【作者】 李朝生；

【导师】 慈龙骏； 杨晓晖；

【作者基本信息】 中国林业科学研究院 ， 森林培育， 2005， 博士

【摘要】 地球表面的环境因子与植被在反馈与响应中形成动态平衡,但是这些平衡因种种原因而被不断打破,常常引发生态系统结构和功能的退变,使人类的生存环境不断恶化。本文以鄂尔多斯高原北部沙区这一典型生态过渡区为研究对象,就该区植被一环境关系从不同尺度、不同角度进行了剖析,以此为基础,提出了该区域相应的分区生态环境建设对策。通过初步分析得到以下结论:(1)植物区系:现知研究区的63科、236属、427种、19变种维管束植物中,科的数量组成中菊科、禾本科、豆科、藜科占优势,属则是蒿属、黄芪属、藜属、蓼属等占优势;科、属的分布类型均以温带分布与世界分布型中的温带分布类群为主。独特的气候地理条件使本区形成了以中生、旱生的多年生草本为主,一二年生草本植物层片明显,灌木、半灌木相对发达的区系系统,且地带上存在一定的替代性。(2)植被空间分布:运用3S技术首次确定库布齐沙区的总面积为20394 km~2(2002年)。研究区的植被背景整体上是以油蒿为建群种的沙生植物群落,在其中镶嵌其它群落类型,从而形成了研究区较为独特并具代表性的植被格局。无论是地带性植被还是沙生植被,均表现出东西向和南北向明显的分异规律:即自东向西随干旱程度的不断加剧,形成了典型草原、荒漠草原以及草原化荒漠替代分布格局;自南向北形成了地带性植被、沙漠-沙地植被、隐域性低湿地植被+人工植被的替代分布格局。(3)植被-气候分区与植被格局动态:按照伊凡诺夫湿润指数所划分的4个植被.气候小区内地带性植被和沙生植被的分布均带有鲜明的气候烙印。白东向西在各植被-气候区内,不但油蒿群系发育面积不断缩小,而且群丛分布替代的格局明显。从20世纪70年代末到21世纪初,气候的暖湿化和植被建设使鄂尔多斯高原北部沙区的流动、半流动沙地的面积减小,使油蒿为主的稳定性沙生植被的面积有所增加。(4)不同植被类型下土壤要素的分布特征:各植被类型下土壤特征要素的差异较为明显,草原植物种出现的区域比沙生植被分布的区域土壤条件有所改善。库布齐沙漠与黄河河岸过渡区域中土壤都较为贫瘠;且盐碱危害较重;过渡区土壤养分的供给强度和盐化程度有随深度的增加而降低的趋势。小尺度下,人工植被土壤水分和盐分分布的均匀性也远好于自然植被;所研究的10种植被类型的土壤盐分和水分大部分具有较高的空间相关性。(5)不同植被类型下大气降水.土壤含水.地下水的特征:沙漠边缘的大气降水、土壤水分、地下水埋深三者之间的关系明显不同于沙漠绿洲交错区和绿洲内部:具有土壤含水量相对较低且土层间变异较大、地下水位埋深较深但稳定、土壤水分与地下水关系不明确、大气降水在土壤中运移快等特征。黄河覆沙低阶地植被、沙丘间地植被以及平沙更多还原

