Abstract
Soil respiration is one of the main fluxes in the global carbon cycle. The effect of temperature on soil respiration is well understood. The response of soil respiration to temperature warming is called apparent temperature sensitivity (Q10) of soil respiration, which is an important parameter in modeling soil CO2 effluxes under global climate warming. The difference of Q10 between daytime and nighttime was hardly reported although attentions are attracted by the differences of temperature change and its effects on vegetation productivity. In this study, we investigated the Q10 of soil respiration in daytime and nighttime by modeling empirical functions based on the in situ measurement of soil respiration and temperature in temperate and subtropical forests of eastern China. Our results showed that the Q10 of soil respiration is higher in nighttime with the mean value of 2.74 and 2.35 than daytime with the average of 2.49 and 2.18 in all measured months and growing season, respectively. Moreover, the explanatory rate of soil temperature to soil respiration in nighttime is also higher than in daytime in each site in both all measured and growing seasons. The Q10 and explanatory rate of soil temperature to soil respiration in nighttime is 1.08 and 1.15 times in daytime in growing season. These findings indicate that soil respiration has a bigger sensitivity to temperature in nighttime than daytime. The change of soil temperature explains more variation of soil respiration in nighttime than daytime.
Highlights
The largest C pool is that of the soil, possessing 3.3 times as much C as the atmospheric pool and 4.5 times the C of the biotic pool (Lal, 2004)
Small changes to the soil C pool result in large fluctuations in atmospheric CO2, which will affect the stability of global climate (Friedlingstein et al, 2006)
We studied the responses of soil respiration to temperature changes in daytime and nighttime, respectively based on a field in-situ determination of soil respiration and soil temperature in eastern China
Summary
The largest C pool is that of the soil, possessing 3.3 times as much C as the atmospheric pool and 4.5 times the C of the biotic pool (Lal, 2004). Soil respiration (Rs) is one of the main fluxes in the global carbon cycle, and the second-largest terrestrial carbon flux after gross primary production. Forests contain the largest soil C pool, with 73% of the global soil C (Pan et al, 2011), playing a critical role in maintaining global C balance and modulating global climate change (Schlesinger and Andrews, 2000). The response of soil respiration to climate warming, which usually is called apparent temperature sensitivity of RS (Q10 value) and estimated based on empirical functions, is of importance in predicting the direction and magnitude of terrestrial carbon cycle feedback to climate warming (Davidson et al, 2006; Zhou et al, 2015).
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