Environment and the Structure of Scrub Communities on the Limestone Plateaux of Northern Cyrenaica

Abstract

Between the desert lowlands of Egypt and Tripolitania and the wastes of the Libyan 'sand sea', the stepped plateaux of the Jebel el Akhdar of Cyrenaica project, island-like, into the Mediterranean. This area is of outstanding botanical interest, owing partly to its altitude, exceeding 2000 ft. (610 m.) in places, and partly to a geographical isolation almost as effective as that of an island, resulting from the extension of the Libyan desert up to the coast at Agedabia in the west and Tobruk in the east (see map, Fig. 1). It was visited in September 1951, during the first 'phase' of the Aberdeen University Expedition to Cyrenaica.* The expedition was primarily geographical in character, being led by Dr W. B. Fisher (Lecturer in the Department of Geography), and while in this region its main objective was to carry out surveys relating to geomorphology, land utilization and water economy in the neighbourhoods of Derna and Cyrene (Fisher, 1952). The botanical contribution to this end was the comparison of the various communities encountered, in terms of their perennial components which form the permanent structural framework of the vegetation. As far as the short time permitted, evidence of their origins or relationships, and information regarding the effects of certain environmental influences, were sought. Among features of interest in the flora of this area is the fact that its geographical affinities lie mainly with the east Mediterranean (Palestine to Greece) rather than with neighbouring parts of North Africa, and particularly striking are numerous floristic links with Crete (Sandwith & Simpson, 1941). Rikli (1943-8) describes the geographical distri-