Int. J, Biometeor., 1981, Vol. 25, Number 1, pp. 21-28. Acclimatization of Eucalypts under Semi-Arid Conditions by Y. Reves* and D. Eisikowitch** ABSTRACT. -- Eucalypts were screened all over Israel; survival, habitus, colour, height, mean increment, growth assessment, flowering period, amount of pollen and nectar and fodder quality was recorded. These data were recorded in experimental plots which were established by the Forest Department during the past 30 years. In this paper we have been concentrating on an experimental plot in Gilath area which was planted 6 years ago in 1974. Gilath experimental plot is situated in an area of semi-arid climate conditions; the rainfall is 150-300 mm per annum. The soil in Gilath and the surroundings is loess and sandy loess which is not saline. The Eucalypt species which we found most promising in the Gilath climatic and edaphic conditions were found also most promising in Australia. INTRODUCTION Since the beginningof the present century, many attempts to accomplish afforestation have been made in Israel, among others, introduction of many forest trees and shrubs, in experimental plots, which were planted all over Israel (Heth, 1961; Kaplan, 1963). Many of the species have been introduced from semi-arid zones throughout the world. A significant ,number of plants have been introduced from Australia, among them about 300 different Eucalypts. In this paper we would like to summarize some practical experience which is based on our observations and on previous work. Some of the afforestation purposes are presented in the paper of Kaplan, Karschon and Kolar, published in 1970, and are briefly presented hereby: 1. To provide shelter belts of windbreaks to protect agricultural crops, settlements and industrial plants from wind, sand and dust storms. 2. To protect the soil against water and wind erosion, with vast areas of broken land to be reclaimed by levelling with heavy mechanical equipment and tree planting and inland and coastal sand dunes to be fixed to arrest their advance. 3. To provide recreation grounds to meet the ever increasing demand for outdoor recreation. 4. To produce timber for agriculture and industry, with small size timber and slash for production of fiberboard. * Forest Department, J. N. F. Kiryat-Haim, P. O. Box45, Israel. ** Department of Botany, Tel Aviv University, Tel Aviv, Israel. Present at the Eighth International Congress of Biometeorology, 9-14 September 1979, Shefayim, Israel.