Formation of Forest Biogeocenoses on Disturbed Lands of the Northern Caspian Region

Abstract

Features, trends and the rates of formation of new forest biogeocenoses on anthropogenically disturbed lands, in particular, on an unused pond created on heavy loamy soils in the semi-desert of the Northern Caspian region are analyzed. At an early stage of spontaneous pond colonization by vegetation, the maximum influence on its development was exerted by the presence of a seed source 300 meters away – in the Arboretum of the Dzhanybek Research Station of the Institute of Forest Sciences (Russian Academy of Sciences) with 120 species of introduced tree and shrub plants. Initially 34 pioneer species colonized the lower parts of the unused pond, and 29 species survived by 2018. The formation of intrazonal willow-oleaster-poplar communities of a quasitugai type with a grass-wet-meadow association has been revealed. Their development was influenced by geographical isolation, self-regulation under rather unstable moisture conditions caused by occasional flooding by melt snow waters and bogging. A differentiation of the upper part of the soil-forming rock brought to the surface has occurred. The forest leaf litter has been formed from uncut moquette with a thickness of 1–2 cm, reaching currently quite substantial deposits of 0.953±0.196 kg/m2 , with the ash content reaching 13.85%. Ca prevails absolutely in the ash composition; while the amounts of Mg, Fe, and K are significantly lower. A humus horizon has been formed and the soil effervescence depth has changed. In the whole, for almost 40 years of vegetation colonization, the previously infertile substrate has acquired features of an immature soil, which is characterized by manifesttion of humus-accumulative process, gradual humification of organic matter and decarbonization of the material. In general, compact, diverse in structure, spontaneously arising self-developing forest biogeocenoses could significantly transform disturbed semi-desert territories. The peculiarities of their structure and the composition of emerging species make it possible to properly choose species preferred for landscaping.