沙漠化地区两种生态治理政策交易成本的比较研究

本文将交易成本分析引入沙漠化地区生态治理政策分析过程,构建生态治理政策交易成本分析框架,确定交易成本计算方法,估算内蒙古乌审旗退耕还林政策执行期间的交易成本为每年4 931.92元·hm-2。其中,政府直接支付占交易成本的50.06%,农户支付占交易成本的46.86%,政府直接支付是退耕还林机会成本的118.75%。草原休牧政策执行期间的交易成本为每年906.07元·hm-2,政府直接支付占交易成本的12.86%,农户支付占交易成本的80.35%,政府直接支付是草原休牧机会成本的23.30%。退耕还林政策的政府支付与退耕还林的机会成本大致相同,因此该政策执行效果良好,并且实现了退耕还林地区的全面禁牧。草原休牧政策的政府支付达不到休牧机会成本的1/4,牧民利益受到损失,牧民偷牧率达到100%,致使草原休牧流于形式。生态治理政策的交易成本分析,将为不同生态治理政策的比较和绩效评价提供一个新的角度,具有重要意义。     

生态建设政策对沙漠化影响的定量分析

本文从分析沙漠化的物理机制入手,将生态建设政策对沙漠化的作用以政策指数（PIX ）来表示,并将其分解为空间广度（PSS）和时间强度（PEF）两个变量,PIX=（PSS+PEF）/2。以宁夏盐池县退耕还林和草地禁牧两种政策为例,在政策实施区分别选取40个样本点,提取沙漠化变化、植被指数变化、政策指数等数据。计算表明：退耕还林和草地禁牧政策与沙漠化变化相关系数分别为-0.664和-0.746,两种政策都对沙漠化面积的减少起到了显著的作用。政策广度和政策强度都与沙漠化的逆转显著相关,说明构建的政策指数可以更准确地反映政策因素对沙漠化的作用。政策因素对沙漠化作用的定量分析,对沙漠化治理政策的绩效评价以及新制度的设计,都有重要意义。     

论我国半干旱草原地区沙漠化防治战略的转型

我国的治沙事业虽已取得很大成就, 但总体而言, 依然是点上治理、面上扩大, 治理速度赶不上沙化速度。针对我国北方半干旱地区的环境特点, 通过分析、比较, 提出应将生态建设的重点从强烈发展中的、严重的沙漠化土地转向正在发展中的和潜在的沙漠化土地。     

沙漠化地区可持续发展的概念模型

就沙漠化地区可持续发展概念模型进行了分析,并进一步对比了沙漠化地区可持续发展与沙漠化防治实现途径之间的关系。提出,可持续发展与沙漠化防治尽管目标不同,可内容一致、手段相同,就沙漠化地区而言,其可持续发展的过程就是对沙漠化土地的治理过程、是消除沙漠化发生隐患的过程,也是确保区域发展不受沙漠化困扰、可以持续稳定发展的过程。     

沙漠化预测的度量分析

文章据据沙漠化发生的特性,运用数学方法建立预测模型,试图以定量研究代替传统的定性分析,经实例验证,取得了与文献资料一致的结果,对予测一地区是否发生沙漠化具有广泛的适用性。     

科尔沁地区现代沙漠化过程的驱动因素分析

基于近50a科尔沁地区沙漠化土地发展-再发展-逆转的时空变化的研究结果, 以气候波动和人类活动变化作为主驱动因子, 探讨现代沙漠化过程的驱动因素的作用。近40多年气候的波动在一定程度上直接地通过不同时期的降水-温度组合影响着沙漠化的进程, 间接地通过人类对气候波动的响应而产生的经济活动来加速沙漠化的进程。尽管科尔沁地区的气候驱动因子呈现出有利于沙漠化发展过程的趋势, 但在近10多年来, 这种驱动力的作用被有利于沙漠化逆转过程的驱动力所抵消。人类活动是研究区沙漠化过程中更加活跃的驱动因子, 体现在土地利用方式的转变和强度的增加, 以及由此而产生的对自然植被群落毁灭性的破坏而加速了沙漠化的进程。以土壤风蚀为例, 这种加速可以是自然条件下的4~10倍; 随着沙漠化程度的加剧, 所产生的在土壤养分、生物多样性和生物生产量等方面退化的加速也与自然条件下的情况相差3~10倍以上。同样是人类活动, 在合理的土地利用、采取各种沙漠化防治措施的情况下, 又可使沙漠化过程逆转。从这一点上来说, 人为驱动因素应是起绝对主导作用的。     

