SUIVI A LONG-TERME DANS LA STEPPE D'ARMOISE BLANCHE (ARTEMISIA HERBA-ALBA ASSO.) DU SUD-ORANAIS (ALGERIE) : FACTEURS ET INDICATEURS DE CHANGEMENTS
Abstract
Long-term monitoring of Gray-leaved Sagebrush (Artemisia herba-alba Asso.) steppe in southern Oran Region (Algeria): factors and indicators of change. The Gray-leaved Sagebrush (Artemisia herbs Alba Asso.) steppes in the Southern Oran region in Algeria are rangelands of great pastoral interest. 40 Years long-term dynamics of these steppes has been studied since 1975 using a diachronic monitoring (i) in permanent site considering five reference years and (ii) in 30 sites in the rest of the sagebrush steppe in 1975-76 and 2013-2015. Results generally show degradation with changes in the community composition and species dominance with appearance or extension of indicator species reflecting changes in land -use and environmental conditions. The increase in ephemeral species may explain the increase in the beta diversity, while the gamma diversity decreased underlying a trend toward banalization of the plant community composition. Unlike the rest of the pre-existing sagebrush steppe, in the monitoring site, following a series of rainy years, sand which had been fixed would have played an important role in the recovery of the vegetation cover.