堆对土壤、水分、动植物以及碳资源的汇聚作用。(2)用L函数和g函数计算的结果表明，白刺沙堆在水平空间上分布为随机性；用沙堆高度和半径的标记点格局分析表明，不同沙堆之间在小于沙堆平均距离6.40m尺度内表现为一定的竞争关系，在大于这个尺度范围内则表现为弱的相关性和不相关性，这说明白刺个体间在自疏化过程以后，能够相对独立的发展，这种独立的基础是基于沙堆的形成；用Moran的I系数计算的沙堆高度的空间自相关结果表明，相近高度(发育阶段)白刺沙堆在空间的各个方向上分布不均匀，表现为空间上的随机分布：用L函数和g函数计算的结果表明，雾冰藜在接近沙堆平均直径5.54m小尺度范围内表现为聚集分布，较大的尺度内表现为随机分，这说明其在沙堆上为聚集分布，而在大尺度内的分布受白刺沙堆分布的影响较大，这间接的证明了它与白刺之间存在密切的关系。对白刺沙堆及沙堆上植物空间分布格局的结果，说明了白刺对群落空间结构异质性的作用，也证实了白刺沙堆对促进生物多样性的贡献。(3)白刺沙堆表层土壤养分在水平空间上表现为“岛状斑块”分布，它说明了白刺对群落资源异质性的驱动作用，以及对群落结构的影响：白刺沙堆聚集资源的结构，与传统概念的“资源岛”有一些区别，因此不能简单用的它的理论来解释白刺形成沙堆的过程。这些区别主要表现在：第一，白刺沙堆所聚集的大部资源来自于群落系统的外部：第二，它所聚集的资源，如土壤，其单位养分含量并不比沙堆间地的高：第三，白刺作为构建系统异质性结构的驱动因子，在形成沙堆以后会起到维持系统结构和功能的作用，而不会随着这种异质化斑块比例升高，加速系统结构和功能的不稳定趋势，因此可以认为白刺沙堆具有另一种资源汇集的结构特征。总之，白刺及其形成的沙堆对区域生态系统的结构和功能都有重要的影响，所以深入的研究对防治区域荒漠化具有重要意义。更多还原

【Abstract】 Generally, arid ecosystems are some kinds of dynamic balance systems which have beenthe long—term development, although these systems are undulation, but still could maintaintheir structure and function in some certain space and time. However under the change ofnatural conditions and some unreasonable artificial disturbances, these systems will change thestructure and function, then initiate a series of changes, if these disturbances surpasses thethreshold value, which are keeping the system dynamic balance, It will cause the overallsystem change, some intense disturbances finally cause desertification. The arid and semiariddesert—river ecotone is such kind of latent desertification region. The native plant resourcesplay an essential role to maintain the ecosystem normal operation in these regions. Thereforetheir existence and the reasonable disposition can not be substituted for the stabilization andsustainable development of regional frail ecosystem.The Tangut Nitraria broadly spread not only between Kubqi desert and Yellow river innorth edge Ordos plateau, But also in more than ten provinces of China, because they can bearAlkalized-Stalinized condition and be tolerant to sand buried. Such kinds of plants are veryimportant to the combating desertification and keeping stability of ecosystem in some regions.Therefore I hoped the research on the individual characteristics and special distribution patternsof Tangut Nitraria sand mounds, can provide the theory support for the desertificationcombating in north edge Ordos, and also can provide the reference about use and protect theseplants for other people.In this research I except used some conventional methods to analysis the characteristics onthe structure, soil, animals, plants as well as carbon of the individual Tangut Nitraria sandmounds, but also attempted some methods to analysis their spatial distribution patterns. Suchas geostatistics and the pattern analysis, and used software such as Arcgis, GS+ and Surfer tosimulating the spatial distribute on of the sand mounds, analyzed their influences on the otherplants. The finally results show that (1)The fine grain matters have the trend of escalation from the crown to ground in the sand mounds; The soil moisture and soil nutrient have the obviousincrease from surface to ground in the mounds, and they are most remarkable in the 0—10cmbelow ground; This layer of soil on the surface of the ground is very important to plant growth;The particle size and nutrient of soil have the obvious difference between the sand mounds andthe intersand mounds spaces, the soil is mainly the fine sand which is between 0.05 to 0.25 mmin the sand mounds, but they are mainly the fine sand and coarse grains which are between0.05 to 0.25 mm and 0.01 to 0.05mm in the intersand mounds spaces, the soil’s fine grainscontent of sand mounds, are between 0.001 to 0.005 mm, are increased more significantly thanthe same level of intersand mounds spaces., it show sand mounds are helpful to improve thestructure of soil; The animals and plants on the sand mounds are more than the intersandmounds spaces; The thin roots in the 0—30cm of sand mounds are more dense, they have thepositive roles to absorb the nutrient sand moisture as well as pool sand; The Tangut Nitrariaand their sand mounds can pool about 356.134t carbon in the 1.33km2 area by the preliminaryestimate. The research on individual sand mounds confirmed their gathering function about soil,moisture, animals, plants and carbon (2)The sand mounds show randomly distribution inhorizon with the analysis of L and g function; and different sand mounds appear certaincompetition when their distances are short than the mean distance 6.40m, This shows that theindividual Tangut Nitraria have been the process of self—thinning, and they are relative to bedevelopment of an independent, Such independence is based on the formation of the sandmounds; Moran’s I was used to calculated the spatial autocorrelation on the height of sandmounds, the result shows that the similar height (growth stages) sand mounds are unevendistribution in all directions, and appear the random distribution; The calculation results showthat Bassia dasyphylla are gathering distribution when their distance approach the meandiameter 5.54m of sand mounds, and randomly distribute when their distance surpass the scope,It can explain their gathering on the sand mounds and they have the close relation with the sandmounds. These results can prove Tangut Nitraria sand mounds have the function ofheterogeneity and the biodiversity contribution in the community. (3) The surface soil nutrienton these sand mounds appears to be the plots shape of "island" in horizon. If analyze with the conclusion on the individual sand mounds, It shows Tangut Nitraria are the driving force to theresources heterogeneity and the community structure of community; these sand mounds’characteristics have some differences with the traditional concept of "resource islands",Therefore we can not simply use its theory to explain the formation of Tangut Nitraria sandmounds. The distinctions are mainly in these aspects. Firstly, Tangut Nitraria sand moundsgathered majority of resources are from the external community system; Secondly, they capturethe resources, such as soil, its unit nutrient content is not higher than the intersand moundsspaces; Thirdly, as the driving factor of building system’s heterogeneity structure, TangutNitraria could maintain the structure and function after the formation of sand mounds, but notaccelerate system unstable with the increase of proportion heterogeneity plots, So the TangutNitraria sand mounds are other types of resource pool.In short, Tangut Nitraria and their sand mounds have an important role to the regionalecosystem structure and function. Therefore, an in—depth study on them has a far—reachingsignificance for the regional desertification combating.更多还原