Effects of reclamation measures on plant colonization on lignite waste in the eastern Pyrenees, Spain

Abstract

Abstract. This paper deals with vegetation establishment on waste dumps in the montane and submontane belts of the eastern Pyrenees, where submediterranean Quercus humilis forests, Pinus sylvestris forests and mesoxerophilous pastures make up most of the landscape; these are considered as target communities for reclamation. The waste consists of marl and lime regolith, very poor in nutrients and structure (Poch et al. 1989). The dumps were terraced in 1985–1986; some were left for spontaneous re‐colonization and others were reclaimed in various ways. In 1992 we took 36 vegetation samples on the dumps, based on the point quadrat procedure, to evaluate the colonization status and the differences between reclamation techniques. The samples were analysed on the basis of their species composition (ecological groups and multivariate analysis) and structural aspects (coverage, diversity, etc.). Reclamation treatment results varied widely, most of the dumps showing a low degree of naturalness. Colonizing vegetation ranged from a mixture of opportunist and stress‐resistant taxa, forming poorly covered surfaces on the dumps where colonization has been poor, to dense grasslands dominated by one (or a few) introduced competitive grass species, where reclamation procedures had been intensive. Sowing treatments, where pasture species were sown onto dumps, produced intermediate results, as resulting vegetation cover was similar to control plots and naturalness was low, but in a few cases they yielded more interesting swards, fairly dense and diverse, and including high numbers of spontaneous species. Choice of sown species and proximity to undisturbed vegetation accelerate succession.