西双版纳热带森林土壤微生物生物量碳与生物功能研究

Soil Microbial Biomass Carbon and Biological Function of Tropical Forest in Xishuangbanna

对云南西双版纳地区的热带季雨林、次生林和种植15a(中龄林)的橡胶林的土壤微生物生物量碳含量和微生物功能进行研究,测定土壤理化性质、养分和微生物生物量碳含量,同时测定土壤微生物纤维素分解作用、硝化作用、固氮作用、氨化作用和呼吸作用。结果表明,3种森林类型的土壤微生物生物量碳含量在145.01-231.81mg/kg之间,橡胶林的土壤微生物生物量碳含量显著低于次生林和季雨林,土壤质量存在一定的下降。次生林和季雨林的土壤微生物生物量碳含量在旱季和雨季之间有显著性差异,橡胶林则无显著性差异。生物量碳含量与6种土壤养分和环境因子之间的回归关系均不显著。从旱季进入雨季,不同森林类型的土壤微生物纤维素分解强度逐渐增强,其中中龄橡胶林和次生林下的土壤微生物纤维素分解作用在不同季节有显著性差异;3种林型的硝化作用均先增强后减弱;中龄橡胶林和次生林的土壤微生物固氮作用均逐渐减弱;3种林型的土壤微生物氨化作用均逐渐减弱;呼吸作用强度随季节逐渐增强,中龄橡胶林和次生林差异显著。西双版纳季雨林除硝化和氨化作用在不同季节有显著差异外,其他微生物功能无显著差异,说明季雨林比橡胶林和次生林更加稳定。西双版纳地区5种土壤微生物功能的相关性并不高。

This paper was mainly studied on soil microbial biomass carbon and functions of some forest,including tropical monsoon rain forest,secondary forest and rubber forest planted for 15 years in Xishuangbanna,Yunnan Province.Soil physical and chemical properties,nutrients and microbial biomass carbon were determined,and soil microbial cellulose decomposition,nitrification,nitrogen fixation,ammoniation and respiration were determined.The results showed that the soil microbial biomass carbon content of three forest types ranged from 145.01 mg/kg to 231.81 mg/kg.Soil microbial biomass carbon content of rubber forest was significantly lower than that of secondary forest and seasonal rainforest,and soil quality decreased to a certain extent.The carbon content of soil microbial biomass in secondary forest and seasonal rainforest had significant difference between dry season and rainy season,while that in rubber forest had no significant difference.The regression relationship between microbial biomass carbon content and six soil nutrients and environmental factors was not significant.From dry season to rainy season,the decomposition intensity of soil microbial cellulose increased gradually in different forest types,and there was significant difference in different seasons between aged rubber forest and secondary forest.The nitrification of the three forest types all increased at first and then weakened.Soil microbial nitrogen fixation in middle-aged rubber forest and secondary forest gradually weakened.The soil microbial ammoniation of the three forest types gradually weakened,and the respiratory intensity increased gradually with the season,and there was a significant difference between the middle-aged rubber forest and the secondary forest.Except for the significant differences in nitrification and ammoniation in different seasons,there were no significant differences in other microbial functions in Xishuangbanna seasonal rain forest which indicating that the seasonal rain forest is more stable than rubber forest and secondary forest.Our research indicated that there was no significant correlation between the functions of five kinds of soil microorganisms in Xishuangbanna.