U.S. Department of Energy Office of Biological and Environmental Research

PI-Submitted Research Highlights for
Terrestrial Ecosystem Science Program

Linking Microbial Community Composition To Carbon Loss Rates During Wood Decomposition

Chonggang Xu
Los Alamos National Laboratory

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April 10, 2017

Fungal community is the dominant decomposer of wood at early stages.

The Science  
Microbial community was shifted from fungi-dominated community at early stages to relatively more bacteria-dominated ones at later stages during wood decomposition. Fungal community dominance during early decomposition stages is associated with relatively high-quality C compounds and low wood moisture contents.

The Impact
Our results highlight the fact that fungal groups were strongly influenced by relatively high-quality organic C, but bacterial groups are positively correlated with low-quality C compounds. This is in contrast to the observations of leaf litter decomposition and will provide a key insight toward a better wood decomposition model in DOE’s Earth system model.

Summary
Although decaying wood plays an important role in global carbon (C) cycling, how changes in microbial community are related to wood C quality and then affect wood organic C loss during wood decomposition remains unclear. In this study, a chronosequence method was used to examine the relationships between wood C loss rates and microbial community compositions during Chinese fir (Cunninghamia lanceolata) stump decomposition. Our results showed that the microbial community shifted from fungi-dominated community at early stages to relatively more bacteria-dominated ones at later stages during wood decomposition. Fungal phospholipid fatty acids content primarily explained wood C loss rates during wood decomposition. Interestingly, fungi biomass was positively correlated with proportions of relatively high-quality C (e.g., O-alkyl-C), but bacterial biomass was positively correlated with low-quality C. In addition, fungi biomass dominance at the early stages (0-15 years) was associated with low wood moisture (< 20%), while the increase in bacteria biomass at later stages (15-35 years) was associated with increasing wood moisture. Our findings suggest that the fungal community is the dominant decomposer of wood at early stages and may be positively influenced by relatively high-quality wood C and low wood moisture contents.  Bacteria were positively influenced by low-quality wood C and high wood moisture contents at later stages. Enhanced understanding of microbial responses to wood quality and environment is important to improve predictions in wood decomposition models.

(PI Contact)
Chonggang Xu 
Los Alamos National Laboratory
cxu@lanl.gov; 505-665-9773

Contacts (BER PM)
Daniel Stover
SC-23.1
Daniel.Stover@science.doe.gov (301-903-0289)

Funding
This study was funded by the National Natural Science Foundation of China (41371269 and 31570604), the National “973” Program of China (2014CB954002), the China Scholarship Council (201506100166) and the US Department of Energy’s Next Generation Ecosystem Experiment-Tropics.

Publications
Hu Z., Xu C., McDowell N.G., Johnson D.J., Wang M, Huang Z, Zhou X (2017), Linking microbial community composition to C loss during wood decomposition. Soil Biology and Biochemistry, 104: 108-116. doi:10.1016/j.soilbio.2016.10.017. (Reference link)

NGEE-Tropics

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