THE FORMATION OF STEPPE AND PROTECTIVE AFFORESTATION: THEORETICAL AND APPLIED ASPECTS IN THE CONTEMPORARY CONTEXT

Abstract

Introduction. One of the main reasons for the lack of effectiveness of steppe and protective afforestation is the low durability of plantations. Scientific knowledge and practical experience accumulated in Russia, indicate the possibility of its substantial increase. However, they haven’t been implemented within strictly reasonable technological regimes of the creation and growing of plantations and has not received complete scientific formalization. In addition, a comprehensive, quantitative substantiation of the concept of "steppe treelesssness plains", assessment of the forest suitability lands. Consensus in the evaluation of the significance of differentiation, admixture of shrub and pure cultures to improve the drought resistance of the forest haven’t been found. The formula for the optimal mixing of species in cultures of oak hasn’t been revealed, and some other problems have not been resolved. That is, neither theoretical nor practical justification of the optimal ratio between the landscape and forest approaches in the afforestation of lands of the arid zone is still not completed. Aim of the paper. Development of scientific bases and suggestions to the technology of creation of sustainable broadband and massive forestations on complexes of zonal soils with high atmospheric moisture deficit of territory. Objects and methods. The main object of theoretical and experimental studies was water regime of pine monocultures, which is made on numerical and physical models of plantations in the South of the East European plain; the growth and current status of the state defensive forest belts, "industrial oak forests" in the lower reaches of the Volga and Don – on temporary sample plots by standard methods using system data analysis. Results. It has been found out that the main cause of steppe plains forestless and the fragility of planted forests is an excessive dynamic atmospheric moistening by years, a critical decrease in the stock of soil moisture and moisture supplies of a forest stand during drought years. In continental climate, moisture dynamics of the root zone by precipitation is inversely proportional to their annual rate and is directly proportional to the water holding capacity of that layer, and instability of water supply in plantations is directly proportional to their requirements in soil moisture and dynamics of atmospheric moisture. Forest suitability of lands is a gradient multi-vector field with increasing indifference of the edaphic forest formation vector in the direction of increasing the climate aridity and the plantations age. Estimation must be done by the ability of the soil potential rhizosphere to meet the nutritional requirements of young fast-growing closed stands, i.e. in the period of the most intense precipitation consumption for evapotranspiration. The steppe territory is mostly occupied by conditionally forest suitable land on which forest formation isn’t possible without artificial stimulation. When foresting it is necessary to eliminate competitors and provide a starting supply of soil moisture, the rapid closing of the plantations, the decrease of the damping of moisture, prolonging the period of active growth, differentiation of forest and preservation of forest environment. Conclusions. Forestations on the southern black and chestnut types of non-saline and slightly saline soil of the East European plain should be created in a multiannual follows. Pure cultures of English oak with a density of 7-10 thousand/ha and inter-row space of no wider than 2.5 - 3.0 m should been of higher preference. It is necessary to carry out cutting frequent improvements of low intensity in well closed forest stands, and to form shading understory trees of soil-improving light-requiring species in the rapidly thinning middle-aged plantations.