Characteristics Of Soil Phosphorus Under Typical Vegetation Types In Subtropical Forests And The Affecting Factors

Phosphorus?P?is an essential but highly limited nutrient for plant growth in subtropical forest soils.Comparing the characteristics and effect factors of soil phosphorus fractions across different vegetation types is important to reveal mechanisms that sustain and enhance forest ecosystem function.Soils were analyzed for the basic physicochemical characteristics,P fraction,and microbial community characteristics under evergreen broad-leaf forest?BF?and mixed forest?MF?or coniferous forest?CF?in Daiyun Mountain in summer and winter.The following main results were obtained:1)The soil labile P,moderately labile P,and biological P fractions were significantly higher in evergreen broad-leaf forest than in mixed forest and coniferous forest,indicating that evergreen broad-leaf forest is more beneficial to improving the availability of soil P,when compared with mixed forest and coniferous forest.2)The soil labile P,moderately labile P,and biological P fractions in evergreen broad-leaf forest did not change markedly in winter compared to summer,whereas those in mixed forest and coniferous forest significantly decreased than in summer.Non-labile P and geochemical P concentrations in evergreen broad-leaf forest significantly increased,but those in mixed forest and coniferous forest had no significant changes.These results indicate that the availability of soil phosphorus in evergreen broad-leaf forests is less affected by seasons and less restricted by habitat conditions.3)Microbial biomass phosphorus?MBP?in the evergreen broad-leaf forests soils was significantly higher than that in mixed forest and coniferous forest soils regardless of seasons,demonstrating evergreen broad-leaf forest has great potential to supply available P.Vegetation types altered soil phosphatase activity,but this alteration differed in two seasons,which was the combined effect of the P demand of organisms and substrate availability.4)The differences in microbial community composition in forest systems may be mainly attributed to Proteobacteria,Acidobacteria,Chloroflexi,Basidiomycota,Ascomycota,Zygomycota,as evidenced by biomarkers that had significant differences among the three forest vegetation types using LEfSe analysis.In addition,there were significant differences in soil microbial community groups between different seasons,which may be related to seasonal differences in soil nutrients and nutrient strategies of microorganisms.5)For horizon A,redundancy analysis?RDA?indicated that the changes in P fractions were mainly driven by soil NO₃^--N,and acid phosphomonoesterase?ACP?in summer,and by MBP in winter.For horizon B,Chloroflexi,dissolved organic nitrogen?DON?and soil organic carbon?SOC?were important factors affecting changes in P fractions of the soils in summer,whereas DON and total nitrogen?TN?were main effect factors in winter.The results suggest that the characteristics of soil P fractions under different vegetation types is the result of the combined action of biological and abiotic factors,in which soil microorganisms and N level are integral to the soil P cycle and as such play an important role in mediating the availability of P for plants.