Arbuscular mycorrhizal fungi community in soils under desertification and restoration in the Brazilian semiarid.

Soil desertification has a significant social, economic, and environmental impact worldwide. Mycorrhizal diversity remains poorly understood in semiarid regions impacted by desertification, especially in Brazilian drylands. More importantly, positive impacts of grazing exclusion on mycorrhizal communities are still incipient. Here, we hypothesized that overgrazing changes the structure of Arbuscular Mycorrhizal Fungi (AMF) community compared to native areas and, grazing exclusion is effective to restore the AMF community. Thus, we analyzed the status of AMF community in soils under desertification (overgrazing) and restoration (twenty-years of grazing exclusion) in the Brazilian semiarid. AMF-spores were extracted via humid decantation methodology, morphologically classified, and alpha diversity metrics were calculated. Soil samples were chemically, and physically characterized and multivariate statistical analyses were applied to verify the impact of soil degradation and restoration on AMF-community. Briefly, native, and restored areas presented higher contents of organic matter, phosphorus, microbial carbon, and β-glucosidase activity. However, degraded soil showed higher Al3+, Na+, and bulk soil density values. The abundance of AMF spores was higher in restored soil, followed by degraded and native vegetation, and Shannon's diversity index was significantly higher in restored soils, followed by native vegetation. AMF-spores were classified into four families (Gigasporaceae > Acaulosporaceae > Glomeraceae > Ambisporaceae). Ambisporaceae was closed correlated with degraded soil, mainly with Al3+, Na+, and bulk soil density properties. On the other hand, Acaulosporaceae and Glomeraceae were positively correlated with native vegetation and restored soil, respectively, thereby improving Shannon index, richness, enzyme activity, and soil respiration. Thus, grazing exclusion, in long term, can be a good strategy to restore AMF-diversity in soils in the Brazilian semiarid.

Silva DFD ，Moreira JV ，Sousa LIS ，Santana MC ，Mota JCA ，Queiroz ADS ，Nascimento ÍVD ，Silva AMM ，Araújo ASF ，Melo VMM ，Medeiros ÉV ，Cardoso EJBN ，Pereira APA ... -  《-》

Grazing exclusion-induced changes in soil fungal communities in a highly desertified Brazilian dryland.

Soil desertification poses a critical ecological challenge in arid and semiarid climates worldwide, leading to decreased soil productivity due to the disruption of essential microbial community processes. Fungi, as one of the most important soil microbial communities, play a crucial role in enhancing nutrient and water uptake by plants through mycorrhizal associations. However, the impact of overgrazing-induced desertification on fungal community structure, particularly in the Caatinga biome of semiarid regions, remains unclear. In this study, we assessed the changes in both the total fungal community and the arbuscular mycorrhizal fungal community (AMF) across 1. Natural vegetation (native), 2. Grazing exclusion (20 years) (restored), and 3. affected by overgrazing-induced degradation (degraded) scenarios. Our assessment, conducted during both the dry and rainy seasons in Irauçuba, Ceará, utilized Internal Transcribed Spacer (ITS) gene sequencing via Illumina® platform. Our findings highlighted the significant roles of the AMF families Glomeraceae (∼71% of the total sequences) and Acaulosporaceae (∼14% of the total sequences) as potential key taxa in mitigating climate change within dryland areas. Moreover, we identified the orders Pleosporales (∼35% of the total sequences) and Capnodiales (∼21% of the total sequences) as the most abundant soil fungal communities in the Caatinga biome. The structure of the total fungal community differed when comparing native and restored areas to degraded areas. Total fungal communities from native and restored areas clustered together, suggesting that grazing exclusion has the potential to improve soil properties and recover fungal community structure amid global climate change challenges.

Silva DF ，Mazza Rodrigues JL ，Erikson C ，Silva AMM ，Huang L ，Araujo VLVP ，Matteoli FP ，Mendes LW ，Araujo ASF ，Pereira APA ，Melo VMM ，Cardoso EJBN ... -  《-》

Trait-based assembly of arbuscular mycorrhizal fungal communities determines soil carbon formation and retention.

Fungi are crucial for soil organic carbon (SOC) formation, especially for the more persistent mineral-associated organic C (MAOC) pool. Yet, evidence for this often overlooks arbuscular mycorrhizal fungi (AMF) communities and how their composition and traits impact SOC accumulation. We grew sudangrass with AMF communities representing different traits conserved at the family level: competitors, from the Gigasporaceae family; ruderals, from the Glomeraceae family; or both families combined. We labeled sudangrass with 13 C-CO2 to assess AMF contributions to SOC, impacts on SOC priming, and fungal biomass persistence in MAOC. Single-family AMF communities decreased total SOC by 13.8%, likely due to fungal priming. Despite net SOC losses, all AMF communities contributed fungal C to soil but only the Glomeraceae community initially contributed to MAOC. After a month of decomposition, both the Glomeraceae and mixed-family communities contributed to MAOC formation. Plant phosphorus uptake, but not hyphal chemistry, was positively related to AMF soil C and MAOC accumulation. Arbuscular mycorrhizal fungi contribution to MAOC is dependent on the specific traits of the AMF community and related to phosphorus uptake. These findings provide insight into how variations in AMF community composition and traits, and thus processes like environmental filtering of AMF, may impact SOC accumulation.

Horsch CCA ，Antunes PM ，Fahey C ，Grandy AS ，Kallenbach CM ... -  《-》

Soil lead pollution modifies the structure of arbuscular mycorrhizal fungal communities.

Faggioli V ，Menoyo E ，Geml J ，Kemppainen M ，Pardo A ，Salazar MJ ，Becerra AG ... -  《-》

Composition and seasonal variation of the arbuscular mycorrhizal fungi spore community in litter, root mat, and soil from a subtropical rain forest.

Community composition and seasonal variation of sporulation of arbuscular mycorrhizal fungi (AMF) have been studied in soils from many ecosystems including subtropical forest. Yet, AMF community composition has been surveyed only from the mineral soil but not from the litter layer and the root mat, and long-term variation in sporulation is not fully understood. We sampled a 75-m2 plot from a subtropical forest to determine AMF community composition in the following habitats: the litter layer, the root mat, and the mineral soil. Moreover, samples were taken in fall, winter, spring, and summer over a 2-year period to follow the seasonal variation of AMF sporulation. We detected 47 AMF species belonging to six families and 14 genera, Glomeraceae and Acaulosporaceae being the most represented families. Sixteen species were common to all three habitats, five species were shared between two habitats, and 26 species were recovered exclusively from single habitats. While species richness was not significantly different among habitats, AMF total spore numbers were significantly higher in the litter and root mat compared to the soil. PERMANOVA did not detect a significant effect of habitats on community composition when species presence/absence was considered, but significant differences between litter versus soil and root mat versus soil were detected when spore abundance was considered. A seasonal pattern of spore abundance for species was not observed over the 2-year sampling period regardless of habitat. This study revealed that (i) different AMF species sporulate in the different habitats; thus, field surveys considering only the mineral soil might underestimate species richness and (ii) AMF species sporulate asynchronously in subtropical forest.

Kemmelmeier K ，Dos Santos DA ，Grittz GS ，Stürmer SL ... -  《-》