| 其他摘要 | 本研究针对黄土高原丘陵区退耕还林（草）和国家生态建设中生态经济系统健康评估的需求，以退耕地植被自然恢复、小流域和中尺度生态经济系统为研究对象，采用以空间序列代替时间序列的方法，从侵蚀环境特点及生态恢复关键因子入手，重点研究生态恢复过程，分析其与社会经济人文的协调效应以及各环境因子间的关系。提出了侵蚀环境下生态经济系统健康内涵与特征。在此基础上，探索不同尺度生态恢复健康诊断评价的科学方法，为分析该区生态恢复的健康状况，科学评价生态建设效果提供有效手段。主要结果如下：1．在黄土丘陵区侵蚀环境下，根据生态恢复过程中的物种变化动态，结合其重要值、生物量及生态位等进行综合分析，可以将退耕撂荒地草本植被自然演替过程划分为：先锋植物物种期（1～5a），物种渐繁荣期（6～8a），物种鼎盛期（9～13a），物种准稳定期（13～20a），物种相对稳定期（20～30a）和灌木先锋物种入侵期（30～50a）。先锋植物物种期以茵陈蒿、苦买菜、猪毛菜为关键种，物种渐繁荣期以委陵菜、阿尔泰狗哇花和隐子草为关键种，物种鼎盛期多物种共存，关键种不明显，物种准稳定期以长芒草、铁杆蒿和达乌里胡枝子为关键种，物种相对稳定期以铁杆蒿、达乌里胡枝子为关键种，灌木先锋物种主要有杠柳、木本铁线莲、绣线菊等。演替中植物种群的数量调节主要由种群密度、侵蚀环境植被恢复小生境和种间竞争控制。其种群的替代过程通过物种的生态适应性和种间竞争来实现，生态适应性和种间竞争导致了群落中物种的生态位分化，是物种相互替代的主要驱动力。2．物种多样性是反映群落组织化水平，并通过结构与功能的关系间接反映群落功能特征的指标，同时与物种均匀度、群落优势度、群落生物量和植被覆盖度共同影响着群落稳定性。群落的季节性波动是群落演替的量变积累，也对群落结构稳定性有影响。研究结果表明，退耕地植被自然恢复过程中，群落稳定性呈阶梯式增强，这种阶梯式的变化推动着群落向更高级方向演替，其主要原因是群落环境的逐步改善。群落的季节性波动的幅度亦随群落演替的进展而逐渐减小。3．在生态恢复过程中，土壤质量的生物学性能改善较快，化学性能居中，物理结构性能相对较慢，但三者都表现为随植被演替而逐渐恢复。研究建立了土壤物理、化学、生物质量与恢复年限的关系方程。土壤物理结构随着退耕撂荒演替进展而不断改善，稳定性不断提高，抵抗侵蚀能力逐渐增强。土壤化学性变化中，有机质但随着退耕撂荒演替而不断增加，从撂荒初期的0.53％增加到50年时的1.05％。在土壤无机营养元素中，C、N、K各元素含量随植被恢复逐渐增大，P没有明显变化。土壤生物学性能在退耕撂荒10年左右便可以得到基本恢复，土壤微生物量C、N、P含量随演替进展均呈逐渐增加，土壤呼吸强度也随演替进展而呈对数函数增长。4．在以人工措施为主的生态恢复过程中，流域社会经济人文状况与生态因子具有密切关系，表现出较好的协调效应。生态状况的改善能促使社会经济发展，同时，社会经济的发展亦能推动生态环境恢复。国家政策策略对生态恢复具有重要的导向作用。在生态要素间，植被与土壤环境因子具有显著的相关关系，植被恢复促使土壤质量不断改善，土壤质量的改善又促进植被进一步恢复演替，二者之间表现为正向互作效应。建立了流域生态经济系统生态恢复的经济与环境系列效应方程。5．以小流域和中尺度流域为研究对象，提出了黄土丘陵区侵蚀环境下生态系统健康的内涵与特征。基于生态恢复过程动态分析，对小流域和中尺度生态经济恢复过程中健康状况进行了定量分析。以生态经济系统所达到的最佳现实状态值为目标，引入障碍度和优势度等概念，运用通径分析理论进行了小流域和中尺度生态经济系统健康障碍、优势诊断。运用比较生态学方法，以小流域为单元，根据流域生态经济系统特点，构建了生态健康评价的指标体系和评价模型（健康指数）。运用均方差决策法有效解决了客观确定生态、经济社会与人文因素权重问题，并系统比较了不同恢复模式流域生态经济系统健康状况。研究表明，黄土丘陵区侵蚀环境下生态经济系统在科学调整土地利用格局、退耕还林还草等策略下，健康状况得到逐步改善，其健康水平呈逐年波动式上升趋势。且在当前状况下，资源环境因子改善效果较经济社会和人文因素显著。在以退耕还林还草为主导的生态恢复策略中，生态建设与经济协调发展是改善流域健康的的重要途径。分析表明，不同生态经济建设模式其健康状况及改善速度各有差异，在黄土丘陵区延安试验示范区，5年的生态经济建设结果（健康）排序为：飞马河（农＋苹果型）＞燕沟（水资源高效利用综合农业型）＞县南沟（农＋经济林果型）＞河庄坪（高效设施农业型）＞高桥（农＋畜牧型）。6．初步探索了侵蚀环境生态恢复效果评价的可拓学方法。生态系统恢复具有发散性、可扩性、相关性和共扼性的特点，分析表明，运用可拓工程方法进行生态恢复健康程度评价是可行的，从而为拓展生态健康评价理论和评价方法提供新的途径。; Ecological rehabilitation by “grain for green in loess hilly region is highly required for eco-economy assessment. This paper, from the process analysis of natural succession of vegetation, small and meso-scale of watershed ecosystem, presented the term of ecosystem health in the erosive environment. The ecosystem health indicator and approach were also studied to provide the methods of ecological rehabilitation benefits and situation. The main results are as follows: 1. Under the erosive environment, the vegetation succession in the abandoned tillage and desolated lands under might experienced six periods: like the settlement stage of the pioneering species(1～5a), the gradually booming stage (6~8a), the prosperity stages of species(9~13a), the stable stages (13~20a), the relative stable stage of species(20~30a), and the invasive stage of the pioneering species by the shrubs(30~50a). In the settlement stage of the pioneering species Achillea capillaries, Ixeris denticulate, and Salsola collina were the key species. Similarly, the gradually booming stage of species with Potentilla spp., Heteropappus altaicus, and Cleistogenes spp. were the dominant species, the peak prosperity stages of species with more species and without significant key species, the near stable stages of species with Stipa bungeana, Artemisia sacrorum, and Lespedeza dahurica, the relative stable stage of species with Artemisia sacrorum and Lespedeza dahurica, and the invasive stage of the pioneering species with the key shrubs like Periploca sepium, Clematis fruicosa and Spiraea spp.. The quantitative regulation of plant populations in the succession was determined by population density, site habitats and the inter-specific competition. The substitution of plant populations was caused by the eco-adaptability and inter-specific competition of species, which induced the eco-status division of species in the population. 2. The species biodiversity, as an indicator, is reflected the organization level of the community, and indicated the function characteristics in associated with community structure and its function. The stabilizations was also effected by species, the dominant, uniformity evenness index, community dominance, the biomass and the coverage rate of the vegetation The seasonal change of community could also influence its structure stability by the accumulative succession. The research showed that the community stabilization was improved gradually like a ladder under erosive circumstance, which promoted the community succession to a higher level by possibly gradual improvement of community habitats. The scope of community seasonal fluctuation would decrease gradually with the progress of the community succession. 