重度火烧迹地兴安落叶松(Larix gmelinii)根际土壤真菌群落研究

Abstract

为探究内蒙古根河大兴安岭林区重度火烧迹地不同生长状态的兴安落叶松根际土壤真菌群落特征，选取火烧枯立木（BDW）、火烧存活木（BSW）、未火烧对照木（CK），通过磷脂脂肪酸方法分析根际土壤真菌群落生物量变化，利用高通量测序技术对根际土壤真菌群落组成与功能进行分析，探讨影响根际土壤真菌群落的主要环境因子。结果表明：（1）相较于未火烧对照木，火烧枯立木与火烧存活木根际土壤真菌群落磷脂脂肪酸含量显著降低，真菌群落α多样性显著降低。β多样性分析与群落相似性分析结果显示，火烧枯立木、火烧存活木、未火烧对照木根际土壤真菌群落组成存在显著差异。（2）相较于未火烧对照木，火烧枯立木与火烧存活木根际土壤中担子菌门（Basidiomycota）真菌相对丰度显著下降，子囊菌门（Ascomycota）真菌相对丰度显著升高。子囊菌门（Ascomycota）内，火烧枯立木根际土壤中内生真菌相对丰度显著高于火烧存活木与未火烧对照木，而火烧存活木根际土壤中腐生-外生菌根复合型真菌相对丰度显著高于火烧枯立木与未火烧对照木。（3）根际土壤总磷、总钾含量是影响重度火烧迹地兴安落叶松根际土壤真菌群落优势菌门由担子菌门（Basidiomycota）转变为子囊菌门（Ascomycota）的主要环境因子，而根际土壤总碳、总氮、总磷含量则是造成火烧枯立木与火烧存活木根际土壤真菌群落组成与功能差异的主要环境因子。本研究有助于了解大兴安岭林区土壤真菌群落结构，对真菌群落多样性的维持与管理具有参考价值。;Fire is an important disturbance factor in forest. The severe fire will significantly change the structure and succession process of forest ecosystem. As an important component of soil microorganisms, fungi respond quickly to fire disturbance and are very sensitive to changes in soil physicochemical properties. The composition and function of fungal communities are important biological indicators for restoration after severe fire. When plants are disturbed by fire, the fungal community are also affected. In the case of severe fire, such a correlation will persist for a long time. The Great Xing'an Mountain forest ecosystem is of great strategic significance to China, and is also the area of frequent forest fires. L. gmelinii is the main zonal vegetation in this area. The restoration of L. gmelinii is of great importance to the restoration of forest ecosystem after fire. The relationship between the growth status of L. gmelinii and rhizosphere soil fungal community after severe fire has not been studied.The purpose of this study was to investigate the characteristics of the rhizosphere soil fungal community of L. gmelinii in different growth status in the severe burned area of Great Xing'an Mountain, Genhe, the Inner Mongolia Autonomous Region. We investigated the growth status of L. gmelinii, selected the burned dry wood (BDW), burned survival wood (BSW) and unburned control wood (CK). We measured the physicochemical properties of rhizosphere soil. The phospholipid fatty acid of rhizosphere soil was sampled and analyzed to understand the change of fungal community biomass, and the composition and function differences of the fungal community were analyzed by high-throughput sequencing. We also discussed the key environmental factors affecting the rhizosphere soil fungal community. Results show that:(1) compared with CK, the content of phospholipid fatty acid and alpha diversity of fungal community in the rhizosphere soil of BDW and BSW were significantly reduced. Beta diversity and community similarity analysis showed that there were significant differences in the rhizosphere soil fungal community between BDW, BSW and CK. (2) The relative content of Basidiomycota decreased significantly and the relative content of Ascomycetes increased significantly in the rhizosphere soil of BDW and BSW compared with those of CK. In Ascomycota, the relative content of endophyte fungi in the rhizosphere soil of BDW was significantly higher than that of BSW and CK, the relative content of saprophytic-ectomycorrhizal compound fungi in the rhizosphere soil of BSW was significantly higher than that of BDW and CK. (3) The contents of total phosphorus and total potassium in rhizosphere soil were the main environmental factors affecting the transformation of the dominant fungi phylum from Basidiomycota to Ascomycota in the rhizosphere soil of L. gmelinii after severe burned. The contents of total carbon, total nitrogen, total phosphorus were the main environmental factors that caused the differences in the composition and function of fungi in the rhizosphere soil between BDW and BSW. The study is helpful to understand the structure of soil fungal community in the Great Xing'an Mountain forest ecosystem and has reference value for the maintenance and management of fungal community diversity.