杉木—光皮桦混交林对微生物量碳氮与酶活性的影响

以杉木—光皮桦混交林、杉木(Cunninghamia lanceolata)和光皮桦(Betula luminifera)纯林3种营造模式作为研究对象,分别对不同土层(0~5、5~20、20~40 cm)的土壤微生物生物量(SMBC、SMBN)的生态分布特征以及有机质、有效氮、土壤酶活性(酸性磷酸酶(ACP)、脲酶(URE)、蔗糖酶(INV)和过氧化氢酶(CAT))进行相关分析。结果表明:相同土层条件下,杉木—光皮桦混交林下土壤有机质、有效氮、SMBC、SMBN、ACP、URE及INV的酶活性均显著高于杉木、光皮桦纯林,然CAT活性略高;随着土层加深,各林下土壤有机质、有效氮、SMBC、SMBN、ACP、URE和INV均呈明显下降趋势。相关分析表明,不同林地和土层的土壤有机质、有效氮、微生物碳氮、土壤酶活性之间均存在正相关关系。混交模式下的林地土壤生物量、有机质、有效氮以及酶活性均高于杉木纯林模式,土壤生物学性质更加完善。

Effect of Cunninghamia lanceolata-Betula luminifera Mixed Forests on Soil Microbial Biomass and Enzyme Activi-ty

We studied three kinds of construction modal forests , Cunninghamia lanceolata-Betula luminifera mixed forest, C. lanceolata pure forest and B.luminifera pure forest to analyze soil microbial biomass , carbon and nitrogen contents and en-zyme activities in soils of C.lanceolata-B.luminifera mixed forest in northern Sichuan .We also analyzed the spatial charac-teristics and the effects of three different soil layers ( 0-5, 10-20, 20-40 cm ) on soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN), catalase (CAT), invertase (INV), acid Phosphatase (ACP) and urease(URE), respectively.The available N, SMBC, SMBN, INV, ACP and URE of C.lanceolata-B.luminifera mixed forests were significantly more than that of C.lanceolata forest and B.luminifera forest, and CAT activity was slightly more than that in the same soil layer .With the decreasing of the soil depths , the contents of organic and available N , and the enzymatic activities of SMBC ,SMBN , INV, ACP and URE all showed clear downward trends .By correlation analysis , there were significant ( P<0.05) or higher significant ( P<0.01) positive correlations between SMBC ,SMBN , INV, ACP and URE in different forests and soil layers .The soil microbial biomass , soil microorganism quantities , soil enzyme activi-ties and soil biological properties of C.lanceolata-B.lumi nifera mixed forest were higher than those in C.lanceolata pure forest and B.luminifera pure forest.