FOREST HEALTH DYNAMICS IN DAMAGED BY SURFACE FIRE YOUNG PINE STANDS THAT HAVE NATURAL ORIGIN

Abstract

The study of trees health changes in after a surface fire is relevant, because such data will significantly expand the understanding of post-pyrogenic growth and development of pine`s natural regeneration and its quality. In addition, such studies are forming a theoretical basis for further study of the impact of surface fires on pine forests and justification of forestry treatments in such stands. Natural regeneration plays an important role in the reproduction and preservation of the forests of the city’s green areas, allowing for the formation of more sustainable plantations. These researches help to make management decisions about carrying out forestry treatments after a fire (such as salvage logging) and to ensure the preservation of fire-damaged trees. On the territory of the green zone, each preserved tree plays an important role in ensuring the comfortable life of the urban population and providing a number of ecosystem services. The study of the dynamics of the sanitary condition of trees similar in age, but different in Kraft Classes (KC), will allow to better forecast possible economic and ecological losses as a result of the post-fire tree mortality. The aim of the work is to determine the effect of surface fire on changes in the health condition and postfire mortality of young pines with the natural origin. To analyze the effect of thermal impact from the surface fire on individual trees, char height on the trunk and “relative char height”, were taking into account as well as the degree of development of each particular tree according to the Kraft Class. For each tree, the main forestry indicators were measured: diameter, height and sanitary condition. The main signs of fire damage were identified, their assessment and changes were carried out several months after the fire. Correlation analysis shows that the tree mortality had significant positive relation with char height and a negative one with tree size (DBH and KC). To determine the impact of the fire, trees on an sampling plot were measured and compared. Pure pine stand on sampling plots (damaged and control) were 10 years old and grow in B2 soil conditions. It has been established that the most severely affected were trees with retardation in the growth and development (IV and V KC). In this case, tree mortality reached 80 to 100%, even with minimal fire damage. In this way, the surface fire accelerated the process of natural liquefaction in young pine trees. In contrast, the analysis of the post-fire forest health changes of dominant and co-dominant trees (I and II KC) revealed their greater resistance to damage and can be used for rational planning of forestry activities. A comparison of this area with the control (undamaged) sampling plot proved that even severely retarded trees in growth and development (IV and V KC) have a sanitary condition mainly at the level of “severely weakened”. Data from the study of changes in state and drying helped to establish clear correlational dependences of the change of these indicators on “relative soot” because of a spring lowland fire.