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通过室内培养实验,研究铵态氮和硝态氮添加对我国南方亚热带湿地松森林生态系统土壤微生物特性的影响。采用的氮添加处理为:对照(CK)、铵态氮(NH_4~+-N)和硝态氮(NO_3~–-N)。经7天和15天培养,分别分析两种不同粒径(大团聚体(>250μm)和微团聚体(53–250μm))样品的土壤特性、酶活性及微生物群落。结果表明,NH_4~+-N比NO_3~–-N更显著影响土壤微生物活性。添加NH_4~+-N培养7天和15天,土壤大团聚体和微团聚体的β-1,4-葡萄糖苷酶(βG)和β-1,4-N-乙酰葡糖胺糖苷酶(NAG)的活性显著增加,而添加NO_3~–-N仅使大团聚体中的β-1,4-葡萄糖苷酶(βG)和β-1,4-N-乙酰葡糖胺糖苷酶(NAG)的活性显著增加。NH_4~+-N和NO_3~–-N添加导致土壤微团聚体革兰氏阳性细菌的磷脂脂肪酸含量显著增加。然而,仅在大团聚体中,土壤养分含量与酶活性呈显著相关。本文结果表明土壤团聚体结构对土壤酶活性具有重要影响。
Through laboratory culture experiments, the effects of ammonium nitrogen and nitrate nitrogen on the soil microbial characteristics of Pinus elliottii Ecosystem in southern China were studied. The nitrogen addition treatments were CK, NH4 + -N and NO3- -N. After 7 days and 15 days culture, the soil characteristics, enzyme activities and microbial communities of two samples with different particle sizes (> 250μm and microaggregates (53-250μm)) were analyzed. The results showed that NH_4 ~ + -N ratio NO_3 ~ --N significantly affected soil microbial activity. Β-1,4-glucosidase (βG) and β-1,4-N-acetylglucosaminidase (βG) in soil aggregates and microaggregates after adding NH_4 ~ + -N for 7 days and 15 days NAG), while the addition of NO_3 ~ --N only caused β-1,4-glucosidase (βG) and β-1,4-N-acetylglucosaminidase ) Activity was significantly increased. The addition of NH_4 ~ + -N and NO_3 ~ - N resulted in a significant increase of phospholipid fatty acid content of soil microaggregate Gram-positive bacteria. However, in large aggregates, soil nutrient content was significantly correlated with enzyme activity. The results show that soil aggregate structure has an important impact on soil enzyme activity.