An Analysis On Soil Microbial Community Structure And Diversity Of Mixed Coniferous And Broadleaved Plantations Of Pinus Koraiensis

The coniferous and broadleaved mixed plantation in Northeast China is a transitional type between cold-temperate coniferous forest and heliophilous broadleaved forest.The mixed coniferous and broadleaved plantation of Pinus Koraiensis has been known as the top-level community in the northeastern region.Compared with the pure coniferous plantation,it has improved resistance of pests and diseases.Meanwhile,mixed plantation accelerates the decomposition of withered matter and enhances biodiversity.The Fraxinus mandshurica and Jugla mandshurica are the two of the precious 'three hardened' tree species(called the three hardwoods)in the northeast of China,and they also become rare and protected trees.The soil microbial community and population of forests directly affect soil physicochemical properties and fertility,and affect the growth and development of forest further.The soil microbial diversity and variability reflect the adaptability of habitat quality,and are the most sensitive biological indicators.The effects of the construction of coniferous and broadleaved mixed plantation of Pinus Koraiensis on soil microbial diversity and structure,namely the interspecific relationships between the types of coniferous and broadleaved mixed plantation of Pinus Koraiensis and soil microbial community structure and diversity,is one of the key factors to maintain the sustainable development of Pinus Koraien Pinus northeast region.In this study,the mixed coniferous and broadleaved plantations of Pinus Koraiensis(28 years old)were built in 1986 on the Jianlagou plantation cultivation experimental station of Maoershan which was selected as the research platform,our chosen plantations were pure plantation of Pinus koraiensis,pure plantation of Juglans mandshurica,pure plantation of Fraxinus mandshurica,Pinus koraiensis and Juglans mandshurica mixed plantation,and Pinus koraiensis and Fraxinus mandshurica mixed plantation.The seasonal dynamics of soil chemical properties and soil enzyme activities were analyzed,and the effects of plantation type and plantation pattern on soil microbial carbon metabolism diversity were determined.The high-throughput sequencing was used to determine the microbial community structure and diversity including bacteria,fungi and ammonia-oxidizing microbes in the mixed coniferous and broadleaved plantations of Pinus Koraiensis.The results are as follows:(1)An analysis on seasonal dynamics of growth on soil chemical properties,soil enzyme activities showed that plantation type,mixed pattern and seasons significantly affected soil chemical properties and soil enzyme activities in the mixed coniferous and broadleaved plantations of Pinus Koraiensis.In the mixed plantation of Pinus koraiensis and Juglans mandshurica,the contents of soil available potassium and total carbon in Pinus koraiensis stand were significantly increased,and the contents of total nitrogen and total carbon in Juglans mandshurica stand were also markedly improved.In the mixed plantation of Pinus koraiensis and Fraxinus mandshurica,the contents of soil total nitrogen and total carbon in Pinus koraiensis stand were significantly reduced.The content of available phosphorus in pure plantations was highest in summer,while the content in mixed plantations was highest in autumn.Soil available potassium content in pure plantations was highest in summer,while the content in mixed plantations was highest in spring.Soil total phosphorus and total carbon contents in pure or mixed plantations were highest in summer and autumn,respectively.The maximum values of soil acid phosphatase and sucrase activity presented in spring,and the maximum values of soil urease and catalase activity presented in autumn.(2)An analysis on carbon metabolism functional diversity of soil microbial community in the mixed coniferous and broadleaved plantation of Pinus Koraiensis.The carbon metabolism activities of soil microbial community in the broadleaved plantations(Jugla mandshurica and Fraxinus mandshurica)were higher than that of the coniferous plantation(Pinus koraiensis).The main types of carbon sources utilized by soil microbial community were carbohydrate,carboxylic acid and amino acid in the pure plantations and mixed coniferous and broadleaved plantations of Pinus koraiensis.The carbon metabolic activities and diversity of soil microbial community in broadleaved stands(Jugla mandshurica and Fraxinus mandshurica)were markedly reduced in the mixed coniferous and broadleaved plantations of Pinus Koraiensis.The carbon metabolic activities and diversity of soil microbial community in coniferous stands were also significantly reduced in the mixed plantations.From the perspective on carbon metabolic functional diversity of soil microbial community,Jugla mandshurica stand should be selected.