Forest ecosystems function as the largest carbon (C) sink in terrestrial ecosystems, and nearly half of the C in forest ecosystems is stored in forest soils. However, the patterns of two main fractions of soil organic C, particulate organic C (POC) and mineral-associated organic C (MAOC), across various types of forest ecosystems remain unclear. In this study, soil samples were collected from depths of 0–100 ​cm at eight sites located between 18° and 48° north latitude in eastern China. The soil samples were then separated into particulate organic matter (POM) and mineral-associated organic matter (MAOM) based on particle size to analyze the distribution of C within each fraction. The results showed that the C stored as POC increased with latitude and decreased with soil depth. Specifically, 28.1%, 38.5% and 55.6% of C was stored as POC in the topsoil (0–30 ​cm) of tropical, subtropical and temperate forests, respectively, while 24.0%, 24.3% and 38.9% of C was stored as POC in the subsoil (30–100 ​cm) of the corresponding forests, respectively. MAOC experienced a higher degree of microbial processing (indicated by differences in δ¹³C, δ¹⁵N and C:N between POM and MAOM) than POC, with a more pronounced difference in microbial processing between MAOC and POC at lower latitudes than at higher latitudes. These findings contribute to a comprehensive understanding of the characteristics of forest SOC and offer potential strategies for enhancing forest C sequestration.

The unique ecological environment and minimal human interference in Medog County endow it with abundant and distinctive macrofungi resources. But in the past, there have been few research reports on the investigation of macrofungi in Medog County. In this study, we systematically investigated macrofungi in forests of different altitudinal gradients in Medog County and collected some specimens, especially those growing on wood. Morphology and phylogenetic analysis were used to study the specimens which could not be identified as species. Phylogenetic analysis was based on DNA sequences including the internal transcribed spacer regions (ITS) and the large subunit of nuclear ribosomal RNA gene (nLSU). Based on morphological characterisation and molecular data, this study identified 192 macrofungi species in the Basidiomycota and Ascomycota from Medog County, belonging to 15 orders, 62 families, and 123 genera. Among these species, 12 new species belong to eight genera, four families within Marasmiineae were recognised, viz. Collybiopsis incarnatus, C. medogensis, C. salmonea, C. submenehune, Crustomyces subisabellinus, Gymnopus subfoetidus, Marasmiellus medogensis, M. subgregarius, Marasmius medogensis, Mycetinis rhododendri, Oudemansiella nivea, and Pusillomyces tropicalis. Basidiomata and microscopic structure diagrams and detailed morphological descriptions of the novel species are provided.

China has a complex and diverse forest ecological environment, which breeds abundant forest macrofungi, including some edible, medicinal, and poisonous species. During the investigations of macrofungi in the Saihanba National Nature Reserve, North China, we collected abundant specimens of Agaricales and Polyporales within the Agaricomycetes. Based on the morphological characters and molecular evidence of DNA sequences including the internal transcribed spacer (ITS) regions, the large subunit of nuclear ribosomal RNA gene (nLSU), the small subunit of mitochondrial rRNA gene (mtSSU), the small subunit of nuclear ribosomal RNA gene (nuSSU), the largest subunit of RNA polymerase Ⅱ (RPB1), the second largest subunit of RNA polymerase Ⅱ gene (RPB2), the β-tubulin gene (TUB), and the translation elongation factor 1-α gene (TEF1), this study identifies ten species of Agaricales and Polyporales new to science, viz. Cyanosporus subpopuli, Gelatinofungus betulina, Lycoperdon pseudoperlatum, Macrocystidia hebeiensis, Mycena subbrunnea, M. subpura, M. variispora, M. violocea-ardesiaca, Picipes griseus, and Pleuroflammula hebeiensis. Detailed morphological descriptions, fruiting bodies, and microscopic structure diagrams of these ten novel species are provided.