摘要
黄土高原植被生长的水分环境从东南向西北呈现明显的梯度变化,定量分析各降水梯度带植被覆盖度空间分布特征和演变趋势,对正确评价退耕还林草工程的生态效应具有重要意义。选择一条垂直于降水梯度变化的样带,利用MODIS/NDVI数据,基于像元二分模型获取了研究区2000—2010年植被覆盖度空间分布特征,采用斜率法和相关系数法分析了植被覆盖度的变化趋势和影响因素。结果表明:(1)研究区植被覆盖度在空间分布上由东南向西北降低,东南部地区植被覆盖度达82.6%,北部荒漠地区仅为38.6%;(2)由于退耕还林草工程的实施,该区11a间植被覆盖度整体呈现上升趋势,其中2007年植被覆盖度值最高,为65.3%,与降水年际变化趋势一致;(3)研究区植被覆盖度主要受当年4—8月降雨量和气温影响,时间序列具有显著相关性。
Soil water condition for vegetative growth in Loess Plateau presents a gradient change from Southeast to Northwest.Quantitative analyses of spatial distribution and temporal change of fractional vegetative cover（Fc）can offer an important indication for evaluating the regional environmental changes after the implementation of returning farming land to forestry and grass land.The MODIS/NDVI images with 250m×250 m spatial resolution were used as the data source to estimate Fcin the central precipitation gradient zone of Loess Plateau based on a dimidiate pixel method,and the spatial distribution and temporal change of Fcwere obtained for the period from 2000to 2010.The spatial characteristics and temporal trend of Fc were analyzed,while the relationships of Fcwith climatic factors were discussed.Results showed that：（1）The Fcin the studied zone presented a decreasing trend from southeast to northwest.The maximumFcvalue in southeastern region was 82.6%and the minimumFcvalue in northwestern desert was only 38.6%;（2）The average Fcvalue in the studied zone appeared an increasing trend from 2000to 2010due to implementation of the project of returning farming land to forestry or grass land.The maximum average Fcvalue of 65.3% occurred in 2007because of the maximum annual precipitation during the studied period;（3）The Fcvalue in the studied zone was affected by the precipitation and the temperature during the period of April to August in each year,the regression analyses of time series proved a significantly positive correlation between Fcand total precipitation and between Fcand average temperature.
出处
《水土保持通报》
CSCD
北大核心
2014年第2期272-275,325,共4页
Bulletin of Soil and Water Conservation
基金
国家自然科学基金项目"黄土高原降水梯度带生态水文过程演变与最佳植被盖度研究"(41171186)
关键词
植被覆盖度
NDVI
动态变化
黄土高原
fractional vegetation cover
NDVI
dynamic change
the Loess Plateau
