黄土丘陵区土地资源生态安全及其动态评价

A Dynamic Assessment of Ecological Security of Land Resources in Loess Hills Region

土地资源生态安全研究是当前区域可持续发展研究的前沿课题，科学评价区域土地资源生态安全状态及变化，是土地利用科学决策及土地利用模式优化的基础和依据。本文界定了土地资源生态安全的概念，针对黄土丘陵区土地资源特点及面临的主要生态问题，基于P．S．R概念模型运用层次分析法建立了黄土丘陵区土地资源生态安全评价指标体系，并对指标安全闽值的确定进行了初步探讨。鉴于土地资源生态安全的动态特性，提出了基于状态评价模型和趋势分析模型相结合的区域土地资源生态安全动态评价方法，弥补了传统静态评价方法的不足，以地处宁南黄土丘陵区的彭阳县为例，进行了实证研究，对彭阳县1986年～2004年土地资源生态安全状态及变化趋势进行了评价和分析，结果表明近20年来该区域土地资源生态安全变化趋势趋于改善，但目前安全状态仍处于较不安全等级，评价结果能较为全面客观地反映该区域土地资源生态安全状况。

Regional land resource ecological security is a challenging issue to human survival and development, especially in eco-vulnerable region, and there is an urgent need for improving the status of land resource ecological security. Study on land resource ecological security has become a forefront topic of regional sustainable development, and assessment of regional land resource eco-security is one of the most important issues, which closely related to regional development. Through the assessment decision makers can get more information of the status and changes of land resource ecological security, so that they can make sound strategies to resolve the problems. However, existing methods are focused on static evaluation,and limited in the changes and trends of assessment of regional land resource eco-security. This paper defined the concept of land resources ecological security firstly; and then focused on the characteristics and main eco-problems of land eco-system of Loess Hills region, which is one of the most eco-vulnerable regions in China. This article established an indicator system based on P-S-R model and AHP method, and put forward a dynamic assessment method based on status assessment model and trend analysis model, which could make up for the shortcoming of static evaluation method. In order to testify this dynamic assessment method, a case study was conducted in Pengyang county, a typical Loess Hills region and located in southern Ningxia, where land eco-security is seriously restricted by soil erosion, water losses, drought and shortage of water. The results indicate that the measures adopted in soil erosion control, ecological and environment construction have certainly improved the situation of land resource ecosecurity in the region during the last two decades. But the current status is still not satisfactory, and the level of regional land resource eco-security is still belong to the relatively insecurity grade. So implementation of water and soil conservation projects, increasing water-saving irrigation equipments, effectively controlling population growth, and rational use of chemical fertilizers and pesticides are the key ways to improve land resource eco-security status in this region. The evaluation results could objectively reflect the actual situation in the region. This research develops a vehicle to promote land resource ecological security study, provides a way to establish a practical assessment method, and facilitates to achieve regional landuse sustainability.