Український науково-дослідний інститут лісового господарства та агролісомеліорації ім. Г. М. Висоцького Проведено кількісне оцінювання використання лісорослинного потенціалу насадженнями основних лісоутворювальних порід України (сосни звичайної та дуба звичайного) за природними зонами та типами лісу. Розроблено таблиці продуктивності модальних та високопродуктивних соснових і дубових деревостанів. Встановлено, що в середньому лісорослинний потенціал земель використовується насадженнями на 50-75 %. Середньозважений показник використання лісорослинного потенціалу сосняками Полісся становить 68-76 %, Правобережного та Лівобережного Лісостепу -70-78 % та 68-73 % відповідно, Степу -54-78 %, дубовими насадженнями Правобережного та Лівобережного Лісостепу -71-75 % та 63-71 % відповідно, Степу -65-75 %. Підтверджено, що основою підвищення продуктивності лісів має стати диференціація систем ведення лісового господарства та окремих лісогосподарських заходів на зонально-типологічній основі.
Changes in the areas and stock volumes of oak stands were analyzed within the six administrative regions in the plain area of Ukraine, based on forest management data (subcompartment database) as of 2001 and 2016. The studied regions geographically related to the Left-bank Forest-Steppe zone of Ukraine (Kyiv, Poltava, Sumy, Kharkiv, Cherkasy and Chernihiv Regions). The analyzed area was over 284,000 hectares. The paper outlines the present state of the oak stands, concerning their origin (vegetative, natural seed and planted seed stands). Forestry-taxation indices of the stands were determined by grouping the plots according to age and further clustering in four age groups. The natural regeneration under a canopy in oak stands was accounted and estimated using circular 10 m2 (R = 178 cm) accounting plots. The oak forests were found to be dominated by stands of vegetative (coppice) origin (57%). Planted seed-origin oak stands covered 101,000 ha or 36% of the total area (284,000 ha). Stands of natural seed origin amounted to 7%. From 2001 to 2016, the total area of oak forests in the study region decreased by nearly 7,000 hectares. The analysis of literature sources allowed identifying numerous factors, which have the greatest influence on the emergence, liveability, and growth of natural regeneration of pedunculated oak. Only 20% of the investigated oak stands were found to have a sufficient amount of oak regeneration. For the implementation of sustainable forest management, activities should be aimed at optimizing the age structure of oak forests and growing natural forests from seeds.
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.
Yield tables are the basis of regulatory materials for forest fund accounting, design and planning of forestry operations, and implementation of measures to increase forest productivity.Growth modeling of oak stands and construction of yield tables were performed according to generally accepted methods by analyzing the Database of Production Association «Ukrderzhlisproekt». The correlation bonds of the main taxations indexes of artificial oak stands within the territory of the Left-bank Forest-Steppe zone were revealed. The calculated correlation coefficients to select adequate regression models of growth were used. To simulate the growth processes of forest plantations, the Mitcherlich function is used which takes into account the biological features of oak growth.On the basis of presented the mathematical models regional tables of growth of modal and reference plantations artificial oak forest stands of the Left-bank Foreststeppe zone of Ukraine created in conditions of fresh maple-lime oak forest are compiled. The resulting yield tables describe tree stands and their removed parts (due to natural thinning or forest management operations). It is determined that the age of quantitative maturity of the reference artificial oak stands comes earlier (43 years) than of the modal artificial oak stands (48 years). The index of the forest growth potential utilization of forest lands is defined for modal stands of artificial origin in the studied forest area. By comparison with reference artificial oak stands of the Left-bank Forest-steppe zone the importance of indexes of the forest growth potential utilization of forest lands is in the range of 49 % (stands 10 years old) to 83 % (stands 120 years old). The weighted average was 75 %.The resulting yield tables of modal and reference plantations artificial oak forest stands of the Left-bank Forest-steppe zone of Ukraine it is appropriate to apply at the time of the planning of forestry operations (in particular care fellings).
The study was conducted in pure Scots pine (Pinus sylvestris L.) stands within the forest steppe physiographic region of Ukraine damaged by surface fires with different intensity. The aim of the research is to determine the effect of different fire intensity on pine stand and individual trees, considering tree morphometric parameters and type of damage. The intensity and duration of fire-related tree mortality was different in stands with different age. We found that tree fire resistance is driven by tree diameter, height of the rough bark, and natural degree of thickness. The proportion of dead trees one year after the spring fires in the middle-aged pine stands was 5 times lower and in mature pine stands even 10 times lower than after the summer fires. The critical damage to tree crowns in young pine trees causing their death is 80% of the needles burned. In the middle-aged pine trees, critical damage depended on the size of trees. The death of large, mature trees after smoldering summer fires was associated with the accumulation of a large stock of forest litter and duff near the tree-base, which contributed to the increased intensity of fire and its localization near the base part of the trees. Based on our findings, postfire tree mortality models have been developed for different age groups of pine stands.
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