This study assessed the effects of Betula dahurica (BD), Betula platyphylla (BP), Larix gmelinii (LG), Quercus mongolica (QM), and a mixed conifer–broadleaf forest composed of LG and QM (LGQM) on the soil physicochemical parameters and community structure of fungi in the Zhongyangzhan Black-billed Capercaillie Nature Reserve. Fungal community structures were characterized via ITS rRNA sequencing. The effects of soil parameters on the community structure of soil fungi were assessed by Pearson correlation analysis and redundancy analysis (RDA). LGQM exhibited lower C/N, available nitrogen (AN), total phosphorus (TP), and available phosphorus (AP) compared with the QM broadleaf forest. The fungal Shannon and Simpson diversity indices were highest in BP, whereas LG exhibited the highest ACE index. The Basidiomycota, Ascomycota, Mortierellomycota, and Mucoromycota fungal phyla were dominant across all vegetation types. Each of the different vegetation types studied herein exhibited a unique fungal community structure. The RDA results indicated that fungal community structures were primarily shaped by the total N, available N, and available P of soil. Our findings thus indicated that forests restored with different species of trees may exhibit variations in soil quality and characteristics despite sharing the same climate. Furthermore, broadleaved and coniferous forests exhibited a unique fungal community diversity and composition.

Forest fires are an important disturbance factor in forest ecosystems, and obviously change the soil environment. Arbuscular mycorrhizal fungi, as a medium and bridge between vegetation and soil, play a crucial role in mediating plant nutrient uptake and regulating the productivity, stability, and succession of vegetation–soil systems. To investigate the effects of forest fires on the community structure and diversity of arbuscular mycorrhizal fungi in cold-temperate Larix gmelinii forests, we collected soils from light, moderate, and heavy fire disturbance forests and a natural forest as a control forest in Greater Khingan Larix gmelinii forests, in the northeast of China. The community structure and diversity of arbuscular mycorrhizal fungi was sequenced using Illumina MiSeq technology and we analyzed the correlation with the soil physicochemical characteristics. The results showed that the contents of microbial biomass content (MBC), moisture content (MC), total nitrogen (TN), and available phosphors (AP) increased significantly (p < 0.05) with increasing fire intensity (from Light to heavy fire), but available potassium (AK) decreased significantly (p < 0.05). These changes were not significant. A total of 14,554 valid sequences from all sequences were classified into 66 ASVs that belonged into one phylum, one order, four families, and four genera. The genera included Glomus, Ambispora, Paraglomus, and Acaulospora, and Glomus was the dominant genus (the genera with the five most relative abundances) in the control and heavy-fire forests. Non-metric multidimensional scaling (NMDS) analysis showed that forest fires significantly affected the community structure of arbuscular mycorrhizal fungi (p < 0.01). Redundancy analysis (RDA) showed that MBC, SOC, and AP contents significantly affected the composition structure and diversity of arbuscular mycorrhizal fungi communities. This study indicated that forest fires affected the composition and diversity of soil arbuscular mycorrhizal fungi communities through changing the soil physicochemical parameters (MBC, SOC, and AP) in cold-temperate Larix gmelinii forests. The study of soil physicochemical properties and arbuscular mycorrhizal fungi diversity in cold-temperate Larix gmelinii forests in the Greater Khingan Mountains after forest fires provides a reference basis for the revegetation and reconstruction of fire sites.

Fire is a crucial disturbance factor for the structure and function of forest ecosystems, as it directly or indirectly affects plant growth, animal life and soil biogeochemical properties. Here, the effects of different fire severities and key driving environmental factors on soil microbial diversity and biomass were investigated in taiga forests that had undergone light, moderate or heavy fires, more recently or in the past, with unburned taiga forest included as a control (CK). The sample sites were located in the Greater Khingan mountains in the northeast of China. Critical soil parameters were determined, and bacterial and fungal content was inferred from determined phospholipid fatty acids (TPLFAs). The results showed that (1) all three fire severities significantly increased the concentrations of soil microbial carbon (MBC), moisture content (MC) and total nitrogen content (TN), but they significantly decreased soil available potassium (AK) content compared with the CK. (2) Recent light and moderate fires significantly decreased the Simpson and Shannon indices of soil microbial communities compared to CK; moderate fire did not change the Menhinick and Margalef indices. (3) Following moderate fire disturbance, there were no significant differences (p > 0.05) in relative abundance of total soil bacteria (Ba), Gram-positive bacteria (G⁺), Gram-negative bacteria (G⁻) and content of TPLFAs compared to the control, either as a result of more recent fires or earlier fires. (4) Redundancy analysis revealed that soil MC, TN, soil organic carbon (SOC), available P (AP) and alkaline N (AN) all strongly significantly affected the composition of the microbial communities, with a total explanation of 85.16% of the data. The species diversity and biomass of Ba, G⁺, G⁻ and TPLFAs were in accordance with the intermediate disturbance hypothesis. The change pattern of soil fungi was in accordance with their own characteristics of reproduction and growth, which was in line with k-selection and ecological countermeasures.

