Soil erosion modeled with USLE, GIS, and remote sensing: a case study of Ikkour watershed in Middle Atlas (Morocco)

Abstract The Ikkour watershed located in the Middle Atlas Mountain (Morocco) has been a subject of serious soil erosion problems. This study aimed to assess the soil erosion susceptibility in this mountainous watershed using Universal Soil Loss Equation (USLE) and spectral indices integrated with Geographic Information System (GIS) environment. The USLE model required the integration of thematic factors’ maps which are rainfall aggressiveness, length and steepness of the slope, vegetation cover, soil erodibility, and erosion control practices. These factors were calculated using remote sensing data and GIS. The USLE-based assessment showed that the estimated total annual potential soil loss was about 70.66 ton ha−1 year−1. This soil loss is favored by the steep slopes and degraded vegetation cover. The spectral index method, offering a qualitative evaluation of water erosion, showed different degrees of soil degradation in the study watershed according to FI, BI, CI, and NDVI. The results of this study displayed an agreement between the USLE model and spectral index approach, and indicated that the predicted soil erosion rate can be due to the most rugged land topography and an increase in agricultural areas. Indeed, these results can further assist the decision makers in implementation of suitable conservation program to reduce soil erosion

African pollen database inventory of tree and shrub pollen types

African pollen data have been used in many empirical or quantitative palaeoenvironmental reconstructions. However, the pollen types used in these studies were not controlled and standardised, preventing the precise understanding of pollen-plant and pollen-climate relation that is necessary for the accurate quantification of continental scale climate change or ecological processes in the past. This paper presents a summary of the progress made with the African Pollen Database (APD) inventory of plant diversity from pollen data extracted from 276 fossil sites and more than 1500 modem samples, with a focus on tropical tree pollen types. This inventory (1145 taxa) gives, for each pollen taxon whose nomenclature is discussed, information on the habit, habitat and phytogeographical distribution of the plants they come from. Special attention has been paid to pollen types with similar morphology, which include several plant species or genera, whose biological or environmental parameters can differ considerably