【作者】 许端阳；

【导师】 庄大方； 潘剑君；

【作者基本信息】 南京农业大学 ， 土壤学， 2009， 博士

【摘要】 沙漠化是荒漠化的主要类型,它作为极其重要的环境和社会经济问题困扰着当今世界,威胁着人类的生存和发展。中国是世界上受沙漠化影响最为严重的国家之一,沙漠化引起的土壤质量下降、土地资源减少以及沙尘暴等问题严重制约了社会经济的可持续发展以及和谐社会的构建。近年来,尽管我国的沙漠化防治工作取得了一定的成效,但是整体上其形势依然严峻。沙漠化过程的驱动力作用研究是沙漠化研究的基础。气候变化和人类活动是导致土地沙漠化的两个主要驱动力,在不同尺度下开展气候变化和人类活动在土地沙漠化过程中相对作用的定量评价,对于沙漠化治理和沙漠化的理论研究具有重要意义。气候变化和人类活动在沙漠化过程中相对作用的定量研究,是准确评价沙漠化动态过程、研究沙漠化对全球气候变化响应以及制定沙漠化防治对策与战略的基础。探索有效方法开展气候变化和人类活动在沙漠化过程中相对作用的定量研究,突破目前的研究瓶颈,不仅能够丰富沙漠化科学研究的理论基础、澄清目前沙漠化研究中的一些误区,而且能为区域和国家尺度上沙漠化防治对策与战略的制定提供理论依据。本研究以鄂尔多斯高原为典型研究区,在系统分析近30年来鄂尔多斯高原气候变化和人类活动特征变化的基础上,建立沙漠化的定量监测以及沙漠化过程中气候变化和人类活动相对作用的定量评价方法,最终对鄂尔多斯高原沙漠化过程中气候变化和人类活动的相对作用进行多尺度研究。论文以定量研究为主线,从方法论的角度对沙漠化过程中驱动力作用研究进行突破,主要取得了以下的成果和结论：1、建立基于Landsat数据的鄂尔多斯高原沙漠化定量监测方法。从沙漠化引起的地表特征变化入手,选取NDVI、MSDI以及Albedo三个指标分别代表沙漠化地表的植被丰度、景观格局以及地表微气候条件,来进行沙漠化定量监测。针对Landsat数据特点,在提出各个指标的反演算法的基础上,综合考虑不同植被类型区以及遥感影像获取的时间,建立了基于决策树模型的沙漠化定量监测方法。根据精度检验的结果,该方法监测精度较高,可以准确地用于鄂尔多斯高原沙漠化的监测研究。2、1980-2005年间,鄂尔多斯高原沙漠化变化趋势呈一种逆转与发展同时存在,但是逆转整体大于发展的态势。在1980-1990年间,逆转的沙漠化土地在鄂尔多斯高原分布相对分散,而发展的沙漠化土地的空间分布相对较为集中,主要分布在杭锦旗东南部的温带落叶灌丛与荒漠草原的过渡区域、准格尔旗西部的温带禾草草原区域、以及鄂托克前旗南部的温带落叶灌丛区。在1990-2000年间,沙漠化逆转的土地面积略高于沙漠化发展的土地面积,明显逆转的沙漠化土地集中分布在伊金霍洛旗西北部的温带落叶灌丛与温带禾草草原的过渡区以及鄂托克前旗西部的温带落叶灌丛区；而沙漠化发展的土地主要集中在达拉特旗、杭锦旗、准格尔旗、乌审旗以及东胜。在2000-2005年,该时段年均沙漠化的逆转面积最大,逆转的沙漠化土地主要分布于鄂尔多斯高原东北部的准格尔旗、达拉特旗和东胜这三个旗县的大部分地区；而发展的沙漠化土地主要集中分布在伊金霍洛旗以及鄂托克前旗西北部的温带落叶灌丛与荒漠草原的过渡地带。3、气候变化和人类活动在沙漠化过程中相对作用定量评价方法的建立。选择净初级生产力NPP为衡量沙漠化过程中气候变化和人类活动相对作用的公共指标,利用潜在NPP以及潜在NPP与实际NPP的差值来衡量气候变化和人类活动在沙漠化过程中的相对作用,通过拆分复杂的沙漠化驱动力过程,根据沙漠化逆转和发展与气候变化和人类活动引起的NPP变化趋势之间的可能情景,构建沙漠化过程中气候变化和人类活动的定量评价方法。在建立概念框架的基础上,对评价过程中所需的数据进行量化,其中用CASA模型来模拟实际NPP,并在CASA模型的基础上建立了潜在NPP的计算方法。通过对实际NPP以及定量评价结果的验证,表明本研究提出的定量评价方法可以用于沙漠化过程中气候变化和人类活动相对作用的评价。4、不同时间尺度下,鄂尔多斯高原沙漠化过程中气候变化和人类活动相对作用存在明显的差异。1980-1990年时间尺度下,气候变化是鄂尔多斯高原沙漠化逆转的主要原因,以气候变化为主导因素的逆转的沙漠化土地面积占总逆转面积的89.45%；人类活动则是沙漠化发展的主要原因,以人类活动为主导因素的发展的沙漠化土地占总发展面积的83.93%。在1990-2000年时间尺度下,人类活动是沙漠化逆转的主导因素,以人类活动为主导因素的逆转的沙漠化土地面积占总逆转面积的90.04%；而气候变化则主导了该时期的沙漠化发展,以气候变化为主导因素的发展的沙漠化土地面积占总发展面积的91.20%。在1980-2000年时间尺度下,人类活动是鄂尔多斯高原沙漠化逆转的主要原因,以人类活动为主导因素的逆转的沙漠化土地面积占总逆转面积的93.02%；而气候变化则是导致沙漠化发展的主要因素,以气候变化为主导因素的发展的沙漠化土地面积占总发展面积的85.77%。1980-2005年时间尺度下,气候变化和人类活动共同导致了鄂尔多斯高原的沙漠化逆转,其中气候变化主导的沙漠化逆转面积略大,占59.71%；而对于沙漠化发展,人类活动则是该时间尺度下的沙漠化发展的主导因素,以人类活动为主导因素的发展的沙漠化土地占总发展面积的62.35%。5、不同空间尺度下,鄂尔多斯高原沙漠化过程中气候变化和人类活动相对作用也存在明显的差异。在1980-2005年时间尺度下,随着空间尺度的增加,气候变化和人类活动主导的沙漠化逆转面积均呈增加的趋势,直到旗县尺度达到最大；而气候变化和人类活动主导的沙漠化发展以及评价过程中的误差面积都表现为先增加后降低的趋势,直到旗县尺度减低为0。更多还原

【Abstract】 As the main type of desertification, sandy desertification is becoming one of the most serious global social-economic-environmental issues of our time, which threatens human survival and development. China is one of the countries which are severely affected by sandy desertification in the world. Sandy desertification caused a lot of problems such as reduction of land quality, decrease of land resources, sand storm, etc., which seriously impede the sustained development of economy and construction of harmonious society. The whole country is still in a serious condition though we have achieved some good results in preventing sandy desertification in recent years.Assessing the driving forces of sandy desertification is fundamental and important for sandy desertification research. Climate change and human activities are main driving forces of sandy decertification. The research of the relative role of climate change and human activities in sandy desertification at different temporal and spatial scales has important significance in the prevention of sandy desertification and the research of sandy desertification theory. The quantitative assessment of the relative role of climate change and human activities in sandy desertification is the foundation for accurately evaluating the dynamic progress of sandy desertification, researching the sandy desertification in response to climate change and formulating the strategies of preventing the sandy desertification. Exploring effective methods to carry out the quantitative assessment of the relative role of climate change and human activities in sandy desertification and breaking the present research bottleneck, which not only