Stem Shape and Productivity Dynamics of Plantation Crops of Scots Pine of Different Initial Density

Abstract

The stem form and growth dynamic in the 42 years old artificial Scotch pine stands of various density are investigated. These stands are planted on the drained swamp with use of fertilisers in mid-taiga subzone of Karelia. On each sample plot ordinary stand measurement was made and on 10 sample trees stem diameters at relative heights (up to 0,8H) was measured using theodolite 2T30 which mean square mistake (30") provides the diameter measurement accuracy up to 2 mm. For more detailed growth assessment dynamics from each sample tree cores by Pressler's drill at the height of 1.3 m were taken. At the time of research on the plot with planting density of 1 thous/ha was similar to initial, and in other plots the density was reduced twice. The main distinctions between plots are reached in the first 20 years of growth after planting. After that year rings width in all stands of experience was practically equal and after 30 years was stabilized at the level of 1 mm. Calculation of stem form coefficients showed statistically reliable distinctions between plots with minimum and maximum density only for the coefficients of q2 and q3 characterizing the middle and the top stem parts. For more detailed research of stem form dependence of absolute and relative diameters on relative height was approximated using polynoms of 6 and 5 degrees. The determination coefficients of the received regression equations R2=0,94- 0,96. The substitution in these equations of identical values of height (17 m) and diameter at the breast height (20 cm) showed that stem volume in the stands with initial density 2 and 4 thous/ha is 7 and 12% higher in comparison with the plot of rare planting and 18–25% above in comparison with the assortment tables accepted for the region. The received results give the serious grounds for correction of regulatory base of an assessment of cut-down stands.