AOBPreview originally published online on December 5, 2007
Annals of Botany 2008 101(3):469-477; doi:10.1093/aob/mcm304
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Seasonal Variation in CO2 Efflux of Stems and Branches of Norway Spruce Trees
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1
1 Laboratory of Plants Ecological Physiology, Institute of Systems Biology and Ecology, Academy of Sciences of the Czech Republic, Porici 3b, 603 00 Brno, The Czech Republic
2 Institute of Forest Ecology, Faculty of Forestry and Woody Technology, Mendel University of Agriculture and Forestry, Zem
dlská 3, 613 00 Brno, The Czech Republic
* For correspondence. E-mail manuel{at}usbe.cas.cz
Received: 10 July 2007 Returned for revision: 27 September 2007 Accepted: 2 November 2007 Published electronically: 5 December 2007
Background and Aims: Stem and branch respiration, important components of total forest ecosystem respiration, were measured on Norway spruce (Picea abies) trees from May to October in four consecutive years in order (1) to evaluate the influence of temperature on woody tissue CO2 efflux with special focus on variation in Q10 (change in respiration rate resulting from a 10 °C increase in temperature) within and between seasons, and (2) to quantify the contribution of above-ground woody tissue (stem and branch) respiration to the carbon balance of the forest ecosystem.
Methods: Stem and branch CO2 efflux were measured, using an IRGA and a closed gas exchange system, 3–4 times per month on 22-year-old trees under natural conditions. Measurements of ecosystem CO2 fluxes were also determined during the whole experiment by using the eddy covariance system. Stem and branch temperatures were monitored at 10-min intervals during the whole experiment.
Key Results: The temperature of the woody tissue of stems and branches explained up to 68 % of their CO2 efflux. The mean annual Q10 values ranged from 2·20 to 2·32 for stems and from 2·03 to 2·25 for branches. The mean annual normalized respiration rate, R10, for stems and branches ranged from 1·71 to 2·12 µmol CO2 m–2s –1 and from 0·24 to 0·31 µmol CO2 m–2 s–1, respectively. The annual contribution of stem and branch CO2 efflux to total ecosystem respiration were, respectively, 8·9 and 8·1 % in 1999, 9·2 and 9·2 % in 2000, 7·6 and 8·6 % in 2001, and 8·6 and 7·9 % in 2002. Standard deviation for both components ranged from 3 to 8 % of the mean.
Conclusions: Stem and branch CO2 efflux varied diurnally and seasonally, and were related to the temperature of the woody tissue and to growth. The proportion of CO2 efflux from stems and branches is a significant component of the total forest ecosystem respiration, approx. 8 % over the 4 years, and predictive models must take their contribution into account.
Key words: Stem respiration, branch respiration, Picea abies, seasonal variation, temperature, Q10, R10
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