can enrich the theoretical basis of sandy desertification research and clarify some mistakes in sandy desertification research, but also can provide theoretical basis for formulating strategy of sandy desertification prevention on the district and country scale. In this study, Ordos plateau was selected as the typical research region. Based on analyzing the character of climate change and human activities, this study formulated quantitative monitoring of sandy decertification and quantitative assessment of the relative role of climate change and human activities in the process of sandy decertification, and carried out the research of the relative role of climate change and human activities in sandy desertification in Ordos plateau at multi-scales. This paper takes the quantitative research as masterstroke and breaks the research of driving forces in the progress of sandy desertification from methodology’s point of view. The followings are the productions and conclusions of this dissertation:1 Developed a quantitative method for monitoring sandy desertification in Ordos Plateau based on Landsat data. Based on the characteristics of the change of land surface induced by sandy desertification, the author selected NDVI, MSDI and Albedo as the indicators to represent the abundant of vegetation, landscape and micrometeorological condition of land surface with sandy desertification respectively for monitoring sandy desertification. Based on the characteristics of Landsat data, the author developed the methods for retrieving the there indicators, and built the quantitative method for monitoring sandy desertification based on Decision tree model with considering the effects of vegetation types and the image date on the value of indicators. According to the results of accuracies checking, there was relative higher accuracy of this method, which made it can be applied to monitor sandy desertification in Ordos Plateau accurately in this study.2 From 1980 to 2005, some regions of Ordos Plateau experienced sandy desertification reversion and some places experienced sandy desertification expansion; however, there had a situation that the area of sandy desertification reversion was higher than that of sandy desertification expansion in this period. From 1980 to 1990, the distribution of the area of sandy desertification reversion was relatively scattered while the distribution of the area of sandy desertification expansion was relatively concentrative. The areas of reversed sandy desertification were mainly distributed in the transition zone between temperate deciduous scrubs and desert steppe in the south east of Hanjin Banner, temperate steppe in the east of Zhunger Banner and the temperate deciduous scrubs in the south of Etuokeqian Banner. From 1990 to 2000, the area of sandy desertification reversion was higher than that of sandy desertification expansion. The regions experienced obviously sandy desertification reversion mainly distributed in the transition zone between temperate deciduous scrubs and temperate steppe in the north west of Yijinhuoluo Banner, and the temperate deciduous scrubs in the west of Etuokeqian Banner. However, the area of sandy desertification expansion mainly distributed in Dalate, Hangjin, Zhungeer, Wushen Banner and Dongsheng city. From 2000 to 2005, mean annul revised sandy desertification area in this period was biggest in the three periods, which mainly distributed in the most areas of Zhunger Banner, Dalate Banner and Dongsheng city, while the areas of reversed sandy desertification centralizely distributed in Yijinhuoluo Banner and the transition zone between temperate steppe and temperate deciduous scrubs in the north west of Wushen Banner.3 Formulate a quantitative method for assessing the relative role of climate change and human activities in sandy decertification. NPP was selected as the indicator to measure and assess the impact of climate change and human activities on sandy desertification in this study. Potential NPP and the difference between potential NPP and actual NPP were used to measure and assess