Growth and development of crowns and closure of Quercus robur L. stands planted with various types of planting material

Abstract

Introduction

Planted stands are evaluated and reclassified to wooded lands according to such characteristics as age, species, height, relative density of stocking, and density. The ways planted stands grow and develop slightly differ by the above-mentioned characteristics (indices) if they were created from various types of planting material (acorns sowing, or containerized or bare root seedlings). Relative density of stocking in the stands depends on their density and extent to which trees’ crowns spread along (lengthwise) and across (crosswise) a row. The stands created from the containerized planting material have better indices as they have a higher survival ability and, accordingly, shorter terms for their crowns to get dense.

Materials and Methods

To carry out a complex study, we laid out 10 sample plots in the planted stands aged from 5 to 9 in Lytovske and Neskuchanske Forestries of the Trostianetske Forestry Enterprise. We studied specific aspects of growth and development of planted stands created from various types of planting material. We also observed how they form their crowns, and evaluated how they get dense. We carried out complete accounts and scaling of diameters, height and diameter of crowns lengthwise and crosswise in rows. We used standard forestry (ecological), mensuration and statistical methods to do all the measurements and calculations.

Results

On all sample plots the height of the studied trees surpassed the regulatory value given in the ‘Regulations…’ to reclassify them to the forested land category. Even 5-year-old trees were 2.4 m high, which was 41% higher than the regulatory value. Trees with the average height of 3 m and higher were the trees of 8 and 9 years old planted with containerized seedlings. Their height was 3.2 and 3.6 m respectively. The average heights in other studies varied from 2.4 m to 2.9 m. Generally, the age trend persists: older trees are higher, except 8-year-old trees growing in the upper part of the hill in a slightly poorer and drier site.

The crown cross-section values, crown area, and relative area of crown projections have a strong correlation with the tree height. The correlation coefficient between the height and crown cross-section in a row makes 0.98, and it is 0.95 between the height and crown width across a row. Rather high coefficients point at a very strong correlation between these biometric indices. The correlation with the height can be considered natural and thus applied to evaluate planted stands’ quality and the closing canopy process in a row for further stand reclassification to forested lands.

Conclusions

English oak stands planted using containerized planting material have a higher vitality compared to those planted with bareroot plants or acorn sowing. Furthermore, they grow into the second development stage faster. At that stage, the trees begin to differ in their height. To evaluate the quality of planted trees, in addition to the number of trees per hectare, it is enough to know the height as this index has a strong correlation with crowns’ size and their projection area per hectare. However, even 9-year-old stands planted using containerized planting stock, which were reclassified to forested lands with the 1^st quality class at the age of 6, do not correspond to the 1^st quality class in the canopy density category.

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