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东亚飞蝗自 2 0世纪 80年代以来在我国再度猖獗危害。本文选择国家一类蝗区河北省南大港农场水库为实验区 ,以2 0 0 2年东亚飞蝗 (夏蝗 )大发生为背景 ,测定了不同受害程度芦苇的光谱曲线 ,并用MODIS遥感数据分析蝗灾危害范围和程度。结果表明 ,健康芦苇 (未受害 )呈现出典型植被光谱的“峰和谷”特征 ;而受害芦苇 ,其红光区处反射率增加 ,且受害程度越重 ,增加愈显著 ,近红外区的反射率则显著降低 ,且受害程度越重 ,反射率愈低。比较多时相归一化植被指数(NDVI)受灾前后的变化 ,NDVI值增加表明未受蝗虫危害 ,而其下降则表明是受灾区域 ,结合地面数据 ,找出了不同危害程度的NDVI临界值 ;其次根据像元累计法 ,确定了不同受灾程度的面积。结果显示 ,NDVI小于 0 2 15 6和 0 2 389分别为严重受灾区和中等受灾区 ,其发生面积依次为 16 8 74hm2 和 337 4 8hm2 ,判对率分别为 72 97%和 6 8 35 %。MODIS遥感监测蝗灾发生面积 (中等受灾及严重受灾 )占实际发生面积的 82 76 %。研究结果为实时、快速、大面积监测蝗虫种群动态奠定了基础 ,并为合理、经济地防治蝗灾提供了科学依据
Locusta migratoria has been rampant in China since the 1980s. In this paper, we select the farmhouses of Nangangang in Hebei Province as the experimental area for a class of locusts in China. Taking the occurrence of Locusta migratoria manilensis (Locusta migratoria manilensis) in 2002 as the background, the spectral curves of Phragmites communis under different degrees of damage were determined and analyzed by MODIS remote sensing data The scope and extent of locust hazards. The results showed that healthy reed (unharmed) showed the characteristic of “peak and valley” of typical vegetation spectrum; while the reed damaged, the reflectivity of red reed increased, and the more serious the damage was, the more significant the reflection of near-infrared The rate is significantly lower, and the more serious victims, the lower the reflectivity. Compared NDVI NDVI changes before and after the disaster, the NDVI increase indicates that it is not affected by locusts, while the decrease indicates that it is the affected area. Based on the ground data, NDVI critical values for different degrees of harm are found. According to the pixel cumulative method, the area of different degrees of damage is determined. The results showed that NDVI less than 0 2 15 6 and 0 2 389 were severely affected areas and moderately affected areas respectively. The occurrence area of NDVI was 16 8 74 hm 2 and 337 4 8 hm 2, respectively, with the discriminant rates of 72 97% and 68 35% respectively. MODIS remote sensing monitoring of locust plagues (moderately affected and severely affected) accounted for 82.76% of the actual area. The results laid the foundation for real-time, rapid and large-scale monitoring of locust population dynamics and provided a scientific basis for the rational and economical prevention and control of locust plague