The current study described and compared the plant species structure, composition and diversity in Lebanon and California the only mediterranean climate areas in the Northern Hemisphere. The mediterranean-type climate is characterized by a dry hot summer and a wet mild winter. An altitudinal gradient was set up extending from sea level to 1750 m.a.s.l. and 63 relevés of 10 m x 10 m were sampled throughout the mosaic in each study area. The selected areas were located at the same latitude, i.e. at latitude 34° 24' to 34° 33? N and longitude 35° 48' to 36° 04' E for Lebanon and at 34° 24' to 34° 40' N and longitude 119° 34' to 120° 14' W for California, respectively. Among the numerous research questions that such an analysis might generate are the following: a) How do community composition, structure and diversity change with altitude? b) Which growth forms contribute strongly to plant species diversity in both study areas? c) How do environmental variables, in particular soil variables, change with altitude? d) What is the effect of disturbance on species composition and diversity?weiterlesen