Intensity of ecohydrological interactions in reclaimed Mediterranean slopes: Effects of run-off redistribution on plant performance

We have conducted a field experiment to ascertain the role of ecohydrological interactions between run-off source areas and sink patches in the dynamics of artificial slopes derived from open cast coal mining in central-eastern Spain. We analysed the effects of run-off interruption on soil moisture, on the leaf water potential of woody species and on the herbaceous biomass in vegetation patches of three reclaimed slopes subjected to a different disturbance degree resulting from different overland flow volumes running down the slopes. Soil moisture and plant performance were seriously affected by run-off exclusion, and this effect was more intense as level of disturbance increased. In fact, run-off redistribution appeared to be determinant for plant performance in the more disturbed slope, whereas the presence of the shrub Genista scorpius appeared to be more determinant for plants in the less disturbed slope. Our results confirm the validity of the Trigger-Transfer-Reserve-Pulse model in artificial slopes during the aggradation process. These results point out the importance of run-off redistribution between vegetation patches in the evolution of artificial slopes by creating fertility islands that improve the performance of vegetation. Restoration practices in drylands may thus significantly improve if a 'run-off expert management' strategy is adopted. © 2012 John Wiley & Sons, Ltd.