大兴安岭植被指数年际变化及影响因子分析

Inter-annual variation in vegetation index and analysis of factors affecting it in Daxing 'an Mountains

通过遥感数据获取的归一化植被指数（NDVI）能够较好地反映植被的生长状况,并且为区域尺度、长时间序列的植被监测提供可能。本研究采用黑龙江大兴安岭地区2000—2009年MODIS/NDVI月值数据,分析和监测该地区年际NDVI变化,并利用趋势分析、假设检验、相关分析等方法研究了多种影响因子对该地区NDVI变化的影响。结果表明：研究区10年间年平均NDVI在0.455 4～0.509 3之间变化,平均值为0.477 3,年际间变化呈现出无规律的波动,没有显著的变化趋势;分析了森林火灾、温度和降水对NDVI的影响,一般森林火灾对过火区域NDVI的变化没有显著影响,重大森林火灾和过火面积小于1万hm2的特大森林火灾会促进过火区域NDVI的增长,过火面积大于1万hm2的特大森林火灾会使过火区域NDVI大幅降低;温度在10～25℃时会促进森林NDVI增长,在5℃以下对NDVI变化无显著影响;月降水量在75 mm以下会促进森林NDVI增长,大于100 mm对NDVI变化无显著影响。

The normalized difference vegetation index（ NDVI） could accurately reflect the growing status of vegetation,and it could facilitate the long-term monitoring of vegetation at regional scale. In this study we monitored and analyzed the inter-annual changes of the NDVI based on the monthly MODIS / NDVI data of Daxing＇an Mountains region from 2000 to 2009. And we used trend analysis,hypothesis testing and correlation analysis to investigate the effects of various factors on the changes of the NDVI values. The results showed that the annual NDVI ranged from 0. 455 4- 0. 509 3,with the average NDVI of 0. 477 3from 2000 to 2009. No regular trend was observed for the annual variations. In addition,the effects of the forest fire,temperature and precipitation on the NDVI were analyzed. It was found that the general forest fires had no significant impact on the variation of NDVI value,while the serious forest fires and the major forest fires with the burned area smaller than 10 000 ha promoted the growth of the NDVI value; the major forest fires with the burned area larger than 10 000 ha forest fires significantly reduced the NDVI value. The temperature between 10 and 25 ℃ promoted the NDVI value,and no significant impact on the NDVI changes was observed when the temperature was below 5 ℃. The monthly precipitation less than 75 mm promoted the NDVI value,and no obvious impacts on the NDVI changes were found when the monthly precipitation was more than 100 mm.