A Study On The Use Of MODIS Data To Detect The Possible Relationship Between Outbreaks Of The Oriental Migratory Locust And The Vegetation Growth

The Oriental Migratory Locust, possibly due to its highly divergent ecological habitats, formidable appetite, and amazing ability to migrate over large distances in swarms and rapidly increase its numbers, will cause tremendous destructive losses to agricultural production whenever it outbreaks.Locust plagues, as the world's agriculture biological hazard, have been threatening about 100 countries or areas in various degrees, particularly in some African and Asian areas where the frequent massive outbreaks of locust can do extensive damages. In China, the oriental migratory locusts have perhaps been the most important agricultural pests. Since the last two decades of the 20~th century, outbreaks of the migratory locusts have once again become a serious problem in China because of the climate abnormity and the expansion of human activity.Today the rapid development of modern remote sensing technology makes it possible to acquire land surface information quickly and dynamically from large area. One of the typical breeding areas of Locusta migrataria manilensis (Meyen), Huanghua in Hebei Province was chosen as study area in this dissertation. In the growing period of nymph, the spectral reflectance curves of vegetation cover conditions, by the use of dynamic continuous coverage MODIS data from early May to late June in 2002, were measured, determined and analyzed to obtain various vegetation indices to monitor the vegetation growth in Nandagang reservoir and Huangzao, two different locusts swarming areas. Therefore a particular discussion is made to explore the feasibility of applying remote sensing system to identifying major locust outbreaks in an attempt to establish the link between the perennial vegetation increase and the volumes of vegetation the locusts consume, aiming to provide some theoretical and experimental foundations to build remote sensing monitoring system for the Oriental Migratory Locust.Consequently some tentative conclusions can be reached as follows:1. The notion of time filtering has been introduced and employed to the satellitesensor-based MODIS data processing, which could eliminate the originally undetected cloud pixels in collecting remote sensing data.2. NDVI (Normalized Difference Vegetation Index) changes, derived from MODIS data through the process of time filtering, contribute greatly to monitor the occurrence of locust plagues in the study area. The formula is to be summarized as below:NDVI= -0.004f +0.0582T +0.2005 (R2=0.7113)3. In this study, the analyses of all these indices have demonstrated that volumes of vegetation the Oriental Migratory Locust consumed are speeding up continuously. In addition, the vegetation damage caused by the locusts will also rise with the locust's developing, so the negative growth will appear at certain stage and aggravate increasingly. Comparisons between the vegetation growth and vegetation consumed illustrate that there is still surplus in May 24 - 31, whereas from 31 May, the swarm is estimated to consume vegetation in excess of the vegetation growth. These findings are conducive to monitoring and controlling locust plague scientifically.