基于公共价值的沙漠化治理政策绩效评价研究

首先从分析沙漠化的物理机制入手,将生态建设政策对沙漠化的作用以政策指数PIX来表示,分解为空间广度[PSS]和时间强度[PEF]两个变量,PIX=（PSS+PEF）/2,定量计算政策指数与沙漠化变化的相关性。其次以公共价值为基本框架,构建沙漠化治理政策的执行过程+生态效果的绩效评价体系,从政策过程的“公平性”、对“合作生产”主体的尊重性、政府部门管理的“效率性”、生态效果的“可持续性”、政策对沙漠化变化的相关性等方面提取指标因子,定量评价沙漠化治理政策的绩效。以宁夏盐池县草地禁牧政策为例进行研究。结果表明：禁牧政策与沙漠化面积减少显著相关,草地禁牧政策公共价值绩效得分0.378 3,效果较差。因此,提出的基于公共价值的沙漠化治理政策绩效评价指标和模型都是可行的。     

沙漠化过程中植物群落组成的分析：以神木大保当地区为例

沙漠化过程中,植被生活型谱中地面芽植物明显减少,隐芽植物增多。群落最小面积由潜在沙漠化阶段的45m~2减少到沙漠化第5阶段的2.25m~2。投影盖度为“s”型分布,油蒿群丛盖度大于臭柏群丛。油蒿群丛盖度达31.62％,臭柏群丛只有24.99％。Simpson指数减少,种均匀度指数增大,该变化趋势与森林、草原植被演替过程中均匀度的变化规律相反。或许为沙生植被所特有。群丛优势度指数增大。优势度—多样性曲线在沙漠化发生前和初期为对数正态分布,沙漠化后期为几何级数分布。     

禁牧政策对北方农牧交错区草地沙漠化逆转过程影响的定量评价

为定量评价禁牧政策对北方农牧交错区草地沙漠化逆转过程的影响程度,以宁夏盐池县为研究区域,选取对沙漠化正逆发展过程影响较大的自然和人为因素指标,应用系统动力学方法构建模型,模拟研究了目前盐池县所实施的禁牧政策对草地沙漠化逆转过程的影响程度,并进行定量化初步评价。研究结果表明,当禁牧程度达到完全禁牧的30%,沙漠化开始出现逆转,而达到完全禁牧的40%,沙漠化的逆转趋势基本趋于稳定。本研究结论可为盐池县及类似地区禁牧政策的合理实施与改进提供理论依据。     

科尔沁沙地典型地区人工造林对沙漠化过程的影响

在3S技术的支持下,以奈曼旗1975年、1985年、1995年和2005年的遥感影像为信息源,分析了研究区近30 a人工造林对沙漠化过程的影响。结果表明,在持续的人工造林过程影响下,沙地面积呈现出持续减少的趋势,其中固定沙丘面积减少幅度尤为显著,面积净减量为39 545.77 hm2;沙漠化程度指数呈现出线性减少的变化趋势,自1985年以来,减少幅度尤为明显,由1985年的0.21下降到2005年的0.03;土地沙漠化正、逆过程同时存在,但逆转趋势远大于发展趋势,土地沙漠化过程总体上正处于全面逆转期;斑块数和景观形状指数均呈现出先增后减的变化趋势,斑块形状经历简单—复杂—简单的变化过程。     

Progress in sandy desertification researchof China

Sandy desertification is land degradation characterized by wind erosion mainly resulted from the excessive human activities in arid, semiarid and part of sub-humid regions in northern China. The research on sandy desertification has experienced more than 5 decades of arduous course of the struggle along with the establishment and development of China's desert science. Researches in this field have made a great contribution to the national economic construction, and environmental protection. This paper focuses on presenting the major progress and achievements in the sandy desertification research during the last 50 years, including the stages of study on sandy desertification, background environment of sandy desertification and its changes, the conception, causes, process, monitoring and assessment of sandy desertification, the vegetation succession, landscape ecology, plant physiology, impacts on ecosystem, high-effective use of water and land resources and sustainable development in sandy desertified regions, sandy desertification control models and techniques etc.     

