Effects of tree species assembly on bioavailable P components in rhizosphere soil of southern subtropical plantation
Improving the availability of soil phosphorus(P)and promoting tree growth through tree species selec-tion and assembly are the critical issue.We conducted an afforestation experiment following randomized block experimental design with 1,2,4,and 6 tree species richness in south subtropics,including Pinus massoniana,Mytilaria laosensis,Erythrophleum fordii,Castanopsis hystrix,Michelia macclurei,Manglietia glauca,Aquilaria sinensis,and Dalbergia odorifera.We measured the bioavailable P components(CaCl2-P,citrate-P,enzyme-P and HCl-P)and examined the effects of different tree species assembly on bioavailable P components and tree growth.The results showed that,compared with non-nitrogen-fixing tree species,the mixing of nitrogen-fixing tree species(E.fordii and D.odorifera)effectively increased the contents of soil water,total nitrogen,total phosphorus,and microbial biomass P(MBP).The assembly of specific tree species improved the accumulation of bioavailable P.Mixing of nitrogen-fixing tree species significantly increased CaCl2-P content by 46.2％to 160.3％,the enzyme-P content produced by microbial mineralization by 69.3％to 688.2％,and HCl-P by 31.5％to 81.3％,increased MBP by 81.8％to 149.4％,and microbial biomass N(MBN)by 88.1％to 160.6％,respectively.Redundancy and correlation analysis results showed that MBP,available P,total phosphorus,L-leucine aminopeptidase,cellobiose,acid phosphatase,MBN and soil organic carbon were key factors driving the variation of rhizosphere soil bioavail-able P.Mixing of nitrogen-fixing tree species increased enzyme-P and citrate-P,and the availability of which were positively correlated to tree basal area.In this study,mixing of nitrogen-fixing tree species increased the rhizosphere soil bioavailable P content,which facilitates tree growth.
south subtropicsplantationbioavailable Ptree species assemblystand growth
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