基于GIS和GS的东亚飞蝗卵块空间格局的研究

Spatial distribution of the Oriental migratory locust (Orthoptera: Acrididae) egg pods studied with GIS and GS

本文以沿渤海蝗区东亚飞蝗Locusta migratoria manilensis（Meyen）越冬卵块为研究对象,野外采用450 m和50 m规则栅格取样,包括卵量、植被覆盖度、土壤含水量、含盐量、土壤pH和有机质等,利用地统计学方法,在GIS平台下,分析研究区域内影响蝗虫产卵选择的环境因子、蝗虫卵块的空间异质性及分布格局.结果表明,植被覆盖度、土壤含盐量和土壤含水量在有卵和无卵的环境中存在极显著的差异,飞蝗产卵时最适宜的植被覆盖度、土壤含水量和盐度范围分别为0～30%、10.1%～20.0%和0.09%～1.99%,且当小环境植被覆盖度＞50%、土壤含水量＞30%或含盐量＞3%时,飞蝗不再选择产卵.蝗虫卵块具有高度空间异质性,其空间自相关范围平均为390m且呈斑块、聚集分布,蝗虫卵块变异函数曲线为球状模型.利用块段克立格法进行空间局部插值,得到研究区域卵块的空间分布格局图,可较准确地描述飞蝗卵块在研究区域内的空间分布、形状、地理位置及相对位置.研究结果可为地面卵块抽样调查、实时跟踪蝗卵胚胎发育进程、确定蝗灾早期发生点、片防治区域及蝗灾早期遥感预警提供科学依据.

The spatial distribution of the Oriental migratory locust, Locusta migratoria manilensis （Meyen） egg pods was studied by integrating geostatistical analysis and GIS techniques. Data of egg pods were collected from both spatial scales over two years of extensive surveys： 450 m intervals for the whole study area, then 50 m grid for possible egg-laying areas which were located on the areas damaged by the locust plague or covered with sparse vegetation. Meanwhile, site ecological variables including vegetation coverage, and soil parameters （salinity, pH, water content at 5 cm depth, organic matter, etc. ） were surveyed at these grid points. The results showed that three site variables including vegetation coverage, soil water content at 5 cm depth and soil salinity were significantly different between sites with and without egg pods, and the preferable ranges for L. m. maniliensis oviposition were 0 - 30%, 10.1% - 20.0% and 0.09% - 1.99% for these three variables, respectively. No eggs were laid when vegetation coverage exceeded 50%, soil water content at 5 cm depth was higher than 30%, or soil salinity was above 3%. Semivariograms indicated that the distribution of egg pods was in high heterogeneity. Spatial autocorrelation in egg pod distribution was at distances about 390 m. The spatial distribution of egg pods was patchy and aggregated in the two years and could be best described using spherical models. GIS risk assessment maps, derived by block kriging, displayed the probabilities of occurrence of the locust egg pods at an area-wide scale. The results may provide useful information on planning for sampling in the field, tracking embryo developments, monitoring targets and taking site-specific measures towards this locust.