3种人工林土壤微生物群落结构与可溶性有机氮的相关性

Relations between Soil Soluble Organic Nitrogen and Microbial Compositions in Three Plantations

土壤可溶性有机氮(SON)不仅直接影响生态系统土壤养分的有效性和流动性,还在微生物生化循环中起着关键作用,但是目前有关土壤微生物群落组成与SON含量的相关性报道很少。测定了南方3种人工林土壤SON含量及土壤微生物群落结构,结果表明土壤水溶性SON含量表现出明显的垂直分布,表层土壤(0～20 cm)水溶性SON含量极显著地高于深层土壤(20～40 cm);不同林型土壤SON含量差异不显著;针阔混交林土壤微生物、细菌、真菌和放线菌的相对生物量极显著地高于阔叶林和针叶林(P<0.001),阔叶林土壤微生物量、细菌和放线菌显著高于针叶林,但阔叶林土壤真菌的相对生物量显著低于针叶林(P<0.05)。假单孢菌和甲烷氧化菌的相对生物量以阔叶林为最高(分别为9 756.3±751.7和1 476.3±15.5 nmol PLFA/g),显著高于针阔混交林和针叶林,而针阔混交林显著高于针叶林(P<0.05)。土壤SON与土壤微生物各组分之间存在显著的正相关性。

Soil SON directly affects the effectuality and fluidity of soil nutrients in the ecosystem, and plays a vital role in microbe biogeochemistry cycling. The concentration of SON is controlled by the diversity of soil microbe. However, studies on the relations between soil microbial compositions and SON concentration have been rarely reported. In the present study, the SON concentration and the composition of microbe in three plantations in mid-subtropics were measured. The results showed that： The contents of water - soluble SON in soil showed significant vertical differences, which were very significantly higher in the 0 -20 cm soil layer than those in the deep soil layer （20 -40 cm）. The differences in the SON content among different-type forest soil. were not significant. The relative biomasses of microorganisms, bacteria, fungi and actinomycetes inthe mixed coniferous forest soil were extremely significantly higher than those in the broad-leaved forest or in the coniferous forest （P 〈0.001 ）, and the relative biomasses of microbial, bacteria and actinomycetes in the broad-leaved forest soil were significantly higher than those in the coniferous forest soil, but the relative bio- mass of fungi in the broad-leaved forest soil was significantly lower than that in the coniferous forest soil（P 〈 0.05 ）. The relative biomasses of pseudomonas bacteria and methane-oxidizing bacteria in the broadleaf forest soil（9 756.3 ±751.7 and 1 476.3 ± 15.5 nmol of PLFA/g, respectively）, were significantly higher than those in the mixed coniferous or in coniferous forest soil, and that in the mixed coniferous was significantly higher than that in the coniferous forest soil （ P 〈 0.05 ）. There existed significant positive correlation between the content of soil SON and the relative biomass of various components of the soil microbial flora.