华北落叶松—白桦混交对土壤养分与微生物群落结构的影响OA

The aim of this study is to investigate the effects of Larix gmelinii var.principis-rupprechtii and Betula platyphylla mixed forest on soil nutrients and microbial community structure.Soil pH,nutrients,enzyme activities,microbial community composition,and the relationship between microorganisms and nitrogen and phosphorus cycling in rhizosphere soil and non-rhizosphere soil were analyzed by biochemical and high-throughput sequencing techniques.The main results were as follows:total nitrogen,ammonium nitrogen,nitrate nitrogen,total phosphorus,total potassium,available phosphorus and available potassium in the rhizosphere and non-rhizosphere soils were significantly higher than those of pure larch forest,but soil pH was lower than that of pure larch.In addition,except for ammonium nitrogen,all other indices in rhizosphere soil was higher than that of non-rhizosphere soil,showing a positive rhizosphere effect,and the mixed forest was higher than that of pure forest.The rhizosphere effects of total nitrogen,total phosphorus,available phosphorus and nitrate nitrogen were enhanced by 14.27％、9％、4.6％and 23.79％,respectively.The soil enzyme activities were also greater in mixed forests and rhizosphere soils than that in the pure forests and non-rhizosphere soils.Compared with the pure forests,the correlation between urease and nitrogen decreased after mixing,but the correlation between phosphorus cycle-related enzymes and phosphorus increased.The mixing increased the community diversity of soil fungi and bacteria,and the relative abundance of dominant bacteria changed,especially the relative abundance of dominant fungi changed,which increased the abundance of Basidiomycota and Ascomycota,and decreased the abundance of Mortierellomycota.Funguild functional prediction showed an increase in the relative abundance of Ectomycorrhizal fungi and a decrease in the relative abundance of Pathogenic fungi and Saprophytes.The relative abundance of dominant bacteria remained unchanged,and they followed the order of Pseudomonadota＞Acidobacteriota＞Actinomycetota.Compared with pure forest,the correlation between microorganisms and nitrogen in the mixed forest decreased,the correlation between microorganisms and phosphorus increased,so the limiting effect of nitrogen on microorganisms decreased.Therefore,the larch and birch mixed stand promoted soil nutrient cycling and alleviated soil fertility decline by changing the structure and function of microbial communities.The results of this study can provide technical support for the sustainable management of Larix principis-rupprechtii.