Piliostima reticulatum shrubs constitute "islands of fertility" in the soil beneath the canopy with better availability of water and more intense biological activity. Assessment of diversity and understanding factors underlying species distribution are fundamental themes in ecology. However, the diversity of native Vesicular Arbuscular Mycorrhizal (VAM) species in sudano-sahelian agro-ecosystems are weakly known. This research was carried out to understand the contribution of VAM on “islands of fertility” by (i) assessing the morphological diversity of indigenous VAM species in soils within and outside the influence of the shrub Piliostigma reticulatum in Senegal and (ii) examining the effects of soil chemical properties on this diversity. Soils were collected from a depth of 0 - 30 cm in the beneath of canopy (SC) and outside canopy (HC) at ISRA experimental station located at Nioro du Rip in Kaolack, Senegal. Morphological diversity of VAM spores was done after extraction by wet sieving. The effect of the presence or absence of P. reticulatum were analyzed with a one-factor ANOVA. Principal Components Analysis (PCA) was performed to determine relationships between morpho-species diversity parameters and soil chemical properties. Results showed that the genus Glomus, Scutellospora and Gigaspora were found in both soils (SC and HC) and Sclerocystis spores were only found outside canopy (HC). VAM spores were more abundant and more diverse in soil outside the influence of P. reticulatum (HC) than the soils beneath canopy (SC). Ultimately, this study tends to confirm that soil chemical properties have effect on VAM diversity.