基于时序NDVI的湖北省植被覆盖动态变化监测分析

基于1998～2011年7、8月份SPOT VEGETATION NDVI数据，求取两月份NDVI平均值，构建14 a间的NDVI时序文件，通过对NDVI时序文件进行信息提取、分析,反映湖北省植被生长情况，从而监测、研究湖北省植被生长高峰期植被覆盖动态变化及趋势。具体为：利用植被覆盖分区法，将研究区分为弱植被覆盖区、稀疏植被覆盖区、低植被覆盖区、中植被覆盖区、高植被覆盖区和密集植被覆盖区等区域，监测各区域14 a间植被覆盖动态变化，结果表明，研究区整体上植被覆盖变化不大；利用Mann Kendall趋势分析法，对研究区植被覆盖变化趋势进行研究，结果表明绝大部分呈现无明显变化趋势，1655%的区域表现增加趋势，033%的区域表现减少趋势。通过以上分析结论可知，植被覆盖分区法和Mann Kendall趋势分析法的分析结果基本一致，表明两种方法能从植被覆盖状况和变化趋势角度动态反映植被的变化情况

DYNAMIC CHANGE MONITORING AND ANALYSIS OF VEGETATION COVER IN HUBEI PROVINCE BASED ON TIME SERIES NDVI DATA

A lot of studies have demonstrated that the NDVI and vegetation cover conditions showed a significant positive correlation,which could well reflect the status of vegetation cover.Thus,NDVI was subsequently used to study the changes in vegetation spatial and temporal dynamics.In this paper,we made use of the SPOT VEGETATION NDVI data between July and August from 1998 to 2011,computed two months NDVI average for each year,thereby generated the NDVI time series file of 14 years.We processed the NDVI time series file,extracted information and analyzed it,so as to reflect the vegetation growth conditions in Hubei Province as well as monitor and study the dynamic changes and trends of vegetation cover during vegetation growth peak in Hubei Province.The study area was divided into weak vegetation coverage area (NDVI value from 0 to 013),sparse vegetation cover area (NDVI value from 013 to 03),low vegetation cover area (NDVI value from 03 to 045),medium vegetation cover area (NDVI value from 045 to 06),high vegetation cover area (NDVI value from 06 to 075),dense vegetation cover area (NDVI value from 075 to 1) by vegetation cover partition method,to monitor the dynamic change of each vegetation cover areas during these 14 years.The results showed that with the exception of the dense vegetation cover area,vegetation area ratio in the other vegetation cover areas was basically stable,and the change extent was not great.They all increased firstly and then reduced,while the dense vegetation cover area showed decreased change in 1998 to 2002,and increased change from 2003 to 2011.Overall,the vegetation cover ratio of the study area had little change.After the analysis of vegetation cover dynamic change,we made use of the Mann Kendall trend analysis method to research on change trends of vegetation cover over 14 years.The results showed that the majority of the study area showed no significant change in trend,1655% of the region showed increasing trend,033% of the region showed decreasing trend.In order to analyze the influence factors of vegetation cover changes in Hubei Province,we collected the relevant statistic data about urban development,population and vegetation composition in Hubei Province from 1998 to 2011,researched on the relationship between the above factors and vegetation cover.The results showed that the urban sprawl,population growth and vegetation composition of the study area during these 14 years did not changed tremendously,so vegetation cover could be protected and vegetation cover was relatively stable.Through the above analysis,the study results based on vegetation cover areas method and the Mann Kendall trend analysis method were basically the same,indicating that the two methods could reflect the changes in vegetation cover from the vegetation cover status and trends angle dynamics.Besides,the two methods were an effective way to study temporal and spatial change of regional vegetation cover