Pattern of natural plant colonization of opencut spoil banks in the Khakass Arid Areas

Abstract

Data are given from 5-year observations of a pattern of natural regeneration of the plant cover in opencut spoil banks formed in the eighties of the last century as a result of open-pit coal mining in the arid regions of Khakasia. Dumps formed in the eighties are related to external ones. Primary successions on opencut spoil banks are characterized by grass colonization type. A dominating role in plant communities belongs to synanthropic motley grasses species: mugwort ( Artemisia vulgaris ), sieversian wormwood ( A. sieversiana ), tansy-leaved wormwood ( A. tanacetifolia ), wormseed wallflower ( Erysimum cheiranthoides) , bristly thistle ( Cirsium setosum ), and etc. Among grasses, the following species prevail: Krylov feather grass ( Stipa krylovii ), branched wheatgrass ( Agropyron ramosum ) (plateau), steppe bluegrass ( Poa stepposa ) (northern slope), green foxtail ( Setaria viridis ) (western slope); among legumes, this is yellow melilot ( Melilotus officinalis ) (northern slope) badly eaten by animals. Phytocoenoses with a specific set of dominant species distinguished by the vertical structure and biomass reserves are formed at each element of mesorelief (slopes of northern and western exposure, plateau). Phytomass of pioneer communities on dumps formed in the eighties is higher than that of sod grass steppes, which existed here previously. At all sites studied, the aboveground phytomass dominates the underground mass. The highest values of biomass reserves in the plant communities covering overburden dumps in the Khakass dry steppe have been observed on the plateau and slopes of northern exposure, where the best micro-climatic conditions are.