Effect Of Moso Bamboo Expands To Broadleaf And Conifer Forests On Soil Phosphorus Bioavailability And Its Mechanism

In order to explore the effect of soil phosphorus bioavailability during the moso bamboo expansion into broadleaf and conifer forests,we compared moso bamboo,mixed bamboo-broadleaf,broadleaf,mixed bamboo-conifer,and conifer forests.Soil physical and chemical properties,soil phosphorus sorption and desorption capacity,and soil microbial community were measured in three soil layers,and the differences in soil phosphorus fractions and influencing factors were analyzed.The results were as follows:（1）The effects of moso bamboo expansion on the phosphorus fractions content differed among the three soil layers.The moso bamboo expansion into broadleaf forest increased the content of Ca Cl₂-P,Enzyme-P and HCl-P in the 0-10 cm soil layer,increased Enzyme-P and decreased Citrate-P in the 10-20 cm soil layer,and increased Ca Cl₂-P and decreased Citrate-P and Enzyme-P in the 20-40 cm soil layer.The moso bamboo expansion into conifer forest increased the content of Citrate-P,Enzyme-P and HCl-P in the 0-10 cm soil layer,increased the content of Ca Cl₂-P and Enzyme-P in the 10-20 cm soil layer,increased the content of Ca Cl₂-P but decreased the content of Citrate-P in the 20-40 cm soil layer.（2）The expansion of moso bamboo into broadleaf and conifer forests significantly increased NH₄⁺-N content in the 0-10 cm soil layer,but decreased SWC,TN,NO₃^--N,SOC and Al_d content and increased the p H in the three soil layers.The Olsen-P content was significantly reduced in the 0-10 cm soil layer with the moso bamboo expansion into broadleaf forests;the Olsen-P content was increased,and the Fe_d content was reduced in three soil layers with the moso bamboo expansion into conifer forest.The Ca Cl₂-P content of soil in moso bamboo expansion into broadleaf forests was significantly and negatively correlated with SWC,Citrate-P content was significantly and positively correlated with SWC,SOC and TN in the 10-40 cm soil layer;the Ca Cl₂-P content of soil in the moso bamboo expansion into conifer forests was negatively correlated with SWC,TN,Fe_d and Al_d,and positively correlated with p H and Olsen-P in the 10-40 cm soil layer.（3）The soil phosphorus sorption and desorption capacity in the three soil layers was significantly enhanced in the expansion of moso bamboo into broadleaf and conifer forests.The soil phosphorus sorption and desorption capacity in moso bamboo forest and mixed bamboo and broadleaf forests was significantly higher than that in broadleaf forests.The soil phosphorus sorption and desorption capacity of moso bamboo forests was significantly higher than that of conifer forests and mixed bamboo and conifer forests.Both Enzyme-P and HCl-P content were negatively correlated with MBC and K in the 0-10 cm soil layer in the expansion of moso bamboo into broadleaf forest.Both Ca Cl₂-P and HCl-P were positively correlated with Q_max in the 0-20 cm soil layer in the expansion of moso bamboo into conifer forests,and both the content of Ca Cl₂-P and Enzyme-P were negatively correlated with MBC in the 10-40 cm soil layer.（4）The expansion moso bamboo into broadleaf/coniferous forests significantly altered soil microbial diversity and community composition in three different soil layers.The relative abundance of Ascomycota was increased in the 0-10 cm soil layer in the expansion of moso bamboo into broadleaf and conifer forests.The relative abundance of Basidiomycota,Mortierellomycota and Rozellomycota was reduced in the 0-10 cm soil layer in the expansion of moso bamboo into broadleaf forests.There was no significant effect on the relative abundance of the major bacteriophyta.The relative abundance of Ascomycota was highly positively correlated with soil HCl-P content in the expansion of moso bamboo into broadleaf and conifer forests.In the expansion of moso bamboo into broadleaf forests,the relative abundance of Actinobacteriota was highly negatively correlated with soil Ca Cl₂-P content;the relative abundance of Rozellomycota was positively correlated with Citrate-P content;Enzyme-P content was positively correlated with bacterial community richness,fungal community richness and diversity.In the expansion of moso bamboo into conifer forests,the relative abundance of Actinobacteriota was positively correlated with Citrate-P content;HCl-P content was negatively correlated with the relative abundance of Chloroflexi and positively correlated with the relative abundance of Mortierellomycota.