<i>ANALYSING SOILS AND SPONTANEOUS PLANT SPECIES OF SEALED LANDFILLS FOR THE PHYTORESTORATION OF POLLUTED AND DEGRADED SOILS OF CENTRAL SPAIN</i>

Abstract

The soils of old, sealed landfills in the Madrid Community, which are of a mixed nature (urban and industrial waste), are among the most contaminated in heavy metals of the area. Several features of these environments are presently being evaluated. The aim of this report was to provide an overview of the main plant species growing in these soils. An inventory was made of the plant species that spontaneously grow in the soil cover of 14 landfills. In most of these dumps, pollution-salinity problems are added to those of strong erosion processes. Close to 300 species were recorded in landfills situated on arkose substrates, and 170 species were found growing in landfills overlying granite. Landfills on limestone-marlaceous substrates sustained the growth of some 230 species. Approximately 100 species were found to grow over gypsum. Poaceae were the most numerous species recorded in landfills overlying granite and «gypsum and gypsiferous marl». Asteraceae species were the most abundant in arkosic and «limestone-marlaceous» soils. The third most represented family was the Fabaceae, which was followed by the Caryophyllaceae and Cruciferae. The species Lolium rigidum and Dactylis glomerata were commonly observed in most of the landfills and substrates. These species are of particular interest, since they are able to fix soils and protect them from erosion. Anacyclus clavatus was the most commonly found Asteraceae, and Hirschfeldia incana and Spergularia rubra were, respectively, the most represented Cruciferae and Caryophylaceae in all the landfills. Most of the soil variables determined were generally higher in the landfills with respect to those of surrounding reference ecosystems.