Characteristics of the temperature coefficient, Q
10, for the respiration of non-photosynthetic organs and soils of forest ecosystems |
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Authors: | Wenjie Wang Huimei Wang Yuangang Zu Xueying Li Takayoshi Koike |
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Institution: | (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 |
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Abstract: | The temperature coefficient, Q
10 (fractional change in rate with a 10°C increase in temperature) describes the temperature sensitivity of soils, roots, and
stems, as well as their possible performance in global warming processes. It is also a necessary parameter for the estimation
of total CO2 efflux from each element. A number of studies have focused on Q
10 values to date; however, their conclusions are not universal and do not always agree. A review of these reported Q
10 values therefore becomes necessary and important for a global understanding of the temperature sensitivity of different forest
types and elements. The aims of our present paper are, first, to find the frequency distribution pattern of soils, roots,
and stems (branches) and compare their temperature sensitivity; then, to find the Q
10 differences between conifer and deciduous tree species and the effect of methodology on Q
10 values; finally we want to give a perspective on future Q
10-related studies. We found that most Q
10 values of each element were concentrated in a relatively narrow range despite a total data distribution over quite a wide
range. For soil respiration, the median Q
10 value was 2.74 and the center of the frequency distribution was between 2.0 and 2.5 with a percentage of 23%. Most of the
data (>80%) were within the range from 1.0 to 4.0. The median Q
10 value for root respiration was 2.40 and the center of the frequency distribution was from 2.5 to 3.0 with a percentage of
33%. Most of the results (>80%) ranged from 1.0 to 3.0. For stem respiration, the median Q
10 value was 1.91 and the frequency distribution was concentrated between 1.5 and 2.0. Over 90% of the data ranged from 1.0
to 3.0. Obvious differences in Q
10 value were found between different elements, stem < root < soil including root < soil excluding root. The differences between
woody organisms of stems, roots, and soils excluding roots were statistically significant (p<0.05), indicating that heterotrophic respiration from microorganism activity may be more sensitive to global warming. The
duration of the period with leaves slightly affects the temperature sensitivity of woody organisms since the Q
10 values for root and stem of coniferous evergreen trees did not differ significantly from deciduous trees (p>0.10). CO2 analytical methods (soda lime absorption method, IRGA (Infra-read gas analysis), and chromatograph analysis) and root separation
methods (excised root and trenched box) slightly affected the Q
10 values of soil and root respiration (p>0.10), but an in vitro measurement of stem respiration yielded a significantly higher Q
10 value than an in vivo method (p<0.05). In general, although the Q
10 values of non-photosynthetic organisms stayed within a relatively conservative range, considerable variation between and
within elements were still detectable. Accordingly, attention should be paid to the quantitative estimation of total CO2 efflux by Q
10-related models. In future studies, the biochemical factors and the environmental and biological factors controlling respiration
should be emphasized for precise estimation of total CO2 efflux. The difficulty is how to clarify the underlying mechanism for fluctuations of Q
10 values for one specific habitat and element (e.g. temperature acclimation or adaptation of Q
10 values) and then allow the Q
10 values to be more conservative for representation of temperature sensitivity in global warming processes.
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Translated from Acta Phytoecologica Sinica, 2005, 29(4) 译自:植物生态学报, 2005, 29 (4)] |
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Keywords: | non-photosynthetic organisms of forest soil respiration stem respiration root respiration Q 10 frequency distribution |
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