the impact of climate change and human activities on sandy desertification. Through the process of splitting the driving forces of sandy desertification and basing on the scenarios between the sandy desertification reversion and expansion and the changes of NPP induced by climate change and human activities, formulate the quantitative assessment of the relative role of climate change and human activities in sandy decertification. On the basis of setting up the conceptual model, the author quantified the required date in the assessment process. CASA model was used to simulate the actual NPP, and establish the calculate method of potential NPP based on CASA model. According to the validation of the actual NPP and the results of quantitative assessment, it proved that the quantitative assessing method developed in this study can be used to assess the relative role of climate change and human activities in sandy decertification.4 The relative role of climate change and human activities in sandy desertification of Ordos Plateau showed significant differences when it assessed at different temporal scales. When it was assessed at the temporal scale from 1980 to 1990, climate change was the dominant factor that induced the reversion of sandy desertification, and the area of reversed sandy desertification which was induced by climate change was 89.45 percent of the total area of reversed sandy desertification. While human activities was the dominant factor that induced the expansion of sandy desertification, and the area of expanded sandy desertification which was induced by human activities was 83.93 percent of the total area of expanded sandy desertification in this period. When it was assessed at the temporal scale from 1990 to 2000, human activities was the dominant factor that induced the reversion of sandy desertification, and the area of reversed sandy desertification which was induced by human activities was 90.04 percent of the total area of reversed sandy desertification. While climate change was the dominant factor that induced the expansion of sandy desertification in this period, and the area of expanded sandy desertification which was induced by climate change was 91.20 percent of the total area of expanded sandy desertification. When it was assessed at the temporal scale from 1980 to 2000, human activities was the dominant factor that induced the reversion of sandy desertification, and the area of reversed sandy desertification which was induced by human activities was 93.02 percent of the total area of reversed sandy desertification. While climate change was the dominant factor that induced the expansion of sandy desertification, and the area of expanded sandy desertification which was induced by climate change was 85.77 percent of the total area of expanded sandy desertification. However, when it was assessed at the temporal scale from 1980 to 2005, both climate change and human activities induced the reversion of sandy desertification, but the areas of reversed sandy desertification which was induced by climate change were slightly bigger and reached 59.71 percent of the total revised area; while human activities was the dominant factor that induced the expansion of sandy desertification in this period. The area of expanded sandy desertification which was induced by human activities was 62.35 percent of the total area of expanded sandy desertification.5 When it assessed at different spatial scales, there were also differences in the relative role of climate change and human activities in sandy desertification of Ordos Plateau. Along with the increase of spatial scale, there is a growing tendency for the areas of reversed sandy desertification which was induced by both climate changes and human activities, and both of them reached the biggest when it assessed at banner scale. But the expansion of sandy desertification induced by climate change and human activities and error area in the process of assessment are represented by the trend of lowing after increasing, and both of them reached 0 when it assessed at banner scale.更多还原