反复计划火烧对滇西北云南松林土壤细菌群落的影响

Effects of Repeated Prescribed Burning on Soil Bacterial Community of Pinus yunnanensis Forest in Northwest Yunnan

以云南洱源县平头山经历了长期反复计划火烧的区域作为研究样区,以云南松(Pinus yunnanensis)林土壤为研究对象;2019年5月17日,在选定的反复计划火烧区域、非火烧区域(为对照)分别各设置1个10 m×10 m样方,采用5点采样法(4角及中心)设置土壤样本采集点,按照土层深度0~5 cm,每个样区采集5份土壤样本(每份500 g);应用高通量测序方法对土壤细菌群落进行测序,应用Mothur(Version 1.30.1)进行α多样性分析,采用R语言vegan程序包(vegan package)进行细菌群落整体差异非度量多维尺度(NMDS)分析、差异显著物种分析,综合试验结果分析实施反复计划火烧对云南大理洱源县云南松林地土壤细菌群落的影响。结果表明:经反复计划火烧的云南松林地,土壤细菌群落发生了显著变化,多样性显著降低;但不同物种变化趋势不同。门水平变化最明显的为酸杆菌门(Acidobacteria),在反复计划火烧地,酸杆菌门在群落中的总比例显著低于非火烧地;其次是放线菌门(Actinobacteria),在反复计划火烧地,放线菌门在群落中的总比例显著高于非火烧地。反复计划火烧不利于土壤细菌多样性维持和群落稳定,地下生态系统不稳定,会影响地上森林生态系统的稳定性;反复计划火烧策略,应在考虑土壤微生物的基础上进一步优化。

The study area which had experienced long-term repeated prescribed burning in Pingtou Mountain in Eryuan County, Yunnan Province, was selected and the Pinus yunnanensis soil was collected as study subject. On May 17, 2019, two 10 m×10 m quadrats were selected in repeated prescribed burning field and the unburned field(as the control), respectively. Five-point sampling method(4 corners and center) was used to set up the soil sample collection point, and the five soil samples(500 g each) at a depth of 0-5 cm were collected from each sample area. The high-throughput sequencing was used to analyze the sequences of bacterial communities;Mothur(Version 1.30.1) was used for α-diversity analysis, non-metric multidimensional scaling(NMDS) analysis and significantly different species analysis of bacterial communities were performed using the vegan package in R language. All results were comprehensively analyzed to understand the effects of repeated prescribed burning on soil bacterial community of Pinus yunnanensis forest in Eryuan County, Dali, Yunnan Province. Under repeated prescribed burning soil bacterial communities changed evidently and the diversity were decreasing markedly, but the trends are different for different species. The phylum Acidobacteria had the most obvious change and showed the significantly reduced in abundance in burned field when compared to the unburned field. The second is Actinobacteria, the abundance of which are much higher in the burned field than in the unburned field. The repeated prescribed burning was not conducive to the maintenance of soil bacterial diversity and community stability, and the instability of the underground ecosystem will inevitably affect the stability of the overground forest ecosystem, so the strategy of prescribed burning in the future should be optimized considering the soil micro-organisms.