我国土地资源安全及相关研究进展

土地资源是人类赖以生存和发展的重要基础,是人类社会不可替代的物质财富。在人口持续增长、经济快速发展和不合理土地利用方式导致土地严重退化的现实面前,我国土地资源正经受着养活众多人口、满足建设占用、保障农业发展和支撑生态修复的历史性考验,土地资源安全已成为国家经济社会可持续发展的重大问题。因此,探讨新时期土地资源安全战略,对我国社会、经济的可持续发展具有重要意义。     

关于西南岩溶山区生态建设的一些讨论—－以贵州省为例

在分析20世纪90年代以来南方岩溶山区生态退化和重建研究实践方面的薄弱环节及国外岩溶区生态建设经验的基础上,对岩溶山区生态建设的特殊性进行了重新认识。指出岩溶山地的生态环境建设必须是一种经济建设,石漠化综合治理模式必须由扶贫型向质量型转变,由单一坡改梯向多途径特色农业转变,由防护型向开发型转变,由政府主导向参与式转变。在恢复和治理生态的前提下调整农业内部结构,发展特色产业,将环境资源转化为有形商业产品,形成生态环境外部经济效益良性循环的机制,以中止岩溶脆弱生态背景上土地退化的恶性循环。      

黔桂岩溶山区土地利用变化的社会经济因素分析

基于黔桂岩溶山区1990、2015年的土地利用数据和社会经济统计资料,利用典范对应分析方法对1990-2015年25年间的土地利用变化及社会经济驱动因素进行了实证分析。结论如下:（1）黔桂岩溶山区土地利用变化存在明显的时空分异现象;（2）贵州高原区以草地大幅减少和林地增加为主要特征;黔桂峰丛洼地区以水域面积增加和草地减少为主要特征;广西丘陵区的主要特征是耕地减少和建设用地增加。（3）贵州高原区土地利用类型变化以经济和人口因素为主要驱动力;广西丘陵区土地利用类型变化以经济因素和农业结构水平为主要驱动力;农业因素对黔桂峰丛洼地区的土地利用变化驱动作用明显。未来应提高贵州高原和黔桂峰丛洼地区岩溶山区草地生态功能重要性的认识,在加强森林植被恢复的同时加强草地资源保护;城镇化发展背景下黔桂岩溶山区应减少优质耕地占用,开发低丘缓坡土地,建设山地特色城市。      

典型岩溶流域土地整理的生态评价——以云南小江流域为例

以云南小江典型岩溶流域为例,在GIS支持下,通过选择评价因子和建立评价模型对岩溶区的土地整理进行了生态评价。结果表明: 流域生态评价分值较高的土地面积较少,而生态评价分值较低的土地面积较大。分值在80～ 100的土地整理主要任务是在保护生态环境质量和耕地数量的前提下,加快流域经济结构的调整,提高土地利用的经济效益;分值在70～ 80的土地整理主要任务是耕地数量保护和质量保护并重,提高土地的生产能力,提高经济效益,同时防止水土流失及化肥、农药施用对地下水造成的非点源污染; 分值在60～ 70的土地整理主要任务是着重于生态环境的保护和重建以及立体农业的综合开发; 分值在60以下的土地整理主要任务是土地石漠化的治理。      

生态问题的社会经济检视

人类社会经济活动是造成生态问题的主要和根本原因,生态问题又反过来冲击社会经济,因此必须从社会经济的视角来检视生态问题。国际学术界对"人类世"概念的认同,以及"国际全球环境变化人文因素计划"和"未来地球计划"的执行,都表明对当代生态问题进行社会经济透视的重要性。生态问题本质上是社会经济问题,需要从社会、经济、政治的角度去认识,于是产生了政治生态学、"公地的悲剧"以及社会—生态系统分析等理论。以社会经济的视角检视生态问题的制度因素和退化生态系统治理,表明需要加强从社会经济方面寻求根本解决途径的研究,以助力社会经济的发展并使退化生态系统走上"以自然恢复为主"的轨道。为此,生态问题研究要在体制与政策变革、发展模式转型以及科学技术创新3个层面上寻求解决之道。     

商河县郑路镇中低产田项目治理综合效益分析

土地整理效益研究是土地整理理论及实践研究的重要组成部分,也是当今土地科学领域专家和学者关注的重要课题。结合商河县郑路镇项目区的自然和社会经济条件以及土地利用状况,对土地开发整理项目进行社会效益、生态效益及经济效益分析,指出土地整理应寻求社会、生态和经济三大效益的最大结合,实现效益最大化,最终促进农村经济的可持续发展。     

