Ecohydrological response of dryland ecosystems to aridification: the role of runoff water redistribution

In general, according to our results we may conclude that the effect of runoff water redistribution by increasing water and related nutrients for vegetation and underlying soil microbial communities buffer the expected negative response of drylands to aridification. The magnitude of this effect depends on the interplay with other environmental factors controlling soil hydrology, such as lithology legacy on soil properties. Finally, we found that this positive buffer effect could be counterbalance in areas of high human disturbance, as the negative effects of degradation on soils and vegetation could exacerbate runoff and nutrients losses and limit the capacity of the remaining vegetation to trap and retain the runoff-water and related nutrients. 

The new set of allometric equations developed in this thesis for the quantification of green biomass and the proposed ecohydrological index can be easily combined to provide a comprehensive coupled assessment of vegetation dynamics and the related processes of water and nutrient transfer from open spaces to plants. Thus, they constitute crucial tools for evaluating the effects of runoff water redistribution across different spatial and temporal scales and for incorporating these effects on Earth System Models (ESMs).