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Abstract
In Morocco, rosemary stands are mainly threatened by current practices which compromise their sustainability. To improve harvesting practices within natural stands, an experimental design was followed during 4 years in Debdou forest, Eastern Region of Morocco, where rosemary covers large areas. Harvesting practices tested to operate rosemary at different seasons of the year influenced regeneration of leaf biomass and essential oils production. During spring, the clear-cut allowed the best resumption, the highest yield of essential oil (2.03 %), and a supported production in leaf biomass. In summer, harvesting operations must be avoided because of their negative effect on vegetal growth and essential oils yields. Harvesting half of the clumps during autumn has the advantage to keep the part of the plant that is going to flower soon at the end of autumn, thus allowing rosemary clumps to play, firstly, their nectar-producing to beekeeping role, and secondly, to ensure the production of seeds for natural regeneration. Finally, winter is a convenient period for the rejuvenation of rosemary shrubs. Therefore, the best rate of resumption was obtained by clear-cutting (179.4 %) which allows a better regeneration and an improvement of the production. The best essential oil yields extracted from leaves, by hydro-distillation, were obtained during spring. Results of a chemical analysis, by GC-MS, showed that chemical composition did not varied drastically during different seasons and these essential oils were characterized by high amounts of 1,8-cineol (51.6–54.9 %) followed by significant quantities of α-pinene (6.4–8.5 %), camphor (12.6–16.9 %) and borneol (5.3–8.6 %).