Effects of restoration actions on soil and landscape functions : Atriplex nummularia L. plantations in Ouled Dlim (Central Morocco)

Fodder shrub plantations (Atriplex nummularia L.) were extensively introduced in dryland areas of central Morocco (Marrakech province, Ouled Dlim and Ouled Nejim municipalities) to rehabilitate degraded rangeland and to mitigate desertification processes. These interventions deeply modified the original rural landscape, characterized by sparse vegetation cover in relation to a long history of intense grazing and subsistence cropping, and by soils prone to surface crusting and to high runoff generation. The Landscape Function Analysis (LFA) was applied to study the effects of the Atriplex plantation on soil and landscape functions. The LFA landscape functional indicators (Landscape Organization Index, LOI; Patch Area Index, PAI; Number of Patches, NP; Patch Number Index, PNI) were measured along seventeen 50-m-long transects, established to compare five "actions" (CR, Cropped; GR, Grazed; MA, Mature plantation; YA-1, Young plantation with moderate biomass development; YA-2, Young plantation with good biomass development). The LFA soil surface indicators, and the related NC (Nutrient Cycling) and IR (Infiltration/Runoff) indices were assessed in the observed ecological patches and inter-patches, for a total number of 157 microsites. Biomass production was measured in all the studied plantations. Multiple group comparison analysis was performed to compare the mean values of the LFA indices according to action and patch types. Correlation analysis was carried out to study the relationships between biomass and functional indices. The results obtained show that the young and well developed plantations have the stronger impacts on all the LFA indices and that the plantation effects are mostly linked to the localized synergistic effect of the plant-furrow association. In the study area the LFA provided an effective metric to assess the relative effectiveness of the actions compared.