Knowledge Resource Center for Ecological Environment in Arid Area
| 贺兰山西坡植被分布特征与土壤养分分异研究 | |
| 其他题名 | Study on the Characteristics of Vegetation Distribution and the Heterogeneity of Soil Nutrients in the West Slope of Helan Mountain |
| 郑敬刚 | |
| 出版年 | 2007 |
| 学位类型 | 博士 |
| 导师 | 李新荣 |
| 学位授予单位 | 中国科学院寒区旱区环境与工程研究所 |
| 中文摘要 | 我国山地面积高达6.5×106 km2，约占国土总面积的67.7%。山地由于具有浓缩的环境梯度和高度异质化的生境、相对较低的人类干扰程度，以及地质历史上常成为大量物种的避难所和新型植物区系分化繁衍的摇篮，所以发育和保存着较高的生物多样性，成为全球生物多样性研究和保护的重点区域。山地生态系统在我国西部干旱地区的生态意义非常重要，它是区域内重要的水源地和绿色生态屏障。作为我国西部温带荒漠草原与荒漠的分界线和连接青藏高原、蒙古高原及华北植物区系的枢纽，贺兰山以其独特的地理位置和地理环境塑造了其独特的生物类群，是我国西部干旱区重要的生物资源库。本研究采用样线法与典型植被群落分科相结合，研究了贺兰山西坡浅山带（包括南起狭子沟、北至大西沟贺兰山西坡主要核心区，海拔在1250-2200 m之间）海拔梯度上的植被、土壤养分分布特征及其相互关系，并初步探讨了贺兰山西坡草地生态系统的恢复机制。主要结论如下：\n1 植物群落的垂直分布\n海拔1400米以下主要分布着珍珠猪毛菜、红砂、刺叶柄棘豆等耐旱灌木、矮灌木，植物科属以豆科、藜科、禾本科和菊科物所占的比例最高；海拔1401-1600 m范围内，分布的有斑子麻黄、藏锦鸡儿、霸王、灌木亚菊、达乌里胡枝子等灌木，植物科属组成与1400 m以下无明显差异，但是豆科、菊科植物有所增加，而藜科和禾本科植物有所减少；海拔1601-1800 m 范围内主要分布的是短花针茅、狼针茅、阿尔泰针茅等荒漠草地，植物科属以禾本科为主；1801-2000 m范围内分布的是以蒙古扁桃、小叶金露梅等高大灌木为建群种的疏林灌丛，藜科植物的分布稀少，豆科、禾本科植物数量明显下降，蔷薇科植物显著增加。\n2植被带群落多样性对海拔梯度的响应\n荒漠灌丛物种丰富度指数在海拔1250-1400 m范围内无显著变化，1400-1600 m范围内随着海拔的升高而增加；物种多样性和均匀度指数随海拔的升高略微有所增加。该植被带内草本层的物种丰富度大于灌木层，而灌木层物种多样性大于则草本层；\n山地荒漠草地物种丰富度在海拔梯度上呈单峰分布，在海拔1700-1800 m范围内的物种丰富度最高；其物种多样性和均匀度指数都呈现随着海拔的升高先增加而后降低的特点，多样性和均匀度指数在海拔1750-1820 m范围内最小，此后随着海拔的增加，气温下降，相应的多样性和均匀度指数又逐渐增加。该植被带内的草本层的物种丰富度和多样性均大于灌木层。疏林灌丛丰富度和多样性指数随海拔梯度的增加呈单峰曲线变化趋势，最大值出现在1600-1700 m，其均匀度在海拔1300-1550m最低，在1660-2200 m范围内均匀度较高且无较大波动。该植被带内灌木层的物种丰富度和多样性均大于草本层。\n3 土壤理化性质垂直分异\n海拔1400m以下群落样地砂粒含量显著高于其它海拔梯度的灌木和草本样地，粉粒含量则显著低于其他样地，而粘粒含量与其他海拔梯度范围内的样地之间并无显著性差异；土壤水分、有机质、总氮含量随海拔的升高而增大；pH随海拔的升高而减小；电导率在海拔梯度上没有明显的变化。\n4 植被分布对环境因子分异的响应\n植被特征与环境因子的CCA排序结果表明：荒漠灌丛群落的第一排序轴基本上反映了土壤盐碱化梯度，第二排序轴则反映了土壤结构梯度；荒漠草地群落的第一排序轴反映了水分梯度，第二排序轴反映的是海拔梯度上水热组合梯度；疏林灌丛群落的第一排序轴反映的是土壤pH梯度，第二排序轴则主要反映了土壤结构梯度。植物多样性与环境因子相关性分析表明：荒漠灌丛群落多样性与均匀度指数与坡向呈显著正相关，而与土壤水分呈显著负相关；荒漠草地的群落的物种丰富度指数与有机质含量呈显著正相关，多样性和均匀度指数与土壤中砂粒含量呈显著正相关，而与海拔梯度成显著负相关；疏林灌丛群落的物种丰富度与海拔呈显著正相关，物种多样性、均匀度指数与坡位呈显著正相关。\n5 禁牧与山地草场的生态恢复效益\n在贺兰山北段的哈拉乌北沟，围封5年后，短花针茅群落的物种丰富度、多样性指数明显增加。总物种数从围封前5种增加到16种。放牧区的粉粒、粘粒含量比围封区稍大，而相应的砂粒含量则比围封区稍小；有机质、总氮含量表现为围封区>放牧区，电导率（总盐量）则表现为放牧区>围封区，相对而言，围封区和放牧区之间的土壤水分、pH并无显著差异。\n在贺兰山西坡的北段的乱柴沟、中段的哈拉乌南沟和南段的狭子沟，围封两年后，相应地段的植被总盖度分别增加了59%、67%和80%，南段和中段植被盖度的恢复速度明显高于北段；围封两年后中段的鲜草产量比围封前增加了2.5倍，明显高于北段和南段。尽管围封没有显著增加地表枯落物的产量，但围封两年后，各个地段的地表枯落物的持水能力比围封前增加了1倍左右。\n6 草地灌丛化对土壤异质性的影响\n短花针茅群落中珍珠猪毛菜灌丛斑块分布显著促进了冠幅周围表层土壤水分、养分富集，增加了微尺度土壤资源异质性。地统计学分析表明，放牧区土壤水分、有机质、总氮和pH空间自相关距离均大于珍珠猪毛菜平均冠幅，但远小于对照区的土壤资源空间分布尺度，据此推断，放牧区的土壤资源分布与珍珠猪毛菜灌丛斑块大小有密切关系。与内蒙古典型针茅群落的土壤养分的空间分布范围相比，贺兰山西坡哈拉乌坡水分、有机质、总氮、pH较小的空间自相关表明研究区土壤资源异质性的增强，或者说存在潜在的退化趋势，结合前人的研究成果，提出了干旱区山地草场退化过程的概念模型。\n总的来说，海拔高度的不同引起了温度和降水的差异，进而对气候、植物群落及土壤养分分布产生影响；坡向、坡位微地形的差异也在一定程度上增加土壤资源的异质性分布，从而使山地生境有别于其他荒漠区，并导致不同生态位的物种能够共存，为山地丰富多彩植物多样性提供了重要的物质基础。本研究的开展不仅可以为认识我国温带草原与荒漠过渡区植被及土壤养分分布特征提供参考，同时也将为贺兰山草地生态系统保护和草场资源管理提供重要依据。 |
| 英文摘要 | Montane area is about 6.5×106 km2, and approximately account for 67.7% of Chinese national territory total area. With condensed environmental gradient, highly heterogeneous habitats, relatively less human disturbance, and act as a refuge shelter of many species and a differentiated and multiplicate cradle of new vegetational sections in the geological history, it has developed and saved higher biodiversity, and become a key area of studying and protecting global biodiversity. As a regional water resource and green ecological barrier, montane ecosystem plays an important role in regulating and controling the arid region ecological environment of western China. \nHelan Mountain, located in the northwestern part of China, is a transitional zone from steppe to desert regions. It is also an important link connecting the vegetaion sections of Qinghai-Tibet and Mongolia plateau, and the North China plain. Its unique geological location and environment have shaped its unique biologic group, and is an important genetic resources center. Combining line transect method with representative vegetational communities, this paper discusses the