【作者】 韩新辉；

【导师】 杨改河；

【作者基本信息】 西北农林科技大学 ， 生态学， 2008， 博士

【摘要】 本项研究立足于生态学国际前沿课题一生态系统恢复与重建的基本思想，以生态和经济系统极为脆弱的黄土高原为研究对象，通过跨度两年的社会调查和近一年的实地观测试验，采用宏观与微观相结合的方法进行了研究。研究定位了黄土高原生态恢复阶段，诊断了生态系统的结构和服务功能，并以此为基础分析了黄土高原生态恢复过程的主要生态效应，最后探讨了黄土高原林草工程与生态系统变化交互作用的机理。得出主要结论如下：（1）黄土高原退化生态系统阶段确定提出了黄土高原生态环境退化形成与治理的因子触发-响应机制模型，对其生态系统与干扰因子的相互作用机制和生态退化阶段进行了定位，通过初步验证，认为：黄土高原本身维持生态系统自我发展的主导力脆弱，系统演变过程受干扰因子作用而偏离生态演替顶级的趋势提前，系统生态退化处于模型的第Ⅱ阶段，需要通过适宜的人为设计，促使生态系统向自我设计的恢复方向转变。（2）黄土高原退化生态系统结构与功能定位及生态恢复的功能影响机制通过分析黄土高原生态系统的结构，定位和构建了黄土高原生态系统的生态服务功能框架，并对植被恢复影响黄土高原生态系统服务功能的途径和机理进行了探讨。认为：植被恢复对黄土高原生态系统服务功能的影响途径主要通过水土保持功能、土壤保育功能、生物多样性和气候调节来完成。植被恢复随时间尺度和空间规模的不同，表现出不同的生态效应。（3）黄土高原植被恢复的主要生态效应从黄土高原植被的水土保持功能、土壤保育功能及生物多样性维护功能出发，采用试验和观测的手段分析了黄土高原植被恢复的生态效应：水土保持效应：土壤含水量呈现季节性动态变化，不同的植被类型对土壤水分的消耗及植被对雨水的截留能力差异导致土壤平均含水量增值，表现为自然植被＞人工植被＞对照。土壤的持水性能与植被类型和植被生长年限密切相关，植被截持水量乔木＞灌木＞草本。不同植被恢复方式影响着与土壤持水性能有关的土壤物理性质的变化，其中处于长期人为干扰下的对照的土壤物理性质变劣，主要表现在容重、砂粒含量增加，田间持水量、总孔隙度和土壤渗透性能下降。人工植被和自然植被土壤的物理性质有较大改善，变化相对较大的是天然次生林土壤，表现出较强的水文调节功能。植被恢复的土壤保育生态效应：不同的植被恢复方式导致了土壤质量的显著差异。人工植被和自然植被的土壤质量均比长期干扰下的对照土壤质量高，以天然次生林为主的自然植被土壤质量相对比人工林土壤质量高。不同植被恢复方式对土壤生物学特性影响的研究表明，自然植被＞人工植被＞对照。原因在于林地较高的凋落物质量，根系生物量以及物种组成的相对丰富，形成了良好的土壤生态条件。植被恢复的生物多样性效应：不同植被恢复类型、不同恢复年限植被种群和群落的变化有所差异，随着退耕年限的增加，林分郁闭度增大，撂荒地草本覆盖度增大。自然植被、人工植被的群落多样性指数都比农地提高，群落生态效应明显。撂荒初期，表现为物种丰富度和群落多样性指数越来越高，群落生物量也明显提高。总体上，自然恢复的天然次生林生物多样性恢复最快。（4）黄土高原植被恢复的气候效应研究通过分析（1982．1～2003．12）NOAA／AVHRR GIMMS NDVI数据和气象观测、数据分析，探讨了不同中尺度、县域尺度下植被覆盖和气候要素的关系；对于小尺度采用了局地小气候观测试验进行了分析。植被覆盖变化：22年来黄土高原植被明显改善，尤其是在近3年，植被指数增幅最高，达到11．54％。春季和秋季植被恢复较快，植被指数年均增加都为7．0×10^-4。不同季节以春季和秋节植被恢复较明显，春、夏季的植被决定了全年的植被分布状况。此外，其植被覆盖变化存在明显的区域差异，NDVI呈现由西北向东南递增的趋势。黄土高原植被变化与不同尺度气候因子的相关性表明：在中尺度上，植被指数与温度相关性不明显，其相关性的空间结构和植被变化的空间结构基本一致，但温度和NDVI之间为弱相关性。县域尺度上相关分析表明：除气温外，黄土高原典型生长季植被恢复对安塞年均、春季及夏季气候影响显著，以夏季响应最敏感，当生长季植被指数升高0．01时，夏季降水增加86．75mm，蒸发和风速分别下降115．77mm和0．08 m·s^-1，年均风速随黄土高原年均植被指数增加0．01时下降0．09 m·s^-1。黄土高原不同植被恢复局地小气候生态效应强度比较：相同年限的植被小气候效应比较表明，人工植被＞自然恢复＞对照。在局地范围内，人工植被风速和气温均低于撂荒植被，大气相对湿度高于撂荒植被。从效应强度来看，人工植被小气候条件相对优越，自然恢复植被进程较缓慢，采用人工恢复能加速植被的演替进程，可促进多样性增加，优化生态系统的服务功能。从小气候环境的稳定性角度看，人工植被在一定程度上加快了植被恢复的进程，但其土壤含水量的比例明显小于自然恢复。综合来看，自然植被和人工植被的生态效应已有所显现，但人工植被的效益还未充分发挥，在土壤水分、土壤肥力等方面存在一定的弊端，与触发一响应模型判断的结论基本一致，人工植被模式还需进一步完善。（5）黄土高原林草工程与生态系统交互作用机理研究基于DPSIR模型构建了黄土高原林草工程建设与生态系统变化交互作用框架，提出交互作用指数并进行交互作用量化以及情景分析，形成了黄土高原生态系统与林草工程交互作用分析与量化方法。研究从驱动、压力、状态、影响以及响应五个层次进行了林草工程建设与生态系统变化交互作用指标体系构建，分析了较为完整的交互作用体内外联系机制；在具体分析交互作用体内部作用过程中采用了价值分析方法和能值分析结合的形式进行参变量统一化处理，为进行不同类型、不同状态以及不同形式的参变量对比分析提供可能。以安塞为案例进行林草工程与生态系统变化交互作用的实证分析，结果表明：安塞县林草工程目前处于正效应占主导阶段；驱动影响指数II_DI为4．72＞0，表明工程实施6年系统处于收益状态；响应指数II_IR为15．398，表明系统的承载能力较强。综合各方面要素，安塞林草工程建设对生态环境影响有利于整体区域生态、环境与经济的可持续发展。更多还原

【Abstract】 Based on the international frontier topics of ecology-the basic thought of restoration and reconstruction of ecosystem, taken Loess Plateau with flimsily ecological and economical system as case, through social investigation of two years and experiment of one year, the system was studied by combination of macroscopic with microscopic. Through ascertained the stage of ecological restoration in Loess Plateau, the structure and service function of ecosystem were diagnosed. Follow the diagnostic results, the main ecological effects during process of ecological restoration of Loess Plateau were researched as well. At last, the study discussed the interaction mechanism between regressing arable land to forestry （grass） project and change of ecosystem. The main results and conclusion are given as follows:（1） Stage determination of degenerate ecological system of Loess Plateau Triggering factor-ecological response model for degradation and control of ecology inLoess Plateau was proposed, and ascertained the stage of ecological degradation and interaction mechanism between ecosystem and interference factors. Iinitial validation of the model indicate that ecological dominant force of Loess Plateau ecosystem was weak to maintain itself developing. Deviation of the climax of ecological succession from its preconcerted status was ahead of time because influenced by interference factors, and degradation of ecosystem was in stage II. All these changes needed suitable artificial design to impel the ecosystem turn to resumptive direction of self-design.