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Ecophysiological responses of a young blue gum (Eucalyptus globulus) plantation to week control

journal contribution
posted on 2023-05-17, 09:26 authored by Alieta EylesAlieta Eyles, Worledge, D, Sands, P, Ottenschlaeger, ML, Paterson, SC, Daniel Mendham, Anthony O'GradyAnthony O'Grady
Early weed control may improve the growth of forest plantations by influencing soil water and nutrient availability. To understand eucalypt growth responses to weed control, we examined the temporal responses of leaf gas-exchange, leaf nitrogen concentration (N) and water status of 7-month-old Eucalyptus globulus L. trees in a paired-plot field trial. In addition, we monitored the growth, leaf N and water status of the competing vegetation in the weed treatment. By the end of the 11-month experiment, complete weed control (WF treatment) of largely woody competitors increased the basal diameter of E. globulus by 14%. As indicated by pre-dawn water potentials of >− 0.05 MPa, interspecies competition for water resources was minimal at this site. In contrast, competition for N appeared to be the major factor limiting growth. Estimations of total plot leaf N (g m−2 ground) showed that competing vegetation accounted for up to 70% of the total leaf N at the start of the trial. This value fell to 15% by the end of the trial. Despite increased leaf Narea in WF trees 5 months after imposition of weed control, the photosynthetic capacity (A1500) of E. globulus was unaffected by treatment suggesting that the growth gains from weed control were largely unrelated to changes in leaf-level photosynthesis. Increased nutrient availability brought about by weed control enabled trees to increase investment into leaf-area production. Estimates of whole-tree carbon budget based on direct measurements of dark respiration and A1500 allowed us to clearly demonstrate the importance of leaf area driving greater productivity following early weed control in a nutrient-limited site.

History

Publication title

Tree Physiology

Volume

32

Issue

8

Pagination

1008-1020

ISSN

0829-318X

Department/School

Tasmanian Institute of Agriculture (TIA)

Publisher

Heron Publishing

Place of publication

202, 3994 Shelbourne St, Victoria, Canada, Bc, V8N 3E2

Rights statement

Copyright 2012 The Author

Repository Status

  • Restricted

Socio-economic Objectives

Hardwood plantations

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