退耕还林背景下寒地山区土地生态安全格局动态变化

为了研究退耕还林工程引起的土地生态安全格局变化,该文应用遥感和GIS技术对牡丹江地区2000-2014年土地利用变化特征进行了分析,并基于DPSIR概念框架构建评价指标体系,从空间上揭示了研究区退耕还林期间土地生态安全水平及格局变化.结果表明,退耕还林工程的实施对研究区土地利用结构产生了极大的影响,林地面积增加1 520.16 km2,草地、耕地面积分别减少878.50、517.14km2,土地利用强度先下降后上升:退耕还林工程在有效控制坡地垦殖、增加林地面积的同时,能够显著提高区域土地生态安全水平,2000-2014年,各坡度等级内安全、较安全、临界安全面积共增加1 088.6 km2;14 a来研究区土地生态安全水平总体呈“先改善后恶化”的趋势,但仍较2000年工程实施前有了较大幅度的提升,西部、东部及南部地区土地生态安全水平显著提高,但中部牡丹江河谷盆地土地生态安全水平提升缓慢,建议新一轮退耕还林工程将此地区作为重点调控整治区域.

Analysis on dynamic change of ecological security pattern of land in cold mountainous region under background of Grain for Green Project

Abstract: Over the last few decades, humanity has been facing increasingly serious environmental challenges at local and global scales due to industrial revolution and population growth. Moreover, the consumption of forest and the degeneration of grassland and arable land have engendered a frequent alteration in land cover that often leads to a decreased stability of ecosystems. Land has been considered as the foundation of human life, so paying attention to ensure the ecological security of land resources is essential to realize sustainable development of social activities. Land ecological security, which is restricted by natural and human factors, is driven by land use and cover change, and it can be mainly characterized by the appearance of landscape and material cycle, which are essential to regional ecological security. Hence, the Chinese government launched "the Grain for Green Project" in 1999, which aimed at curbing water loss and soil erosion to improve ecological conditions by converting cultivated land with a slope greater than 25° to forest or grassland. Up to now, the Grain for Green Project is an ecological restoration engineering which has the largest investment and the strongest policy all over the world. As a consequence, methods of the land eco-security during the Grain for Green Project in China have gradually become the focus of research by international scholars in recent years. Many scholars attempt to make some breakthrough from the quantity and structure of land resources, and have taken some empirical studies in the region where the ecological environment is typical and fragile. Most of these studies belong to the static research which is combined with LUCC (land use/cover change) and focus on the current environment, and it rarely reflects the dynamic change patterns of land eco-security for the study area. However, the concept of ecological security emphasizes the sustainability of ecosystems, focusing on reducing the probability of ecological disaster with social development. So the land eco-security will be the focus in ecosystem evolution process due to the systemic complexity. The study of pattern changes in the land ecological level caused by the project has an important theoretical significance and practical value for speeding up regional vegetation restoration, reducing the intensity of soil erosion and achieving a sustainable social and economic development. This paper, by using remote sensing and GIS (geographic information system) technologies, analyzes the characteristics of changes in land use from 2000 to 2014. Based on the DPSIR framework, it also reveals the ecological security level and pattern changes of land during the implementation of the project. The results show that: 1) The implementation of the project has significantly influenced the structure of land use in the study area with an increase of forest area by 1 520.16 km2 and a reduction of grassland and arable land respectively by 878.50 and 517.14 km2. The intensity of land use increases after a fall in the first place. 2) While controlling land reclamation and increasing the forest area, the project can remarkably improve the ecological level of regional land. Between 2000 and 2014, the safe, relatively safe and moderately safe areas in different slope levels have increased altogether by 1 088.6 km2. It can see an improvement and then a degradation in the ecological security of land in the study area, but it is still an improvement compared with that in 2000 when the project was not implemented. The ecological levels of land in the east, west and southwest of the areas have increased significantly, but in the middle basin of Mudanjiang River, the improvement is slow. It is recommended that during further implementation of the project, that area should be treated as one area which requires particular regulation and renovation.