Research of recultivated coal mining spoil heap in sw-Hungary

Abstract

Unreclaimed spoil heaps have remarkable impact of the surrounding landscape. The aesthetical value of the landscape is decreased and the damage of environmental pollution is intensified. The purpose of the recultivation is to create new habitats with semi-natural vegetation. Our study was executed in Zobak coal mine in the Mecsek Mountains, in southwest Hungary. The natural vegetation of Zobak area is oak-hornbeam (Asperulo taurinae-Carpinetum) and beech (Helleboro odoro-Fagetum) forest, which can be regarded as the target of the recultivation. Mining in Zobak area has been ended in the year of 2000. The mining company after the closure have planted grasses (2001), trees and shrubs (2002). The planted trees and shrubs: Acer campestre, Carpinus betulus, Cornus mas, Tilia tomentosa, Crataegus monogyna, Fraxinus ornus, Prunus spinosa, Quercus cerris. These species are native in Mecsek Mountains, and some of the species are very dry-tolerant. The research was carried out in spring and summer of 2011. Six transects in six directions (from north to northwest) were placed starting from the south (highest) side of the area. The species composition, and game damage of shrub and herb layer have been determined along the transects. Every woody species were recorded, and measured the height of every individuals, and defined the game damage (browsing damage). The woody species were recorded in five height (0–20,20–40,40–80, 80–160 and above 160 cm), and five game damage category. In the six transects 536 individuals of 14 tree and shrub species were found. All planted species were found in the study area, and moreover we found 6 spontaneous growth species (Eleagnus angustifolia, Ligustrum vulgare, Pyrus pyraster, Robinia pseudo-acacia, Rosa canina, Rubus fruticosus). The majority of measured individuals (66%) were in the 3^rd (between 40-80 cm) and 4^th (between 80-160 cm) height category, some individuals were in 2^nd (between 20–40 cm), and 5^th (above 160 cm) height category. Height of Tilia tomentosa and Quercus cerris individuals were outstanding. From the assessed 536 individuals of shrubs and trees, 195 were undamaged and 341 were browsed by large games. In this area the browsing rate is 64%, so the pressure of wildlife is high. The game damage of Tilia tomentosa, Crataegus monogyna and Quercus cerris individuals were low damaged, and undamaged. 93% of Tilia individuals were in the 1^st (not browsed) game damage category. The highest browsing was found on Carpinus betulus and Fraxinus ornus. These species occurred in greater proportion in the 3^rd and 4^th game damage category. Recultivation followed by ten years of spontaneous development has led to diverse semi-natural vegetation, which fits well into the surrounding landscape. Compared to literature data from nonrecultivated spoil heaps, recultivation accelerated the process of succession with about ten years. The damage of environmental pollution has been discontinued; Zobak spoil heap has been covered with a mosaic of tree stands and herbs. The species selection was successful, all planted species have survived, and grown properly. The two most appropriate species of recultivation are Quercus cerris and Tilia tomentosa. Legally prescribed aims of recultivation are fulfilled, but from the viewpoints of botany and nature conservation, the area is far from natural yet. In the future, more systematic examination of the course of succession, repeated every 5–10 years is recommended