Contrasting photosynthetic characteristics of forest vs. savanna species (far north Queensland, Australia)

Bloomfield, K.J., Domingues, T.F., Saiz, G., Bird, M.I., Crayn, D.M., Ford, A., Metcalfe, D.J., Farquhar, G.D., and Lloyd, Jon (2014) Contrasting photosynthetic characteristics of forest vs. savanna species (far north Queensland, Australia). Biogeosciences Discussions, 11. pp. 7331-7347.

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Abstract

Forest and savanna are the two dominant vegetation types of the tropical regions with very few tree species common to both. Aside from precipitation patterns, boundaries between these two vegetation types are strongly determined by soil characteristics and nutrient availability. For tree species drawn from a range of forest and savanna sites in tropical far north Queensland, Australia, we compared leaf traits of photosynthetic capacity, structure and nutrient concentrations. Area-based photosynthetic capacity was higher for the savanna species with a steeper slope to the photosynthesis - Nitrogen relationship compared with the forest group. Higher leaf mass per unit leaf area for the savanna trees derived from denser rather than thicker leaves and did not appear to restrict rates of light-saturated photosynthesis when expressed on either an area or mass-basis. Median ratios of foliar N to phosphorus were above 20 at all sites, but we found no evidence for a dominant P-limitation of photosynthesis for the forest group. A parsimonious mixed-effects model of area-based photosynthetic capacity retained vegetation type and both N and P as explanatory terms. Resulting model-fitted predictions suggested a good fit to the observed data (R2 = 0.82). The model's random component found variation in area-based photosynthetic response to be much greater among species (71% of response variance) than across sites (9 %). These results suggest that in leaf area-based photosynthetic terms, savanna trees of far north Queensland, Australia are capable of out-performing forest species at their common boundaries.

Item ID: 37266
Item Type: Article (Research - C1)
ISSN: 1810-6285
Additional Information:

© Author(s) 2014. This work is distributed under the Creative Commons Attribution 3.0 License.

Funders: Natural Environment Research Council (NERC), Royal Society of London (RS), Australian Research Council (ARC)
Projects and Grants: NERC NE/F002165/1, RS UK-Australia Award , ARC DP0986823
Date Deposited: 03 Mar 2015 04:06
FoR Codes: 06 BIOLOGICAL SCIENCES > 0607 Plant Biology > 060705 Plant Physiology @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 100%
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