Since their establishment, “traditional” oases have been known to be three-layered, while modern oaseshave been organized from their outset with one layer only of ‘Deglet Nour’ date palm cultivars. However, these definitions may no longer apply for Kebilian oases. A survey was therefore carried out on a random sample of 52 plots in Kebilian oases (“traditional” n=26 and “modern” n=26) to investigate the current situation. The data collected were analysed by the Pivot Tables method and a Chi-2 test of independence, and by a Multiple Component Analysis completed by an Ascending Hierarchical Classification analysis to characterise and classify each oasis type. Our results showed that “modern” oases have greater crop diversity than expected and can be organized in two or three-layer oases. In contrast, high crop diversity and the three vertical layers were found to be less frequent than expected in “traditional” oases. Our investigation found water availability in the oases, and irrigation frequency, to be the key factors of Kebilian oasis layout and typology changes. Agro-biodiversity losses could jeopardize the sustainability of the oasis system in “traditional” oases.