黄双双 裴隆翠 吴艳双 孙海龙

(东北林业大学，哈尔滨，150040)



水曲柳混交林与次生林土壤微生物量与酶活性特征1)

黄双双 裴隆翠 吴艳双 孙海龙

(东北林业大学，哈尔滨，150040)

以天然次生林和人工营造的水曲柳-落叶松(水落)、水曲柳-云杉(水云)和水曲柳-红松(水红)混交林为研究对象，测定了4种林型的土壤微生物量和酶活性。结果表明：次生林和水云混交林土壤中微生物量碳、氮质量分数均高于水落和水红混交林，土壤微生物磷质量分数也表现为水红混交林最低，但是土层深(H)0≤H<10 cm土壤微生物量碳质量分数/总碳质量分数和土壤微生物量氮质量分数/总氮质量分数表现为水红混交林最高，水落混交林最低的趋势。土层0≤H<10 cm土壤过氧化氢酶、蔗糖酶、脲酶和磷酸酶活性均表现为水红混交林最低的趋势。各林型土壤微生物量质量分数与土壤酶活性之间均呈显著正相关关系，且与土壤全碳、全氮、全磷、铵态氮质量分数也呈显著正相关。总之，次生林、水云和水落混交林由于较低的林分密度和较高的阔叶树比例，土壤生物活性较高，而水红混交林则相反。

次生林；水曲柳混交林；土壤微生物；土壤酶活性

Soil microbial biomasses and soil enzyme activities were investigated in the secondary forest (SF) and the mixed plantations ofFraxinusmandshuricaandLarixgmelinii(FLP),FraxinusmandshuricaandPiceakoraiensis(FPKP),FraxinusmandshuricaandPinuskoraiensis(FPP). The soil microbial biomass carbon (MBC) and nitrogen (MBN) were higher in the SF and FPKP than those in the FLP and FKP. Soil microbial biomass phosphorus (MBP) in the FPP were significantly lower. But the ratio of soil MBC to total carbon and MBN to total nitrogen in 0-10 cm depth were highest in the FPP, while the lowest in the FLP. Soil catalase, sucrase, urease and phosphatase activities in 0-10 cm depth were also lower in the FPP. There were a significantly positive correlation between soil microbial biomasses and soil enzyme activities, which were positively correlated with the soil total carbon, total nitrogen, total phosphorus and ammonium nitrogen. Therefore, the lower stand density and higher ratio of broadleaf trees increase the soil biological activities in SF, FLP and FPKP, but they are opposite in FPP.

土壤微生物量是体积小于5×10-3μm3的细菌、真菌、藻类和原生动物等生物的总量[1-3]，参与了土壤碳、氮、磷等营养元素的循环和转化，是土壤有机质的活性部分，也是土壤养分的储备库[4-6]。土壤酶是来自土壤微生物和植物根系的一种生物催化剂[7-8]，参与了土壤中的各种生物和生物化学过程，常用其活性表征这些过程的强度[9-12]。两者对外界干扰的响应均十分敏感，常共同研究用于分析土壤生物活性情况，对于土壤肥力和质量的评价具有重要意义。维持和提高森林土壤质量是森林可持续经营的关键，但是营造人工针叶纯林常导致林地土壤质量下降[5，13-16]，而针叶树与阔叶树的混交林能够缓解这种影响，如云杉(Piceaabies)与山毛榉(Fagussylvatica)混交[17]、落叶松(Larixgmelinii)与水曲柳(Fraxinusmandshurica)混交[18-19]、黑松(Pinusthunbergii)与刺槐(Robiniapseudoacacia)混交[20]等。研究发现，林分混交后土壤质量的这种转变与阔叶树混入后改变了土壤中的生物学过程密切相关[21-22]，因此，增加对混交林中土壤微生物和酶活性的研究有助于深入理解林木混交对土壤肥力影响的机制，并为林分的可持续经营提供理论支持。……