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Modelling environmental limits to light use efficiency for a canopy of two broad-leaved tree species with contrasting leaf habit

Research Archive

Modelling environmental limits to light use efficiency for a canopy of two broad-leaved tree species with contrasting leaf habit

Dungan, Roger John ; Whitehead, David
Type: Journal Article
Permalink: https://hdl.handle.net/10182/3722
Originally published: 2006 by New Zealand Ecological Society and available at http://www.nzes.org.nz/nzje/abstract.php?volume_issue=j30_2&pdf_filename=NZJEcol30_2_251.pdf
Rights: Copyright © New Zealand Ecological Society
Keywords: Aristotelia serrata; Fuchsia excorticata; simulation model; radiation use efficiency; irradiance interception
Fields of Research: 060705 Plant Physiology; 050102 Ecosystem Function

Abstract:

We used outputs from a model of canopy carbon uptake [Dungan et al. (2004) Functional Ecology 18: 34–42] and measurements of irradiance (PAR, 400–700 nm) intercepted by the canopy to investigate the effect of daily changes in environmental conditions on daily light use efficiency, ε, for a canopy comprising two broadleaved New Zealand tree species with contrasting leaf habit. Irradiance absorbed by the canopy was 93% of the incident irradiance, and seasonal changes in the proportion of this absorbed by leaves of each species was estimated with a detailed model of leaf area phenology. Over the year, ε for semi-deciduous wineberry (Aristotelia serrata) was 0.43 g C MJ⁻¹ PAR, with maximum and minimum values of 0.80 g C MJ⁻¹ PAR and 0.07 g C MJ⁻¹ PAR in summer and winter respectively. In contrast annual ε was 0.60 g C MJ⁻¹ PAR for winter deciduous fuchsia, with a maximum value of 0.92 g C MJ⁻¹ PAR in spring. The most important environmental regulator of ε for both species was τ, atmospheric transmissivity. Maximum values for ε were estimated on days when τ ≈0.2, on cloudy days in mid-summer. Limits to photosynthesis from restricted root-zone water availability were also important, showing that drought limitations can restrict ε even at a field site with annual rainfall of 4800 mm. Environmental limits to photosynthesis and ε have been investigated for only a few canopy tree species. Uncertainty in models of the national carbon budget required for reporting purposes would be reduced by considering the environmental regulation of ε for a wider range of tree species.

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