Main problems in natural seed regeneration of pedunculate oak (Quercus robur L.) stands in Ukraine

The literature review article sums up research experiences in natural seed regeneration in oak forests. In the past, the natural habitat for pedunculate oak (Quercus robur L.) was considerably wider than now. The downward trend in the area of oak stands is observed both in Ukraine and other European countries. In Ukraine, the area of natural oak stands of seed origin is decreasing by 2.0 thousand hectares each year. The most significant environmental factor in the emergence and normal growth of young oaks of seed origin is the light amount, which should reach at least 20% of the full sunlight. In addition to the light, the main factors contributing to the emergence of oak seedlings under forest canopies and in cutting areas are the oak fruiting and the litter and soil moisture. On the contrary, the excessive development of forest live cover with sedge and cereal vegetation, root competition from the parent trees, and a dense undergrowth were the hindering factors. In the forests of Ukraine, the largest number of natural seed reproduction of oak (more than 100 thousand stems ha−1) after the harvest year was recorded under the canopy of mature and overmature oak forests with a stocking of 0.6–0.7 and with 70 oaks in the stand species composition, growing in conditions of fresh and moist oak forests of Polissya and Forest-Steppe zones. Scientific and methodical guidelines for using natural reproduction of valuable species during the natural seed regeneration of oak stands were improved.