Abstract
Fires are an important factor impacting forest ecosystems of Daxing’anling and have a significant effect on soil microbial community structure. In this study, high-throughput sequencing for 16S rDNA and ITS rDNA were applied to analyze the changing characteristics and driving factors of bacterial and fungal community structures in burned areas with different fire severity. PICRUSt2 software was used to predict the functional characteristics of burned areas with different fire severity. The purpose was to unveil the responsive relationships among the structure and function of bacterial and fungal communities, fire severity, and post-disturbance restoration times. After high severity fires, the destruction of surface vegetation and loss of soil nutrients reduced the diversity and abundance of soil bacteria and fungi. The soil bacteria community structure, which was dominated by Acidobacteria, Proteobacteria, and Actinobacteria, changed to be dominated by Proteobacteria and Chloroflexi. As well, soil fungal community changed from domination by Helotiales, Eurotiales and Russulales to domination by Archaeorhizomycetales and Helotiales. Over time, soil bacterial community was gradually restored to pre-fire levels 30 years after the fire. Soil fungal community changed and failed to restore to pre-fire levels after 30 years. After low/intermediate severity fires, environmental factors were relatively unchanged so that soil bacteria diversity and abundance increased, optimizing community composition. The diversity and abundance of soil fungi decreased and the community structure changed slightly. Over time, both bacterial and fungal communities were gradually restored to pre-fire levels 30 years after the fire. After fire disturbance, with increasing severity, soil carbon fixation, lignin degradation, mineralization of organic nitrogen and hydrolysis of organic phosphorus are enhanced. Denitrification is weakened. Therefore, forest fires have certain positive effects on carbon, nitrogen and phosphorus cycles where soil bacteria and fungi are involved.
Highlights
Soil microbes have great complexity and diversity and are important for soil composition and nutrient cycling, and drivers of energy flow (Elsas and Boersma 2011) microbes play a critical role in plant growth and development, and in maintaining the productivity, functionality and stability of ecosystems (Felske et al 2000; Kuramae et al 2010)
The removal of undergrowth vegetation caused chemical property changes in forest soils, including water contents, total nitrogen and phosphorus, hydrolyzed nitrogen, and available phosphorus, which in turn caused the reduction of relative abundance of soil bacteria of Proteobacteria, Planctomycetes, and Firmicutes, as well as a reduction in bacterial community diversity (Wu et al 2020)
Fifteen years after the fire, total phosphorus (TP), TK, and available nitrogen (AN) contents were restored to pre-fire levels
Summary
Soil microbes have great complexity and diversity and are important for soil composition and nutrient cycling, and drivers of energy flow (Elsas and Boersma 2011) microbes play a critical role in plant growth and development, and in maintaining the productivity, functionality and stability of ecosystems (Felske et al 2000; Kuramae et al 2010). Coal mining activities on the Loess Plateau have caused soil sedimentation which reduced soil bacterial diversity and resulted in significant changes in community structure (Luo et al 2020). The removal of undergrowth vegetation caused chemical property changes in forest soils, including water contents, total nitrogen and phosphorus, hydrolyzed nitrogen, and available phosphorus, which in turn caused the reduction of relative abundance of soil bacteria of Proteobacteria, Planctomycetes, and Firmicutes, as well as a reduction in bacterial community diversity (Wu et al 2020). Fertilization in a short period increased available nutrients and soil water of a Eucalyptus forest, and the soil fungal community structure, which was dominated by Eurotiales, Archaeorhizomycetales, and Tremellales, changed to be dominated by Boletus and Eurotiales (Chen et al 2020). The relative abundance of Eurotiales and Acidobacteria soil microbes increased dramatically but Basidiomycota levels were reduced significantly, indicating an obvious enhancement of microbe community diversity (Li et al 2020)
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