Effects Of Simulated Acid Rain And Litter On Cryptomeria Fortune Soil Microbial And Enzyme Activities

In order to investigate the effects of acid rain and litter on the soil microbial and enzyme activitiesof Cryptomeria forestry soil in mountain Tianmu, using Cryptomeria fortunei seedling rhizospheresoil as materials, we researched the effects of simulated acid rain （pH3.0,4.0,5.6） and litter (400,500,600g·m^-2) as well as combined of acid rain and litter on the soil microbial biomass C, microbialfunctional diversity and activities of soil enzymes in rhizosphere soil after a short-term （30days）and a long-term （90days） processing. The results showed that:（1） Acid rain and litter reduced C. fortunei rhizosphere soil microbial biomass carbon, thedecreasing extent is pH4.0> pH5.6> pH3.0and400g·m^-2>500g·m^-2>600g·m^-2. After a long-termprocessing, the three levels of litter combind with acid rain could alleviate the inhibition of pH4.0acidrain and enhanced the inhibition of pH3.0and pH5.6acid rain on microbial biomass carbon.（2） The Acid Rain treatment had no significant effect on microbial diversity of C. fortuneiseedlings rhizosphere soil. Litter and combined treatment enhanced the metabolic capacity, richness,species dominance and evenness of the soil microbial community. Among them, pH4.0acid raincombined with400g·m^-2litter and pH3.0and pH4.0acid rain combined with600g·m^-2litter made asignificant differences with the control in the two periods.（3） After a short-term processing, the difference of soil microbial carbon source metaboliccharacteristics between the control with acid rain and400g·m^-2litter composite and pH3.0and pH4.0acid rain combined with500g·m^-2litter reached to the significant level. After a long-term processing,the acid rain of pH4.0and5.6combined with the600g·m^-2litter made the large differences in soilmicrobial carbon source metabolic characteristics with the control.（4） The main carbon source witch affected the microbial metabolism functional diversity of C.fortunei seedling rhizosphere soil was carbohydrates, carboxylic acids and amino acids. Thesetreatments witch soil microbial metabolism functional diversity was higher had higher utilizationcapability of α-D-Lactose, L-arginine,2-hydroxy benzoic acid。（5） Litter processed soil for a long time combined with acid rain, alleviated the inhibition ofdifferent levels of acid rain on soil dehydrogenase, urease, acid phosphatase and invertase activity andpromoted soil peroxidase activity. Each level of litter combind with pH3.0and pH4.0acid rain couldpromote the soil catalase activity;500g·m^-2litter combind with pH3.0and pH4.0acid rain couldpromote the soil polyphenol oxidase activity;500g·m^-2and600g·m^-2litter combind with pH4.0acidrain had a role in promoting the soil protease activity; the rest of combind treatment inhibited the soilcatalase, polyphenol oxidase and protease activity after a long time processing.（6） The impact of acid rain and litter on the enzyme activities of C. fortunei seedlings rhizospheresoil tended to polarize, acid rain tends to inhibit the activity of soil, and litter tends to promote soilenzyme activities. Acid rain and litter combined treatment could ease the impact of both of acid rainand litter on the activity soil enzymes, further more, it was conducive to enhance the overall soil enzymes activity. The400g·m^-2and600g·m^-2litter combined with pH3.0and5.6acid rain as well as600g·m^-2litter combined with pH4.0acid rain processed soil, had a good role in promoting theoverall activity of soil enzymes in the experimental time.