Marcin W. Woch

Flora of spoil heaps after hard coal mining in Trzebinia (southern Poland): effect of substratum properties

Abstract - The aim of the present study was to investigate the composition of spontaneous plant cover and the physicochemical properties of the substratum of spoil heaps of the Siersza hard coal mine in Trzebinia (southern Poland) abandoned in 2001. Floristic and soil analyses were performed in 2011. The substratum was very diverse in terms of texture (sand: 55-92 %, clay: 6-38 %), nutrient content (total C: 1.3-41.0 %, total N: 0.05-0.49 %, total Ca: 0.5-7.3 %) and pH (3.7-8.7). Moreover, total thallium concentration in the substratum was high, ranging from 6.0 to 14.6 mg kg-1. Plant cover varied from 50 to 95 %. The number of plant species per 4m2 varied from 6 to 29 and correlated negatively with total carbon content (r = -0.85, p < 0.01), and positively with sand content in the substratum (r = 66, p < 0.05). The highest number of species per area unit was observed on a humus substratum, where initial soil has developed on the part of carboniferous waste rock spoil under 20-30 year old trees, and the lowest on carbon shale with coal and culm. Among 197 plant species, most belong to Asteraceae, Fabaceae, Poaceae and Rosaceae families. Hemicryptophytes (49%) and terophytes (18%) predominated. The investigated area was primarily colonized by native species spread by the wind. However, invasive alien species also had a significant share (8%) in the plant cover.

Waste heaps left by historical Zn-Pb ore mining are hotspots of species diversity of beech forest understory vegetation

Metalliferous mining and smelting industries are associated with very high levels of heavy metal(loid) contamination of the environment. Heavy metals have been proved to significantly influence the species diversity and composition of grassland communities, but little is known on their effects on forest understory vegetation. Therefore, the aim of this study was to investigate the effects of the presence of small heaps of waste rock left by historical Zn-Pb ore mining on understory vegetation. The heaps are scattered over vast areas of beech forests in southern Poland. Three types of study plots were established: (1) on waste heaps themselves, (2) in their vicinity (5-10m from the foot of the heaps, with no waste rock but potentially influenced by the heaps through drainage water), and (3) at least 100m from the foot of the heaps (pseudo-control). In all plots vegetation parameters, i.e., plant species number, cover and community composition, life forms and strategies, as well as basic soil properties were assessed. Although the heaps contained high concentrations of metals, namely Cd, Pb and Zn, they were characterised by higher cover and diversity of understory vegetation, including ancient forest and endangered species, in comparison to their surroundings. They were also characterised by the distinct species composition of their plant communities. This might have resulted from the beneficial influence of high pH and Ca content originating from waste rock composed of dolomite and calcite, as well as from increased habitat heterogeneity, e.g. soil skeleton and steeper slopes. Another important factor influencing the richness and composition of understory was tree cover, which relates to the light transmissibility of the canopy. Our study proved that the disturbance brought about by the former mining and processing of metal ores led to the formation of species-rich understory with high frequency and cover of naturally-valuable species.

Relationships between waste physicochemical properties, microbial activity and vegetation at coal ash and sludge disposal sites

The aim of the study was to assess the relationships between vegetation, physicochemical and microbial properties of substrate at coal ash and sludge disposal sites. The study was performed on 32 plots classified into 7 categories: dried ash sedimentation ponds, dominated by a grass Calamagrostis epigejos (AH-Ce), with the admixture of Pinus sylvestris (AH-CePs) or Robinia pseudoacacia (AH-CeRp), dry ash landfill dominated by Betula pendula and Pinus sylvestris (AD-BpPs) or Salix viminalis (AD-Sv) and coal sludge pond with drier parts dominated by Tussilago farfara (CS-Tf) and the wetter ones by Cyperus flavescens (CS-Cf). Ash sites were covered with soil layer imported as a part of technical reclamation. Ash had relatively high concentrations of some alkali and alkaline earth metals, Mn and pH, while coal sludge had high water and C, S, P and K contents. Concentrations of heavy metals were lower than allowable limits in all substrate types. Microbial biomass and, particularly, enzymatic activity in ash and sludge were generally low. The only exception were CS-Tf plots characterized by the highest microbial biomass, presumably due to large deposits of organic matter that became available for aerobic microbial biomass when water level fell. The properties of ash and sludge adversely affected microbial biomass and enzymatic activity as indicated by significant negative correlations between the content of alkali/alkaline earth metals, heavy metals, and macronutrients with enzymatic activity and/or microbial biomass, as well as positive correlations of these parameters with metabolic quotient (qCO2). Plant species richness and cover were relatively high, which may be partly associated with alleviating influence of soil covering the ash. The effect of the admixture of R. pseudoacacia or P. sylvestris to stands dominated by C. epigejos was smaller than expected. The former species increased NNH4, NNO3 and arylsulfatase activity, while the latter reduced activity of the enzyme.

Factors of variation in beech forest understory communities on waste heaps left by historical Zn-Pb ore mining

The species trait-environment relationships in understory vegetation were carried out on metalliferous sites created by historical Zn-Pb mining (S Poland), on which natural revegetation took place. The study sites were 31 small heaps of waste rock covered by an 80-120 year old beech forest. The sites were described in terms of plant coverage, species richness and composition, and the composition of plant traits. Three types of understory communities that were identified were compared for environmental variables and plant parameters. Despite a high concentration of heavy metals in soils, namely Cd, Pb, and Zn, the degree of shading by the tree canopy was the main factor determining variation in understory communities. The understories that developed in low and strong shading were similar to some extent: They had high number of species, and they were characterized by a high proportion of the ancient forest species. The species composition changed substantially with increasing coverage of trees; mixed strategy plants withdrew, while the stress tolerant species became more abundant. The other predictor of community structure was the ratio of Cd to Ca, which was responsible for the decrease of woody plants and the endangered species. This study proved that, in the case of highly complex and productive ecosystems, even with a high degree of contamination with heavy metals, the biotic factors play a primary role.