The peculiarities of Larix gmelinii (Rupr.) Rupr. phytocoenoses progressive (after forest fire) successions at the northern range of the Eurasian boreal forest´s extending in the Central Siberia are analyzed in the paper. Methods of forest phytocoenosses´s investigations are discussed. State dynamics and possible directions of forest vegetation changes are analysed using a structure, growth and bioproductivity parameters of the trees and of the stand components.
The structure of young larch stands is characterized by long, steep, right-side asymmetried curves of tree distribution by the major morphometric parameters (i.e. tree height and diameter and crown length and diameter). Empirical curves can be adequately and effectively smoothed with the help of the lognormal distribution probability density function.
Horizontal and vertical tree layer structure is remarkable for the uniform distribution of tree groups across the area, high (>1.0) canopy closure in the biogroups, and easy-to distinct well- and underdeveloped individuals. Morphometric parameters appear to closely correlate both among themselves and with phytomass components (r = 0.5120.950). The relationship between the parameters can be approximated by the linear equation: y=a+bx. Above ground phytomass was measured to be 11,580 kg/ha (absolutely dry weight). Tree trunks account for 71 % of the total phytomass, with timber and bark making up 58 and 13 %. respectively. Understory phytomass is 181 kg/ha. Surface cover phytomass is 5818 kg/ha.
In a larch phytocoenosis, the total above ground phytomass was measured to be 17,579 kg/ha. Of this, 66 % is accounted by the overstory (the major stand component), 33 % by surface cover, and 1 % by understory. Dead organic matter is 44,315 kg/ha. Snags, downed wood, litter, and forest floor make up 46, 22, 5, and 27 % of the total dead material, respectively. In a larch stand, annual average organic matter increment (in kg/ha/year) was measured to be 386 for the overstory, 187 for the surface cover, 6 for understory, 474 for litter and forest floor, and 328 for downed wood. An ecosystem is predicted to completely regenerate to its initial state in 70100 years, provided that vegetation succession occurs in its normal way. From the ecological viewpoint, burned areas should be primarily replanted with edificatory species (pyrogenic demutation) and an initial larch coenopopulation should be formed. As dead organic matter accumulates, repeated prescribed burning in the understory would favor reproduction capability of larch stands (since seed germination will be promoted) and would simultaneously reduce the risk of destructive intense wildfire occurrence.
Keywords: phytocoensis, productivity, succession.
Correspondence: I. M. Danilin, Institute of Forest, Siberian Division, Russian Academy of Sciences, Akademgorodok, Krasnoyarsk 660036, Russia