(3)An analysis on soil bacterial community structure and diversity in the mixed coniferous and broadleaved plantations of Pinus Koraiensis.The relative abundances of Proteobacteria,Actinobacteria and Acidobacteria were over 10%,which were the dominant phyla.In the mixed coniferous and broadleaved plantations of Pinus Koraiensis,bacterial community structures were changed,and richness and diversity indices of bacterial community were improved.It's more beneficial for the soil bacteria growth of Pinus Koraiensis stand in the mixed plantation of Pinus koraiensis and Juglans mandshurica.Soil available potassium and mixed pattern are the main factors affecting soil bacterial community structure.(4)An analysis on soil fungal community structure and diversity in the coniferous and broadleaved mixed plantations of Pinus koraiensis.The main phyla of soil fungi were Ascomycota,Basidiomycota and Zygomycota s.l.(Mucoromycota and Zoopagomycota).In the mixed coniferous and broadleaved plantations of Pinus Koraiensis,soil fungal richness indices of Pinus koraiensis stand were significantly increased,and soil fungal community diversity indices of Pinus koraiensis stand were markedly reduced.Compared with pure broadleaved plantation,the richness and diversity indices of soil fungal community of mixed Jugla mandshurica stand were significantly increased,however the richness and diversity indices of soil fungal community of mixed Fraxinus mandshurica stand were markedly reduced.Mixed pattern affected the growth of fungi.It was found that the relative abundance of Inocybe?Lactarius?Russul and other Ectomycorrhiza were increased in mixed plantations.The abundances of Ectomycorrhiza are vital for the sustainable development of mixed coniferous and broadleaved plantations of Pinus koraiensis.Mixed coniferous and broadleaved plantations of Pinus koraiensis can regulate the abundances of functional fungi to affect the absorption and utilization of soil nutrient for plant.The total carbon is the main factor for soil fungal community.(5)An analysis on soil ammonia-oxidizing microbial community structure and diversity in the coniferous and broadleaved mixed plantations of Pinus koraiensis.In the mixed coniferous and broadleaved plantations of Pinus koraiensis.Crenarchaeota and Thaumarchaeota are the dominant ammonia-oxidizing archaea,accounting for 99.9%of the total sequence.In the mixed coniferous and broadleaved plantations of Pinus koraiensis,the community structures of ammonia-oxidizing archaea in the Pinus koraiensis stand were changed,and the richness and diversity indices of ammonia-oxidizing archaea community in the Pinus koraiensis stand were significantly increased.In the mixed plantations,the richness and diversity indices of ammonia-oxidizing archaea community in the mixed Jugla mandshurica stand were significantly increased,however the richness and diversity indices of ammonia-oxidizing archaea community in the mixed Fraxinus mandshurica stand were significantly reduced.In the mixed plantations,the richness and diversity indices of ammonia-oxidizing bacterial community were not significantly changed.The ammonia-oxidizing bacterial community owns five phyla,in which Proteobateria accounted for 98%of all sequences.Total carbon,total phosphorus,total nitrogen and available potassium were the main factors to change the structure of soil ammonia-oxidizing archaea community,followed by mixed pattern.The changes of soil ammonia-oxidizing bacterial community structure could only be explained by mixed pattern and soil chemical properties by 31%.In conclusion,mixed coniferous and broadleaved plantations improved decomposition ability and humification of organic matter in the mixed Pinus Koraiensis stands during the process of mixed coniferous and broadleaved plantations of Pinus Koraiensis,and it is benifical for accumulation of soul organic matter.This pattern increased soil bacterial community diversity in the mixed Jugla mandshurica stand and made improvements on richness and diversity of soil fungal and ammonia-oxidizing archaea community in the mixed Pinus Koraiensis stands.It was creatively found that mixed pattern increased the relative abundances of valuable Ectomycorrhiza to guarantee the ecological stability of mixed coniferous and broadleaved planations of Pinus Koraiensis.Therefore,it was more benefical for forest ecosystem stability to build the mixed plantation of Pinus Koraiensis and Jugla mandshurica.