Orchid Flora of the Guelma Region (North-Eastern Algeria), a Little-Known Group for Algerian Flora

Knowledge of Algeria's orchid flora has increased considerably over the past two decades; however, certain regions, such as Guelma Province in northeastern Algeria, remain poorly studied. Between 2013 and 2024, survey work was conducted in this region using a subjective sampling approach. A total of 40 stations were inventoried, and ecological variables such as altitude, exposure, and vegetation cover were recorded to interpret the distribution patterns of orchid taxa. In total, 37 taxa including 16 species, 19 subspecies and 2 hybrids were identified, with a predominance of the genus Ophrys (19 taxa). Among these, ten taxa exhibit a close endemic relationship with neighboring North African territories, and 22 are classified as rare in Algeria. Several taxa also appear as widespread and abundant, enriching the known orchid flora of the study area. Multivariate analyses revealed site typologies and environmental variables influencing the distribution of the recorded species. Cluster analysis identified five distinct Operational Biogeographical Units (OBUs), corresponding to specific environmental characteristics and orchid physiognomies. Furthermore, correlations between the studied taxa and environmental factors suggest that their occurrence is strongly influenced by these variables. Given the high vulnerability of the surveyed sites and the increasing anthropogenic pressures they face, the implementation of urgent conservation measures to protect these habitats and their components is strongly recommended.