Cartography and chemical profiling of rosemary essential oil in Eastern High Atlas Mountains, Morocco

Abstract

Rosmarinus officinalis is a shrub grown spontaneously in Mediterranean basin. It has a large use in pharmaceutical industry due to their bioactive molecules within their essential oils and crude extracts. This plant covers huge areas in Morocco and offers considerable incomes to the local cooperatives, particularly in the Eastern High Atlas Mountains. However, lack of accurate data about the distribution range and the geographic chemical variability are impediments to decision makers to set a sustainable management plan and effective marketing strategies for rosemary products. Thus, the aim of this study is to delineate rosemary land cover in this region with focus on the chemical variability of its essential oil. In that respect, four Sentinel-2A L2A satellite images were mosaicked, georeferenced and clipped to the study area, which concerns the collectivities of Boumeriem and Talsint, Bouchaouen, Beni Tedjite, and Maaterka (Oriental, Morocco). Then, the images were assessed with an object based approach through segmentation and binary classification (rosemary’s shrubs; other lands) that were processed respectively by the multi-resolution and random forest algorithms, incorporated in ecogition v8.8 software. Training and validating data were collected through fieldworks. For the chemical characterization, rosemary leaves were harvested from different locations in Boumeriem and Talsint localities, and extracted with Clevenger apparatus. The obtained essential oils underwent later Gas chromatography-mass spectrometry analysis for the chemical identification. As regards cartography, the obtained map have shown that the most important rosemary shrubs cover 60 643 ha and 75 800 ha respectively for Boumeriem and Talsint collectivities. For the chemical composition, all samples showed high content of 1,8-cineole (50.57–62.34%), whereas Camphor and α-Pinene relative concentration didn’t exceed 14.10% and 8.94%, respectively.