高寒高原草地退化及修复研究——以西藏那曲地区为例
文献类型：学位论文
| 作者 | 鄢燕
|
| 学位类别 | 博士 |
| 答辩日期 | 2006 |
| 授予单位 | 中国科学院水利部成都山地灾害与环境研究所 |
| 授予地点 | 成都 |
| 导师 | 钟祥浩 |
| 关键词 | 高寒高原草地 退化机理与原因 空间分布 退化特征 生态经济类型区 宏观调控 恢复重建 |
| 其他题名 | Grassland Degradation and Restoration----a Case Study on the Nakchu Region of Tibetan Plateau |
| 学位专业 | 自然地理学 |
| 中文摘要 | 藏北高原平均海拔4500m以上，是我国乃至世界上高寒草地分布面积最大的地区，具有生态环境脆弱性和对外力作用响应敏感性特点，在人类活动和全球变化影响下，高寒草地生态系统退化严重，不仅影响到西藏自治区的社会经济发展，并且对国家生态安全构成威胁。本文以藏北高原那曲地区为研究对象，以生态学原理和系统科学理论为基础，紧密结合退化生态系统的恢复生态学和可持续发展理论，采用专家集成、3S技术与数学模型等定量与定性相结合的方法，对该区自然生态脆弱性和社会经济发展水平及草地退化空间分布给予全面分析，对高寒高原草地生态系统退化特征进行了全面的调查，对其退化机理及原因进行了深入的分析，在此基础上，提出该地区草地生态系统开发与保护的宏观调控策略和退化草地生态系统恢复重建的途径与措施。研究得出的主要结论和基本认识可归纳为如下几点：（1）明确了高原高寒环境下的草地退化的概念：是指由于高原自然环境恶劣造成生态系统脆弱性，加之气候变化和人类不合理活动的相互作用所导致的草地生态系统逆向演替的过程及其结果。（2）系统分析了自然因素作用下高寒高原草地的退化机理，表现在：在高原自身极不稳定的环境条件及当前全球气候变暖的影响下，高原多年冻土层随时间（昼夜或季节）呈现冻融和干湿交替；冻土层物理性状的交替改变导致水平方向上表层草皮撕裂，垂直方向上草皮层与其下土层分离，进而引起草根断裂，造成草皮层的塌落；风蚀、水蚀等因素进一步加剧了融冻侵蚀作用，随着时间的推移，草地破坏加剧，土壤水分干涸，最终发展成荒漠化土地。（3）在系统分析影响草地退化的自然与社会经济因素的基础上，采用定量综合评价方法，对各种导致草地退化因子的排序为：长期超载过牧>人类不合理活动（铲除草皮、挖药、淘金、修路、挖沙采石和滥垦滥伐等）>蒸发量/降水量>畜群结构不合理>牲畜出栏率>年均降水量>鼠虫、毒杂草危害>年均气温>人口数量>牲畜总数>土壤冻融、侵蚀作用>大风日数。（4）在总结退化草地评价指标的基础上，编制草地退化等级分布图。极度和重度退化草地主要集中在那曲地区东部的巴青、索县、比如、嘉黎，中部的那曲、安多和南部的班戈、申扎区域；轻度退化和无明显变化区域主要分布在西部的班戈、申扎、尼玛三县和双湖区，中部和东部也有少量分布，而中度退化草地在全区都有一定的分布。（5）通过分析不同退化草地生态系统结构退化特点发现：在未退化的情况下群落优势种为各类草地原生植被建群种，如矮嵩草、紫花针茅、藏北嵩草、青藏苔草等；不同草地类型其优势度不同，草甸类其优势度在90％以上，其它类型草地其优势度稍低。轻度退化时原生植被建群种仍然占据优势，但其优势度下降，而中生杂类草和旱生物种增加，如蔷薇科委陵菜属的物种、禾本科早熟禾属的物种、蒿类植物、火绒草等。中度退化的情况下原生建群种的优势度继续下降，而中旱生植物重要性逐渐增加与嵩草构成共建种。重度退化的草地群落物种构成发生重要变化，其优势种被中生和旱生植物替代，如火绒草、矮火绒草、青藏苔草、藏沙蒿等物种，同时一年生和二年生物种在群落中占据重要地位。（6）首次对该地区退化草地地下生物量的退化特征进行了研究，发现：地下总生物量在空间结构上表现为总的T字形趋势下的锯齿状分布，主要分布在0～10cm的草皮层中，并随退化程度的加剧，分布在各层的植物根系量越来越少。（7）首次提出该地区草地保护与开发的宏观调控对策，根据研究区域的生态脆弱性、生态环境承载能力、经济和人口聚集条件以及未来牧业发展布局潜力将那曲地区划区分禁牧区、限制发展区、适度发展区和重点发展区等四个生态经济类型区。禁牧区：是指依法设立的各类自然保护区和生态极度脆弱区，主要包括尼玛县和双湖区的大部分。限制发展区：是指生态高度－中度脆弱和生态环境承载力很弱以及规模集聚经济和人口条件差的区域，包括申扎县和班戈、尼玛、双湖区的部分区域。适度发展区：是指生态环境承载力较弱以及规模集聚经济和人口条件不够好的区域，包括那曲地区的东部四县及班戈县的部分区域。重点发展区：是指生态环境承载力较强以及规模集聚经济和人口条件较好的区域，包括那曲、聂荣和安多三县。（8）对不同生态经济类型区退化草地恢复重建途径与措施进行了系统分析与探索，认为加大重点发展区人工草场建设的科技与资金投入是高寒草地区新农村建设的重点。 |
| 英文摘要 | The North Tibet Plateau with average altitude of above 4,500 meters is the largest distribution region of alpine grassland in the world which has the characteristics of ecological environment frangibility and responsive sensitivity to exogenic action. Affected by the human activites and global changes, the degradation of alpine grassland is extremely severe which not only influences the social and economic development of Tibet Autonomous Region, but also threatens the national ecological security. Based on the ecological principles and system science, this dissertation integrates quantification and qualification methods including expert integration, 3S techniques as well as mathematic models by combination of restoration ecology of degraded ecosystem and sustainable development theory tightly to analyze comprehensively the natural eco-frangibility, social and economic development level of the research region and spatial distribution of degraded grassland. By means of general investigation on the ecological degradation characteristics of alpine grassland, and in-depth analysis of its degradation mechanism and causes, the macroscopical controlling strategies of grassland eco-system exploitation and protection in the research region are brought forward as well as recovery and reconstruction approaches. The primary conclusions and fundamental cognitions are presented as follows: (1) The grassland degradation concept on the condition of alpine plateau can be defined as the converse succession process and consequences of grassland eco-system which deviates from the climax system resulted from the natural geographical environment frangibility of alpine plateau and the interaction of climate changes and unreasonable humane activities (2) The alpine grassland degradation mechanism on the condition of natural factors’ functions is analyzed systematically which is represented as follows: Affected by the extremely unstable environmental conditions of plateau itself and the global temperature warming, the frozen soil layer of plateau displays phenomena of freezing and thawing as well as alternate wetting and drying with time-varying(day and night or seasons); The alternate changes of frozen soil layers’ physical properties result