Spontaneous revegetation of post-mining areas (the Langeri River placer gold deposit, Central Sakhalin, Russia)

The aim of this study was to investigate the role of different vascular plants' life forms in post-mining vegetation cover at the Langeri river placer gold deposit, central Sakhalin, Russia (50°6'21''N, 143°10'23"E). Post-mining areas were left for spontaneous revegetation from 1997 to 2010. 58 releves at 10x10 m and 5x10 m plots were completed in five ecotope types. There were rock dumps after trammel operation, lower sites between rock dumps, tailing ponds, open pit mine areas ("young floodplain" after the river water penetration in the mining area) and young alluvial surfaces along riversides. The relative number of species and the relative plant cover for each group was counted in sample plots. A ternary graph was used to display relative contribution of species groups. PCA with log conversion for initial matrix was used to transform multiple data: six relative plant communities' attributes, total plant cover and floristic richness. This research has identified 25 woody, 78 perennial and 17 annual and biennial herb species. Salix udensis, S. schwerinii,Betulaplatyphylla,Populus suaveolens are frequent and abundant in the woody group. Trifolium repense, Chamaenerion angustifolium, Anaphalis margaritacea, Pilosella x floribunda and Typha latifolia (exclusively in tailing ponds) dominated among herbs. The role of woody plants is great at rock dumps, but the total cover in this ecotope is low (5%, in average). Perennial herbs dominated in open pit mining areas (cover 20%), tailing pond surface (cover 35%) and young alluvial surface along riversides (cover 15%). The total cover of woody and perennial plants at lower sites between rock dumps is about 60%. Annual and biennial species abundance is low in all ecotope types (cover 0.2-0.4%). Plant community species composition at post-mining sites is conditioned by seed rains from the surrounding areas. Although seeds of the surrounding dominant trees germinate on pits and tailings, the herbaceous layer at all sites is specific and is characterized by low cover. PCA shows that the vectors of the relative number and the relative cover of woody species and the vectors of the total plant cover, the relative number and the relative cover of perennial herb species are oppositely directed. The study results conclude that the initial stages of spontaneous revegetation in post-mining areas occur with vascular plants of different life forms. The dominance of plants of a particular life form depends on the ecotope type. The revegatation measures in post-mining areas should take into consideration the peculiarities of all heterogeneous ecotopes and their ability to support plants of different life forms.

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