Elevational variation and drivers of temperature sensitivity of
microbial respiration
Moreover, we also found that Q 10 did not
significantly vary along with the elevation. Similar result was also
observed in a recent global meta-analysis (Li et al. , 2022) and
several observation studies (Schindlbacher et al. , 2010; Xuet al. , 2014; Zuo et al. , 2021), suggesting that microbial
response to temperature was similar among different elevational
gradients. Such results did not support the microbial thermal adaption
that Q 10 declines from low to high temperature
site (or from high to low elevation) (Bradford et al. , 2019).
Moreover, our SEM analysis revealed no significant direct and indirect
effect from MAT on Q 10, suggesting that no
significant influence of elevation and temperature onQ 10 in the elevational gradients. Since many
studies predicted climate warming is faster at high than that at low
elevation (Pepin et al. , 2015), the unifiedQ 10 means future climate warming will cause more
C loss at the high elevation. Meanwhile, other studies reported
different elevational trend of Q 10 thatQ 10 increased (Gutiérrez-Girón et al. ,
2015; Kong et al. , 2022; Okello et al. , 2022; Zenget al. , 2022) or decreased (Lipson, 2007) along with the
elevation, suggesting that the elevational trend ofQ 10 still need more studies to confirm.
In this study, the unchanged Q 10 along with
elevation might be due to tradeoff between the directly negative effect
from elevation and its indirectly positive effect. All these indirect
influences were via the pathway of AccMR_0_perSC, showing that high
elevation indirectly enhanced Q 10 via reducing
AccMR_0_perSC. Low AccMR_0_perSC means low soil C quality and
contributes to high Q 10, similar result was also
observed in previous studies (Ding et al. , 2016). These findings
support previous carbon-quality-temperature hypothesis thatQ 10 of low quality soil C is greater than that of
the high quality soil C (Fierer et al. , 2006; Liu et al. ,
2017; Wang et al. , 2018; Bradford et al. , 2021), and
confirm that soil C quality is a good predictor ofQ 10 value (Davidson and Janssens, 2006).
In summary, elevational variation of soil microbial respiration and its
temperature sensitivity in a subtropical forest in South China were
assessed by using lab incubation experiment. We found that incubated
AccMR increased from low to high elevation. However, significantly
elevational trend of AccMR_MAT was not examined after adjusted by the
field temperature, due to the tradeoff between increasing Soil C
concentration and declining field temperature. We further found thatQ 10 did not vary significantly along the
subtropical forest elevational gradients, the variation ofQ 10 was negatively dominated by soil C quality
(AccMR_0_perSC). Since climate warming is predicted faster at high
elevation than that at low elevation, C loss from high elevation might
be accelerated in the future and need more attentions.