in the rupturing of sward layer horizontally and the separation of sward layer from the underground soil layer vertically which leads to the rupturing of grass roots and falling down of sward layer; Wind erosion and water erosion intensify the freezing and thawing erosion function so that with time-varying grassland destroying is more severe, and the water storage of soil is dried up which lead to the land desertification finally. (3) Based on the systematic analysis of natural and social economic factors influencing on the grassland degradation, the grassland degradation factors are ranked by means of comprehensive quantification method as follows: long-tem overgrazing >unreasonable human activities(such as eradicating the sward, digging medicine, fossicking, repairing roads, digging sand out to quarrying, estrepement and denudation, et al) > evaporation/precipitation > unreasonable drove structure > slaughtering rate > annual precipitation > mouse, pest and weed hazards > annual temperature > population > total livestock numbers > soil freezing, thawing and erosion functions > gale weather. (4) By summarizing the assessment indicators of degraded grassland, the grassland degradation grade distribution map is worked out. The extreme degradation and severe degradation grasslands are centralized which includes Bachen, Sokshan, Dirl, Chali of the eastern part of Nakchu region and Nakchu, Amdo of the middle part and Palgon, Shantsa of the south. The light degradation areas are mainly distributed in the western part including Palgon, Shantsa, Nima counties and double lakes region, and there some are distributed in the middle and eastern part. While the middle degradation grasslands are distributed in all Nakchu region. (5) The following conclusions are presented by analyzing the different degradation characteristics of grassland eco-system structure: Without degradation, the dominant species of the community are the constructive species of original vegetations in various grasslands such as Kobresia humilis, Stipa purpurea, K. littledalei, Carex moorcroftii and so on. The dominance of different grasslands is various. If the dominance of meadow is above 90 percent, then the dominance of other grasslands will be a bit lower. On the condition of light degradation, the constructive species of original vegetation still dominate over others, but their dominances decrease, while the Leymus chinensis xero forbs and xerophytic species increase, such as Potentilla species of Rosaceae, precocious species in Gramineae, ligusticum sinense oliver, Leontopodium leontopodiodes. On the condition of moderate degradation, the constructive species’ dominances of original vegetation decrease continually, while the importance of xerophytic species increase gradually and they will become the co-edificatos with Kobresia . On the condition of severe degradation, the species structure of grassland community changes greatly which arouse the dominant species are substituted by mesophytes and xerophytic species such as Leontopodium leontopodiodes, Leontopodium nanum, Carex moorcroftii, Artemisia weiibyi, et al. And the annual and biennial species take the importance place in the community. (6) The degradation characteristics of the belowground biomass in degraded grassland are studied. We found that the total belowground biomass was mostly distributed in the 0~10cm soil depth with a “T”-shape distribution feature and with the aggravation of degradation, the vegetation root system amount become less. (7)The macroscopic readjustment and control strategies of grassland protection and exploitation in the research region are put forward for the first time. In light of the ecological frangibility, eco-system capacity, economy, population congregation condition and the future stock raising development potential, Nakchu region is classified in to four eco-economic zones of enclosure：restricted development region, moderate development region and key development region. Enclosure refers to the various nature reserve and ecological extremely fragile region including mainly the majority of Nima County and Double Lakes region. The restricted development region refers to those with high or moderate ecological frangibility, low ecological environmental capacity and disadvantaged scale centralization economy and population