安徽查湾自然保护区常绿阔叶林不同林分土壤微生物群落代谢特征

Metabolic Characteristics of Soil Microbial Community in Different Stands of Subtropical Evergreen Broad-leaved Forest at Chaiwan Natural Reserve in Qimen, Anhui

为探讨亚热带常绿阔叶林不同林分土壤微生物群落特征,在安徽祁门县查湾自然保护区亚热带常绿阔叶林内,分别选择以甜槠(Castanopsis eyrei(Champ.)Tutch.)为单一优势种的林分P1,以青冈栎(Cyclobalanopsis glauca(Thunb.)Oerst.)、甜槠和马尾松(Pinus massoniana Lamb.)为优势种的林分P2,各设置3个重复样地,采用Biolog方法探讨了土壤微生物群落功能多样性与林分结构的关系。结果表明,林分P2土壤养分(铵态氮、硝态氮、可溶性有机碳氮)均高于林分P1,但没有显著差异(P>0.05);两种林分0~10 cm土层的土壤养分含量明显高于10~20 cm土层。培养48 h后,林分P2的0~10 cm与10~20 cm土层AWCD均大于P1,并且0~10 cm土层差异较大,但不同土层AWCD在两种林分之间均未达到显著差异(P>0.05)。林分P2 0~10 cm土层AWCD、Shannon指数(H')、Simpson指数(D)、Mclntosh指数(U)和丰富度指数(S)均高于林分P1,林分P2的H'与D显著高于林分P1(P=0.03,P=0.02),但10~20 cm土层所有功能参数在P1与P2之间没有显著差异(P>0.05)。0~10 cm土层,林分P1土壤微生物对醇类和糖类利用率较高,林分P2对糖类和酯类利用率较高。10~20 cm土层,林分P1对醇类利用率较高,林分P2对胺类和醇类利用率较高。冗余分析(RDA)显示,铵氮、林分胸高断面积、林分丰富度指数、土壤含水率、溶解性有机碳(DOC)及溶解性氮(DN)对微生物碳源利用影响较大。其中,铵氮、林分丰富度指数、含水率、DN几乎与所有碳源代谢呈正相关。林分结构因子除林分丰富度指数外均与所有碳源代谢呈负相关;蒙特卡罗置换实验显示林分胸高断面积与土壤微生物群落代谢呈显著负相关(r2=0.42,P=0.02)。以上结果说明亚热带北部常绿阔叶林土壤微生物群落代谢特征受林分结构的制约。

In order to reveal the relationship between soil microbial function diversity and stand structure,two different stands ofevergreen broad-leaved forest in Chaiwan Natural Reserve in Qimen County,Anhui Province,were selected.One stand(P1)wasdominated by Castanopsis sclerophylla,and another(P2)dominated by Cyclobalanopsis glauca,Pinus massoniana and Castaneaseguinii,and each set three repeating plots.The relationship between functional diversity of soil microbial community and standstructure was discussed by Biolog method.The results showed that the concentrations of soil NH4+-N,NO3--N,dissolved organiccarbon(DOC)and nitrogen(DN)in P2were higher than in P1with no significant difference.The soil nutrients in0~10cm soil layerwere significantly higher than in10~20cm.After48h of inoculation,the AWCD values of0~10cm and10~20cm soil layers weregreater in P2than in P1.The Shannon-Wiener(H),Simpson(D),Mclntosh(U)and richness(S)indices in0~10cm soil layer werehigher in P2than in P1,with significant differences in H'and D between P2and P1(P=0.03,P=0.02).There were no significantdifferences in those indices in10~20cm soil layers between P1and P2.In0~10cm soil layer,the high utilization by soil microbeswere alcohols and carbohydrates in P1,while were carbohydrates and esters in P2.In10~20cm soil layer,the high utilization by soilmicrobes was alcohols in P1,while amines and alcohols in P2.The results of redundancy analysis(RDA)showed that NH4+-N,standbasal area,richness index,soil water content,DOC,DN had great effect on soil microbial carbon-source utilization.The microbialcarbon-source metabolism was positively correlated with NH4+-N,richness index,soil water content,DN.There were negative correlationsbetween microbial carbon-source metabolism and stand structure parameters except for richness index.The result indicatesthat the soil microbial metabolism is controlled by stand structure in this subtropical evergreen broad-leaved forest.