Growth and water use ofEucalyptus globulusandE. nitensin irrigated and rainfed plantations

Abstract

Early patterns of growth and water use of Eucalyptus globulus subsp globulus Labill. and Eucalyptus nitens (Deane and Maiden) Maiden were measured for the first four years in a plantation established on a low rainfall site in south-east Tasmania. Half the plantation was irrigated to maintain soil water deficits at levels where available water did not limit growth: the other half was subjected to a series of water stress cycles which were interrupted by rainfall or terminated by supplementary irrigation to end severe drought stress.Height of E. globulus was greater than that of E. nitens irrespective of water status. For both height and diameter, differences due to levels of available water remained insignificant until the third year of growth. Increments in volume were significantly higher in E. globulus than E. nitens in the third and fourth year of growth and these differences were more apparent in the rainfed than the irrigated treatment. However there were no differences in water use between species for either treatment in the second, third or fourth year of growth. Maximum rates of growth were associated with total water use just above pan evaporation.The ratio of water use (mm water) to volume increment (m 3 ) was always lower for E. globulus than E. nitens. It was concluded that E. globulus was more suited to sites where moderate water stress is experienced as part of the normal annual growing cycle.

ABOVEGROUND BIOMASS GROWTH AND YIELD OF FIRST ROTATION CUTTING CYCLE OF Acacia AND Eucalyptus SHORT ROTATION DENDROENERGY CROPS

“…In another study in Tasmania, with soil derived from sands and climatic conditions similar to those of the Santa Rosa site, E. globulus reached a diameter of 50 mm and a height of 235 cm, 14 months after establishment in stocking of 1111 trees ha -1 (O'Grady et al, 2005); these values were higher than those observed herein. Similar results were reported by Honeysett et al (1996), who also reported lower diameters than those obtained in the present study.…”

Daily stem growth patterns in irrigated Eucalyptus globulus and E. nitens in relation to climate

“…515 mm) and below that normally suited to plantation establishment. The management of the site has been described elsewhere (Honeysett et al 1996;White et al 1996). Six weeks after planting, phosphorus was applied as triple superphosphate at 120 kg/ha elemental P. Nitrogen was applied as urea at 100 kg/ha elemental N in three applications (40% in August, 30% in both December and March) in 1990/1991and 1991/1992 and at 60 kg/ha N each August from 1992 to 1996.…”

“…Soil moisture content was monitored regularly throughout the site using a neutron moisture probe (CPN 503 Hydroprobe) (Honeysett et al 1996;Worledge et al 1998). An automatic weather station was located on an exposed hill at the same elevation approximately 500 m south-west of the site.…”

“…Soil water deficit in the irrigated treatment was not allowed to exceed approximately 40 mm (Honeysett et al 1996) except on two occasions during winter to encourage root development. Soil water deficit was defined as the amount of water required to return the soil to field capacity.…”

High-resolution analysis of radial growth and wood density in Eucalyptus nitens, grown under different irrigation regimes

“…The first plot was irrigated (treatment A) to avoid water stress, and the other two plots (treatments B and C) were managed under cycles of drought. Irrigation was applied through micro-sprinklers and soil water deficits of the irrigated plot (treatment A) were not allowed to exceed around 40 m [15], except on two occasions during winter to encourage root development. Soil water deficit was defined as the amount of water required returning the soil to field capacity.…”