Soil microbial dynamic is the key regulator of ecosystem C cycling, it is undisputed that microbial processes should be incorporated into global C model. However, in order to put the microbial processes into C model accurately, much more research work need to be done because the microbial processes are both complex and flexible. Soil microbial carbon use efficiency (CUE), defined as the carbon ratio of growth to assimilation rates, is the key parameter in characterizing soil microbial processes. Current soil microbial models commonly assume a constant CUE or use a T-depent function to simulate CUE. However, in fact, we have few information about the key parameter CUE variation in terrestrial ecosystem. Previous evidence suggests CUE could be divergent in terrestrial ecosystem. For example, CUE value shows very different after being incubated in different substrate. It also changes with the incubation time passing by. Besides, the incubation temperature in which CUE was determined also affects the CUE values. However, we still lack large amounts of experiments and data analysis to confirm whether the CUE is divergent in terrestrial ecosystem or not.
In this study, we did some research work about the key parameter CUE based on published data with two goals followed: 1, Try to answer the question that is CUE value convergent or divergent in terrestrial ecosystem? 2, Try to give an acceptable estimated CUE value based on our research results.
We did a meta-analysis using 578 published soil microbial carbon use efficiency (CUE) values from 78 sites of the whole world.
Results/Conclusions
The frequency of CUE value showed a trend of twin peaks, indicating the divergent distribution of CUE values. The CUE values mostly distribute in the range of 0.057~0.122，0.715~0.737. CUE values shows different in different plant function types. The maximum mean of CUE value was 0.73 in Savannas and the minimum one was 0.22 in Broadleaf Forest. The mean of all the CUE value is 0.44. The mean of CUE values in managed sites was o.12 decreased than the mean CUE value in unmanaged sites, indicating that the management treatment lead to the decreasing of CUE value. We reset the CUE0 and m in the formula of CUE= CUE0+m(T-T0) as 0.506 and -0.011 respectively using the MCMC analysis methods. An estimated global CUE map was drawn based on the 10 years mean annual temperature form 2000~2010.