conditions which include Shantsa, Palgon, Nima counties and Double Lakes region. The moderate development region refers to those with relatively fragile eco-environmental capacity and inadequate scale centralization economy and population conditions including four counties of eastern Nakchu region and part of Palgon County. The key development region refers to those with strong ecological capacity, advantaged scale centralization economy and population conditions including Nakchu, Nyerong and Amdo counties. (8)The way of increasing the scientific and funds input of artificial grassland construction in key development regions is considered as the emphasis of new country construction in alpine grassland through systematic analysis and exploration on the degraded grassland recovery and construction as well as measures of different eco-economic zones.The North Tibet Plateau with average altitude of above 4,500 meters is the largest distribution region of alpine grassland in the world which has the characteristics of ecological environment frangibility and responsive sensitivity to exogenic action. Affected by the human activites and global changes, the degradation of alpine grassland is extremely severe which not only influences the social and economic development of Tibet Autonomous Region, but also threatens the national ecological security. Based on the ecological principles and system science, this dissertation integrates quantification and qualification methods including expert integration, 3S techniques as well as mathematic models by combination of restoration ecology of degraded ecosystem and sustainable development theory tightly to analyze comprehensively the natural eco-frangibility, social and economic development level of the research region and spatial distribution of degraded grassland. By means of general investigation on the ecological degradation characteristics of alpine grassland, and in-depth analysis of its degradation mechanism and causes, the macroscopical controlling strategies of grassland eco-system exploitation and protection in the research region are brought forward as well as recovery and reconstruction approaches. The primary conclusions and fundamental cognitions are presented as follows: (1) The grassland degradation concept on the condition of alpine plateau can be defined as the converse succession process and consequences of grassland eco-system which deviates from the climax system resulted from the natural geographical environment frangibility of alpine plateau and the interaction of climate changes and unreasonable humane activities (2) The alpine grassland degradation mechanism on the condition of natural factors’ functions is analyzed systematically which is represented as follows: Affected by the extremely unstable environmental conditions of plateau itself and the global temperature warming, the frozen soil layer of plateau displays phenomena of freezing and thawing as well as alternate wetting and drying with time-varying(day and night or seasons); The alternate changes of frozen soil layers’ physical properties result in the rupturing of sward layer horizontally and the separation of sward layer from the underground soil layer vertically which leads to the rupturing of grass roots and falling down of sward layer; Wind erosion and water erosion intensify the freezing and thawing erosion function so that with time-varying grassland destroying is more severe, and the water storage of soil is dried up which lead to the land desertification finally. (3) Based on the systematic analysis of natural and social economic factors influencing on the grassland degradation, the grassland degradation factors are ranked by means of comprehensive quantification method as follows: long-tem overgrazing >unreasonable human activities(such as eradicating the sward, digging medicine, fossicking, repairing roads, digging sand out to quarrying, estrepement and denudation, et al) > evaporation/precipitation > unreasonable drove structure > slaughtering rate > annual precipitation > mouse, pest and weed hazards > annual temperature > population > total livestock numbers > soil freezing, thawing and erosion functions > gale weather. (4) By summarizing the assessment indicators of degraded grassland, the grassland degradation grade distribution map is worked