Progress in sandy desertification research of China

Desertification is one of the most serious environmental and socio-economic problems facing the world today. Because the rapid expansion of desertification has resulted in serious environmental deterioration, economic loss, locally unsteadiness political situation and social upheaval, it has become a hot-spot issue of worldwide concern. During the late 1960s and early 1970s, as the catastrophic drought in the west Africa greatly accelerated the development of desertification, the desertificati…     

中国沙漠化研究进展

Sandy desertification is land degradation characterized by wind erosion mainly resulted from the excessive human activities in arid, semiarid and part of sub-humid regions in northern China. The research on sandy desertification has experienced more than 5 decades of arduous course of the struggle along with the establishment and development of China‘s desert science. Researches in this field have made a great contribution to the national economic construction, and environmental protection. This paper focuses on presenting the major progress and achievements in the sandy desertification research during the last 50 years, including the stages of study on sandy desertification,background environment of sandy desertification and its changes, the conception, causes, process,monitoring and assessment of sandy desertification, the vegetation succession, landscape ecology, plant physiology, impacts on ecosystem, high-effective use of water and land resources and sustainable development in sandy desertified regions, sandy desertification control models and techniques etc.     

中国古代沙质荒漠化的历史演变

荒漠化是全球性的环境问题,威胁到人类的生存和发展,中国是受荒漠化严重危害的国家之一。依据历史文献的记载和现代学者研究成果,分秦汉魏晋南北朝时期、隋唐宋元时期和明清时期三个历史阶段,梳理了中国沙质荒漠化的演变过程。研究表明：秦汉魏晋南北朝时期,中国沙质荒漠化主要集中在西北地区,如鄂尔多斯高原、河西走廊和新疆地区;隋唐宋元时期,荒漠化扩展到东北地区,如呼伦贝尔沙地、科尔沁沙地等;明清时期,政府通过修筑长城和封禁政策,客观上抑制了边疆地区的垦殖开荒,但在人口压力下,明朝后期和清朝后期北部边疆的农垦快速发展,加速了鄂尔多斯高原、科尔沁沙地等地区的荒漠化进程。因此,数千年来的气候变化和人类活动,特别是滥垦、滥牧、滥樵采等不合理土地利用方式,致使我国北方干旱和半干旱区的荒漠化日趋严重。     

吉林省西部土地沙化动态变化

吉林省西部沙地位于中国温带半湿润与半干旱的过渡地带 ,是生态环境变化的敏感地区。采用多时相、多波段TM影像 ,结合实地考察 ,建立沙区生态环境地理信息系统 ;选取植被退化状态、风蚀强度和土层厚度为沙化程度评价的综合指标 ,在GIS平台支持下对沙区土地沙漠化进行动态评价。结果表明 ,近 2 0年来土地沙漠化基本得到控制 ,局部有所发展。沙漠化形成的主要自然因素是干燥的气候条件和地表丰富的沙源 ;人类不合理的经济活动加速了沙漠化进程。     

内蒙古达拉特旗高头窑镇土地利用变化及其对土地沙化的影响

以达拉特旗西南部的高头窑镇为研究区域,以达拉特旗1987、1995、2000和2003年四期遥感影像为信息源,在3S技术支持下,对遥感影像进行解译,获得1987-2003年来四个时期的沙漠化动态变化数据,分析了高头窑镇20世纪80年代中期到21世纪初的沙漠化变化情况。结果表明:该地区近20年来,沙漠化土地处于发展-发展-逆转的过程中。研究区是典型的荒漠草原区,草原在各土地利用类型中始终占有绝对优势,农田、林地和高盖度草原的面积变化较大,各种土地利用类型之间的转化主要表现为各种沙丘类型之间的转化、各种草原类型之间的转化和草原与固定沙丘之间的转化。1987-2000年期间,草原和林地的退化是导致沙漠化严重发展的主要原因。2000-2003年间,土地类型之间的转化表现为固定沙丘、半固定沙丘和林地向草原的转化,这种转化有利于沙漠化的逆转。可见,在高头窑地区,草原的退化是导致沙漠化的主要原因,因此,在沙漠化的治理方面,应该合理利用草原,防止过度放牧,大力倡导退林还草。     