Fungi have important ecological functions in the soil of forests, where they decompose organic matter, provide plants with nutrients, increase plant water uptake, and improve plant resistance to adversity, disease, and disturbance. A forest fire presents a serious disturbance of the local ecosystem and can be considered an important component affecting the function of ecosystem biomes; however, the response of soil fungi to fire disturbance is largely unknown. To investigate the effects of fire disturbance on the community composition and diversity of soil fungi in a taiga forest, we collected soil from plots that had undergone a light, moderate, and heavy fire 10 years previously, with the inclusion of a fire-free control. The present soil fungi were characterized using Illumina MiSeq technology, and the sequences were analyzed to identify differences in the community composition and diversity in response to the changed soil physicochemical properties. The results showed that the Chao1 index, which characterizes the alpha diversity of the fungi, did not change significantly. In contrast, the Shannon index increased significantly (p < 0.05) and the Simpson index decreased significantly (p < 0.05) following a light or heavy fire disturbance compared to the control. The relative abundance of Basidiomycota was significantly higher in the soil of the fire sites than that in the control (p < 0.01), and the relative abundance of Ascomycota was significantly lower (p < 0.01). The results of principal coordinates analyses (PCoAs) showed that fire disturbance highly significantly affected the beta diversity of soil fungi (p < 0.001), while the results of canonical correlation analysis (CCA) indicated that the available nitrogen (AN), moisture content (MC), pH, available potassium (AK), and total nitrogen (TN) contents of the soil significantly affected the compositional structure and diversity of the soil fungal communities. The results of functional prediction showed that the majority of the detected soil fungi were symbiotrophs, followed by saprotrophs and saprotroph–symbiotrophs, with ectomycorrhiza being the dominant functional taxon. Fire disturbance significantly reduced the relative abundance of ectomycorrhiza (p < 0.05). This study illustrates that fire disturbance alters the structural composition, diversity, dominance, and relative abundance of the guilds of soil fungal communities in taiga forest, and strongly affected the beta diversity of soil fungi, with AN, MC, pH, AK, and TN being the most important factors affecting their community structure. The results may provide a useful reference for the restoration and rehabilitation of taiga forests after fire disturbance.

Purpose: It is the data support and theoretical basis for the response mechanism of soil fungi to climate warming in permafrost areas in the Greater Xing’an Mountains. Methods: We collected permafrost from the Greater Xing’an Mountains for indoor simulation experiments and took the natural permafrost as the control (CK) and the test groups of 0 °C (T₁), 2 °C (T₂), and 4 °C (T₃) were set. Illumina MiSeq high-throughput sequencing technology was used to understand the changes in characteristics of fungal communities, and the correlations were analyzed combined with the soil physicochemical properties. Results: Compared with CK, the value of pH and the content of available potassium (AK) in the three warming treatment groups were significantly lower (P < 0.05), and the microbial biomass carbon (MBC) content was significantly higher (P < 0.05). The content of total nitrogen (TN) and available nitrogen (AN) in the T₁ and T₃ groups was significantly lower than that in the CK group (P < 0.05). A total of 11 phyla, 39 classes, 89 orders, 187 families, 361 genera, and 522 species were obtained through fungal sequencing and divided into 1463 amplicon sequence variants (ASVs). Ascomycota and Dimorphospora were the dominant phylum and genus, respectively, and there were differences in the response of relative abundance of various groups at the phylum and genus levels to warming. Warming significantly decreased the Sobs and ACE indexes of the treatment groups (P < 0.05), and the Shannon and Shannoneven indexes also showed a downward trend. Moreover, warming significantly changed the fungal beta diversity (P < 0.01), while the value of pH and the content of TN, MBC, and AK could significantly affect the community structure (P < 0.05), and the correlation between fungi at different phyla levels and soil physicochemical properties was different. Conclusions: These results can provide a reference for further study on the changes in composition and structure of fungal communities and the influence factor in permafrost in the Greater Xing’an Mountains under the background of warming.

The wetlands in China’s Sanjiang Plain have experienced intensive anthropogenic disturbance recently, and this has obviously changed their environmental characteristics. Soil microorganisms play an important role in wetland ecosystems. However, the effects of different wetland types on soil microbial diversity and community composition remain largely unclear. Therefore, we assessed the effects of three typical wetland types—permanently flooded wetlands, seasonally flooded wetlands and non-flooded wetlands—on soil microbial communities in the Sanjiang Plain, using phospholipid fatty acid analysis (PLFA) technology. A total of 56 different PLFA compounds were identified, of which 10 are typically produced by uncharacterized bacteria, 15 by Gram-positive bacteria, and 11 by Gram-negative bacteria. In addition, 2 fungal groups were identified, based on four PLFAs, and four PLFAs typical for protozoa were detected. High levels were detected for 16:0 (attributed to bacteria) and i17:1ω9c (produced by Gram-positive bacteria). The latter (i17:1ω9c) was exceptionally high in non-flooded soil (8407.15 ± 2675.84 ng/g). High levels of 18:1ω7c (1939.15 ± 666.13 ng/g) and 18:1ω9c (1713.26 ± 360.65 ng/g) were detected in permanently flooded wetlands and about the same in seasonally flooded wetlands, but lower ranks were present in the drier non-flooded wetlands. The Shannon-Wiener diversity index decreased with permanently flooded wetlands (3.05) > seasonally flooded wetlands (3.02) > non-flooded wetlands (2.12). Redundancy analysis showed that the two axes could explain a total of 94.48% of soil microbial communities. Soil water content, total and available phosphorus, and total and available nitrogen correlated significantly with soil microbial communities of three wetland types. Cluster analysis of correlations between individual PLFA biomarkers and soil physiochemical properties demonstrated the complexity of the community responses to the three different habitats. This study demonstrates that microbial diversity and composition changed sensitivity among the three wetland types, and soil moisture content was the key environmental factor to affect the soil microbial communities.