V. M. Lovynska
The article presents the results on local natural and basic density of trunk phytomass components of Scots pine within the Northern Ravine Steppe of Ukraine. Investigation of the local density variability was performed for 21 model trees, the age range of which was 9-90 years old. It was established that the average bark local natural density is characterized by a gradual increasing type, while local changes in wood showed the decrease in the natural density from the bases to 0,25h with the next increase to the tree top. A gradual decrease from the bases to the tree top is recorded for the wood basic density.
It was investigated that the bark basic density value for specimens with age up to 40 years and in 81-100 years is reduced to the 0,5h relative height. For the fractions of wood and wood in the bark, the investigated value decreased from the bases to the 0,50h relative height and then had tendention to grow. The calculated indices of the local basic density of trunk wood and wood in the bark had a reverse dependence on the age of Scots pine trees.
One-factor regression models of the local basic density dependence from tree age are developed. It has been established that the most accurate and practical mathematical models for the fractions of wood and wood in bark of Scots pine trees were found. It was recorded that the highest determination coefficients (R2 = 0,814–0,954) were calculated for models that describe the dependence of local basic density on 0,5h and 0,75h relative heights. It is indicated that the developed regression equations can be used for the basic density calculations of phytomass components of Scots pine stands in the Steppe zone conditions.
Key words: local natural density, local basic density, Scots pine, bark, wood, trunk, regression models.