Landslide scales affect soil organic carbon accumulation by influencing microbial decomposition of plant-derived carbon after earthquakes

Abstract

Geological movements can affect carbon distribution patterns and turnover mechanisms in terrestrial ecosystems by altering surface landscape patterns. However, little is known about how changes in surface landscape features after geological hazards affect the microecological mechanisms of soil carbon. In this study, eight landslides with similar standing conditions and formation times but different scales were selected in the geologically active zone of Southwest China. A macro genome sequencing approach was used to study the microbial changes in the soil carbon functions of landslides after earthquakes. The results indicated that the scale of landslide scale was a significant factor affecting soil carbon stocks after earthquake. Among the landslide scale factors, landslide width had a greater effect on soil carbon storage than length or area. Landslide width corresponded with increased microbial decomposition of plant (lignin, hemicellulose) and fungal (chitin) carbon sources, but both chitinous soil content and its decomposition function gene abundance were low and had a small effect on the total carbon pool. The major bacterial phyla (Actinobacteria, Candidatus Rokubacteria, and Acidobacteria) mineralize carbon sources from plant and fungal biomass fractions through their selective adaptation mechanisms based on the landslide scale. Starch and polysaccharide related metabolic pathways differed significantly between landslides at different scales. Overall, our results emphasize the importance of microbes in surface carbon dynamics driven by geological movements. It is also noted that the scale of landscape degradation following geological disturbance is a key indicator that soil carbon and that microbes influence postdisaster soil carbon recovery and accumulation by regulating their selection and utilization of plant-derived carbon. The findings of this study help to estimate the turnover and distribution of terrestrial ecosystem carbon driven by geological movements at a larger scale.

Keywords

• Microorganisms
• Functional genes
• Carbon decomposition
• Landscape degradation
• Lignin
• Hemicellulose