科尔沁沙地樟子松人工林土壤真菌共现网络及其与土壤因子的关系

Soil fungi co⁃occurrence network and its relationship with soil factors of Pinus sylvestris var.mongolica plantation in the Horqin Desert

为揭示科尔沁沙地樟子松(Pinus sylvestris var.mongolica)人工林土壤真菌间相互作用,以不同林龄(中龄、近熟和成熟)、不同土层(0—10和10—20 cm)樟子松人工林土壤为研究对象,以未造林地为对照样地,采用分子生态网络分析法,基于随机矩阵理比较分析樟子松人工林土壤真菌网络特征及其影响因素。研究结果表明:(1)中龄林到近熟林阶段,科尔沁沙地樟子松人工林土壤真菌网络平均连通度增大,平均路径长减小,网络愈加复杂,而近熟林到成熟林阶段则相反,网络愈加简单;不同土层间,10—20 cm土层土壤真菌平均路径长度小于0—10 cm土层,平均连通度和聚类系数大于0—10 cm土层,10—20 cm较0—10 cm土壤真菌间相互联系更为密切;与樟子松人工林相比,未造林地土壤真菌网络中的平均连通度略低于近熟林,平均路径长低于樟子松人工林,未造林地土壤真菌群落更不稳定。(2)中龄、近熟和成熟樟子松人工林土壤真菌关键菌种分别为Guehomyces sp.、Oidiodendron sp.和Pseudeurotium sp.,未造林地关键菌种为Alphamyces sp.。在0—10 cm土层樟子松人工林和未造林地土壤关键菌种为红菇属真菌(Russula sp.),在10—20 cm土层土壤关键菌种为Guehomyces sp.。(3)樟子松人工林土壤真菌网络组成与土壤含水量显著相关,土壤全氮与土壤真菌网络呈显著负相关(P<0.05),土壤pH值和速效磷与土壤真菌网络呈显著正相关(P<0.05)。在樟子松人工林中,近熟林土壤真菌群落更复杂;随土壤深度增加,土壤真菌群落联系愈加紧密;种植樟子松后土壤真菌群落更复杂。土壤真菌关键菌种组成在不同林龄和土层间均存在差异,土壤真菌网络组成受土壤含水量影响,中介中心性前50的操作分类单元(OTU)主要受土壤全氮、pH和速效磷等理化性质影响。研究结果有助于深入理解科尔沁沙地樟子松人工林土壤真菌群落结构,并为科尔沁沙地樟子松人工林可持续经营提供理论依据和科技支撑。

To reveal the interactions of soil fungi in Pinus sylvestris var.mongolica plantations in the Horqin Desert,collected the soil of P.sylvestris plantations along stand ages(half-mature,near-mature,and mature forest)with two soil layers(0—10 cm and 10—20 cm),and the undeveloped forest land was regarded as a control.The network characteristics of soil fungi of P.sylvestris plantations and the influence of soil factors were clarified using molecular ecological network analysis based on stochastic matrix theory.The results indicated that(1)from half-mature to near-mature forest,there was an increase in the average degree and a decrease in the average path length decreased with a more complex fungi network;while the network characteristics from near-mature to mature forest were opposite.The soil fungal networks in the 10—20 cm soil layer,with lower average path length and higher average degree and average clustering coefficient,had more close interactions than 0—10 cm soil layer.The average degree of soil fungal network in undeveloped forest land was slightly lower than that in near-mature forest,and the average path length was lower than that in all P.sylvestris plantations.There were higher stability of soil fungal community in P.sylvestris plantations than undeveloped forest land.(2)The key species of soil fungi in half-mature,near-mature,mature plantations and undeveloped forest land were Guehomyces sp.,Oidiodendron sp.,Pseudeurotium sp.,and Alphamyces sp.,respectively.The key species in 0—10 cm soil layer was Russula sp.in P.sylvestris plantations and undeveloped forest land,the key species in 10—20 cm soil layer was Guehomyces sp.(3)The composition of soil fungi network in P.sylvestris plantations was significantly correlated with soil water content(P<0.05).The soil total nitrogen was significantly negatively correlated with the soil fungal network,pH and available phosphorus were significantly positively correlated with soil fungi network(P<0.05).In P.sylvestris plantations,the soil fungi community in the near-mature forest was more complex.With the increase of soil depth,the association of soil fungi are more closely.Soil fungi community was more stable after planting of P.sylvestris plantations.The keystone species of soil fungi were different among the stand ages and soil layers,soil water content is the main influence factor of soil fungi network composition,and the Operational Taxonomic Units(OTUs)of top 50 betweenness centrality were mainly affected by soil total nitrogen,pH,and available phosphorus.The improved information contributes a better understanding of the community structure of soil fungi in P.sylvestris plantations in the Horqin Desert,and provides the theoretical and technological support for P.sylvestris plantation management.