Soil C:N ratio is the major determinant of soil microbial community structure in subtropical coniferous and broadleaf forest plantations

Abstract

Aims This study aimed to determine the influence of tree species on soil microbial community structure. Methods We conducted a litter and root manipulation and a short-term nitrogen (N) addition experiment in 19-yearold broadleaf Mytilaria laosensis (Hamamelidaceae) and coniferous Chinese fir (Cunninghamia lanceolata) plantations in subtropical China. Phospholipid fatty acid (PLFA) analysis was used to examine treatment effects on soil microbial community structure. Redundancy analysis (RDA) was performed to determine the relationships between individual PLFAs and soil properties (soil pH, carbon (C) and N concentration and C:N ratio). ResultsSoil C:N ratio was significantly greater in M. laosensis (17.9) than in C. lanceolata (16.2). Soil C:N ratio was the key factor affecting the soil microbial community regardless of tree species and the litter, root and N treatments at our study site. The fungal biomarkers, 18:1ω9 and 18:2ω6,9 were significantly and positively related to soil C:N ratio and the abundance of bacterial lipid biomarkers was negatively related to soil C:N ratio. N addition for 8 months did not change the biomass and structure of the microbial community in M. laosensis and C. lanceolata soils. Soil nutrient availability before N addition was an important factor in determining the effect of N fertilization on soil microbial biomass and activity. PLFA analysis showed that root exclusion significantly decreased the abundance of the fungal biomarkers and increased the abundance of the Gram-positive bacteria. Rootless plots had a relatively lower Gram-positive to Gram-negative bacteria ratio and a higher fungi to bacteria ratio compared to the plots with roots under both M. laosensis and C. lanceolata. The response of arbuscular mycorrhizal fungi (16:1ω5) to root exclusion was species-specific. Conclusions These observations suggest that soil C:N ratio was an important factor in influencing soil microbial community structure. Further studies are required to confirm the long-term effect of tree species on soil microbial community structure.

A Comparative Study of Fungal Community Structure, Diversity and Richness between the Soil and the Phyllosphere of Native Grass Species in a Copper Tailings Dam in Shanxi Province, China

“…On the other hand, Ascomycota is one of the most abundant fungal phyla, which is able to access nutrition through various means, including saprophytic, parasitic, and symbiotic methods. In addition, N is the main source for microbial nutrition in soil [25], taking part in the synthesis of proteins, nucleic acids, and macromolecular substances as well as supplying a large number of essential elements for microbial growth and its metabolic processes [26]. At the same time, N also plays an important role in the material cycle, energy flow, and multi-element balance of ecosystems and its effect on microbial growth exceeds that of soil pH and other environmental factors [27].…”

Effects of Forest Age on Soil Fungal Community in a Northern Temperate Ecosystem

“…Luo [32] used the DGGE method to study soil microbial communities of long-term fertilized soils, reporting that fertilization changed both soil C/N and microorganism community structure, and both had a significant correlation. Wan [33] used the PFLA method to study the relationship of soil microorganism community and soil pH and C/N in a Swedish boreal forest, and found that changes in soil C/N significantly affected the soil microbial community structure, thereby affecting the nitrogen supply to plants. Finally, Ushio et al [34] reported that the C/N and soil microbial community structure were different in coniferous and broadleaf forests and that the types of returned soil organic matter could cause changes in soil properties and microbial community composition.…”

Spartina alterniflora invasion alters soil microbial community composition and microbial respiration following invasion chronosequence in a coastal wetland of China

“…These invasive plants are ultimately the cause of higher soil C:N ratios relative to the native ecosystem16. The soil C:N ratio is a primary driver for the alteration in the soil microbial community structure17. The fungal biomass is highly associated with soil C:N ratio, whereas the bacterial biomass is negatively correlated with soil C:N ratio1718.…”

“…The soil C:N ratio is a primary driver for the alteration in the soil microbial community structure17. The fungal biomass is highly associated with soil C:N ratio, whereas the bacterial biomass is negatively correlated with soil C:N ratio1718. The response of the soil microbial community structure and activity to plant invasion exhibits high variation, probably as a result of the diverse changes of soil C sources and nutrient availability following invasion of distinct plant species810.…”