The growth specifics of pine crops of various density in the Siberian southern taiga

Abstract

The dynamics of forest inventory indicators, attrition and wood growth of 35­year­old pine Рinus sylvestris L. crops with various density are analyzed, Pine crops were created in 1982 by V. N. Sukachev Institute of Forest Russian Academy of Sciences, Siberian Branch under the leadership of A. I. Buzykin on former agricultural lands in Bolshemurtinsky district of Krasnoyarsk Krai. The initial density of the stands varied in a wide range from 0.5 to 128.0 thousand trees per ha. The assessment of the stand density influence on the growth and productivity of young pine stands at the age of 2, 5, 12, 15, 20, 25, 30 and 35 years old was carried out. It has been established that since the age of five, the process of intensive self­thinning of trees has been observed, at initial planting density 90.0 thousand trees/ha the density decreased to 10 thousand trees/ha by the age of 35 years. At the initial density less than 10 thousand trees/ha the self­thinning intensity is significantly lower and the stand density has decreased by less than 2 times over the same period. It is shown that at the initial stage of stand growth there is a growth increase with the initial planting density, reaching the plateau at a density of over 70.0 thousand trees/ha. With age reaching the plateau occurs with the lower initial density. At the age of 20, the maximum increase was at the initial density from 50.0 to 70.0 thousand trees/ha, by the age of 30 it shifted to a density range from 30.0 to 50.0 thousand trees/ha. The relationship between the current annual increment, age, and the initial and actual densities of pine crops has been established. In the age range studied there is a tendency of increasing the increment with age, although for the crops with the initial density higher than 90 thousand trees per ha in the range of 15 to 22 years the decrease of annual increment is observed, which is evidently connected to the escalating of concurrent relations in cenosis. Thus, it can be suggested that high rates of carbon deposition at the initial stage of high­density stands creation can be maintained under the condition of periodic thinning, regulating the stand density.

Keywords

• carbon deposition
• compensatory planting
• pine crops
• density
• age dynamics
• increment
• modeling