© 2001 Heron Publishing—Victoria, Canada
Effects of thinning on wood production, leaf area index, transpiration and canopy interception of a plantation subject to
drought
David McJannet (1, 3) and Rob Vertessy (2, 3)
1. Monash University, Wellington Rd, Clayton, Victoria 3168, Australia / 2. CSIRO Land and Water, GPO Box 1666, Canberra, ACT, 2601, Australia / 3. Cooperative Research Centre for Catchment Hydrology, Department of Civil Engineering, Monash University, Clayton, Victoria
3168, Australia / Received August 18, 2000
Summary
We conducted thinning trials in a 5-year-old Eucalyptus globulus ssp. globulus Labill plantation near Warrenbayne, northeastern Victoria, Australia, where soil salinization and waterlogging are common,
and assessed treatment effects on tree growth, water use and survival. Half-hectare plots were thinned from the original density
of 1100 stems ha–1 to densities of 800, 600 and 400 stems ha–1, and stem diameter increment, leaf area index, transpiration, canopy interception and depth of tree water source monitored
for 21 months. Two drought periods occurred during the study, rainfall was 30% below the long-term average and there was severe
mortality in all three plots. Analysis of deuterium abundance in soil and xylem water indicated that the trees accessed water
only from the top meter of the soil profile. Transpiration rates were higher in the most heavily thinned plot than in the
least thinned plot, which underwent a reduction in basal area during the study. The most heavily thinned plot increased in
basal area by 10% during the study. Edge trees had significantly greater diameters than trees from the middle of the plots.
Keywords:
edge effect, Eucalyptus globulus, stem diameter increment, transpiration.