喀斯特石漠化概念演绎及其科学内涵的探讨

通过喀斯特石漠化概念、演绎过程的介绍,深入探讨了喀斯特石漠化的科学内涵。喀斯特石漠化是指在亚热带脆弱的喀斯特环境背景下,受人类不合理的社会经济活动的干扰破坏,造成土壤严重侵蚀,基岩大面积出露,土地生产力严重下降,地表出现类似荒漠景观的土地退化过程。喀斯特石漠化是土地荒漠化的主要类型之一,它以脆弱的生态地质环境为基础,以强烈的人类活动为驱动力,以土地生产力退化为本质,以出现类似荒漠景观为标志。      

喀斯特石漠化过程中土壤营养元素含量变化特征

喀斯特石漠化是土地荒漠化的主要类型之一,它强调的是一个非地带性问题,是与自然、社会和经济紧密相关的,以人类活动为主导因素而引起的环境恶化、土地退化过程,其中,表土和养分流失与生态系统退化是其最基本、最突出的问题.     

吉林西部生态系统退化评价

吉林西部是一个典型的自然、经济和社会的复合系统,生态环境脆弱,土地沙化、碱化严重.在分析该区环境的基础上,提出了生态系统退化度的概念.以长岭县为例建立了生态系统退化度评价指标体系,包括土地背景质量、生态环境现状、经济发展水平、生态破坏速度诸要素15项指标.运用RS、GIS和数据库管理技术建立了生态系统退化度研究数据库.采用层次分析法,开展了以乡为单元的生态系统退化度评价,用MapInfo软件绘制了生态系统退化度数字化图,为研究区的生态建设提供了科学依据.     

基于生态足迹模型的新疆区域生态经济可持续发展能力变化分析

生态足迹模型是定量评估区域生态可持续发展能力的有效方法.运用生态足迹模型,从时序上对新疆1990—2006年的生态经济可持续发展能力进行了动态评估,并引入Ulanowicz发展能力和万元GDP生态赤字(盈余)等指标,考察了社会、经济发展和技术进步对新疆可持续发展的影响.结果表明:1990—2006年间新疆生态足迹增长较快,尤其是2001年以后,总量和人均量增长迅速,而人均生态承载力却呈下降趋势,导致人均生态赤字逐年增大,到2006年人均生态赤字达3.87hm2,比1990年增大了5.6倍;生态压力主要集中在耕地、化石能源地和牧草地等三种土地类型上,土地多样化利用程度低,发展力的提升主要来自于生态足迹的增长和区域资源利用效率的提高.针对性的提出:加大政府财政投入,引进新技术,增加单位土地面积的产出量;加强政策落实力度,提高土地化利用程度和能源利用效率,促进新疆区域生态经济系统的可持续发展能力.     

Geospatial tools for assessing land degradation in Budgam district,Kashmir Himalaya,India

Land degradation reduces the ability of the land to perform many biophysical and chemical functions. The main aim of this study was to determine the status of land degradation in the Budgam area of Kashmir Himalaya using remote sensing and geographic information system. The satellite data together with other geospatial datasets were used to quantify different categories of land degradation. The results were validated in the field and an accuracy of 85% was observed. Land use/land cover of the study area was determined in order to know the effect of land use on the rate of land degradation. Normalized differential vegetation index (NDVI) and slope of the area were determined using LANDSAT-enhanced thematic mapper plus (ETM+) data, advanced space borne thermal emission and reflection radiometer, and digital elevation model along with other secondary data were analysed to create various thematic maps, viz., land use/land cover, geology, NDVI and slopes used in modelling land degradation in the Kashmir Himalayan region. The vegetation condition, elevation and land use/land cover information of the area were integrated to assess the land degradation scenario in the area using the ArcGIS ‘Spatial Analyst Module’. The results reveal that about 13.19% of the study area has undergone moderate to high degradation, whereas about 44.12% of the area has undergone slight degradation.     

Land degradation impacts on tropical agricultural basins and their management: the Nigerian example

This study uses the fault-tree technique to identify the major effects of land degradation caused by the adoption of a malfunctioning shifting cultivation technology for food production in tropical basins. Through reference to existing empirical research, the sequence of events in the process of degradation of the Nigerian agricultural basins and the adjoining river systems was identified and related to the appropriate causal agent. A complete picture of the cost of land degradation goes beyond the degraded terrain and includes damage in areas where there is an unloading of large quantities of run-off and sediments. The causal pathway showed that existing land degradation management policies have focused on the symptoms rather than on the cause of the degradation process. Through a thorough examination of those malfunctioning components of the traditional farming technology, appropriate management strategies are proferred. An institutional organization for land degradation management in Nigeria which includes the federal, state and local governments is strongly recommended.     