disttributing characteristics of vegetation and soil resources and their interactions of low montane zone (from southern Xiazi Valley to Northern Daxi Valley), and preliminary discuss the restoration mechanism of grassland ecosystem in the west slope of Helan Mountain. Main results as follows:\n1 Vertical distribution of vegetational communities\t\nXerophytic shrub, such as Salsola passerine, Tamarix reaumuria, Nitraria tangutorum, Oxytropis aciphylla are recorded under 1400 m, and the family of Leguminosae, Chenopodiaceae, Gramineae, Compositae is frequently found. Some semi-shrubs, Ephedra rhytidosperma, Caragana spinifera, Zygophyllum xanthoxylum, Ajania fruticulosa and Lespedeza davurica mainly distribute at 1401-1600 m, and main vegetational family are similar with 1400 m, while the species number of Leguminosae and Compositae increase, but Chenopodiaceae and Gramineae decrease between 1401m and 1600m. Stipa communities, such as S. breviflora, S. krylovii and S. baicalensis are frequently found between 1601 and 1800 m, and the species number of Gramineae increase significantly. However, some tall arbor or shrub, for example, Prunus mongolica, Dasphora parvifolia and Ulmus glaucescens consist of the prairie shrubland zone, and the species number of Leguminosae and Gramineae reduced remarkably, and little Chenopodiaceae can be found, however, the species number of Rosaceae increase significantly.\n2 Response of plant diversity to the altitudinal gradient\nIn the desert shrub zone, the species richness is no significant difference between 1250 and 1400 m, but increases with increasing elevation ranges 1250-1400 m. species diversity and evenness appreciably increase along the elevation. Moreover, the richness of herb layer is higher than shrub layer, while the diversity of shrub layer is higher than herb layer\nIn the montane desert grassland zone, the changes of species richness shows a hump-backed curve along the altitudinal gradient, and is recorded the highest species richness in 1700-1800 m. With the increase of elevation, the diversity and evenness show increase, then reduce, and is found the lowest value in 1750-1820 m. From then on, with the rainfall increase and temperature decline, diversity and evenness increase by degrees. Furthermore, the richness and diversity of herb layer are higher than shrub layer.\nIn the prairie shrubland zone, the changes of species richness and diversity show a hump-backed curve along the altitudinal gradient, and is recorded the highest value in 1600-1700 m. The lowest value of evenness was recored in 1300-1550 m, while the evenness was relative higher in 1660-2200 m, and no obvious fluctuation. In addition, the richness and diversity of shrub layer are higher thant herb layer \n3 The changes of soil properties along the altitudinal gradient\nUnder the elevation of 1400 m, the sand content is remarkably higher than others shrubby and herbaceous samples, however, the silt content is significantly less than other samples, and no significant difference was found on the clay content. Furthermore, the content of soil water, organic matter, total nitrogen indicate a increased trend along the altitudinal gradient, in contrast to pH. Moreover, no significant difference was found for electrical conductivity in the altitudinal gradient.\n4 Response of vegetational distribution to different environmental factors\nCanonical correspondence analysis of vegetational characteristics and environmental factors show that the first ordination axes indicate saline-alkali gradient, and soil structure gradient of the second axes. In the desert grassland, the first axes suggest the water gradient, and water-heat gradient of the second gradient. In the prairie shrubland, the first axes indicates pH gradient, and soil structure gradient of the second axes. Correlation analysis indicate that the index of diversity and evenness are significant positive relation to slope direction, and significant negative correlation with soil water in the desert shrubland. In the desert grassland, species richness is significant positive relation to organic matter content. The index of diversity and evenness are significant positive correlation with the sand content, but remarkable negative relation to the altitudinal gradient. In the prairie shrubland, species richness is significant positive correlation with the elevation. Moreover, the index of diversity and evenness are significant relation to the slope position.