Few studies addressed the distribution of riparian trees and shrubs, and the factors affecting their distribution and structure in Lebanon. The objective of this investigation is to identify the riparian tree and shrub species around Nahr Ibrahim River. We selected 21 sites covering all altitudinal range from sea level up to 1766 m as well as a cross section gradient from river bed. Results showed that biodiversity indices are affected by bioclimatic conditions (vegetation stages) and river flow regime. A moderate dry period of less than 3 months seems to have a positive effect on species richness and composition (trees vs shrubs). A regulated flow would increase the number of tree individuals and reduce biodiversity. Salix acmophylla Boiss., Salix alba L. and Platanus orientalis L. are obligate riparian (phreatophytes) and Salix libani Bornm., Ostrya carpinifolia Scop., Juglans regia L., Crataegus monogyna Jacq. are classified as facultative riparian (facultative phreatophytes). Further we were able to classify riparian species according to gradients related to altitude, slope, distance from river bed and number of dry months. |