2005-2015年贵阳市生境退化程度对土地利用变化的响应

基于2005和2015年贵阳市土地利用数据,利用InVEST模型,分析了2005-2015年贵阳市生境退化程度对土地利用变化的响应,结果表明:（1）2005-2015年贵阳市城镇建设用地、农村居民点和有林地大幅增加,水田和旱地大幅下降,其他地类变化相对较小;水田和旱地转化为城镇建设用地、农村居民点和有林地最为突出;（2）10年间,贵阳市生境退化程度以下降为主,生境退化程度增加区主要分布在南部,下降区主要分布在北部、东部和西部;（3）生境退化程度热点变化以低值减少和高值减少为主;生境退化程度热点空间变化主要分布于南部。退耕还林政策及快速城镇化引起的水田和旱地转化为有林地、城镇建设用地和农村居民点是导致该区生境退化程度变化的主要因素。      

Land degradation,natural resources and local knowledge in the sahel zone of Burkina Faso

This paper proposes a conceptual model that integrates physical and ecological aspects with human aspects of land degradation through a multidisciplinary approach. The model was applied at the local level in a case study in northern Burkina Faso. Assessments of the degradation of the vegetation cover from aerial photographs and a satellite image were analysed in the framework of the model. Another input to the model was results from interviews and field visits with peasants living in the area.The local knowledge of the physical symptoms of land degradation and of the physical variables, eg rainfall and wind, is very close to the scientific logic. However, people do not generally see the links between these variables and the symptoms. Likewise, they do not perceive land degradation to be influenced in any way by human actions. Instead, the cause of land degradation is attributed to God, Allah. Thus, an important field of intervention for governments and development agencies should be to make people aware of their role in land management.     

Assessing the role of winter grazing in historic land degradation,Mývatnssveit,northeast Iceland

This paper assesses the contribution of historical and traditional winter grazing to long‐term land degradation in northeast Iceland. To do so, indicators of soil erosion from two contrasting historical winter grazing areas, set in a tephrochronological framework, are compared against their temporal and regional land degradation contexts. The observations made indicate distinctive and different landscape responses to historical winter grazing depending on location. In both study areas, there is an accelerated level of wind and water erosion with settlement at ca. A.D. 874 through to A.D. 1477. One of these areas had a subsequent reduction in erosion rates to considerably below the regional average, possibly as a result of adaptive land management; the second, more inherently sensitive area, is now subarctic desert. These findings confirm early land management practices as a major factor in Icelandic land degradation, they contribute to explanations of early settlement success and failure, and highlight the significance of historical approaches in addressing contemporary issues of land degradation and conservation responses. © 2004 Wiley Periodicals, Inc.     

Land degradation risk assessment of El Fayoum depression, Egypt

The main objective of this study is to assess the land degradation risk of cultivated land in El Fayoum depression. The physiographic map of the depression was produced by using remote sensing and land surveying data. The depression comprises lacustrine plain, alluvial–lacustrine plain, and alluvial plain representing 12.22%, 53.58%, and 34.20% of the total area, respectively. The soil, climate, and topographic characteristics of the depression were extracted from land surveying, laboratory analyses, digital elevation model, and available reports. A simple model was designed to employ these data for assessing the chemical and physical risk of land degradation using Arc-GIS 9.2 software. The obtained results indicate that severe risk to chemical and physical degradation affect 54.15% and 29.23% of the depression, respectively. The current status of soil salinity, sodicity, and water table indicate that most of lacustrine and alluvial–lacustrine soils are actually degraded by salinization, sodification, and waterlogging. The results of degradation risk and the actual hazard indicate that the human activities are not sufficient to overcome the degradation processes in the most of the depression (80. 22%). Moreover, a negative human impact affects 26.29% of the area mostly in the alluvial plain. Great efforts related to the land management are required to achieve the agriculture sustainability.     

