Growth of English oak (Quercus robur L.) forest plantations established using planting material of different types and cultivation methods, in the Right-Bank Forest-Steppe of Ukraine

Abstract

Introduction

In the plain part of Ukraine, artificial regeneration remains the main method of oak forest restoration, including the establishment of forest plantations using bare-root and containerized seedlings, as well as acorn sowing. It is well known that the proper selection of planting stock type for specific site conditions largely determines the success of artificial reforestation and afforestation. Numerous scientific studies have addressed the selection of planting stock types for artificial regeneration of oak forests, as well as the survival, preservation, and growth performance of plantations established using different types of planting material. However, such studies in the Right-Bank Forest-Steppe of Ukraine remain fragmentary, which determines the relevance of the present research. The aim of this study was to compare the survival, preservation, and growth performance of two-, four-, and five-year-old English oak (Quercus robur L.) plantations established using bare-root seedlings, containerized seedlings, and acorn sowing in the Right-Bank Forest-Steppe of Ukraine.

Materials and Methods

The study of survival rate, preservation, and growth performance of two-, four-, and five-year-old English oak plantations established using bare-root and containerized seedlings, as well as acorn sowing, was conducted in 2025 in the Vinnytsia, Khmelnytskyi, and Cherkasy regions. The survival rate in 1–3-year-old plantations and the preservation rate in older plantations were calculated as the ratio of the number of viable plants at the time of assessment to the initial number of planted individuals, expressed as a percentage. The following growth indicators were determined: average height, height increment, and root collar diameter. Plantation age was determined from the time of seedling planting or acorn sowing. The significance of differences in growth indicators between plantations established using different methods and planting stock types was tested using Student’s t-test at the 5% significance level. The data followed a normal distribution and therefore met the assumptions for applying Student’s t-test.

Results

Higher survival rates were observed in two-year-old oak plantations established using containerized seedlings grown both in polystyrene containers (variant «ЗКС-1») and agrofiber containers (variant «ЗКС-2»), amounting to 94% and 91%, respectively, compared with plantations established using bare-root seedlings (variant «ВКС») – 85%. The differences in average height between plantations in variants «ЗКС-1» and «ЗКС-2» and «ВКС» amounted to 10.8 cm and 20.4 cm, respectively; differences in height increment were 6.0 cm and 12.2 cm, and differences in root collar diameter were 0.9 mm and 1.4 mm. A statistically significant difference in height, height increment, and root collar diameter was found between plantations in variants «ЗКС-2» and «ВКС», whereas between «ЗКС-1» and «ВКС» a significant difference was observed only in height. Higher preservation was observed in four-year-old plantations established using containerized seedlings (variant «ЗКС») – 88%, compared with plantations established using bare-root seedlings (variant «ВКС») – 81%. The differences in average height, height increment, and root collar diameter amounted to 20.6 cm, 10.8 cm, and 4.2 mm, respectively, and were statistically significant for all indicators. Higher preservation rates were also observed in five-year-old plantations established using containerized seedlings (variant «ЗКС») – 89%, compared with plantations established using bare-root seedlings (variant «ВКС») – 81% and acorn sowing (variant «Acorn») – 80%. The differences in average height between plantations in variants «ЗКС» and «ВКС» amounted to 24.8 cm, in height increment – 8.1 cm, and in root collar diameter – 6.7 mm; whereas between «ЗКС» and «Acorn» the differences amounted to 59 cm, 10.9 cm, and 9.9 mm, respectively.

Statistically significant differences in height, height increment, and root collar diameter were found between plantations established using containerized seedlings and those established using bare-root seedlings or acorn sowing. A significant height difference was also observed between plantations established using bare-root seedlings and acorn sowing, whereas differences in height increment and root collar diameter were not significant.

Conclusions

In the Right-Bank Forest-Steppe of Ukraine (Vinnytsia, Khmelnytskyi, and Cherkasy regions), under fresh hornbeam forest and moist hornbeam–oak forest conditions, two-, four-, and five-year-old oak plantations established using containerized seedlings grown both in agrofiber and expanded polystyrene containers demonstrated higher survival, preservation, and growth performance compared with plantations established using bare-root seedlings or acorn sowing. The optimal planting spacing for establishing forest plantations with containerized seedlings is 4.0 x 1.0 m on clear-cut areas without natural regeneration or with insufficient regeneration of dominant and valuable associated species, and 6.0 x 1.0 m on clear-cut areas with satisfactory regeneration of dominant and valuable associated species.

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