DEPENDENCE OF ANNUAL STEM INCREMENT ON INVENTORY AND BIOPRODUCTION INDICATORS OF TREES IN PINE FORESTS OF THE TURGAY DEPRESSION
V. A. Usoltsev1,2
1Botanical Garden, Russian Academy of Sciences, Ural Branch, Yekaterinburg, Russian Federation
2Ural State Forestry Engineering University, Yekaterinburg, Russian Federation
Keywords: functional characteristics of trees, taxation indicators of trees, tree cross-sectional area growth, explanatory ability, allometric models
Abstract
The development of ecology implies the possibility of predicting the ecological functions of plants based on their functional characteristics, in particular, the specific leaf area, as the ratio of leaf surface area to their dry weight (SLA), and leaf mass per area (LMA), as the inverse of SLA. However, it was found that at the global level, SLA explains only 3.1 % of the variability in tree height growth. The introduction and use of the integral production feature Mp, as the product of LMA and the area of the horizontal projection of the crown, showed that the explanation of the variability of tree stem growth on the community of 125 species increased to 31 %, but, at the same time, did not show the advantages of Mp in the explanatory ability of the variability of growth compared with the stem diameter. The purpose of this study is to find out in what ratio, when modeling the tree stem growth, the explanatory power of a production indicator and a set of taxation features, such as stem diameter, tree height and tree age, may consist. For this purpose, according to the data of 300 sample trees taken on 30 sample plots in pure Scots pine forests of the Turgai Depression, a sequence of allometric models in a different combination of dependent and independent variables was calculated. Due to the too high complexity of determining the SLA with sufficient accuracy for 300 trees, the quotient of dividing the needle mass by the area of the horizontal projection of the crown (Pf /Sc) was used as a production indicator. This production indicator has a biological meaning, slightly different from Mp, but in terms of information it is not inferior to the latter. It was found that when calculating the multifactorial dependence of the stem cross-sectional area growth over the past 10 years on (Pf /Sc) and forest inventory indicators of trees, the contribution of (Pf /Sc) to the explanation of the growth variability was only 6 % and it was excluded from the analysis. As a result, a two-factor allometric model of the stem cross-sectional area growth over 10 years on the age and stem diameter at breast height is proposed, explaining 91 % of the variability of the growth. The proposed model makes it possible to determine the cross-sectional area basal growth of a stand in the single-aged pine forests based on the results of the accounting trees by stem diameters.
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