Distribution, growth, and structure of pine-beech forest stands in the Lviv Roztochchia region

In the western part of Ukraine, pine-beech forest stands are widespread only in the physico-geographical regions of Roztochchia and Opillia. Their total area is 8,204.5 hectares, of which 6,246.5 hectares (76.13%) are occupied by stands of natural origin, 1,890.8 hectares (23.05%) are forest plantations, 5.5 hectares (0.07%) are sparse forests, 20.0 hectares (0.24%) are naturally occurring stands with admixture of forest cultures, 41.2 hectares (0.50%) are unclosed forest cultures, and 0.5 hectares (0.01%) are forest nurseries. Based on data on the composition of stands, productivity of the main tree species – Scots pine and European beech, species composition of understory, undergrowth, and herbaceous cover – the forest typological distribution of pine-beech stands was clarified. It was established that under conditions of Roztochchia, pine-beech stands are formed in fresh and moist subores (fairly infertile site types) and fresh and moist sugruds (fairly fertile site types). At the same time, some pine-beech forest cultures were created in conditions uncharacteristic for pine, such as fresh and moist groves. The largest area is occupied by pine-beech stands, in which both Scots pine and European beech are present within 10% of the growing stock (accounting for 21.2% and 21.0% of the total area, respectively). Comparatively significant areas are also occupied by pine-beech plantations with an 80% pine composition (12.1%) and a 60% beech composition (10.8%). The age range of pine-beech stands in Roztochchia covers nineteen ten-year classes, and the distribution of their area by age class is very uneven. The largest areas of stands fall within age classes 8, 7, 9 and 10 (accounting for 24.4%, 17.3%, 13.8%, and 10.1% of the total area, respectively, totaling 65.6%). At the same time, very small areas of pine-beech stands fall into age classes 1, 2, 3, 4 and 5 (9.9% in total). Mature and middle-aged stands account for 31.4% and 41.7%, respectively, while young stands of classes I, II account for 3.3% and 3.0% of the total area, respectively; over mature stands occupy only 0.8% of the area. In Roztochchia, the most common are pine-beech stands with a relative density of 0.7 (40.4%). The vast majority of forest stands involving Scots pine and European beech in Roztochia are characterized by high productivity. Most stands grow according to quality classes I, Ia (43.3% and 37.1% of the total area). The average weighted quality class for stands involving pine and beech is Ia, Ib, and the average weighted growing stock per hectare in pine-beech plantations in Roztochchia is 333 m³. The highest stock is found in middle-aged stands—362 m3∙hа-1. The stock of maturing, mature, and over mature pine-beech stands per hectare is 97.0%, 90.3%, and 93.9% of the middle-aged stock, respectively, while the stock of young stands of classes I, II is 9.4% and 39.5%, respectively. On the whole pine-beech stands in Roztochchia occupy a relatively small area (over 8,000 hectares). At the same time, they are characterized by high forest mensuration indicators. Their stock in favorable forest-growth conditions can reach 420-460 m3∙hа-1.