Practical approaches to determining the dynamics of the stability of stands of breeding objects

Abstract

The article analyzes the indicators that can be used to assess the biotic and ecological stability of forest stands. For breeding facilities, this issue is of relevance when prescribing reforestation measures in forest genetic reserves, assessing the stability when selecting plus stands, assessing selected permanent forest-seed plots to determine the volumes of their formation and tending activities in them and, in the future, their transfer to plus stands, as well as, in general, for isolation of a reserve fund from the forest environment. The methods for assessing the stability of forest stands are based on determining the indicators of forest stand stability, calculated on the basis of tree mensuration in the study area (based on a trial plot) and the sanitary state of the trees. The basis for the determination is the complete tree enumeration and the scale of sanitary state used in production operations (SanitaryForestsReg.Ukraine). The assessment of stand stability is based on the method of calculating the loss of stability (BC)), which was proposed to determine the stability of secondary spruce forests in fertile beech forest types (BlystivV. I. 2006) and later adapted to assess the formation of the stability of hornbeam-beech stands (Blystiv V. I., 2012). The issue of assessing the tension of a stand, using the growing space of the forest is addressed in the methods section of the dissertation work by V.M.Malyuga, 2020. Using the values of the above indicators (KC, ВбС, ВеС), stands can be divided into 3 categories of stability: stable, conditionally stable and unstable. Appropriate forestry activities are proposed according to the categories. They require a special numeric-expressed substantiation, both in relation to the economic group of forest types, forest category, and for targeted activities or research areas - in this case, loss of stability of breeding facilities. Tension studies have shown that by using factors of environmental impact, the conditions are assessed as normal, non-tensioned and tensioned. To assess the indicator values of normal and weakened states, the basic scale of the assessment of biotic stability by stand indexes will be used. For the weakened state, three indexes are identified for the purpose of detailed planning of possible activities. In forest breeding, the selection and formation of forest stands for stability will require parameter-defined indicators, in this case, the forest stand stability coefficient is used. The protective properties of the forest environment, identified with the preservation of genetic diversity, determined by the amount and quality of natural regeneration and associated with ecological stability, can be effectively assessed by its loss according to the above method. The studies on the stand tension, using the factors of environmental impact, have shown that stands growing under tension are those that are somewhat overstocked ones. Pine stands grow optimally when they have a density range of 0.7-1.0. The rest of the stands grow without tension, but they do not make full use of growing space due to varying degrees of stand density. Such medium-stocked stands can be effectively used as selected and appropriately formed permanent forest-seed plots. Assessment of the stand state by impact factors makes it possible to record quantitative changes. The dynamics of areas in accordance with the changes of these indicators by periods characterizes the ecosystem changes (stages of development by successive process) and is important for the facilities of preservation of genetic diversity - especially forest genetic reserves.