Application of geographically weighted principal components analysis based on soybean yield spatial variation for agro-ecological zoning of the territory
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In this study, the geographically weighted principal components analysis as an alternative method for agro-ecological characterization of the region was provided. The spatial and temporal distribution pattern of soybean yield was analyzed by using spatial statistics technology, which provided a good reference for agricultural development planning. The soybean yield was selected for the present study because it is a comprehensive indicator reflecting the production potential of the regional agroecosystems. The organized data set, which included the average per year yields of soybean in 10 regions (206 administrative districts) of Ukraine, was used for analysis. The regular temporal trend, specific for each district, was previously extracted from the time series data. The principal components analysis of the detrended data allowed to identify four principal components, which altogether can explain 58% of the soybean yield variation. The geographically weighted principal components analysis allowed to reveal that four spatially determined processes were influencing the yield of soybeans and had the oscillatory dynamics of different periodicity. It was hypothesized that the oscillating phenomena were of ecological nature. Geographically weighted principal component analysis revealed spatial units with similar oscillatory component of soybean yield variation. Our study confirmed the hypothesis that within the studied territory there are zones with the specific patterns of the temporal dynamics of soybean yield, which are uniform within each area but qualitatively different between zones. The territorial clusters within which the temporal dynamics of soybean yield is identical can be considered as agro-ecological zones for soybean cultivation.