Наукові праці Лісівничої академії наук України (Dec 2019)
Morphological and functional features of Scots pine in pine forest stands of the Small Polissia
Abstract
The paper examines the formation and morphophysiological features of functioning of 27-145-year-old pine forest stands of natural seed origin which grow in dry, fresh, moist, wet, and very wet pine forests of Small Polissia. It was found that Scots pine in the pine forests of Small Polissia grows on the V-I site classes. Mostly pure pine stands are formed here. However, in the composition of about half of the stands, weeping birch also occurs, the share of which ranges from single trees to 10%. It is characterized by a significant lagging behind pine in growth, which is 22.1 to 78.9% in height and 17.4 to 70.1% in diameter. The density of stands of natural origin, regardless of age, ranges from 0.50 to 0.93. The best conditions for the growth and functioning of pine trees are in fresh and moist infertile pine site types. Under these conditions, pine is characterized by high productivity. It forms needles that are most closely related to the genetically determined level in terms of morphological and anatomical parameters and the content of plastid pigments. In wet, and especially in very wet pine forests, a significant deterioration in the condition of Scots pine was revealed, which apears itself in stunted growth of trees, a decrease in the morphological and anatomical parameters of needles and the biosynthesis of green and yellow pigments. Among the morphological and anatomical indicators, the length, cross sectional area and surface area of the needles turned out to be the most sensitive to changes in moisture conditions in the pine forests, while the number of resin channels in the cross-section of the needles is the least dependent on changes in soil moisture. In general, there is a tendency to a decrease in the bioelectric activity of pine with an increase in its age. However, the patterns of change in bioelectric potentials (BEP) in pines of different age groups due to the change of the hygrotope manifest themselves in different ways. It is established that the average daily indexes of bioelectric potentials of root collar in young pine forests of different hygrotopes fluctuate between -36.9 and -77.5, in middle-aged stands - - 21.5 and -58.1, in maturing stands - -18.3 and - 51.8, and in mature stands - -41.0 to - 60.7 mV. Among young stands, it is pine in dry and fresh pine forests that is characterized by high absolute BEP. At the same time, in middle-aged and maturing stands, a significant decrease in the bioelectrical activity of pine trees is observed in dry and fresh pine forests, and an increase in moist, wet and very wet stands. In mature stands, the highest absolute average daily BEP values were found in pine of dry pine forest, and the lowest - in fresh pine forest. It is revealed that the impedance indices in the middle of the growing season in young stands of Scots pines are 15.9-28.1 kOhm, and the polarization capacity is 0.73-1.45 nF. In the middle-aged stands, these figures fluctuate respectively in the range from 13.2 to 30.5 and from 0.70 to 1.41, in the maturing - from 9.5 to 22.1 and from 1.14 to 1.72, and in the mature – from 17.9 to 22.1 kOhm and from 0.94-to 1.05 nF. In young, middle-aged, and maturing stands, a regular increase in impedance and a decrease in polarization capacity with increasing soil moisture was established. Pine in dry and fresh pine forests is characterized by the highest vital potential. The most unfavorable conditions for its growth and vital activity are found in wet pine forests.
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