title: Morphological and moisture availability controls of the leaf area-to-sapwood area ratio: analysis of measurements on Australian trees.
abstract: The leaf area-to-sapwood area ratio (LA:SA) is a key plant trait that links photosynthesis to transpiration. The pipe model theory states that the sapwood cross-sectional area of a stem or branch at any point should scale isometrically with the area of leaves distal to that point. Optimization theory further suggests that LA:SA should decrease toward drier climates. Although acclimation of LA:SA to climate has been reported within species, much less is known about the scaling of this trait with climate among species. We compiled LA:SA measurements from 184 species of Australian evergreen angiosperm trees. The pipe model was broadly confirmed, based on measurements on branches and trunks of trees from one to 27 years old. Despite considerable scatter in LA:SA among species, quantile regression showed strong (0.2 < R1 < 0.65) positive relationships between two climatic moisture indices and the lowermost (5%) and uppermost (5-15%) quantiles of log LA:SA, suggesting that moisture availability constrains the envelope of minimum and maximum values of LA:SA typical for any given climate. Interspecific differences in plant hydraulic conductivity are probably responsible for the large scatter of values in the mid-quantile range and may be an important determinant of tree morphology.
authors: Department of Biological Sciences, Macquarie University Sydney, New South Wales, Australia.
authors: Henrique Furstenau
authors: HF
authors: Togashi
authors: Department of Biological Sciences, Macquarie University Sydney, New South Wales, Australia ; AXA Chair of Biosphere and Climate Impacts, Grand Challenges in Ecosystems and the Environment and Grantham Institute - Climate and Environment, Department of Life Sciences, Imperial College London, UK.
authors: Iain Colin
authors: IC
authors: Prentice
authors: Department of Biological Sciences, Macquarie University Sydney, New South Wales, Australia.
authors: Bradley John
authors: BJ
authors: Evans
authors: Department of Forest and Ecosystem Science, The University of Melbourne Melbourne, Victoria, Australia ; Chair of Silviculture, Faculty of Environment and Natural Resources, Freiburg University Freiburg, Germany.
authors: David Ian
authors: DI
authors: Forrester
authors: Natural Resources Branch, Department of Parks and Wild Life Bentley, Western Australia, Australia ; School of Plant Biology, University of Western Australia Crawley, Western Australia, Australia.
authors: Paul
authors: P
authors: Drake
authors: Chair of Silviculture, Faculty of Environment and Natural Resources, Freiburg University Freiburg, Germany.
authors: Paul
authors: P
authors: Feikema
authors: Agricultural Resource Risk Management, Department of Agriculture and Food Albany, Western Australia, Australia.
authors: Kim
authors: K
authors: Brooksbank
authors: School of Environment, University of Technology Sydney Sydney, New South Wales, Australia ; National Centre for Groundwater Research and Training Sydney, New South Wales, Australia.
authors: Derek
authors: D
authors: Eamus
authors: Department of Biological Sciences, Macquarie University Sydney, New South Wales, Australia.
authors: Daniel
authors: D
authors: Taylor
keywords: Climatic moisture; leaf area; pipe model; plant hydraulics; sapwood area; tree morphology