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Investigating deciduousness in New Zealand trees using a canopy carbon-gain model.
Dungan, Roger*,1,2, Allen, Rob2, Duncan, Richard1, McGlone, Matt2, Whitehead, David2, 1 Ecology and Entomology Group, Lincoln, New Zealand2 Landcare Research Ltd., Lincoln, New Zealand
ABSTRACT- The native New Zealand flora is of relatively recent biogeoraphic origin, and predominantly tropical and sub-tropical in its affiliations. As a result there are few native deciduous tree species, even though bio-climatic modelling and the success of introduced deciduous trees suggest few limitations to the deciduous habit. This suggests that the New Zealand flora should contain more deciduous trees than it does. It is possible that the carbon costs associated with winter leaf loss have constrained the development of deciduousness in New Zealand trees. We use a canopy-scale model to investigate the carbon-consequences of deciduousness in two co-occurring native tree species with similar ecological roles but contrasting phenology; winter-deciduous Fuchsia excorticata and annual-evergreen Aristotelia serrata. The model scales measurements of leaf photosynthesis to the canopy scale, incorporates independent models of leaf emergence and mortality, and is driven by environmental variables. We test the hypothesis that there is no difference in net annual canopy carbon uptake between Aristotelia and Fuchsia . We apply the model to past climate regimes, allowing us to investigate hypotheses regarding the evolution of deciduousness in the New Zealand setting.
KEY WORDS: Modelling, Deciduous, Canopy, New Zealand