太岳山不同林龄人工油松林土壤微生物特征

Investigation of Soil Microbial Characteristics During Stand Development in Pinus tabuliformis Forest in Taiyue Mountain

油松(Pinus tabuliformis Carr.)具有保土保肥和改善水土流失的作用,是黄土高原地区植被恢复中广泛使用的树种.为了探究土壤微生物多样性和群落结构对人工油松林演替的响应及其环境因子驱动机制,以太岳山脉潘家山10、20和30 a人工油松林土壤为研究对象,基于野外采样、室内理化分析和高通量测序等手段,分析不同林龄表层和亚表层土壤微生物群落结构、多样性及其与土壤理化性质之间的关系.结果表明:(1)30 a的人工油松林演替显著改变了土壤养分状况. SOM、TN、NH_(4)^(+)-N、NO_(3)^(-)-N、AP和AK均随演替的进行显著升高;TP和TK含量随演替年限逐渐降低.(2)不同林龄油松林土壤真菌的优势门为子囊菌门、担子菌门和被孢菌门,细菌的优势门为放线菌门、变形菌门、酸杆菌门、绿弯菌门和芽单胞菌门.(3)油松林土壤微生物中细菌占绝对优势,真菌和细菌拷贝数随林龄增加均显著增加,30 a油松林土壤真菌拷贝数和细菌拷贝数分别是10 a油松林的6.61倍和2.55倍.(4)随着林龄增加,土壤真菌多样性显著下降.属水平上,子囊菌门中青霉菌属相对丰度大幅下降,达21.07%,担子菌门中红菇属相对丰度增加了14.2%;细菌多样性和群落结构总体变化较小,属水平上变形菌门中慢生根瘤菌属在演替过程仅增加3.03%.(5)油松林演替过程中,土壤细菌和真菌生物量、红菇属相对丰度与SOM和TN显著正相关,真菌多样性、青霉菌属相对丰度与土壤TP含量显著正相关.综上,油松演替过程中,土壤微生物量、多样性及群落结构的变化受土壤养分的共同驱动.研究结果可为区域植被恢复的生态效益评价提供基础数据和理论参考.

Pinus tabuliformis,commonly known as Chinese pine,plays a significant role in soil and water conservation as well as mitigating soil erosion.It is widely utilized as a tree species for vegetation restoration in the Loess Plateau Region.In order to investigate the response of soil microbial diversity and community structure to P.tabuliformis forest succession and its driving mechanisms by environmental factors,we studied P.tabuliformis plantations that were 10,20,and 30 years old in the Taiyue Mountain,Shanxi Province.Field sampling,indoor physicochemical analysis,and high-throughput sequencing were combined to analyze the relationship between soil microbial community structure,diversity,and soil physicochemical properties in the surface and subsurface soil layers across different forest ages.The results showed that:①The 30-year succession of P.tabuliformis forest significantly altered soil nutrient contents.The soil organic matter(SOM),total nitrogen(TN),ammonium nitrogen(NH_(4)^(+)-N),and nitrate nitrogen(NO_(3)^(-)-N)in the 30-year-old P.tabuliformis forest were significantly higher than those in the 10-year and 20-year-old forests,whereas the concentrations of total phosphorus(TP)and total potassium(TK)decreased gradually with the growth of P.tabuliformis stands.In addition,the SOM and nutrient concentrations in the topsoil were higher than those in the subsoil.②The dominant phyla of soil fungi in different-aged P.tabuliformis forests were Ascomycota,Basidiomycota,and Mortierellomycota,and the dominant phyla of soil bacteria were Actinobacteria,Proteobacteria,Acidobacteria,Chloroflexi,and Gemmatimonadetes.③Bacteria dominated the soil microbial community in the soil of P.tabuliformis forests,and the copy numbers of fungi and bacteria both significantly increased with the age of the forest stands.The copy numbers of fungi and bacteria in the 30-year-old P.tabuliformis forest were 6.61 times and 2.55 times higher,respectively,than those in the 10-year-old P.tabuliformis forest.④The diversity of soil fungi decreased significantly with increasing forest age.At the genus level,the relative abundance of Penicillium in the phylum Ascomycota decreased significantly by 21.07%,whereas the relative abundance of Russula in the phylum Basidiomycota increased significantly by 14.2%.Bacterial diversity and community structure showed relatively minor changes.At the genus level,the relative abundance of Bradyrhizobium in the phylum Proteobacteria slightly increased by 3.03%during the succession process.⑤During the succession of P.tabuliformis forests,the soil bacterial and fungal biomass and the relative abundance of Russula were significantly positively correlated with SOM and TN,respectively,and the fungal diversity and relative abundance of Penicillium were significantly positively correlated with TP.In summary,changes in soil microbial abundance,diversity,and community structure during the succession of P.tabuliformis were collectively driven by soil nutrient concentrations.These results can provide fundamental data and theoretical references for the ecological benefit evaluation of regional vegetation restoration.