（2） Determination of structure and service function of the ecosystem and influencing mechanism on function of ecological restoration in Loess PlateauThe study analyzed the structure of the ecosystem of Loess Plateau, ascertained and constructed framework of service function of the ecosystem, and discussed the way and mechanism that effects of restoration vegetation on service function of the ecosystem. It was considered that the effects of restoration vegetation on service functions of the ecosystem was completed by function of soil conservation and soil and water conservation, biodiversity and adjustment of climate. Restoration vegetation shown different ecological effect with change of time scale and spatial size.（3） The main ecological effect of restoration vegetation in Loess PlateauFrom function of soil conservation and soil and water conservation, maintenance of biodiversity, ecological effect of restoration vegetation in Loess Plateau was analyzed by experiment and observation.Soil and water conservation effect: soil water content shown seasonal variation. The average soil water content was increased because of significantly difference between water consumption and sequestration by different vegetation type. The increased extent of water content shown natural vegetation > artificial vegetation > control. The natural vegetation was made for accumulation of average soil water content. Soil water-holding capacity was closely related with type and growth of vegetation.The capacity of sequestrating water in different plant shown arbor > shrub > herbage. Different way of restoration vegetation could aroused change of soil physical properties that was closely related with soil water-holding capacity. The physical properties of control soil become bad under long term human disturbance. The main manifestations were increase of bulk density and sand content, decrease of field water capacity, total porosity and soil permeability capability. The soil physical properties were obviously improved under natural vegetation and artificial vegetation, especial natural secondary forest soil shown stronger function for adjustment of hydrology.Ecological effect of soil conservation under restoration vegetation: different way of restoration vegetation result in significantly difference on soil quality. The soil quality of natural and artificial vegetation was higher than control soil that was under long term human disturbance. The quality of natural secondary forest soil was higher than artificial vegetation soil. The main reasons for lower quality in control soil and artificial vegetation soil was that periodically forest tending made decrease in quality and amount of litter, biological function become bad, soil physical structure was break and soil nutrient loss was seriously. The study of effect of different way of restoration vegetation on biological characteristics indicated natural vegetation > artificial vegetation > control. The reason was higher quality of litter, amount of root biomass and abundant species in forest land, which formed benign ecological condition in soil.