\n5 Enclosure and the benefit of montane ecological restoration \nIn the northern Halawu Valley, enclosed for 5 years, the index of specis richness and diversity of Stipa community increased significantly from 5 to 16. In the grazing site, the content of silt and clay is somewhat higher than that in the enclosed site, and similar change for electrical conductivity, while the content of sand is less than that in the enclosed site. Furthermore, organic matter and total nitrogen showed the enclosed site > the grazing site. In addition, no significant differences were found for soil water and pH between the grazing site and enclosed site.\nIn the southern northern Luancha Valley, middle Halawu Valley and southern Xiazi Valley, after two years of enclosure, the total vegetational cover of have increased by 59%, 67% and 80%, respectively, and the restoration velocity of the vegetational cover in the middle and southern parts were faster than that in the northern part. Furthermore, the enclosure promoted the increase of fresh biomass, and that of 2002 in the middle part was 2.5 times than that in 2000, and significantly higher than that in the northern and southern part. No significant difference were found for the litter, however, the water retention of litter in the west slope in Helan Mountain have increased 1 times after 2 years enclosed.\n6 Effects of shrub patches on the soil heterogeneity\nS. passerine shrub patches expansion in the Stipa grassland, increased the soil water, nutrients enrichment, increased the degree of mocroscale heterogeneity in soil. Geostatistic analysis indicate the spatial autocorrelation of soil water, organic matter, total and pH are somewhat larger than the averaged shrubby canopy in the shrub patches, but less than that in the enclosed grassland. We concluded that the distribution of soil resources was associated with the patch scales of S. passerina in the shrub patches site. Comparing with the spatial distribution distance of Stipa community in Inner Mongolia, the smaller spatial autocorrelation of the west slope in the Helan Mountain, indicate a increased soil heterogeneity, or a degraded trend. Finally, a conceptual model was developed to demonstrate the degradation process of montane grassland following overgrazing.\n Altitudinal gradients cause to the difference of temperature and rainfall, anf further impose on the distributions of climate, vegetaion communities and soil resources. To a certain degree, the difference of the slope exposure and location increase the degree of soil resources. Therefore, montane habitats distinguish others desert area, and result in the species coexistence of different ecologcial inche, that provide an important matter basis for colorful montane biodiversity. This research not only offers a reference for understanding the vegetation and soil resources distribution of temperate steppe and desert, but also provide an important bases for protecting grassland ecosystem and managing grassland resources |
| 中文关键词 | 植物多样性 ; 土壤资源 ; 生态恢复 ; 贺兰山 |
| 英文关键词 | vegetational diversity soil resources ecological restoration Helan Mountain |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 自然地理学 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/286562 |
| 推荐引用方式 GB/T 7714 | 郑敬刚. 贺兰山西坡植被分布特征与土壤养分分异研究[D]. 中国科学院寒区旱区环境与工程研究所,2007. |
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