Elevational gradients do not significantly alter soil microbial
respiration and temperature sensitivity in a subtropical forest
Abstract
Soil carbon (C) cycling plays critical role in regulating global C
budget and atmosphere CO2 concentration. The ongoing global warming
potentially accelerates soil C loss induced by microbial respiration
(MR) and makes soil a large C source to atmosphere. Quantifying the
drivers of MR and its response to rising temperature (also called
temperature sensitivity, Q10) is a high priority in order to improve the
modelling and prediction of terrestrial C cycle under global warming. In
this study, we applied a standardized soil sampling along 9 gradients
from 400 m to 1100 m in a subtropical forest in South China, and
conducted the incubation experiment at the same temperature ranges (from
10 °C to 25 °C) to measure MR and Q10, then the measured MR was adjusted
by the field temperature of sampling site. Our objectives were to
examine the response of MR and Q10 to the environmental change induced
by elevational gradients in the subtropical forest, and then quantify
their main drivers. We totally collected 54 abiotic and biotic factors
relative to the MR and Q10. Our results showed that the incubated MR
increased from low to high elevation. However, significantly elevational
trend of the adjusted MR was not examined after adjusted by the field
temperature of sampling sites, due to the tradeoff between increasing
soil C concentration and declining temperature as elevation increased.
We further found that the 9 elevational gradients did not cause
significant change of Q10. The variation of Q10 was negatively dominated
by soil C quality. 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 in the further
studies