Effects of soil environmental changes accompanying soil erosion on the soil prokaryotes and fungi of cool temperate forests in Southern Japan

ABSTRACTSoil erosion, which involves the degradation of the physical and chemical properties of soil, is a major threat to the soil environment. Although the effects of soil erosion on the physical or chemical properties of forests have been studied, little has been reported on the soil microbial community, which is likely to affect forest ecosystems. This study aimed to elucidate how the microbiome changed with the soil environment accompanying soil erosion in cool temperate mixed forests in Southern Japan, where soil erosion has been accelerated by the increased population of sika deer. We investigated the soil microbial communities of the different soil erosion intensities at three forest sites. In prokaryotic communities, diversity indices were increased with the sum of the height of exposed roots (SUMH), an index of soil erosion. In fungal communities, the relative abundances of plant pathogenic and wood saprotroph fungi were increased as SUMH increased and those of symbiotrophs and ectomycorrhizal fungi were increased with humus organic matter content, suggesting that the difficulties in establishing plants would be increased as soil erosion progressed because of the changes in the composition and function of fungal communities in eroded areas. Moreover, soil fungal communities had a more complex co-occurrence network than that of prokaryote, suggesting that the effects of soil erosion on fungal network is smaller than those on bacterial network. Changes in the soil environment induced by soil erosion altered the microbiomes in the deeper layers of the soil and had different effect on prokaryotes and fungi.KEYWORDS: Japanese beech (Fagus crenata)Microbial diversityMultifunctionalitySoil lossSymbiotrophic fungi Disclosure statementThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.Author contributionsA.K. and Y.T, conceptualized, designed, and administrated this project, and lead the funding acquisition of this study; F.C., A.K., M.O. and Y.T. conducted the sample and data collections and raw data curation; F.C. and Y.T. designed and analyzed the study data and prepared the draft; all authors reviewed manuscript critically and wrote the manuscript.Data availability materialsAll the raw sequence data of the prokaryotic 16S rDNA and eukaryotic 18S rRNA genes were submitted in the Sequence Read Archive of DDBJ database under the accession number DRA015283.Geolocation information32°22’N, 131°11’E,32°22ʹN, 131°08ʹE,32°09’N, 130°55’ESupplementary materialSupplemental data for this article can be accessed online at https://doi.org/10.1080/13416979.2023.2265006Additional informationFundingThis work was financially supported by Nippon Life Insurance Foundation (2021-03), Leading Initiative for Excellent Young Researchers from the Ministry of Education, Culture, Sports, Science and Technology, Japan (Grant Number JPMXS0320220123), and Japan Society for the Promotion of Science Grant-in-Aid for Scientific Research (B) (Grant Number 22H03793).