论土地环境的退化

土地是人类生存和发展的基础,土地环境的退化直接威胁土地生态平衡,制约国民经济的发展。本文通过对我国土地环境的调查与分析,发现存在的问题,商讨保护土地资源和优化土地环境的对策。

Land Use/Cover Changes and Environmental Consequences in Songnen Plain,Northeast China

The Songnen Plain in Northeast China,one of the key national bases of agricultural production,went through remarkable land use/cover changes in recent years.This study aimed to explore the long-term land use/cover changes and the effects of these changes on the environment.The Landsat-based analysis showed that,during 1986-2000,cropland,built-up land and barren land had increased,among which cropland had the largest increase of 9,198km2 with an increase rate of 7.5%.Woodland,grassland,water body and swampland had decreased correspondingly,among which grassland had the most dramatic decrease of 6,127km2 with a decrease rate of 25.6%.The transition matrix results revealed that grassland,woodland and swampland were the three main land use types converted to cropland.Climate warming created the potential environment for the conversion of grassland and swampland into cropland.Land resources policy made by central and provincial governments of China affected the pattern and intensity of land use.Land use/cover changes accompanied by climatic variation brought out a series of environmental consequences,such as sand desertification of land,land salinization and alkalinization,grassland degradation,and more frequent floods.Under this circumstance,optimized land use structure and restoration measures are needed.

The Impact of the Ghana＇s Oil Discovery on Land Investment and Its Implications in the People, Agriculture and the Environment （Case Study： Cape Three Points, Ghana）

The study was conducted to assess the impact of Ghana＇s oil discovery on the land values, the extent of acquisition, and their implications of the land investment in the people, agriculture and the environment in the Cape Three Points area, which is the communities close to the oil field. Questionnaires were designed and administered to collect data from the chiefs, queen mothers, family heads and opinion leaders of the area. Results of the studies indicated that there had been an increase of about 2000% in land values from 2007 to 2011. Also there was an increase in demand for lands in the Cape Three Points with acquisitions usually ranging from 10 acres to over 600 acres. It also emerged that the livelihood of the inhabitants of Cape Three Points was threatened due to the conversion of arable land to non-agriculture uses. This change in land uses has significant negative impacts on land degradation and its related reduction of agricultural and food production in the area. The technical difficulties of assessing land degradation, the weakness of existing databases, and the poorly explored linkages between land degradation and other aspects of rural development were some of the limitation of the studies. The study increased awareness of the chiefs and other land owners to reserve land for the future generation and for agriculture purposes. The study drew government＇s attention through the Ahanta West District Assembly to the planning needs of the towns in the Cape Three Points to streamline land use of the area.

Payments for Grassland Ecosystem Services:A Comparison of Two Examples in China and Germany

目前,草地生态系统退化成为全球关注的问题。生态补偿机制(PES)是为了草地生态系统的恢复/保护,采取补贴或支付费用的方式,改变使用者资源利用方式的制度安排。科学、合理的生态补偿制度需要全面地考虑可能出现的风险和挑战:如环境效益的滞后性,不可预见的监督、管理成本和社会经济目标(足额补偿标准、公平)的实现。本文的目标是通过中德两国生态补偿措施的对比(选取中国内蒙古锡林郭勒盟,德国勃兰登堡州为案例区域进行研究),为今后中德两国的生态补偿理论和实践提供依据。研究着重以下四个方面进行分析:中德两国生态补偿的实施框架,目标人群,实施效果评估等。研究结果表明,由于缺乏有效的激励机制,农户作为最基层的执行单位和实施者,其参与的主动性不够,中德两国生态补偿措施实施的成效有待提高。基于研究结果,提出了今后生态补偿项目设计中,中国应侧重于项目实施的监控和管理制度;而德国应在空间目标规划和具体管理措施和方式等方面进行完善。