Аналіз показників асиміляційної складової у структурі надземної фітомаси деревних порід степових лісостанів України
Analysis of the parameters of the assimilation component of above ground biomass of forest-forming species in the steppe zone of Ukraine

Summary/Abstract: The purpose this research is to study the parameters of leaf (needle) share in the trees’ greenery fraction and the content of absolutely dry matter in fresh leaves of black locust and Scots pine. The leaf (needle) share in the trees greenery fraction and the content of absolutely dry matter were determined by their quantitative measures (weight and volume). The results of the research reveal that the leaf share in the structure of a tree’s greenery fraction has a broad range of values: 43.0–72.8% for black locust and 49.1–75.4% for Scots pine. The minimum value of this parameter was recorded for an over mature Robinia specimen of 41 years of age, while the maximum was for a 3-year-old tree. For pine trees the lowest values of the given parameter were registered for the specimens aged 38, 49 and 84, the maximum – for 30–31-year-old trees. For both investigated species it should be noted that there is a consistent pattern indicated by the following trend line: with the increase of tree age, height and trunk diameter, there is a decrease of leaf share value in the trees’ greenery fraction. Such characteristic parameter as absolutely dry mass has a sufficient range of values from 0.321 to 0.524, with the extreme values for the trees belonging to the young stock group in the case of the black locust. The absolutely dry matter content in Scots pine needles showed a significant variability of values from 0.426 to 0.620. The trend line shows a tendency of increase in the value of absolutely dry matter mass in the leaves of both investigated species with the increase in the values of the tree taxation parameters. There is no statistically proven dependency of the parameter indicating leaf share in the trees greenery fraction on the age, trunk diameter and height of trees. The most important biometric indicator, which shows a moderate relationship with the greenery fraction of a tree is the average diameter of the trunk of model trees of the two studied species. This is confirmed by values of correlation coefficients. The indicator of greenery fraction is inversely dependent on the height, trunk diameter and tree age, i.e. the increase in the values of these parameters leads to the decrease in the share of the photosynthetic active component of trees of the studied tree species in the steppe zone. The value of leaf (needle) share in trees’ greenery fraction decreases with the increasing age, height and diameter values, which is quite natural. Correlation indices of absolutely dry matter according to age, height and diameter of sample trees have negative values, while the index of leaf (needle) share of trees’ greenery fraction has a direct correlation with all the studied influence factors.

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