Analyzing cereal and grain legumes (pulses) yields patterns in the forest and forest-steppe zones of Ukraine using geographically weighted principal components analysis

This paper aims to explore spatial heterogeneity present in the crop yields data collected from 170 administrative districts in the forest and forest-steppe zones of Ukraine for 27 years using the PCA and GWPCA methods. As a result of the principal component analysis of cereal and grain legumes (pulses) yields variability seven principal components were determined which together explain 66.8 % of the overall yields variability. The global PCA revealed the presence of dynamic processes of the cereal and grain legumes yields variation which have the oscillatory nature with different frequencies. We associate oscillatory processes of the varying frequency with causes of a different nature. The oscillating processes with a period of ten years or more may be of climatic origin. The oscillatory process with the longest period (13 years) is characteristic for the principal component 1, which explains the largest part of cereal and grain legumes yields variability (22.6 %). It is possible to assume that among agroecological factors climate change mostly affects crop productivity. The cluster analysis of administrative districts was conducted based on the cereal and leguminous yield dynamics. The clusters are geographically defined administrative districts that together forming spatially connected areas, which we identified as agroecological zones.