Conversion of low-value stands by corridor method in Left-Bank Forest-Steppe, Ukraine

The aim of the study was to identify the influence of different widths and cardinal directions of felled corridors on the condition and mensuration characteristics of the English oak trees planted there during the conversion of low-value young stands using the corridor method. The study was carried out in oak forests in the forest-steppe zone at a permanent sample plot. The experiment included the conversion of a low-value 8-year-old stand to improve its species composition. The sample plots were laid out in a fertile hardwood forest site. The conversion was realised by felling corridors of various widths (6, 9 and 12 m) and directions and planting English oak trees (Quercus robur L.) within them in rows. For the planted oaks, tending felling was carried out three times: weeding (8 years), cleaning (13 years) and thinning (32 years). A comparative analysis of mensuration characteristics (average height, diameter, growing stock, radial increment, health condition, etc.) was carried out for 32-year-old oak trees grown in the corridors and a part of a low-value stand in the unfelled strips after the tending felling. It was found that the average height and diameter at breast height of oaks in the 6, 9 and 12 m wide corridors of different cardinal directions did not differ significantly. The difference in oak stocks within 6 and 9 m wide corridors of different cardinal directions was also insignificant. The stock differences were statistically significant for 6 and 12 m wide corridors as well as for 9 and 12 m wide ones. The article made recommendations on the width of felled corridors and unfelled strips to effectively convert low-value young stands by the corridor method.