COS 148-2 - Linking microbial community composition and soil environment to soil respiration response to drought in a subtropical forest

Thursday, August 10, 2017: 1:50 PM
B117, Oregon Convention Center
Guiyao Zhou, East China Normal University, China and Xuhui Zhou, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China
Background/Question/Methods

Extreme drought is predicted to be more frequent and intense accompanying climate change and may have profound impacts on soil respiration (Rs) and its components [i.e., autotrophic (Ra) and heterotrophic respiration (Rh)]. Despite the fact that numerous individual studies had been conducted, how long term drought affects these fluxes are highly uncertain due to the limited understanding of the belowground biogeochemical processes controls over C release. In this study, we have conducted a 3-year field drought experiment to examine the response of Rs, Ra, and Rh to long term drought.

Results/Conclusions

Our results showed that, on average, drought significantly decreased Rs in the second and third year by 16.33% and 22.89%, respectively, but no effect in the first year. Drought significantly decreased fine root biomass, and the fine root biomass exhibited a significant negative correlation with Ra and Rs. Meanwhile´╝îmicrobial community suffered a significantly higher physiological or nutritional stress induced by drought, with decreased bacteria, fungi, actionbacteria and glomeromycota PLFAs by 35.75%, 37.94%, 24.93% and 38.42% respectively. Combined stepwise regression and generalized additive models revealed that the variations of Rs were primarily related to abiotic variables, with 48.7% explain degree significantly higher than those by biotic factors with 19.5%. Specifically, soil temperature exerts the most control over Rs changes, where bacteria are more directly associated with Rs changes in forest ecosystems. Our findings highlight the importance of the effects of drought on Rs and its components, which may need to be incorporated into Earth System Models for predicting effects of future climate change on forest ecosystems and assessing the climate-biosphere feedbacks.

Extreme drought is predicted to be more frequent and intense accompanying climate change and may have profound impacts on soil respiration (Rs) and its components [i.e., autotrophic (Ra) and heterotrophic respiration (Rh)]. Despite the fact that numerous individual studies had been conducted, how long term drought affects these fluxes are highly uncertain due to the limited understanding of the belowground biogeochemical processes controls over C release. [S1] In this study, we have conducted a 3-year field drought experiment to examine the response of Rs, Ra, and Rh to long term drought.