Abstrakt
Post-mining sites are characterised by unfavourable soil conditions which limit the recovery of ecosystem functions. The growth of legumes, which are able to increase soil nitrogen content and accelerate the primary succession, can be limited by soil conditions as well as by grass competition.
We performed a greenhouse pot experiment using various soils from spoil heaps where we planted legumes, namely, Trifolium pratense and Lotus corniculatus, and a grass, Poa compressa. The aim was to determine their growth and interaction-competition vs facilitation - with respect to their biomass and a response to the δ(15)N in plant biomass.
The variation of substrates was given by using soils of various ages (from 15 to 60 years old) and their previous management-reclaimed or unreclaimed (spontaneously overgrown) sites in spoil heaps in the Sokolov coal mining district (The Czech Republic). The growth of plants studied increased with substrate age and plants grew faster in reclaimed than successional substrates, but the differences decreased with age.
Symbiotic nitrogen fixation supported the growth of legumes and made them favourable, especially in early substrates, where the grass was suppressed. The legume-grass competition increased with substrate age and nitrogen content in soil but was not significant for T. pratense.
The effect of facilitation was not observed. Legumes showed as strong competitors with the grass in post-mining sites substrates and do not facilitate the grass.
Legumes could contribute to adding nitrogen to the poor substrates through the decomposition of their high biomass, according to the studies done in a real situation.