Study On Soil Organic Carbon Mineralization In Different Forests Of Fengyang Mountain

This research choosed forest stands soil of 3 plots of Fengyang mountain in Zhejiang province for the sampling and analysis,6 kinds of forest are Cryptomeria fortune of Feng Yanghu,Mixed forest of Feng Yanghu,Broadleaf forest of Shi Liangao,Mixed forest of Shang Yuqiao,Fir wood of Shi Liangao and Fir wood of Shang Yuqiao. By using laboratory incubation test method,the research studied dynamic process of soil organic carbon mineralization and microbial biomass carbon and nitrogen in size in 80 day,and compared the differences in soil organic carbon mineralization and microbial biomass carbon and nitrogen in different stands, temperature and depth.The study also analysis the correlation between the mineralization of organic carbon in biomass, microbial carbon and nitrogen, soil fertility and soil enzyme.The results show that:(1) The daily mineralization of soil organic carbon between different depth exist significant difference. Six forest daily mineralization of organic carbon decreased with depth increasing, The daily mineralization of 0~20cm layer(19.35 m LCO2·kg-1·d-1) was significantly higher than that of 20~40cm layer(8.92 m LCO2·kg-1·d-1) and 40~60cm layer(6.78 m L m LCO2·kg-1·d-1), the significant difference between 20~40cm layer and 40~60cm layer in response to changes in temperature and stand.Daily mineralization of organic carbon in different forest soils did not exist significant difference(P<0.05), there was a logarithmic relationship between daily mineralization of organic carbon content and incubation time.(2) The accumulation of organic carbon mineralization in different temperature existed significant difference.6 kinds of forest soil organic carbon accumulated mineralization increased with temperature increasing,accumulation of SOC mineralization values of 30℃ were significantly higher than that of 10℃ and 20℃.In addition to Mixed forest of Shang Yuqiao, cumulative mineralization values of 20℃ was significantly higher than 10℃.The accumulation of organic carbon mineralization of Broadleaf forest of Shi Liangao(637.48 m LCO2·kg-1) was significantly higher than that of the Mixed forest of Feng Yanghu(518.21 m LCO2·kg-1) and Cryptomeria fortune of Feng Yanghu(502.63 m LCO2·kg-1), and the rest did not exist significant difference(P<0.05).There was a linear relationship between accumulated mineralization of organic carbon content and incubation time.(3) Soil organic carbon mineralization rate in different temperature existed significant difference.6 kinds of stands 20℃and 30℃mineralization rate was significantly greater than 10℃, but there was no significant difference between 20℃ and 30℃(P<0.05). Soil organic carbon mineralization rate increased with depth increasing under three kinds of temperature, soil mineralization rate in 20~40cm layer and 40~60cm layer, Broadleaf forest of Shi Liangao(3.81) significantly greater than other forest stands,and there was no significant difference among 6 forest in 0cm~20cm layer(P < 0.05).(4) Soil microbial biomass carbon rate in different temperature existed significant difference.Soil microbial carbon appeared to decrease with the temperature increasing trend. In addition to the Mixed forest of Feng Yanghu, other stand at 10℃ in the microbial biomass carbon was significantly higher than that of 20℃ and 30 ℃,and differences between 20℃and 30 ℃ in response to changes of temperature and stand.There was no significant difference between different forest soil microbial biomass carbon, that ranged 558mg/kg~686mg/kg. Soil microbial biomass nitrogen in different stands was significantly different, Cryptomeria fortune of Feng Yanghu(36.47 mg/kg), Mixed forest of Feng Yanghu(35.57 mg/kg) and Mixed forest of Shang Yuqiao(34.88 mg/kg), significantly higher than the other stand(24.62 mg/kg).The microbial biomass carbon and nitrogen increased first and then decreased, after rising again and tended to balance during the incubation period, and the trend was similar with microbial biomass carbon of variation.Soil microbial biomass C/N existed the significant difference between different stands.Broadleaf forest of Shi Liangao(25.55), Fir wood of Shi Liangao(24.38) and Fir wood of Shang Yuqiao(24.12) of microbial biomass C/N was significantly higher than that of other stand, and that was opposite of microbial biomass carbon and nitrogen(P < 0.05).(5) The soil microbial quotient and microbial nitrogen/total nitrogen existed significant difference between different forest. Cryptomeria fortune of Feng Yanghu and Mixed forest of Shang Yuqiao microbial quotient and microbial biomass nitrogen/total nitrogen were significantly higher than that of the Fir wood of Shang Yuqiao and Broadleaf forest of Shi Liangao.Soil microbial metabolic quotient of Broadleaf forest of Shi Liangao(0.105) was significantly higher than that of Cryptomeria fortune of Feng Yanghu(0.068), the rest did not exist significant difference(P<0.05). The dynamic laws of the three was first increased,then decreased, and finally tends to be balanced, but order of magnitude of the microbial quotient, microbial nitrogen / total nitrogen and microbial metabolic quotient was different,and 6 kinds of forest of soil microbial biomass carbon and nitrogen ratio far less than microbial quotient.(6) 4 kinds of soil enzyme activity existded significant difference among different stands.Urease of Mixed forest of Shang Yuqiao,Cryptomeria fortune of Feng Yanghu å'Œ Fir wood of Shang Yuqiao was significantly greater than the other stand. Invertase activity of Mixed forest of Shang Yuqiao was significantly greater than Fir wood of Shang Yuqiao and Broadleaf forest of Shi Liangao.The acid phosphatase of Broadleaf forest of Shi Liangao å'Œ Fir wood of Shi Liangao was significantly smaller than the other stand. Catalase was significantly greater than the other stand of Broadleaf forest of Shi Liangao and Fir wood of Shang Yuqiao. The other did not exist significant differences between the stand(P<0.05).(7) The correlation analysis showed that: microbial carbon and nitrogen, soil enzyme, soil fertility was closely related. Urease, acid phosphatase and catalase and organic carbon, total nitrogen and microbial biomass nitrogen was significantly related(P<0.01), catalase with organic carbon and soil carbon and nitrogen ratio is negative correlation. Correlation between the 4 kinds of soil enzyme,potassium and water content did not reach significant level(P<0.05). invertase and microbial biomass carbon(0.533*) were significantly correlated. Microbial nitrogen and organic carbon and total nitrogen had a significant correlation(P<0.01).