吉林省西部土地沙化动态变化

The sandy land of the western part of Jilin Province is located in the ecotone of semi-humid and semi-arid area in the temperate zone of China. The sandy desertification has widely spread in the region because of the vulnerable natural conditions and the unreasonable human activity; as a result of this, the precious land resources and the economic development in the area have been seriously impacted. In this paper, the sandy land ecologic environment geographic information system is established based on the multi-spectral, multi-temporal Landsat TM images and field investigation. The comprehensive indexes of sandy desertification extent assessment which include vegetation degradation, wind erosion extent and soil depth are presented to classify the sandy land in western Jilin into three levels--slight, moderate and severe sandy desertification with the support of GIS platform. The results demonstrate that the sandy desertification has been partly controlled in the past twenty years, except some small sites. However, this doesn‘t necessarily mean that there is nothing for more concern. The two main causes of sandy desertification have not been eliminated yet, one is its natural factor, especially the physical and chemical characters of sandy soil and dry climate; another is the immoderate economic activity of human being that has highly accelerated the sandy desertification process.     

Spatial distribution of sandy desertification change in the west of Jilin Province

The sandy land of the western part of Jilin Province is located in the ecotone of semi-humid and semi-arid area in the temperate zone of China. The sandy desertification has widely spread in the region because of the vulnerable natural conditions and the unreasonable human activity; as a result of this, the precious land resources and the economic development in the area have been seriously impacted. In this paper, the sandy land ecologic environment geographic information system is established based on the multi-spectral, multi-temporal Landsat TM images and field investigation. The comprehensive indexes of sandy desertification extent assessment which include vegetation degradation, wind erosion extent and soil depth are presented to classify the sandy land in western Jilin into three levels--slight, moderate and severe sandy desertification with the support of GIS platform. The results demonstrate that the sandy desertification has been partly controlled in the past twenty years, except some small sites. However, this doesn't necessarily mean that there is nothing for more concern. The two main causes of sandy desertification have not been eliminated yet, one is its natural factor, especially the physical and chemical characters of sandy soil and dry climate; another is the immoderate economic activity of human being that has highly accelerated the sandy desertification process.     

基于景观格局的区域沙漠化程度评价模型构建

区域沙漠化程度评价对于防沙治沙具有重要意义。本研究在当前区域沙漠化程度评价方法中补充了在不同类型沙漠化土地空间分布的生态意义及其对区域沙漠化整体程度的影响因子,使其能评价各类沙漠化土地面积相等时几个区域的沙漠化程度。本文应用景观生态学原理,通过对空间分布差异而引起生态过程不同的理论分析,筛选出表征沙漠化土地空间分布生态意义的景观格局指数--聚集度,结合遥感与地理信息系统技术构建出区域沙漠化程度评价模型,并应用该模型对内蒙古浑善达克沙地六旗县的区域沙漠化程度进行了评价。结果对该各旗县不同时期的沙漠化程度的区分度较好,按沙漠化程度的不同,提出对正蓝旗的沙漠化要加强治理,对沽源县和太仆寺旗的沙漠化应采取预防措施的区域沙漠化防治对策。     

Assessment of sandy desertification trends in the Shule River Basin from 1978 to 2010

Sandy desertification in the Shule River Basin has expanded dramatically during the past 30 years. We evaluated the status, evolution, and main causes of sandy desertification by interpreting Landsat images which were acquired in 1978, 1990, 2000, 2005, and 2010, and analyzing the relevant meteorological data. The results show there was 3,477.95 km2, 3,733.32 km2, 3,620.29 km2, 3,565.65 km2, and 3,557.88 km2 of sandy desertified land in 1978, 1990, 2000, 2005, and 2010, respectively. From 1978 to 1990, not only the area of sandy desertified land （SDL） but also the degree of SDL levels increased. From 1990 to 2010 there was widespread restoration of SDL but the recovery trend of SDL gradually slowed. Although climate change contributes to expanding sandy desertification, human activities can either accelerate or reverse trends of natural sandy desertification. Some detrimental human activities can accelerate sandy desertification, but, conversely, desertification control measures such as the Three-North Shelter Forest Project and watershed rehabilitation programs in areas including the Shule River Basin resulted in many SDL being turned into grasslands or forest lands when shrubs and trees were planted to fix mobile sands at the edges of oases and cities. With population growth, much SDL has been reclaimed as farm land using water-saving agricultural methods or has been turned into built-up land as a result of urbanization.