out. The extreme degradation and severe degradation grasslands are centralized which includes Bachen, Sokshan, Dirl, Chali of the eastern part of Nakchu region and Nakchu, Amdo of the middle part and Palgon, Shantsa of the south. The light degradation areas are mainly distributed in the western part including Palgon, Shantsa, Nima counties and double lakes region, and there some are distributed in the middle and eastern part. While the middle degradation grasslands are distributed in all Nakchu region. (5) The following conclusions are presented by analyzing the different degradation characteristics of grassland eco-system structure: Without degradation, the dominant species of the community are the constructive species of original vegetations in various grasslands such as Kobresia humilis, Stipa purpurea, K. littledalei, Carex moorcroftii and so on. The dominance of different grasslands is various. If the dominance of meadow is above 90 percent, then the dominance of other grasslands will be a bit lower. On the condition of light degradation, the constructive species of original vegetation still dominate over others, but their dominances decrease, while the Leymus chinensis xero forbs and xerophytic species increase, such as Potentilla species of Rosaceae, precocious species in Gramineae, ligusticum sinense oliver, Leontopodium leontopodiodes. On the condition of moderate degradation, the constructive species’ dominances of original vegetation decrease continually, while the importance of xerophytic species increase gradually and they will become the co-edificatos with Kobresia . On the condition of severe degradation, the species structure of grassland community changes greatly which arouse the dominant species are substituted by mesophytes and xerophytic species such as Leontopodium leontopodiodes, Leontopodium nanum, Carex moorcroftii, Artemisia weiibyi, et al. And the annual and biennial species take the importance place in the community. (6) The degradation characteristics of the belowground biomass in degraded grassland are studied. We found that the total belowground biomass was mostly distributed in the 0~10cm soil depth with a “T”-shape distribution feature and with the aggravation of degradation, the vegetation root system amount become less. (7)The macroscopic readjustment and control strategies of grassland protection and exploitation in the research region are put forward for the first time. In light of the ecological frangibility, eco-system capacity, economy, population congregation condition and the future stock raising development potential, Nakchu region is classified in to four eco-economic zones of enclosure：restricted development region, moderate development region and key development region. Enclosure refers to the various nature reserve and ecological extremely fragile region including mainly the majority of Nima County and Double Lakes region. The restricted development region refers to those with high or moderate ecological frangibility, low ecological environmental capacity and disadvantaged scale centralization economy and population conditions which include Shantsa, Palgon, Nima counties and Double Lakes region. The moderate development region refers to those with relatively fragile eco-environmental capacity and inadequate scale centralization economy and population conditions including four counties of eastern Nakchu region and part of Palgon County. The key development region refers to those with strong ecological capacity, advantaged scale centralization economy and population conditions including Nakchu, Nyerong and Amdo counties. (8)The way of increasing the scientific and funds input of artificial grassland construction in key development regions is considered as the emphasis of new country construction in alpine grassland through systematic analysis and exploration on the degraded grassland recovery and construction as well as measures of different eco-economic zones. |
| 学科主题 | 自然地理学 ; 生态学 ; 环境学 |
| 语种 | 中文 |
| 公开日期 | 2010-10-22 |
| 分类号 | S81;R5 |
| 源URL | [http://ir.imde.ac.cn/handle/131551/2314]  |
| 专题 | 成都山地灾害与环境研究所_成都山地所知识仓储（2009年以前） 成都山地灾害与环境研究所_山地表生过程与生态调控重点实验室 |
| 推荐引用方式 GB/T 7714 | 鄢燕. 高寒高原草地退化及修复研究——以西藏那曲地区为例[D]. 成都. 中国科学院水利部成都山地灾害与环境研究所. 2006. |
入库方式： OAI收割
来源：成都山地灾害与环境研究所
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