Soil Microbial Diversity And Abundance Of Phosphorus Transforming Microorganisms In Two Subtropical Forest Types

Phosphorus(P)is essential to the vital activity of plant,and is the main limiting nutrient elements for plant growth and development.However,95%to 99%of soil P is present in the form of polymers that are difficult for plants to absorb,plants are often under P deficiency stress,especially in the subtropical acid red soil hilly region.Microorganism is the engine driving of soil P biogeochemical cycle,participate in most processes of soil P transformation,and it plays a key role in these processes.The physical and chemical properties of soil or the microbial functional groups would be different,when the forest in a different type or operating way.The differences of ectoenzyme affect the soil P cycle process and its effectiveness greatly.But what about the current influence of forest types on soil P availability,and how does the abundance and diversity of soil microbial functional communities(especially the p-transforming microbial functional communities)respond to forest types,the research on this aspect has not been reported yet.In this study,two forest types with similar ages,adjacent regions and basically environmental conditions(slope,slope aspect,altitude and soil)were selected in the subtropical hilly region:Pinus massoniana plantation(PMP)with close-nature management,Pinus massoniana-lithocarpus glaber(PLF)mixed coniferous and broad-leaved secondary forest,and take them as the research object,set up a fixed and standard sample plot,collect the soil samples,use modern molecular biology techniques(functional gene sequencing,enzyme kinetics)to study soil physical and chemical properties,phosphatase activity,microbial diversity and the abundance of alkaline phosphatase coding genes,to explore the influence mechanism of soil microbial diversity and alkaline phosphatase encoding gene abundance in PMP and PLF,it is of great significance to reveal the transformation mechanism of soil P availability by forest type,provide scientific foundation for sustainable management and nutrient management for subtropical forest ecosystem.The main findings are as follows:(1)The pH value of the two forest soils is 3.89-4.42,which is typical acid red soil.The pH in 0-15 cm soil layer of PMP was significantly higher than that of PLF,but the moisture content and AK content of PMP were significantly lower than those of PLF;SMBC,SMBN,SMBP,ACP,ALP between PMP and PLF had no significant differences.In the vertical distribution,the moisture content,SOC,TN,AP,AK,SMBC,SMBN,SMBP,ACP and ALP contents in PMP humus layer were significantly higher than those in 0-15cm soil layer,but the pH and TK contents in it were significantly lower than those in 0-15cm soil layer.The moisture content,pH,SOC,TN,AP,AK,SMBC,SMBN,SMBP,ACP,ALP of PLF humus layer were significantly higher than those of 0-15cm soil layer,but TK content in it was significantly lower than that in 0-15cm soil layer.In PMP,ACP and ALP were significantly positively correlated with SOC,TN,AP,AK,SMBC,SMBN,SMBP,but negatively correlated with TK,and ALP was also significantly positively correlated with water content and negatively correlated with pH.In PLF,ACP and ALP were significantly positively correlated with SOC,TN,SMBC,SMBN,SMBP,and ALP were also significantly positively correlated with AK.(2)There was no significant difference in soil fungal community structure between PMP and PLF.Basidiomycota(38.75%-60.30%),Ascomycota(24.68%-39.24%)and Unclassified_K_fungi(8.29%-23.83%)were the dominant fungi in the two forest types.The soil fungal community structure of PMP was positively correlated with TK,but negatively correlated with AP,TN and AK.There was no significant correlation between fungal community structure and soil factors in PLF soil.There was no significant difference in soil fungal diversity between PMP and PLF.The PMP richness index(ACE index,Chao1 index)was significantly positively correlated with ACP,SMBC,SMBN,and the PLF richness index was significantly positively correlated with ACP.(3)There was no significant difference in bacterial community structure between PMP and PLF.Proteobacteria(26.99%-29.84%),Acidobacteriota(22.32%-26.96%)and Actinobacteriota(18.35%-28.42%)were the dominant phyla in both types of forests.The bacterial community structure of PMP soil was significantly positively correlated with pH and SOC,and negatively correlated with water content,ACP,ALP,SMBP and SMBN.There was no significant correlation between bacterial community structure and soil factors in PLF soil.There was no significant difference in soil bacterial diversity between PMP and PLF.The Shannon index of PMP was negatively correlated with water content,and positively correlated with pH.The Chao1 index of PLF was positively correlated with pH.(4)There was no significant difference in the abundance of phoD gene between PMP and PLF phoD gene abundance of PMP was not significantly correlated with soil factors,while phoD gene abundance of PLF was significantly positively correlated with water content,AP and SMBN.The above results indicated that,there was no significant difference in the effects of Pinus massoniana plantation with close-nature management and Pinus massoniana-lithocarpus glaber mixed coniferous and broad-leaved secondary forest on soil physical and chemical properties,soil microbial diversity and the abundance of P transformed microorganisms.