Discussion
Relative to previous studies determining Rm with traditional method that
incubation temperature differs from the ambient soil temperature
(Jenkinson & Ladd, 1981), we used a novel method to incubate soils at
the MAT of their corresponding sites when MAT was higher than 10 °C. As
Xu et al. (2017) reported, our measured Rm based on MAT may be more
representative for soil microbial activity and also more useful in
process modeling because MAT is near to ambient soil temperature.
Furthermore, in the previous studies estimating Rm at the same
incubation temperature for all soils collected from different sites may
have a deviation in Rm values because Rm is generally positively related
to incubation temperature (Hamdi et al., 2013; Wang et al., 2019). That
is to say, Rm in high latitude biomes with low MAT (e.g., boreal
forests) would be overestimated when incubation temperature was higher
than their MAT, while in low latitude biomes with high MAT (e.g.,
tropical forests) Rm would be underestimated. Therefore, we believe that
the findings from our novel incubation experiment may somewhat advance
our understanding of Rm’s spatial variations and enhance the accuracy of
predicting Rm and its feedback to global change under the environment
change scenario.