冀北地区植被指数变化特征及影响因素分析

Spatial Characteristic and Influencing Factors of Vegetation Change in north of Hebei Province

利用8km分辨率的NOVV／AVHRR NDVI数据、土地利用／覆被变化TM影像解译数据、气候数据、DEM数据和经济统计数据，对冀北地区1987～2000年植被覆被变化特征及影响因素进行了分析，得出主要结论如下：冀北地区土地覆被变化下NDVI平均增加值为0．35，变化特征为集中连片。土地利用变化导致NDVI平均减小值为0．17，变化特征呈斑块状离散分布。土地利用类型变化、错季蔬菜生产等人为因素对土地覆被变化下NDVI变化贡献率较低，降水、特别是生长季降水分布特征是影响NDVI变化的重要因素。

The study area is located in the north of Hebei Province with a total area of 76 275.6 km^2. In recent years, artificial activity changed the land use type and the plant degradation arose the attention of people. This study assessed the trend and spatial-temporal distribution of vegetation index change, which is related with vegetation degradation, in North of Hebei Province using multi-temporal NOAA/AVHRR NDVI data （8 km spatial resolution） from 1987 to 2000 provided by NASA, meteorologic data, DEM data （1： 250000） and relative economic data. Results show that the characteristic of NDVI change owing to land cover are concentrative and connective, while the characteristics of NDVI change owing to land use are sparse and scattered. The average change of NDVI is 0.35 for land cover change and the average change of NDVI is - 0. 17 for land use change and they have contrary change direction. The artificial factors such as the changes of land use or crop type have contribution to NDVI change, but the influence is limited. Precipitation, especially its distribution in growth season is the important influencing factor for NDVI change.