Total nitrogen is the main soil property associated with soil fungal community in karst rocky desertification regions in southwest China

Habitat ecological characteristics and soil fungal community structure of Paphiopedilum subgenus Brachypetalum Hallier (Orchidaceae) plants in Southwest China

Species of the subgenus Brachypetalum are the most primitive, most ornamental and most threatened group in the Orchid. This study revealed the ecological characteristics, soil nutrient characteristics and soil fungal community structure of habitats of the subgenus Brachypetalum in Southwest China. Lays a foundation for research on the wild populations and conservation Brachypetalum. The results showed that species of the subgenus Brachypetalum preferred a cool and humid environment, grew in scattered or aggregated form in narrow negative terrain, mainly in humic soil. The soil physical and chemical properties and soil enzyme activity indexes of the habitats were significantly different among different species, and the soil properties of different distribution points of the same species also varied greatly. There were significant differences in the soil fungal community structure among the habitats of different species. Basidiomycetes and ascomycetes were the main fungi in habitats of subgenus Brachypetalum species, and their relative abundance varied among different species. The functional groups of soil fungi were mainly symbiotic fungi and saprophytic fungi. LEfSe analysis found that there were different numbers and species of biomarkers in the habitats of subgenus Brachypetalum species, indicating that the habitat preference characteristics of each species in subgenus Brachypetalum were reflected in the fungal community. It was found that environmental factors had an impact on the changes in soil fungal communities in the habitats of subgenus Brachypetalum species, with climatic factors having the highest explanation rate (20.96%). Soil properties were significantly positively or negatively correlated with a variety of dominant soil fungal groups. Conclusions: The results of this study lay the foundation for the study of the habitat characteristics of wild populations of subgenus Brachypetalum and provides data to support in situ and ex situ conservation in the future.

Soil microbial biodiversity promotes crop productivity and agro-ecosystem functioning in experimental microcosms

Soil biota contribute substantially to multiple ecosystem functions that are key for geochemical cycles and plant performance. However, soil biodiversity is currently threatened by land-use intensification, and a mechanistic understanding of how soil biodiversity loss interacts with the myriad of intensification elements (e.g., the application of chemical fertilizers) is still unresolved. Here we experimentally simplified soil biological communities in microcosms to test whether changes in the soil microbiome influenced soil multifunctionality including crop productivity (leek, Allium porrum). Additionally, half of microcosms were fertilized to further explore how different levels of soil biodiversity interact with nutrient additions. Our experimental manipulation achieved a significant reduction of soil alpha-diversity (45.9 % reduction in bacterial richness, 82.9 % reduction in eukaryote richness) and resulted in the complete removal of key taxa (i.e., arbuscular mycorrhizal fungi). Soil community simplification led to an overall decrease in ecosystem multifunctionality; particularly, plant productivity and soil nutrient retention capacity were reduced with reduced levels of soil biodiversity. Ecosystem multifunctionality was positively correlated with soil biodiversity (R = 0.79). Mineral fertilizer application had little effect on multifunctionality compared to soil biodiversity reduction, but it reduced leek nitrogen uptake from decomposing litter by 38.8 %. This suggests that natural processes and organic nitrogen acquisition are impaired by fertilization. Random forest analyses revealed a few members of protists (i.e., Paraflabellula), Actinobacteria (i.e., Micolunatus), and Firmicutes (i.e., Bacillus) as indicators of ecosystem multifunctionality. Our results suggest that preserving the diversity of soil bacterial and eukaryotic communities within agroecosystems is crucial to ensure the provisioning of multiple ecosystem functions, particularly those directly related to essential ecosystem services such as food provision.