Dynamics of Space Structure of Plant Communities on the Slashes of Birch Groves with Spruce of Preliminary Generation

Introduction. The necessity to improve the silvicultural activities on the slashes of small-leaved stands using the knowledge about the dynamics of space structure of forest communities in the course of forest-forming process determines the topicality of the studied problem. This problem is lack of study in the taiga zone forest. The goal of the paper is to study a long term dynamics of space structure of forest communities after felling of secondary birch groves with conservation of spruce of preliminary generation. Objects and methods. The fellings of birch groves with spruce of preliminary generation growing in the sorrel - myrtillus forest type were chosen to be the object of the research (North forest experiment station of the Institute of Forest Science, RAS, Yaroslavl oblast). Measurement was taken in 2, 7, 12, and 22 years after stand felling and it was also taken on the controlled sampling area. Dynamics of the structure of plant communities was analyzed by the groups of parcels. Results. The slashes are of vast space diversity: in 2-year cuttings, there are 3 times more parcels in comparison with the data from the controlled sampling area. The parcels were divided into 11 groups by similarity of the structure of plant communities. In 12-year old cuttings, the area of parcels with spruce has increased 60 %, which is determined with inten-sive growth of this species after removal of upper layer of birch. In the cutting area of 22-year old slashes, the parcels with young trees (38 % of the area) and polewood of spruce (21 %) predominate, aspen groves in the stage of polewood are developing(33 % of the area). Birch regeneration is 10 years later because of quick colonization of the area with woodreed and tussock-grass. The parcels with young birch (20 %) are developed in 20 years only. In the skidding trails of 22-year old cuttings, the parcels with grassy suffruticose layer (47 %) predominate. Conclusion. Location and the area of parcels on the slashes of small-leaved stands in the taiga zone forests is determined with the structure of plant community before felling, with location of engineering elements on the slash and with the time passed after felling. Study of the parcel structure in plant communities and its transformation on the slashes makes it possible to under-stand the reasons, determining recovery-age dynamics of stands which defined the choice of the system of silvicultural activities, directed to establishment of highly -productive coniferous stands.