Retrospective analysis of forest stands preliminary generations formation

The problem of preserving undercanopy renewal in forest exploitation is still considered very debatable. Today one of the most acute questions about the height of the preserved undergrowth that would ensure the formation of coniferous plantations. In connection with the foregoing there is a specific interest in forestry research according to the retrospective analysis of plantations formation from the preserved undercanopy renewal in forest exploitation. The object of research is plantings formed from preliminary renewal in the clear cutting of the southern taiga subzone within Tomsk oblast. The research was carried out by temporary trial area method (TTA). The challenge, taxation and TTA data processing were performed by conventional methods outlined in special literature, in accordance with the requirements of OST 56-69-83 «Trial area of organization. The method of distinguishing». Complete enumeration tonnage capacity measured 8.2 thousand trees. Based on the enumeration of trees there was selected models in the average number of 30 pieces on TTA (from 22 to 38, which depended on the species composition and forest stand structure). There were cut down and measured 617 model trees of cedar, spruce, fir, birch and aspen according to a standard method. The size of the trunk was determined by a complicatedformula of the median cross-sections (Huber complex formula). The total of 21 TTA were introduced in five most common types of forests: small grassy-mossy, mossy, grassy-swampy, ferny and grassy ones. The age of cutting is 36-49years. In our studies, we mean forest young generation by "undergrowth", which has an average height of no more than % of the height of the main canopy, otherwise undercanopy renewal was attributed to the immature element of the forest stand. Since the average height of the felled trees amounted to about 24 m, the specimens were attributed to the undergrowth height of about 6 m and more than 6 meters - to the immature element of the forest stand. Thus, the formation of the undergrowth and trees on clear cutting of the southern taiga in Tomsk oblast is due to conifer species (spruce, fir and cedar), with the height from 2 to 6 m. The age varies in the range from 15 to 45 years. In one of our work, we analyzed the potential of the renewable conifer plantations in the study area according to the mass inventory (89889 ha). According to the research, the undergrowth renewal age ranged from 5 to 55 years. But the age of 20 is most often found (17%), 25 (18%) and 30 (24%). This situation is typical of all types of forests. The height ofpreliminary renewal resume ranges from 0.5 to 6.0 m, but the most frequently encountered undergrowth height is 2 m (24%), 2.5 m (17%) and 3.0 m (16%). This situation is also typical of all types of forests as well. These data indirectly confirm the reliability of the findings of the retrospective analysis ofplantation growth from the undergrowth. It was revealed that the values of the average growth at the time of cutting was more than 8 cm for small and medium undergrowth, 11 cm for big undergrowth and 19 cm for the immature element of the forest stand, there is a high probability of forming dark coniferous stands without silvicultural departures.

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