【作者】 杨万勤；

【导师】 宋光煜； 何毓蓉；

【作者基本信息】 西南农业大学 ， 土壤学， 2001， 博士

【摘要】 土壤生态系统是由生物系统、土壤系统和环境系统之间通过物质循环、能量转换和信息传递等相互联系、相互制约和相互协调而构成的有机功能整体。土壤生态退化是指由于人类活动及恶劣的自然环境条件作用或二者共同作用下造成的土壤生态系统结构破坏、系统功能衰退、土壤生物多样性减少、土壤生产力下降以及土壤荒漠化、干旱化、板结化、酸化、盐碱化和养分亏缺与失衡等一系列土壤生态环境恶化的过程和现象。它与土壤学中关于土壤退化的定义和生态学中关于生态退化的定义密切相关，是21世纪土壤学和生态学的焦点问题。因此，退化土壤生态系统的恢复与重建既是土壤学和生态学的研究热点，又是全人类共同关心和迫切需要解决的难点问题。但在经典土壤学和生态学中，土壤学家很重视土壤系统本身的退化研究，往往忽视生物系统退化的研究，而生态学家强调植被系统退化的研究，常常忽视土壤系统和土壤生物系统的研究，更缺乏植被系统、土壤生物系统和土壤系统之间的关系研究。在土壤生态退化程度及退化土壤生态系统的恢复与重建的评价指标中，或重视土壤养分退化的评价，或重视土壤生物学活性的退化研究，缺乏对整个生态系统的综合评价指标体系研究，缺乏地上和地下部分生物多样性的关系研究。值得提出的是，在土壤生态系统的恢复与重建研究方面，往往缺乏个别物种在形态、生理生态和营养生态等方面对退化土壤生态条件和极端环境因子的生态适应性研究，缺乏个别物种对退化土壤生物修复的作用研究。 金沙江干热河谷是横断山区干旱河谷的一种极端类型，元谋干热河谷则是金沙江干热河谷的典型区域。区域内光热资源丰富，有利于各种热带亚热带植物生长发育。但区域内水热矛盾和光肥矛盾突出，植被覆盖率低，水土流失严重，是一个典型的生态环境脆弱带。区域内的基带土壤（燥红土）和变性土的荒漠化、干旱化和养分亏缺与失衡严重，土壤生产力低下，植彼恢复与重建困难。因此，本项研究试图以金沙江干热河谷为例，采用野外调查和室内分析相结合的手段，采用宏观与微观相结合以及定性与定量相结合的方法，从土壤生态系统、生物群落、种群等不同层次和角度，研究了干热河谷区的植被特点，不同退化程度的两类土壤生态系统的土壤物理、土壤化学和生物学特征以及系统内的植物群落生物量和生物多样性等，探讨了土壤系统、土壤生物系统和植被系统之间的关系，阐述了土壤生态退化的机理和过程；以酸角为研究材料，以玉米为参比材料，采用野外调查、盆栽试验与室内分析相结合的方法，研究了酸角和玉米在形态、微形态、生理生态和营养生态方面对退化燥红土和变性土的生态反应和适应性，探讨了植物对退化土壤和干热气候的生态适应性机理；研究了植物在不同条件下对退化土壤的生物修复效应，以期为金沙江干热河谷退化土壤生态系统的恢复与重建提供切实可行的科学依据。研究结果表明： 1．金沙江于热河谷上壤生态退化机理与特征 ＊）元谋干热河谷的植被系统是适应干热条件和贫瘠土壤生态条件为特征的植被生态系统。燥红土和变性土生态系统的植物种类、植被盖度、植物群落生物量、植物物种丰富度、物种多样性均随着土壤生态退化程度加剧而下降，即使耐干热耐贫瘠的禾草类植物的种类和数量均减少。极重度退化变性土上草本层植物的丧失，意味着生态系统己处于极度退化的状态。经治理后的生态系统中，植被盖度，植物群落生物量和植物多样性增加，尤其是多年生植物的种类和数量增加。 m从燥红土和变性土生态退化系列的 6个样地中共获取土壤动物 11 718头，隶属于2门 5纲 15目（类），其中燥红土生态系统中共获取 7031头，分属于 2门 5纲 15目（类）膜翅目、弹尾目和蜘蛛目为优势类群，其与婢螨目和线虫类等常见类群构成了燥红土生态系统中土壤动物群落的主体。变性土生态系统共获土壤动物4687头，隶属于2门4纲14 目（类），优势类群为膜翅目和弹尾目，与蜘蛛目、婢螨目、直翅目和线虫类构成了变性土生态系统土壤动物群落的主体。两类上壤生态系统内土壤动物群落的种类组成与季节、土壤生态退化程度有关，反映了元谋干热河谷“干热”条件和不同土壤生态条件对土壤动物群落的影响。土壤动物群落的类群数、个体数量、物种多样性指数、物种丰富度均随上壤生态退化而降低。轻度退化燥红上的土壤动物数量分别为中度和重度退化燥红土的＊42和6．25倍；中度退化变性土的土壤动物数量分别为重度和极重度退化变性土的3．40和27．75倍，表明随着土壤生态退化，土壤动物群落的结构遭到破坏，生物多样性下降，结构向简单化方向发展。 门）燥红土和变性土生态系统内的土壤细菌、放线菌、真菌数量及三大微生物总数在雨季、于湿交替季节和旱季均随着土壤生态退化而降低，燥红上的微生物数量明显高于变性土。土壤细菌、放线菌和真菌数量总体上表现为雨季＞干湿交替季节＞旱季。极重度退化变性土生态系统的微生物数量的季节变幅最大，雨季与旱季相?更多还原

