Chin J Plant Ecol ›› 2005, Vol. 29 ›› Issue (4): 680-691.

• Research Articles •

### CHARACTERISTICS OF ROOT, STEM, AND SOIL RESPIRATION Q10 TEMPERATURE COEFFICIENTS IN FOREST ECOSYSTEMS

WANG Wen-Jie1(), WANG Hui-Mei1, ZU Yuan-Gang1, LI Xue-Ying1, KOIKE Takayoshi2

1. 1 Key Laboratory of Forest Plant Ecology, Ministry of Education, Northeast Forestry University, Harbin 150040, China
2 Hokkaido University Forests, FSC, Sapporo 060-0809, Japan
• Received:2004-04-13 Accepted:2004-10-20 Online:2005-04-13 Published:2005-07-31

Abstract:

The temperature coefficient, Q10 (Fractional change in rate with a 10 ℃ increase in temperature), can describe the response of organisms to temperature increases as a result of global warming. It is also a necessary parameter for estimating CO2 efflux. Although many studies have focused on Q10 values, reported values are highly variable. To better understand the sensitivity of forests to global warming, we reviewed and summarized reported Q10 values in the literature. Our specific objectives were the following: 1) to calculate the frequency distribution of Q10 values for soil, tree root and tree stem respiration and compare the temperature sensitivity of these different forest ecosystem compartments; 2) to determine the Q10 values of evergreen and deciduous tree species and examine the methodological influences on their calculation; and 3) to discuss future Q10-related studies. We found that most Q10 values reported for soil, root and stem respiration fell within a relatively narrow range although there were some outliers. For soil respiration, the median Q10 value was 2.74 with 23% of the values falling between 2.0 - 2.5 and 80% falling between 1.0 to 4.0. The median Q10 value for root respiration was 2.40 with 33% of the values falling between 2.5 - 3.0 and 80% between 1.0 - 3.0. The median Q10 value for stem respiration was 1.91 with 90% of the values falling between 1.0 - 3.0. The stem respiration Q10 value was significantly less than both the root and soil respiration Q10 values. There were no significant differences between the Q10 values for root and stem respiration of evergreen and deciduous trees (p>0.10). Methods for CO2 analysis (Soda lime absorption, IRGA and chromatograph analysis) and root separation methods (Excised root and trenched box) did not have a significant effect on Q10 values of soil and root respiration (p>0.10), butin vitro measurements of stem respiration yielded a significantly higher Q10 value than in vivo methods (p<0.05). In general, although theQ10 values of stem and root respiration fell within a relatively narrow range, there still was considerable variation between and within reported values for stems and roots. More attention should be paid to the quantitative estimation of total CO2 efflux by Q10 related models. Future research should focus on the biochemical, environmental and biological factors that control respiration for more precise estimation of total CO2 efflux. The greatest challenge is to better understand the underlying mechanisms that result in the variation in Q10 values between habitats and tree components to make Q10 values more universal for representation of temperature sensitivity to global warming.