The results of observations on permanent plots in pine and spruce stands are presented. The permanent plots were established in 19291930 and in 19681973. There are 10 series of old plot and 9 series of new ones. Each permanent plot series consist of several thinned plots and a control plot. Plots we remeasured every 510 years. Soil and grass cover are studies periodically. The method and regime of thinning have to be defined exactly at first. This problem is solved. The growth trends depending of site, origin and management have to be studied now. The experiments are set up in must spreaded types of site of south taiga.
Key words: growth trends, pine, spruce.
Correspondence: Svetosar Nicolaevich Sennov, Petersburg Forest Academy, Institutsky per 5, SU-194018 St. Petersburg, Russia