（4） Climate effect of restoration vegetation in Loess PlateauThe study analyzed the date of NDVI and climate during 1982-2003, and discussed the relationship between vegetation coverage and climate factors on different middle scale and county scale. The experiment of observation on climate in region was used to analyze climate in small scale.Change of vegetation coverage: the vegetation in Loess Plateau was significantly improved in 22 years, especially in recent 3years. NDVI was increased highest with 11.54%. The restoration vegetation in spring and summer was faster than other seasons, increased with 7.0×10^-4·a^-1. The vegetation in spring and summer determined the distribution of vegetation in whole year. In addition the change of vegetation has obviously difference among region, the NDVI shown increasing trend from northwest to southeast.The relationship between change of vegetation in middle scale and climate factors indicated there was not obviously correlation between NDVI and temperature at middle scale, however it was similar in change of spatial structure of them. Analyse of correlation in county scale indicated that restoration vegetation in typical growth season have significant influence on climate of whole year, spring and summer. The summer climate was the most sensitive to restoration vegetation. When NDVI in typical growth season increased 0.01, the precipitation of summer was increased 86.75mm, evaporation and wind velocity were decreased 115.77mm and 0.08 m·s^-1 respectively. Annual wind velocity was decreased 0.09 m·s^-1 when annual NDVI of Loess Plateau was increased 0.01.Comparison of microclimate ecological effect strength by different vegetation in recovery of local ground on Loess Plateau: The results of the microclimate effect comparison of vegetation in the same year indicated that artificial vegetation > natural restoration > control. In the range of local ground ,the wind speed and temperature of the artificial vegetation was lower than the abandonment.we see from the strength of effect that the microclimate condition of the artificial vegetation was relatively proper, the process of natural restoration vegetation was slower, adopting artificial recovery could accelerated the successional process of vegetation, so as to promote the increase of diversity, optimizate the service function of ecosystem. But from the stability of the microclimate environment, artificial vegetation has accelerated the process of vegetation restoration to a certain extent, but the proportion of its soil water content was significantly lower than natural restoration.Sum up above, ecological effect of artificial vegetation and natural vegetation has been shown. But effect of artificial vegetation still did not fully shown. There some disadvantages in soil water and fertility, which same with conclusion of factor-ecological response model. So artificial vegetation should be further improved.（5）The study of interaction mechanism between forestry （grass） engineering and ecosystem in Loess PlateauBased on the DPSIR model, we build the interactional framework between the loess plateau forestry （grass） engineering and change of ecosystem, use the interaction index to quantify interaction and analyze scene, and form systemic interaction analysis and quantitative methods. We research from the five aspects of forestry （grass） engineering construction and change of ecosystem, including the driver, pressure, state, impact and response, to construct systemic index, and analyzed the complete interaction inner and outer liaison mechanism. In detailed analysis of internal interaction process, we used the valuable analytical methods and the energy analysis to unify, which makes comparative analysis possible between different types, different states and different forms parameters. The interaction between the forestry （grass） project construction and the change of ecosystem in Ansai were researched. The study concluded that the positive effect was the dominant stage in the Ansai currently. The effect-driven index IIDI was 3.92> 0, which indicated that the project was in income condition after six years. The response index IIIR was 14.35, indicated that the carrying capacity of the system was very strong. Synthesizing all elements, we concluded that the impact of Ansai county’s forestry （grass） project on ecosystem environment was conducive to the overall regional ecology, environment and the sustainable economic development.更多还原