Seasonal Variation in CO2 Efflux of Stems and Branches of Norway Spruce Trees

来自 EBSCO

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作者：

Manuel Acosta Marian Pavelka Radek Pokorny Dalibor Janou and Michal V. Marek

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摘要：

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 CO efflux with special focus on variation in Q (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 CO 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 CO 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 CO efflux. The mean annual Q 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, R, for stems and branches ranged from 1·71 to 2·12 μmol CO m s and from 0·24 to 0·31 μmol CO m s, respectively. The annual contribution of stem and branch CO 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 CO efflux varied diurnally and seasonally, and were related to the temperature of the woody tissue and to growth. The proportion of CO 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.

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关键词：

Stem respiration branch respiration Picea abies seasonal variation temperature Q 10 R 10

DOI：

10.1093/aob/mcm304

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年份：

2008