【Abstract】 Soil ecosystem is an organic integrative system consisting of biotic system, soil system and environment system mutually and harmoniously through material circulation, energy conversion and information transmisson. Soil ecological degradation can be defined as the process and phenomenon of a series of deterioration of soil ecological environment such as structural destruction and functional recession of soil ecosystem, decrease of soil biodiversity and productivity, dcsertification, drought, hardness, acidification and salination of soils, deficit and unbalance of soil nutrients, and loss of soil and water, resulting from human activities and adverse natural environmental conditions. It is related to the definition of soil degradation in soil science and the definition of ecological degradation in ecology, is the focal points of soil science and ecology in the twenty-first centuly. Therefore, restoration and reconstruction of degraded soil ecosystems is not only a hot points of soil science and ecology but also a difficult points that is concerned by the whole mankind and need solving urgently. However, soil scientists usually attached importance to the degradation of soil system itself, neglecting studying the degradation of biotic system. On the contrary, ecologists paid attention to studying the degradation of vegetation system, usually neglecting studying the degradation of soil system and soil biotic system, and was wanting in studying the relationship among vegetation system, soil biotic and soil system. Among the assessment indices of soil ecological degradation and restoration and reconstruction of degraded soil ecosystems, or the assessment indice of biotic activity degradation was paid attention to, it was lack of comprehensive A part of cooperation projectStudy on Land Degradation and its Control in the Typical Region of Dry and Hot Valley of the Jinsha Rivc( by Yunnan Province and the Chinese Academy of Sciences. assessment index system and relationship between above and below ground biodiversity. To be mentioned, it was lack of studying on ecological adaptation of specific species to degraded soil ecological conditions and extremely environmental factors by morpha, physiological ecology and nutrient ecology; it was lack of studying on bioremediation of specific species to degraded soils. Dry and hot valley of the Jinsha River is an extreme type in the dry valley of Hengduan mountain area, and Yuanmou dry and hot valley is the typical region of the dry and hot valley region of the Jinsha River. There is advantageous to the growth and development of tropical and subtropical plants because of abundant light and heat in the region. The region is a typical ecotone due to prominent contradictions of water and heat, and light and soil fertility, low vegetation coverage, and serious loss of water and soil. Vegetation restoration and reconstruction is very difficult because of serious desertification, drought, deficit and unbanlance of soil nutrients, and lower productivity of zonal soils (dry-red soils) and vertisols in this region. Therefore, this project dealt with the vegetation features, soil physic, chemical and biological characteristics, and plant community biomass and biodiversity of two types of different degradation degree of soil ecosystems in the dry and hot valley, discussed the relationships among soil system, soil biotic system and vegetation system, elaborated the process and mechanism of soil ecological degradation from the angle and level of soil ecosystem, biotic community and population by the methods of combining field investigat更多还原