Photosynthesis and water-use efficiency of seedlings from northern Australian monsoon forest, savanna and swamp habitats grown in a common garden

Orchard, Kim A., Cernusak, Lucas A., and Hutley, Lindsay B. (2010) Photosynthesis and water-use efficiency of seedlings from northern Australian monsoon forest, savanna and swamp habitats grown in a common garden. Functional Plant Biology, 37 (11). pp. 1050-1060.

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Abstract

Islands of monsoon rainforest and Melaleuca swamp punctuate vast tracts of savanna in monsoonal northern Australia. Seedlings of species from each of these habitat associations were grown in a common garden. Monsoon forest species had higher specific leaf area, lower photosynthetic capacity and lower photosynthetic light compensation points, and required lower irradiance to achieve 50% of light-saturated photosynthesis compared with savanna or swamp species. These traits probably contribute towards greater shade tolerance beneath dense monsoon-forest canopies, whereas savanna and swamp canopies are relatively open. Swamp species, especially two Melaleuca species, had high stomatal conductance and small CO2 drawdown during photosynthesis, and more negative leaf δ13C, compared with monsoon forest and savanna species. Higher stomatal conductance increases carbon uptake during photosynthesis and a high transpiration rate would increase transport of nutrients to absorbing surfaces in the root by mass flow. Thus, a strategy of high transpiration and low water-use efficiency appears to be favoured in swamp species compared with monsoon-forest and savanna species. Instantaneous measurements of the ratio of intercellular to ambient CO2 concentrations (ci/ca) explained 81% of variation in leaf δ13C across 44 species sampled in this and other studies, suggesting that leaf δ13C generally provides a robust proxy for comparisons of ci/ca, even when applied across species.

Item ID: 30287
Item Type: Article (Research - C1)
ISSN: 1445-4416
Keywords: carbon isotope ratio, Melaleuca, transpiration
Funders: Australian Research Council (ARC)
Projects and Grants: ARC DP0771427
Date Deposited: 20 Nov 2013 09:33
FoR Codes: 06 BIOLOGICAL SCIENCES > 0607 Plant Biology > 060705 Plant Physiology @ 60%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060208 Terrestrial Ecology @ 40%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960806 Forest and Woodlands Flora, Fauna and Biodiversity @ 100%
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