Linking Microbial Community Composition to Carbon Loss Rates During Wood Decomposition

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

The Science

During wood decomposition, microbial community composition shifted from fungi-dominated at early stages to relatively more bacteria-dominated ones at later stages. Fungal community dominance during early decomposition stages is associated with relatively high quality carbon compounds and low wood-moisture contents.

The Impact

Project results highlight that fungal groups were strongly influenced by relatively high quality organic carbon, but bacterial groups are positively correlated with low-quality carbon compounds. This contrasts with the observations of leaf litter decomposition and will provide a key insight toward a better wood decomposition model in the U.S. Department of Energy’s (DOE) Earth system model.

Summary

Although decaying wood plays an important role in global carbon cycling, how changes in microbial community are related to wood carbon quality and then affect wood organic carbon loss during wood decomposition remains unclear. In this study, a chronosequence method was used to examine the relationships between wood carbon loss rates and microbial community compositions during Chinese fir (Cunninghamia lanceolata) stump decomposition. 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 acid content primarily explained wood carbon loss rates during decomposition. Interestingly, fungi biomass was positively correlated with proportions of relatively high quality carbon (e.g., O-alkyl-C), but bacterial biomass was positively correlated with low-quality carbon. In addition, fungi biomass dominance at the early stages (0 to 15 years) was associated with low wood moisture (<20%), while the increase in bacteria biomass at later stages (15 to 35 years) was associated with increasing wood moisture. Project 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-carbon and low wood-moisture contents. Bacteria were positively influenced by low-quality wood-carbon 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.

Principal Investigator

Chonggang Xu
Los Alamos National Laboratory
cxu@lanl.gov

Program Manager

Daniel Stover
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science
daniel.stover@science.doe.gov

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 Next-Generation Ecosystem Experiments (NGEE)–Tropics project of the Office of Biological and Environmental Research, within the U.S. Department of Energy Office of Science.

References

Hu Z., C. Xu, N. G. McDowell, and D. J. Johnson, et al. "Linking microbial community composition to C loss during wood decomposition". Soil Biology and Biochemistry 104 108–116  (2017). https://doi.org/10.1016/j.soilbio.2016.10.017.