【Abstract】 Environmental factors and vegetation form a dynamic balance between feedback and response in the globe surface. But the dynamic balance was broken constantly by all kinds of causes, which changed the structure and function of the ecosystem, and deteriorated the living environment.Vegetation-environment relationships were analyzed by different scale and view in the sandy region in North of Ordos Plateau, a representative ecological transitional area. Based on the relationships, ecological restoration recommendation was presented for different subarea. After preliminary analysis, results were got as following:(1) Flora: There are 63 families, 236 genera, 427 species and 19 variations vascular plants in the study region, which in the composing of families, Compositae, Gramineae, Leguminosae and Chenopodiacea are preponderant, while in the composing of genera, Artemisia, Astragalus, Chenopodium, Polygonum are preponderant. The distribution types of family and genus are mostly temperate distribution. With the unique climatic and geographic conditions, the region formed the flora system that composing dominantly the perennial herbage of mesic and xerophytic, characterized by obvious layer of annual or biennial herbage and relatively developed shrub and semi-shrub. And the flora has substitute attribute.(2)Spatial distribution of vegetation: Confirmed the Kubuqi sandy region area (20394 km2) for the first time in 2002 by 3S techniques. As a whole, the vegetation background of the study region was psammophyte community with the essential species of Artemisia ordosica, and other community types mosaiced among it. Thus formed the particular and representational vegetation pattern. Both the zonation and psammophyte vegetation have distinct law of segregation from east to west and from south to north, i.e. from east to west formed alternative distribution pattern of typical steppe, desert steppe and steppe desert, and from south to north formed that of zonation vegetation, desert-sand vegetation and intrazonal low wet land vegetation + artificial vegetation.(3) Subarea of vegetation-climate and dynamic of vegetation pattern: The zonation vegetation and psammophyte vegetation in the 4 subarea of vegetation-climate compartmentalized by Ivanovii humidity index both characterized obviously by climate. In each subarea of vegetation-climate from east to west, not only the area of Form. Artemisia ordosica shrinked constantly, the substitute pattern of association was apparent. From the end of the seventies of the 20th century to the beginning of 21st century, the warm-humiditization of climate and revegetation caused the area of traveling sand and semi-mobile sand in thesandy region in North of Ordos plateau to decrease and the area of steady psammophyte vegetation composed mainly by Artemisia ordosica to increase.(4) The distribution characteristics of the content of soil under different vegetation types: The difference of the content of soil under different vegetation types in the study region was obvious. The soil condition at the region where steppe plant species presented was better than that at the region where psammophyte vegetation distributed. The soil was infertile and saline-alkali seriously in the ecotone between the Kubuqi Desert and the riverbank of the Yellow River. With the depth deeper, the soil trended to be more infertile and the soil salt content to be decreased. At a small scale, the distribution evenness of the soil moisture and soil salt under the artificial vegetation was far better than that under the natural vegetation. The soil salt and soil moisture under the studied 10 vegetation types mostly had relatively higher spatial correlation.(5) Characteristics of atmospheric precipitation-soil moisture-ground water for different vegetation types: The relationships among the atmospheric precipitation, soil moisture and ground water at the edge of desert characterized by lower soil moisture and biggish variance between layers, lower groundwater level but steady, fuzzy relations between soil moisture and ground water, quick movement in soil of atmospheric precipitation, which were visibly different from that at the ecotone which between desert and oasis, and that inside the oasis. The soil moisture under the vegetation at the Yellow River low step mulching sand, under the vegetation between sand dunes, and under the vegetation at the flat sand and stabilized dune decreased in turn. Precipitation has great importance on the increase of the soil moisture, and such change trend has a consanguineous relation with the topography and vegetation type, and the difference was especially obvious between different vegetation types.(6) Effects of grazing disturbance on saline grassland and soil characteristics: Grazing disturbance caused the spatial heterogeneity to increase further, the heterogeneity was the vegetation distribution mosaic pattern of Nitraria sppAvtas and low step meadow between dunes at saline grassland in study region. And grazing disturbance decreased the vegetation cover, species abundance and species diversity at saline grassland, but it had not obvious effects on species evenness. Heavy grazing caused the dominant species succession, and the decrease of dainty species. Shrub had functions protecting annual herbage for some certain. Continuous grazing was a stable structure factor that impacted the spatial distribution, weakened the spatial heterogeneity and strengthened the evenness of soil water and salt in saline grassland. And thus function could not be ignored in the soil water and salt movement and redistribution in saline grassland.(7) Recommendations of ecological restoration: Based on the studies above and based on thesubarea, analyzed the main ecological environment problems, discussed the construction objects and rules, and presented the construction contents and approaches to actualize.更多还原