Dynamic bioproductivity of Scots pine stands within Northern Steppe of Ukraine conditions

Abstract

Dynamic changes in forest ecosystems, which can be both short-term and long-term, are assessed on the scale of long-term biologically determined stages, through the determi-nation of age parameters. In this context, the results on the dynamic changes of the components of the aboveground phytomass of Scots pine in the northern steppe zone of Ukraine are presented. Based on the simulated growth tables of the studied modal artificial pine stands, standards for the dynamics of their bioproductivity have been developed for such components of aboveground phytomass as trunk in bark, branches in bark and needles. Modeling and statistical evaluation to determine the phytomass of the aboveground part of the pine stand: wood and bark of the trunk, branches and needles of the crown in a completely dry state. Tables of theoretical distribution of indicators of components of phytomass of pines for an age category from 10 to 80 years are con-structed. Regularities of phytomass changes of trunk components in bark and crown for stands of I–IV classes of quality were found. It is established that the dynamics of changes in the components of both the stem part and the components of the crown is characterized by a gradual increase in phytomass with age. The trend of dynamic changes is similar for all studied rating classes. It is ob-vious that stands of the first quality have the highest productivity of the studied classes. Decreased creditworthiness is accompanied by a gradual decline in productivity. It is investigated that the most significant differences in the phytomass parameters of different qualities are characteristic of older stands. It is calculated that the phytomass of the trunk in the bark varies from 5.4 t/ha (10 years) to 144 t/ha (80 years), and the nature of changes in the phytomass of the crown with age actually reflects the trend of phytomass dynamics of branches compared to pine. A comparative assessment of the dynamic changes of phytomass components of pine stands of the northern steppe part with the results of bioproductivity of pines of Ukrainian Polissya and Forest-Steppe, forest-steppe and northern-steppe regions of the European part, Kazakhstan and Siberia is given. On the basis of the received tables of dynamic changes of bioproductive processes in pines of the Northern Steppe the theoretical substantiation of practical use of normative-reference material for conditions of steppe part of Ukraine is made. The obtained results provide an opportunity to assess the current state of pine forests in the study region and predict the dynamics of their changes, which will allow the objective implementation of forestry measures, taking into account the regional peculiarities of pine formation.