不同遥感指数提取林火迹地研究

森林火灾是一种重要的森林扰动,是导致森林碳储量减少的重要途径之一,及时、准确地获取林火迹地对于研究全球碳循环及气候变化具有重要意义。以江西省武宁县为研究区,选用1991年和1992年两期Landsat TM遥感影像,采用区分指数(M),分析了Landsat TM 7个波段、植被指数、火烧迹地指数及其改进指数对林火迹地的提取能力,并评价其分类精度。结果表明:TM4 、TM7和TM6波段区分度较高,能较好地反映林火迹地的特征;18个不同的遥感指数中,NBR、NSTV1、NSTV2和NSEV1区分度大于1.5,林火迹地提取精度达到85%以上,具有较高的林火迹地提取能力,EVI、BAI、MIRBI、SAVIT和NSEV2指数提取能力相对较弱;而以引入TM6波段的改进指数NSTV2提取能力最高,适当的方式引入热红外波段可改进遥感指数对林火迹地的提取能力。

Evaluating Different Remote Sensing Indexes for Forest Burn Scars Extraction

Forest fire is an important forest disturbance which leads to reduction in forest carbon stocks.Timely and accurately distribution information of forest burn scars is of great significance for the study of the global carbon cycle and climate change.Wuning,a county in Jiangxi Province,is taken as a study case.By using 1991 and 1992 TM images and the separability index (M),the Landsat TM 7 bands,vegetation index,burn scars index and the improvement burned index for the burned forest extraction capacity are analyzed,and the classification accuracy is evaluated.The results show that TM4,TM7 and TM6 band have higher distinguishing ability,which reflects the characteristics of the burned forest more precisely.NBR,NSTV1,NSTV2 and NSEV1 among 18 different remote sensing indexes have higher separability value,and the extraction accuracy for burned forest is higher than 85%,in addition,extraction capacity of EVI,BAI,MIRBI,SAVIT and NSEV2 is relatively weak.The improvement burned index NSTV2 is the highest as TM6 band is introduced,indicating that properly introduction of thermal infrared band can improve the extraction capacity of burned forest.