3. In the restoration process, the biological property of soil quality was improved rapidly, the chemistry property was in intermediate, and the physics performance has a lowest rate. However all three properties would be improved gradually with the vegetation succession. The relation equation with the restore ration period ware established. In the soil physics property, physical structure was improved gradually which enhance the soil stabilization and ability of soil anti-scourability. The chemistry property of the soil was increased with the succession to 1.05％ from 0.53％ of the beginning in 50years. The dynamic of soil mineral elements such as C, N, and K increased gradually with the restoration process, except for P with no significant change. The soil biological property showed rapidly improvement in10 years. The elements of C, N, and P in the microorganisms could increase with the eco-restoration succession progress. Particularly, the soil respiration displayed an increase with logarithm function.4. In the eco-restoration procedure under the artificial measurements, the social economy and humanity status had closely relations with the eco-factors in the watershed ecosystem, vice versa The improvement of ecological condition would propel the development of the social economy. National policies and strategies will determine eco-restoration development. Among ecological factors, vegetation had a significant relationship with soil factors. It implied the vegetation restoration would improve soil quality. Vice versa, the improvement of soil quality would force further succession of the community. the vegetation and soil eco-factors showed a positive interaction significantly. Further more, the policy and strategy from the nation would also affect the eco-restoration development by the oriented guidance. 5. The connotation and character of a healthy ecosystem in small and meso-scale watershed under the erosive environment was defined and described. The health condition of the ecosystem in watershed scale was also analyzed quantitatively during the process of the ecosystem restoration. The healthy status in ecosystem restoration on different scales under erosive environment was evaluated according to inner mechanism in ecosystem restoration. Taking on the realized optimal value of the watershed ecosystem as target value, based on the theory of path analysis, the advantages and the obstacles of the watershed ecosystem health was diagnosed with some new indicators such as the dominant rate and the drawback ratio. The weight value of different indicators was calculated by the method of mean variance. Finally, the watershed ecosystem health condition under different ecosystem restoration models was compared. The results showed that the health condition in the eco-economy system of Loess hilly regions was becoming better and the health index was fluctuant improved with the landuses change and the implement of “grain for green” policy. Compared with the factors of natural resources, the factors of social economic and humanistic were responded lightly. The research demonstrated that ecological construction and economic development harmoniously was an important way to reach a healthy watershed ecosystem during ecosystem restoration. The relative analyses exhibited that healthy condition and improving rate in different modes of eco-economy development differed significantly. In Yan’an trial demonstration area from Loess hilly regions, healthy degree after five years development of ecology and economy declined gradually with Feimahe watershed (Agriculture ＋Apple industry), Yanggou valley (Integrative agriculture dominated by efficient water utilization) , Xiannangou valley(Agriculture ＋Cash forest and fruits industry), Hezhuangping watershed(Efficient instrument agriculture) and Gaoqiao area (Agriculture ＋livestock industry).6. A method named “extensible analysis” was explored primarily to evaluate ecological restoration result under erosive condition. Given that the restoration eco-system owned more traits like emanation, extensiveness, relationship, and coupling, the research implied that the appraisal of eco-system health under the extension engineering theory was feasible, which offer novel approaches for expanding healthy assessment theory of eco-restoration and developing relative evaluation method. |
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