Ref ID: 9013
Ref Type: Journal
Authors: Henskens, F. L., Battaglia, M., Cherry, M. L., and Beadle, C. L.
Pub Date: 2001
Journal Name: Trees: Structure and Function
Volume: 15
Issue: 6
Start Page: 365
End Page: 377
ISBN/ISSN: 0931-1890
Keywords: branch angle/leaf area index/biomass/block/branch/canopy/cost/density/distribution/effect/efficiency/Eucalyptus/farm/foliage/forestry/form/Eucalyptus globulus/growth/implication/isolation/leaf/light/model/parameter/photosynthesis/physiology/plantation/production/spacing/stand/stem/structure/timber/tree
Abstract: We examine the effects of spacing and layout on the growth and form of 3- to 4-year-old Eucalyptus globulus in a farm forestry context. Four planting layouts were chosen. These represented the range commonly in use in farm forestry: block plantings (2x4 in), triple rows (2x4 in) at 10-m intervals, single rows (2x10 in) and isolated trees (10x10 in). The physiological significance of key results is interpreted in terms of changes in the parameters of a simple plantation growth model. Under conditions where levels of direct light are high, for example during summer, block-planted trees intercepted only 38% of the light intercepted by isolated trees. On a stand basis, however, the combination of incident radiation and ground coverage declined with lower stand densities. While stand leaf area index declined from around 6 to 1 with increased spacing, individual tree leaf areas rose from around 50 m(2) in block plantings to 150 m(2) in isolated trees. The proportion of above-ground biomass found in stems declined with increasing spacing as the mass in foliage and branches increased. Stems accounted for 65% of above-ground biomass in block-planted trees but only 35% in isolated trees. The contributions of leaves and branches correspondingly rose from 19% to 35% and from 16% to 29%, respectively. Changes in biomass distribution were accompanied by increasing branch number, branch thickness, flatter branch angles and the longer retention of lower branches with greater spacing. These changes have implications for the merchantability of the timber. The efficiency of above-round radiation conversion was constant at 0.67 g MJ(-1) irrespective of spacing. We estimated that foliar maintenance respiration (R-m) accounted for about 90% of above-ground R-m. On a stand basis R-m costs block plantings 23.90 t DM ha(-1) year(-1) (50% annual above-ground photosynthetic production) compared with 6.22 t DM ha(-1) year(-1) (40% annual above-ground photosynthetic production) in stands of isolated trees.
Notes: Entered by san077 (5/7/2001):
Reprint: Not in File
Program: SPF Sustainable Management
Project: B4
Deliverable: B4-1.2
Confidentiality: Public
Availability: Authors;
Report: Annual Report 2000/1; Annual Report 2001/2
Type: Article
Address: frieda.henskens@ffp.csiro.au