Growth and Vitality of English Oak in Plantations after Improvement Thinning

Issue of deterioration of condition and preservation of protective forest plantations, loss of their protective and ameliorative functions due to the lack of forest management service have become more urgent in recent decades in forest and agrarian landscapes of the Central Black Earth Region. Improvement thinning is the main tool in the forestry practice system which provides improvement in growth, development and sanitary state of protective forest plantations. The purpose of our research is to determine the effect from improvement thinning on growth and sanitary state of forest belt stand and its main species - English oak. Forest valuation and pathology research were carried out in Kamennaya Steppe (Talovsky district, Voronezh region) in the period of 1986-2017. Afforestation belt no. 240 was a research object laid out according to line planting with the following scheme of species mixture: where - silver birch, - Norway maple, - English oak. Stationary experiment is presented by the following plots: 1 -control without improvement thinning; 2 -plantation thinning with intensity of 21-33 % of wood stock by means of dominating thinning of fast-growing species (silver birch and balsam poplar), thinning of weak and bruised trees of the main species (English oak) and associated species (Norway maple) with felling waste removal from the plantation; 3 - the same as 2, but with lifting the canopy to the height of 1.5-2 m; 4 -the same as 3, but with clearing by scattering slash under stand's canopy. Length of plots 1-3 is 250 m, plot 4 - 140 m. It is established that thinning contribute to the improvement of forestry and biological indicators of English oak. Preservation excess of vigorous trees of the main species at the plots with improvement thinning in comparison with control plot is 13.0-24.3 %. Preserved trees of English oak on the plot without improvement thinning stunt in trunk diameter for 1.2-5.0 cm and height for 0.1-1.3 m. Proportion of forest mortality and inviable trees of English oak is increasing and proportion of viable and partially viable trees decreases after thinning. There is a need to carry out improvement thinning during growth and development of plantations for cultivating them sustainable, ameliorative and effective.