During long-term research (almost forty years) of tailings containment in Chvaletice (Eastern Bohemia) were also carried out studies on the role of each plant dominants in succession. This review presents the most interesting results of these studies.
Responses of Vegetation Stages with Woody Dominants to Stress and Disturbance During Succession on Abandoned Tailings in Cultural Landscape
Studies of ecological succession on tailing containments (abandoned sedimentation basins with waste deposited by a factory producing sulphuric acid from pyrite ore) near the village of Chvaletice (Eastern Bohemia, Czech Republic) were carried out since 1973 with increased intensity and complexity between 1986 and 2002 (Kovář 2004). Vegetation cover in its relationships to various factors has been periodically monitored up to now. The abandoned ore-washery deposit is characterized by relative strong toxicity of the sediment material (high heavy metal content) and fluctuations of the microsite conditions up to extreme values (pH, salinity, surface temperatures). Species richness and the courses of some ecological processes are influenced both by availability of plant diaspores (regional species pool) determined with the presence of adequate dispersal mechanisms (anemochory, zoochory) and by the seasonal moderation of environmental variables excluding stress non-tolerant species at extreme epizodes and enabling survival of resistant species during the competition. Long lasting existence of patches without any vegetation together with herbaceous types of stands and woody successional stages create mosaics on the surface plateau. The oldest tree stands (in average 20 - 30 years old) are predominantly formed by Populus tremula and Betula pendula, with minor admixture of Salix sp. div. (mainly S. caprea), Pinus sylvestris, Quercus robur or Cerassus avium, rarely Sarothamnus scoparius. The abundance ratio of two main dominants, aspen and birch, was changed for the benefit of the first one after the summer fire in extremely hot days. The effect of clonality on aspen regeneration and regrowth immediately after the fire disturbance was profitably manifested and it apparently facilitates the present state with aspen prevailing in the most forested tailing places at present, seventeen years after the fire. This fact supports the importance of clonal plant species role during primary succession.
This article examines the consequences of a fire (August 1994) which burned the vegetated surface of abandoned tailings containment in mosaic pattern, in Chvaletice (Eastern River Elbe basin, Czech Republic). Vegetation succession with adjacent processes (such as leaf litter decomposition) was then monitored in comparisons on burned and unburned plots. The influence of the introduced plant organic matter by mulching on the biological soil crust was also investigated. Apart from the naturally burned plots, some plots were also experimentally burned. The soil moisture and surface temperatures in different temporal distances from the fire experiment were measured. There were no significant differences in decomposition rate between the plots that were affected and/or unaffected by fire. The daily temperatures of the burned soil surface increased after the fire, while its night temperatures decreased. The moisture content of the soil surface was reduced after the fire. Addition of dry local aboveground plant biomass on the substrate surface suggests that substrate roughness provides retention to seeds transported by wind, and protects the rhizosphere against extreme heat, drought and salt incrustation. Furthermore, it positively modifies the hydrological regime of microsites and stimulates the creation of a humus soil layer and enrichment of the substrate by nutrients. Finally, it facilitates colonisation by plant seedlings from seeds transported by anemochorous or zoochorous mechanisms.
control of the monomeric composition of the products. Moreover, continuous cultivations allow using substratestoxic already at low concentration, such as precursors of special PHA building blocks. While one-stage continuous processes are rather the method of choice for production of compounds of the primary metabolism, but not for secondary products synthesized by multistage processes, as it is the case for PHA, it is beneficial to produce catalytically active biomass in a first continuous stage at high cell densities; in a second stage, this biomass accumulates PHA