河北滨海盐碱土地生态安全评价

滨海盐碱地盐渍化较严重,土地生态环境脆弱,了解滨海盐碱区的土地生态安全状态,探讨其驱动机制,可为滨海盐碱区土地结构调整与土地功能提升提供依据。本文以河北省黄骅市为研究区域,以土地利用类型为基础,设计了黄骅市土地利用生态安全(LUES)分级标准,计算得出研究时段内的LUES值,阐明了黄骅市土地利用生态安全状态并探寻起主要作用的关键土地利用类型。在此基础上,利用2000—2010年TM遥感影像数据和社会经济数据,借助Erdas、Arc GIS与Fragstats软件平台,选择了包括LUES在内16个指标,构建了黄骅市P-S-R土地生态安全评价模型,探讨了黄骅市土地生态安全状态。结果表明:(1)2000—2010年间,黄骅市LUES值为0.458~0.466,土地利用生态安全处于临界安全状态,应控制建设用地、盐场及重度盐碱地面积;(2)黄骅市土地利用生态安全提升主要得益于土壤盐渍化的降低,中、重度盐碱地面积减少及轻度盐碱地面积增加带来的生态正效应超过了建设用地面积增加带来的生态负效应,这是LUES提高的主要原因;(3)黄骅市土地生态安全指数(LESI)呈逐年上升趋势,安全状态由2000年的较不安全(LESI为0.431)提升至2010年的较安全(LESI为0.666)状态;(4)压力指数(P)在逐年减小,响应指数(R)在逐年增加,2010年响应指数对LESI贡献最大,其贡献率为45.3%,说明人为措施减小了土地生态风险。本研究结果可为黄骅市土地生态利用提供科学依据。

Evaluation of ecological security of coastal saline land in Hebei

Severe soil salinization and fragile ecological environment are characteristic features of coastal saline land. It is therefore very important to analyze the state of ecological security of coastal saline land and the driving mechanisms in order to lay the basis for struc-tural land adjustment and land function upgrade. Based on the land use types, a classification standard of land use ecological security (LUES) in coastal saline area of Huanghua City, Hebei Province was developed. LUES values in 2000, 2005 and 2010 were calculated in Huanghua City, and key land use types were explored. Based on the above results, we selected 16 indicators (including LUES) combining with TM data and socio-economic data for 2000-2010, coupling with Erdas, ArcGIS and Fragstats platforms, to construct the P-S-R land ecological security evaluation model, and then used this model to evaluate the state of land ecological security status in Huanghua City. The results showed that: (1) LUES value for Huanghua City was 0.458-0.466 during the period of 2000-2010, LUES was at critical security state; and there was an urgent need to control the areas of construction land, salty land and heavily saline land. (2) Improvement of LUES in Huanghua City was mainly due to the decreased of soil salinization. Positive ecological effects of decrease in both moderate and severe saline land areas, and increase in lightly saline land areas exceeded the negative ecological effects of increase in construction land areas. (3) The land ecological security index (LESI) of Huanghua City showed a rising trend year by year, and the safety state improved from less secure (LESI=0.431) in 2000 to safe (LESI=0.666) in 2010. (4) The stress index (P) decreased, while the response index (R) increased year by year. For 2010, R contributed the most to LESI (45.3%), which indicated that the developed measures reduced ecological risk of land in the study area. The results provided a scientific basis for ecological utilization of land in Huanghua City.