Vegetation cover of the lahar valley on the Sarychev Peak volcano(Matua Isl.,Middle Kuril Islands) after the Eruption in 2009: current state and features of succession processes

The paper presents the study of the vegetation recovery after the descent of the lahar during the eruption of the Sarychev Peak volcano(Matua Isl.,Middle Kuriles) in 2009.The works were carried out in 2017.It was found that during the secondary succession,plant communities,typical of the altitudinal zonation of the volcanic structure vegetation,are formed on lahar sediments in the following manner: the upper sections of the slope are occupied by sparse meadow and shrub vegetation,the middle are presented by shrub belt with a developed canopy,and the lower are representative of shrub large-grass belt.At the same time,the ordination analysis of the vegetation cover of the lahar valley by the detrended correspondence analysis(DCA) revealed the dispersion of the counting areas along the altitudinal gradient.This is opposite to that characteristic for both,the background communities on the slopes of the studied volcanic structure,and for communities in dynamical equilibrium of a typical altitude profile.Besides,directly correlating indicators of α-diversity of communities indicate the presence of open young communities at the stage of a complex grouping.Since the species Duschekia fruticosa which is an identifier in buried sites,forms communities in a state of dynamic equilibrium,with individuals of 40–50 years old,and at the time of the work,formed a canopy with individuals of 7–8 years old,a complete recovery of the communities of the lahar valley is possible in no less than 40 years.The acquired data on the recovery of vegetation on lahar contribute to the study of succession processes in the sites located in the zone of active volcanism.In addition,in this work,for the first time,the rates of restoration of the vegetation cover following its destruction as a result of burial by lahar products,are estimated.The specific features of this process are also considered.Employing the broad range of mathematical methods for quantitative analysis of indicators of young communities inhabiting the substrate makes it possible to identify patterns of vegetation formed during succession processes.The specifics of this organization are taken into account in this analysis.