桂林会仙喀斯特湿地芦苇群落土壤微生物数量动态分析

Dynamic changes of soil microbe quantity in reed vegetation of Huixian Karst Wetland,Guilin,China

关键词:  喀斯特湿地, 细菌, 真菌, 放线菌, 根际效应

Key words:  karst wetland, bacteria, fungi, actinomyces, rhizosphere effect

摘要:

以广西桂林会仙喀斯特湿地典型芦苇植物群落为研究对象,于春、夏、秋、冬四个季节分别采集0～10 cm,10～20 cm和20～30 cm不同层次的土壤样品,分析根际微生物与非根际微生物的数量特征及季节动态变化特点,探讨微生物数量对水热季节变化的响应规律。结果表明:不同季节的根际微生物与非根际微生物组成,均以细菌占绝对优势; 微生物数量分布大小顺序为细菌>放线菌>真菌,细菌最高比例为96.62%,放线菌最高比例为35.38%,真菌的比例较低,最高仅为0.30%。细菌,真菌和放线菌的垂直变化明显,均随着土层的增加而呈现递减的趋势。不同土壤层次根际微生物与非根际微生物的季节变化一致,细菌数量表现为夏季>秋季>春季>冬季,真菌数量表现为秋季>夏季>春季>冬季,放线菌数量表现为秋季>春季>夏季>冬季; 细菌、放线菌、真菌的最大值分别为2.70×10⁷ 、1.92×10⁶ 、3.35×10⁴ cfu·g^-1,土壤微生物数量与土壤有机碳、全氮、全磷、全钾、速效氮、速效磷、速效钾等呈显著正相关。芦苇植物群落根际土壤微生物呈现出一定的根际效应,并与微生物数量、土壤深度、月平均降雨量和月平均气温变化等有关,而在冬季的根际效应则表现不显著。土壤养分含量是调节会仙喀斯特湿地土壤微生物数量变化的一个主要因素。

Abstract:

Reed is one of the typical dominant plant communities in Huixian Karst Wetland. In order to investigate the dynamic distribution characteristics of soil microbes of reed plant community in Huixian Karst Wetland and to explore the response mechanism of soil microorganism on water and thermal seasonal change, different levels of soil samples(0-10, 10-20 and 20-30 cm)were collected, and the composition and distribution of bacteria, fungi and actinomycetes between rhizosphere and non-rhizosphere were studied during spring, summer, autumn and winter in reed vegetation, respectively. The results showed that the quantities of rhizosphere and non-rhizosphere microorganism were different at different seasons. Among all microbes, bacteria were the most numerous followed by actinomyces, with fungi the least numerous. The highest proportion of bacteria was 96.62%, actinomycetes was 35.38%, and fungi was very small. The soil vertical change of bacteria, fungi and actinomycetes were obviously. The microbial quantity decreased with the increasing of soil depth on the whole. The seasonal change of different soil levels of rhizosphere microorganism and non-rhizosphere microorganism were consistent in our study plot. The results indicated that the bacteria quantity in the same soil layer followed the way of summer > autumn > spring > winter, but the fungi quantity showed autumn > summer > spring > winter, the actinomycetes quantity was in an order of autumn > spring > summer > winter. Meanwhile, the maximum values of bacteria, actinomycetes and fungi were 2.70×10⁷, 1.92×10⁶ and 3.35×10⁴ cfu·g^-1 relatively. Microorganism in the soil of reed plant community had obvious rhizosphere effect to some extent. The microorganism and soil organic carbon, total nitrogen, total phosphorus, total potassium, available nitrogen, available phosphorus and available potassium had a significant positive correlation. The rhizosphere effect of microorganism associated with microbial type, soil depth, monthly average rainfall and temperature channges, and it was non-significantly in winter as a whole. It had significant seasonal variations as well. The content of soil nutrition may be a major factor for the change of soil microbial quantity in Huixian Karst Wetland. Meanwhile, the dynamic changes of the number of soil microorganism may reveal the environmental effects of wetlands. The scientific data for the wetland sustainable management policy would be suggested for Huixian Karst Wetland.