ARTICLES
WANG Xiaoqin, CHEN Yunzhi, ZHOU Xiaocheng, JIANG Hong
2007, 9(6): 100-102,133-134.
Coastal protective forest is a green protective screen for disaster prevention and mitigation.For government's management and decision,it's very important to fast obtain the dynamic change of coastal protective forest.In this paper,Zhangpu County of Fujian Province is selected as a study area.Multi-source remote sensing data like CBERS-02 acquired in 2005 and ETM+ acquired in 2000 were used.The Normalized Difference Vegetation Index(NDVI) and Non-linear band ratio(NLBR= B4 * B3 / B2,where B2,B3 and B4 are the green,red and near infrared red bands of sensors) were calculated.After analyzing the spectral profile of original bands,NDVI and NLBR of the coastal protective forest and other typical land covers in coastal zone,a method to quickly extract the coastal protective forest for different sensors was developed.We found that jointly using of NDVI and NLBR would effectively acquire the coastal protective forest.NDVI would distinguish vegetation cover from non-vegetation cover,and NLBR would distinguish coastal forest from arable land with vegetation cover.With the rules of NDVI> threshold 1 and NLBR< threshold 2,the coastal protective forests of 2005 and 2000 were acquired,in which the thresholds were determined from the scatter plots of NDVI and NLBR.This method is of reference value to the sensors with similar green,red and near infrared red bands.In the study area,the area of coastal protective forest was 2788.11hm2 in 2000, while that was 2462.28hm2 in 2005.From 2000 to 2005,the decreased area was 1332.04 hm2,which was 1.46 times of that of the increased area.The government agencies should strengthen the management and construction of the coastal protective forest,which will improve the ability to prevent and reduce natural disasters in the coastal zone.
