Methodical aspects for describing post-fire forest site

Descriptions of pre-fire and post-fire vegetation sites are necessary for pyrological studies. Most developed are techniques of pyrological description of vegetation as an object of possible combustion. This paper gives more details on methodical aspects of pyrogenic description of vegetation sites as objects of fire impact. The used terminology is specified as well as the main idea of pyrogenic description, which is to identify the category of a post-fire site, its characteristics and to explain the causes for emergence of this kind of a post-fire biogeocoenosis and possible direction of further succession development. When considering the principles and methods for pyrogenic description of vegetation sites as objects of fire impact, the main focus is on the first stages of pyrogenic successions related with the combustion processes, damage, mortality and destruction (digression), as well as the beginning of recovery (demutation) in terms of components of a forest biogeocoenosis, first of all, the tree stand. The borderline between the time of the digression stage and the time of the demutation stage (initiation of active recovery) is different for various components of one biogeocoenosis. For instance, perennial plants from the grass-shrub layer, especially herbs and sedge grass, are quick to recover after fire. However, the cover of moss and lichen is slow to recover (taking decades for this). When describing the demutation stage on post-fire sites, open burnt areas and in fire-disturbed forests, the main attention should be paid to the assessment of forest restoration success rate taking into account the evenness of sapling distribution, its composition, age, height, vitality, etc. The method of such assessment is developed. The general pyrogenic description of a vegetation site includes: characteristic of a pre-fire stage with moistening regime, site index of a tree stand, pre-fire composition of the forest floor on a non-burnt control site; characteristic of a combustion stage with the fire year identification, fire type and intensity; characteristic of a digression stage with description of the character and degree of tree stand damage by fire as well as the process of tree dying and drying off; the main damage during crown fires is crown scorch, ground fires burn roots leading to tree fall out, surface fires scorch phloem and cambium in the lower part of tree trunks and on root spurs. The scale of vegetation fire impact has been increasing together with climatic changes. This makes fire control and management relevant. For this, detailed pyrogenic descriptions and characteristics of vegetation sites as objects of possible combustion (i.e. as complexes of vegetation fuels) are highly needed. The offered methods of pyrogenic description have both scientific and practical significance in planning post-fire forestry measures.

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