Forest soil carbon (C) accumulates predominantly from the decomposition of plant litter, with most plant-derived C being processed by soil microbes. However, the microbial mechanisms associated with C decomposition in...Forest soil carbon (C) accumulates predominantly from the decomposition of plant litter, with most plant-derived C being processed by soil microbes. However, the microbial mechanisms associated with C decomposition in forests across biomes remain elusive. Using metagenomic sequencing, we explored the topsoil microbial functional group of decomposer microbial carbohydrate-active enzymes (CAZyme) and studied the C decomposition of plant- and microbial-derived components in forests across biomesfrom tropical to temperate regions. The results showed that the composition of soil microbial CAZyme families, which degrade plant- and microbial-derived components, significantly varied from warmer to colder forest biomes. Soils with higher annual temperatures and lower organic matter (OM) recalcitrance (indicated by Alky-C/O-alkyl-C: A/O) in subtropical/tropical forests supported higher proportions of CAZyme genes fundamental for the decomposition of complex plant and fungal derived biomass. In contrast, soils with lower annual temperatures and higher OM recalcitrance (e.g., A/O, organic carbon, microbial biomass) in cold temperate forests exhibited higher proportions of CAZyme genes for the degradation of bacterial-derived peptidoglycan. Such trends of microbial CAZyme families were largely explained by the relative abundance of bacterial dominant phylum members (i.e., Proteobacteria, Actinobacteria, Acidobacteria, and Bacteroidetes). Collectively, our study demonstrated the importance of functional microbiome responsible for the decomposition of plant and microbial inputs, providing a solid mechanism to understand the often-reported responses of soil organic matter decomposition and C sequestration to warming. These results are integral to understanding the contribution of soil microbiome to C fluxes under on-going climate change.展开更多
Afforestation effectively improved soil microbial communities and significantly increased soil nitro-gen mineralization rate(Rm).Soil microorganisms drive Rm by regulating soil N-cycling genes.Soil nitrification genes...Afforestation effectively improved soil microbial communities and significantly increased soil nitro-gen mineralization rate(Rm).Soil microorganisms drive Rm by regulating soil N-cycling genes.Soil nitrification genes had a major effect on soil Rm than denitrification genes after afforestation.Assessing the function of forest ecosystems requires an understanding of the mechanism of soil nitrogen mineralization.However,it remains unclear how soil N-cycling genes drive soil nitrogen mineralization during afforestation.In this study,we collected soil samples from a chrono-sequence of 14,20,30,and 45 years of Robinia pseudoacacia L.(RP14,RP20,RP30,and RP45)with a sloped farmland(FL)as a control.Through metagenomic sequencing analysis,we found significant changes in the diversity and composition of soil microbial communities involved in N-cycling along the afforestation time series,with afforestation effectively increasing the diversity(both alpha and beta diversity)of soil microbial communities.We conducted indoor culture experiments and analyzed correlations,which revealed a significant increase in both soil nitrification rate(Rn)and soil nitrogen mineralization rate(Rm)with increasing stand age.Furthermore,we found a strong correlation between soil Rm and soil microbial diversity(both alpha and beta diversity)and with the abundance of soil N-cycling genes.Partial least squares path modeling(PLS-PM)analysis showed that nitrification genes(narH,narY,nxrB,narG,narZ,nxrA,hao,pmoC-amoC)and denitrification genes(norB,nosZ,nirK)had a greater direct effect on soil Rm compared to their effect on soil microbial communities.Our results reveal the relationships between soil nitrogen mineralization rate and soil microbial communities and between the mineralization rate and functional genes involved in N-cycling,in the context of Robinia pseudoacacia L.restoration on the Loess Plateau.This study enriches the understanding of the effects of microorganisms on soil nitrogen mineralization rate during afforestation and provides a new theoretical basis for evaluating soil nitrogen mineralization mechanisms during forest succession.展开更多
基金financially supported by the Open Fund for Key Laboratory of Low carbon Green Agriculture in Northwestern China,Northwest A&F Universitythe National Natural Science Foundation of China+1 种基金Thanks for the support of the Restoration Project of Mountains,Rivers,Forests,Fields,Lakes,Grasslands and Deserts in the Northern Foothills of Qinling in Shaanxi ProvinceThe authors are also grateful to the anonymous reviewers whose comments and suggestions helped us to enhance the quality of this paper.
