PARENT SESSION
Poster Session #61: Soil Ecology II.
Thursday, August 8. Presentation from 8:00 AM to 9:30 AM. Exhibit Hall B & C, TCC

Measurement of soil respiration: A literature review.

Yan, Meichun^*,1, Luo, Yiqi¹, ¹ University of Oklahoma, Norman, OK

ABSTRACT- In the paper we review several basic and common-used methods of quantifying soil respiration, describe the characteristics of each method and development of the measurement and present comparison among these different methods. To my knowledge of the literature, there are seven basic methods used to measure soil respiration, including static chamber, dynamic chamber, soil-CO₂ profile method, Eddy covariance, modeling, EcoCELLs and micrometeorological methods. The static chamber method, the earliest one used to measure soil respiration, is easy to use and inexpensive but shows underestimation of CO₂ efflux. The dynamic chamber technique provides more accurate estimation of soil CO₂ flux, but the most serious problem with this method is that the results are affected by a pressure difference that occurs when the air is drawn out of or blown through the chamber. The soil-CO₂ profile method calculates the soil respiration from CO₂ concentration measurements in the soil and an estimate of the appropriate diffusion coefficients. Micrometeorological method computes CO₂ fluxes above or within the vegetation from measured CO₂ concentration gradients and estimates of the appropriate transfer coefficients. Two types of the models are used to predict soil respiration in some situations. But accuracy of the soil- CO₂ profile, modeling and micrometeorological method is limited by the measurement of parameters. Eddy covariance is considered to have great potential for directly measuring CO₂ efflux at the floor of a forest canopy. This method can give an averaged estimation of CO₂ efflux with minimal impact on the local environment, but there are strict requirements that must be met for the technique to be applicable. EcoCELLs method is reported for mesocosm scale measurements of gas exchange. However, the measurements of soil CO₂ efflux with this method are higher than with other methods. Therefore, the choice of the method to measure soil respiration may well depend on the actual situations.

KEY WORDS: soil respiration, measurement