Simulating the water balance in an old non-engineered landfill for optimizing plant cover establishment in an arid environment

Landfills constitute extremely variable and heterogeneous environments and noxious landscapes in urban areas. The risk of a non-engineered landfill is relative to its hydrolologic behavior. Natural or planted vegetation on a landfill has an important role in its interior water balance, erosion control and removal of contaminants, besides imparting aesthetic value. Water deficit and heavy metal pollution are two of the most important factors limiting plant growth and establishment in landfills. The aim of this study was to investigate the colonization status, the ability to establish and the ecophysiological efficiency of different plant species grown on a waste landfill in the Mediterranean area in order to assess their potential for restoring waste landfills. For this purpose three grass species (Festuca arundinacea, Koeleria macrantha and Cynodon dactylon) were chosen for the restoration of a landfill in North Greece. Heavy metal concentration in both soil and plant tissues was determined. Plant density, cover and composition were measured after plant establishment. Assimilation and transpiration rate, stomatal conductance, and leaf water potential were seasonally measured and correlated with available soil water which was calculated using a commercial program for simulating the water balance in a landfill. The results indicate that C. dactylon appears to be ecophysiologically more efficient even though F. also seems able to participate in a forage plant cover at the landfill.