文摘Forest soil carbon (C) accumulates predominantly from the decomposition of plant litter, with most plant-derived C being processed by soil microbes. However, the microbial mechanisms associated with C decomposition in forests across biomes remain elusive. Using metagenomic sequencing, we explored the topsoil microbial functional group of decomposer microbial carbohydrate-active enzymes (CAZyme) and studied the C decomposition of plant- and microbial-derived components in forests across biomesfrom tropical to temperate regions. The results showed that the composition of soil microbial CAZyme families, which degrade plant- and microbial-derived components, significantly varied from warmer to colder forest biomes. Soils with higher annual temperatures and lower organic matter (OM) recalcitrance (indicated by Alky-C/O-alkyl-C: A/O) in subtropical/tropical forests supported higher proportions of CAZyme genes fundamental for the decomposition of complex plant and fungal derived biomass. In contrast, soils with lower annual temperatures and higher OM recalcitrance (e.g., A/O, organic carbon, microbial biomass) in cold temperate forests exhibited higher proportions of CAZyme genes for the degradation of bacterial-derived peptidoglycan. Such trends of microbial CAZyme families were largely explained by the relative abundance of bacterial dominant phylum members (i.e., Proteobacteria, Actinobacteria, Acidobacteria, and Bacteroidetes). Collectively, our study demonstrated the importance of functional microbiome responsible for the decomposition of plant and microbial inputs, providing a solid mechanism to understand the often-reported responses of soil organic matter decomposition and C sequestration to warming. These results are integral to understanding the contribution of soil microbiome to C fluxes under on-going climate change.
基金supported by the National Natural Science Foundation of China(No.41907031)the China Postdoctoral Science Foundation(No.2021T140565)the China Postdoctoral Science Foundation(No.2019M650276).
文摘Afforestation effectively improved soil microbial communities and significantly increased soil nitro-gen mineralization rate(Rm).Soil microorganisms drive Rm by regulating soil N-cycling genes.Soil nitrification genes had a major effect on soil Rm than denitrification genes after afforestation.Assessing the function of forest ecosystems requires an understanding of the mechanism of soil nitrogen mineralization.However,it remains unclear how soil N-cycling genes drive soil nitrogen mineralization during afforestation.In this study,we collected soil samples from a chrono-sequence of 14,20,30,and 45 years of Robinia pseudoacacia L.(RP14,RP20,RP30,and RP45)with a sloped farmland(FL)as a control.Through metagenomic sequencing analysis,we found significant changes in the diversity and composition of soil microbial communities involved in N-cycling along the afforestation time series,with afforestation effectively increasing the diversity(both alpha and beta diversity)of soil microbial communities.We conducted indoor culture experiments and analyzed correlations,which revealed a significant increase in both soil nitrification rate(Rn)and soil nitrogen mineralization rate(Rm)with increasing stand age.Furthermore,we found a strong correlation between soil Rm and soil microbial diversity(both alpha and beta diversity)and with the abundance of soil N-cycling genes.Partial least squares path modeling(PLS-PM)analysis showed that nitrification genes(narH,narY,nxrB,narG,narZ,nxrA,hao,pmoC-amoC)and denitrification genes(norB,nosZ,nirK)had a greater direct effect on soil Rm compared to their effect on soil microbial communities.Our results reveal the relationships between soil nitrogen mineralization rate and soil microbial communities and between the mineralization rate and functional genes involved in N-cycling,in the context of Robinia pseudoacacia L.restoration on the Loess Plateau.This study enriches the understanding of the effects of microorganisms on soil nitrogen mineralization rate during afforestation and provides a new theoretical basis for evaluating soil nitrogen mineralization mechanisms during forest succession.
