THE IMPACT OF THE PLANTING MATERIAL ON THE GROWTH RATE OF SPRUCE AND PINE PLANTATIONS ON POST-AGRICULTURAL LANDS OF THE NORTH-WEST OF RUSSIA

Abstract

Introduction. Post-agricultural lands preserve the ploughed horizon for quite a long period even after colonization by trees and shrubs. These lands are highly fertile to produce woody plants. The key plantation restricting factors are the following: water –air condition, high soil density, ramping due to high stock of weed seeds. Our research was aimed at the examination of the impact of planting material types on the survival ability and growth dynamics of wooden plants occurred on post-agricultural lands under various methods of soil cultivation. Materials and methods. The field research was carried out on the post-agricultural lands which rested fallow for up to 30 years. The following methods of soil cultivation were applied to the experimental plots: strip chemical soil cultivation with roundup chemical (4l/ha) with land 1 meter wide strip cultivation using the row agricultural plough PLN-3-35; tillage without chemical soil treatment. The planting material was represented in two options: bare-root tree system and root-balled tree system. In order to evaluate the woody plant growth rate we measured the collar root and the height of the seedling at the end of every vegetation period. By the end of the second or third year we evaluated the survival ability of a plant and by the fifth year we focused on the species viability. Results. In order to establish plantations on post-agricultural lands with optimum soil and hydrological conditions achieved previously during their agricultural use, the soil tillage does not play a significant role. Eliminating the life ground competitive cover is possible as a result of strip chemical tillage and establishing plow layers. Chemical soil treatment prevents the appearance and development of tree and shrub vegetation. Planting material with root-balled tree system demonstrates higher growth rate, which makes it possible to use it under lower biometric parameters unlike bare root tree system. Conclusion. Grass layer and tree and shrub vegetation control are the leading factors in survival and growth phase which exerts impact on the growth rate of spruce and pine plantations established on post-agricultural lands. Planting material selection as well as its biometric parameters should be defined by the technological methods of soil tillage.