Use of herbaceous species in land reclamation of dump areas in Central Spain

Abstract

Land disposal of municipal and domestic refuses is an oíd practice. Extensivo áreas of land, usually within or near urban áreas, are enployed for controlled tipping or dumping of these refuses. This procedure is often more economical than other treatment alternativos but it requires to concéntrate the wastes on small land áreas and at locations of short distance from the source. In semiarid regions of Central Spain, vegetation is either very sparse or entirely absent on waste heaps, and affected áreas inevitably present a depressing and derelict appearance. In the studied landfills the percentage of plant cover did not represent more than 15%. The usual approach in rehabilitating such áreas is to sow the layer of soil covering the waste with a seed mixture. This policy has the advantage that tolerant plant strains which may accumulate undesirable levéis of toxic metáis are avoided, so that the produced sward is less likely to produce ill effects. Nevertheless, for the dry mediterranean área, there is a lack of suitable conunercial seeds. On the basis that the necessary step for the reclamation of these áreas is to achieve their revegetation our work has been focused on two aspects. First, the study of some plant species that could serve as starting material for the revegetation of these landfills. We have tested in field plots of 0.5 x 1 m: a)commercial and autochthonous species (grasses and legumes); bjtwo seeding seasons (spring and autumn) and c)some plant characteristics, suchas, seed production, dispersión fácilities, and growth pattern, all of them interesting to assure soil protection and persistence of established vegetation. And secondly, the identification of the main limiting factors for plant establishment and growth on landfill surfaces through the understanding of the biological, physical and chemical functioning of the landfill cover systems.