Growth and water use by selected seed sources of Eucalyptus under high water table and saline conditions

Abstract

The objectives of the research were (a) to determine which of the several selected Israeli provenances (seed sources) of Eucalyptus camaldulensis and E. occidentalis is growing best under given ecological conditions and high ground water table and salinity; (b) to determine the water consumption, i.e., transpiration (T) of the provenance that is growing best in most of the sites and the influence of the water consumption on the ground water table. Five sites in the Yezre'el valley were selected as representing a wide range of environmental conditions and of secondary salinization. Of the eight provenances selected according to the earlier knowledge, the Hedera and Lake Albaqutya provenances had the highest growth rates at all sites. Under site conditions of low salinity and high ground water table, the 3-year old trees of the Hedera and Lake Albaqutya provenances achieved a mean annual growth rate of 3.7 m in height and 4.3 cm in diameter, respectively. Under higher salinity the mean annual growth rate of the same provenances was reduced to 2.3 m in height and 2.7 cm in diameter. At age of 2.5 years, the daily T of the E. camaldulensis plot of 130 trees per 0.1 ha was between 0.90 and 1.20 mm day −1 in winter time; and between 3.90 and 4.50 mm day −1 on summer days. At age of 3.5 years, T on summer days was between 4.80 and 5.10 mm day −1. The cumulative water uptake by the Eucalyptus trees, i.e., total T from November 1994 to September 1996 was 1882 mm. During this period the effective rainfall amounted to 950 mm, which means that the plantation used 932 mm, in excess of the effective rainfall on the site, which resulted in the lowering of the ground water table by 1.20 m.