Наукові праці Лісівничої академії наук України (Jun 2020)
Influence of meteorological factors on the radial increase of English oak trees in the fresh and moist fairly fertile forest types conditions of the Ukrainian Polissya
Abstract
The important economic, ecological and social functions of the forests with the participation of English oak are presented., The study of their growth conditions, development and biological stability in different natural zones under the climatic factors influence is especially relevant. The research object is the of English oak stand of older age groups which grows in the Ukrainian Polissya. The research purpose is to establish the optimal parameters of meteorological factors that provide the maximum growth in diameter of oak trees in the conditions of fresh and moist fairly fertile forest type of the Polissya. To assess the annual increment of English oak, a number of temporary test plots were laid in the fresh and wet conditions. The model trees (10 - 25 for each trial plots) were selected. Measurements of the width of the annual rings of model trees were performed with the tool "Corim Maxi" with an accuracy of 0.01 mm. To analyze the results relative indicators used: the index of radial increase: I = i / iaverage · 100, where I – annual growth index in shares of the unit; i – the width of the annual layer; iaverage – the average width of the annual layer at this age. An analysis of the correlation among the meteorological factors and the radial growth of oak trees showed that the annual precipitation (r = 0.16), the amount of precipitation during the vegetation season (r = 0.22) and the rainfall of the autumn and winter months of the previous year (r = 0.14) have a slight positive effect on the radial increase of oak trees. It has been established that the years of the highest and lowest values of radial increase depended little in average monthly air temperatures. At the same time, it was found that there is a close correlation between the annual ring width index and the hydrothermal coefficient (HTK - the ratio of precipitation quantity over the growing season (P, mm) to a tenth of the sum of temperatures (t, °C) above 10 °C (HTK = P / 0.1Σt≥10 °). In more than 90% of English oak trees, highest growths with an index > 80 are formed in the years with HTK indices from 1.4 to 1.8. Outside this interval there is a zone of inhibition of trees growth with the lowered indices of radial increase. On the basis of mathematical modelling of the correlation between the radial growth index and the hydrothermal coefficient, it was found that the HTK values for fresh and wet fairly fertile forest types optimal for the growth of ordinary oak stands are 1.65 and 1.62, respectively. At the same time, the radial growth index is much higher in fresh fairly fertile forest type (125.7 versus 114.8 in humid conditions), which indicates a greater sensitivity of oak trees in fresh fairly fertile forest type to changes in weather conditions. The revealed correlations between the parameters of radial growth and climatic indicators can be used in the future for constructing climatic reconstructions and forecasting the oak stands productivity in the future.
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