Plant occurrence on burning coal waste – a case study from the Katowice-Wełnowiec dump, Poland

Coal-waste dumps superimposed on former rubbish dump frequently undergo selfheating and selfignition of organic matter dispersed in the waste. The special conditions for plant growth generated as a result have been investigated since 2008 on the municipal dump reclaimed with coal wastes in Katowice-Wełnowiec, Poland. The plants observed most frequently where heating has occurred are Sisymbrium loeselii, Artemisia vulgaris, Sonchus arvensis, Chenopodium album, Achillea millefolium, Cirsium arvense, Amaranthus retroflexus, Atriplex nitens and Solanum nigrum. Some new, rare species such as Portulaca oleracea, first noticed in 2011, may be added. Most of encroaching species are annual, alien archeophytes and neophytes. Native species are mainly perennials. The majority of these species show a tendency to form specimens of huge size (gigantism). The abundance of emitted CO2 and nitrogen compounds is the likely cause of this. Additionally, the plants growing there are not attacked by insects. The heating of the ground liquidates the natural seed bank. After cooling, these places are seeded by species providing seeds at that very moment (pioneer species). Heated places on the dumps allow plant growth even in the middle of winter. As the seasonal vegetation cycle is disturbed, plants may be found seeding, blooming and fruiting at the same time.