Land degradation in the source region of the Yellow River, northeast Qinghai-Xizang Plateau: classification and evaluation

Land degradation imposes a great threat to the world. It is not merely an environmental issue, but also a social and economic problem. Land desertification is among the main aspects of environment changes in the source region of the Yellow River. Previous studies focused on water resource utilization and soil erosion, but land degradation in the source region of the Yellow River even the whole Qinghai-Xizang Plateau received little attention. Based on the data obtained by field investigation and TM satellite images of 2000, this study provides the classification and evaluation information of the land degradation in the source region of the Yellow River. There are six types of land degradation in this region: water erosion in the northern mountains around the Gonghe Basin, sandy desertification in the Gonghe Basin and Upland Plain Area, aridization in the lower reaches, salinization in the Gonghe Basin, vegetation degradation in the intramontance basin and freezing and thawing erosion in the high mountains. The total degraded area is 34,429.6 km², making up 37.5% of the land in the study area. Finally, land degradation in the source region of the Yellow River was evaluated according to changes in the physical structure and chemical component of soils, land productivity, secondary soil salt and water conditions.     

Chemical weathering and gully erosion causing land degradation in a complex river basin of Eastern India: an integrated field,analytical and artificial intelligence approach

Hot and humid subtropical plateau regions are susceptible to land degradation in the form of weathering and gully erosion. Here, we investigate chemical weathering, gully erosion and cohesiveness through field-based measurements with a view to understand the controlling factors of potential land degradation, in complex river basin of the Chotanagpur plateau region in Eastern India. The layers of controlling factors of gully erosion were developed and prioritized considering boosted regression tree (BRT), alternative decision tree (ADT), particle swarm optimization (PSO) and random forest (RF) algorithms in the R software, and the results of these methods were also validated using receiver operating characteristic (ROC) curves. The spectroscopic analysis was carried out of collected soil samples to measure the degree of chemical weathering and cohesiveness. Furthermore, the climatic elements like temperature and rainfall were also considered for estimating the chemical weathering. The results of the gully erosion models (i.e., BRT, ADT, PSO and RF) show remarkable accuracy with ROC values of 0.93, 0.89, 0.91 and 0.84, respectively. An advanced decision tree model was integrated with the results of degree of chemical weathering and cohesiveness in geographical information system platform. The land degradation map developed from this approach shows that 10.53% of the study area is highly affected, whereas 17.36% area is moderately affected and the rest of the 73.85% area is less affected by land degradation. Our results provide essential information for policy makers in adopting measures for minimizing and controlling the land degradation. Our novel approach is significant to assess land degradation to a large scale.

     

贵州省喀斯特地区土地退化与生态重建研究进展

喀斯特地区环境独特、生态脆弱，一直是科学界关注的热点地区。早期的研究多集中在喀斯特地区的水文、地质和地球化学等领域。近10多年来，喀斯特地区的土地退化乃至石漠化的问题日益严重，人类活动对生态的压力逐渐成为人们关注的焦点。我国西南喀斯特地区是世界上最大的喀斯特连续带，贫困人口集中，人口压力大，经济落后，土地退化严重，人地矛盾异常尖锐，如何开展生态建设、促进社会经济发展，成为西部大开发中最为紧迫的任务之一。贵州省是西南喀斯特地区的典型代表，部分地区已经失去了依靠自身力量进行生态恢复和发展的可能性，因而需要在科学研究的基础上，制定合理的规划和管理措施，针对性的增加外部投入，进行生态重建。对生态重建的理论、方法、技术和模式进行了总结，认为喀斯特地区土地退化是区域人地复杂巨系统结构损害和功能紊乱的集中表现，片面的环境保护和单独的生态治理工程无法解决这个系统问题，区域的生态重建需要采用系统科学的思路。在此基础上，提出喀斯特地区土地退化和生态重建研究中需要深入研究的一些问题。     

Eco-environmental change detection by using remote sensing and GIS techniques: a case study Basrah province, south part of Iraq

This study examines the temporal and spatial dynamics of eco-environment degradation processes and change detection as evident from land use survey datasets (1990–2003) for the Basrah province, Iraq was taken as a case. Using a combination of techniques of RS, GIS, and GPS, the study identifies five prominent eco-environment degradation processes, namely: desertification, secondary salinization, urbanization, vegetation degradation, and loss of wetlands. Rates of conversion were calculated and distribution patterns were mapped with the aid of GIS. The results suggest that wind erosion was the dominant cause of eco-environment degradation in more than half of the study area. Coupled with this were increases in salinization processes, affecting 17.6% of the land area in 2003. Overall, severe eco-environment degradation was noticed to be the dominant eco-environment degradation grade (61.9% of total area), followed by moderate eco-environment degradation (18.9% of total area) in 2003. Incorporation of both natural and anthropogenic factors in the analysis provided realistic assessment of the risk of land degradation. The study area, in general, is exposed to a high-risk of eco-environment degradation.