广西主要人工林土壤微生物动态特征

根据广西区杉木(Cunninghamia lanceolata)、马尾松(Pinus massoniana Lamb)、桉树(eucalyptus)3种人工林分布情况,按其在各县市的分布权重选取不同龄级(幼龄林、中龄林、近熟林、成熟林、过熟林)典型样地,样地面积20m*50m,采用网格法采集表层土壤(0cm-10cm),采用稀释平板涂抹法测定土壤微生物数量,氯仿熏蒸法测定土壤微生物生物量。结果表明:3种人工林各林龄阶段土壤可培养微生物中,细菌数量占有绝对优势,幼龄、中龄、过熟龄阶段微生物数量大小顺序为:杉木>桉树>马尾松,杉木幼龄、马尾松、桉树近熟林微生物数量在各自的林型中最大。微生物生物量碳(Cmic)在杉木幼龄林、马尾松中龄林、桉树过熟林最大,微生物生物量氮(Nmic)在杉木过熟林、马尾松和桉树幼龄林最大,微生物生物量磷(Pmic)在杉木成熟林、马尾松幼龄林、桉树近熟林最大,杉木Cmic、Nmic、Pmic随着林龄的递增呈现出先降低后上升的趋势,马尾松和桉树微生物量随林龄的变化规律不明显。土壤Nmic与土壤细菌数量、真菌数量具有显著的(P<0.05)分形关系,其余的微生物量和微生物数量均不存在分形关系。

Dynamics of Soil Microbes in Dominant Plantations in Guangxi

Different age-level typical sample plot are selected according to the distribution status, which means the distribution weight among each cities and countries of Cunninghanua lanceolata, pinus massoniana lamb and eucalyptus. These sample plots are young growths, immature timbers, near-mature forests, mature forest and overmature forests. The area of sample plot is 20m*50m, the surface soil samples (0cm-10cm) were collected by using grid module method. The microbial amount was detected by using diluted flat smearing method, and the microbial biomass was measured by using chloroform fumigation.The result shows:the bacterial amount is absolute dominance among the cultivatable soil microbes of the three plantations in all age stages. The microbial amount of young growth, immature timber and overmature forest present a downwards order as:Cunninghamia lanceolata >eucalyptus >Pinus massoniana Lamb. The microbial amount of Cunninghamia lanceolata young growth, Pinus massoniana Lamb and eucalyptus near-mature forest are the biggest of the three forest types in all age stages. The microbial carbon (Cmic) of Cunninghamia lanceolata young growth, Pinus massoniana Lamb immature timber and eucalyptus overmature forest are the biggest. The microbial nitrogen (Nmic) of Cunninghamia lanceolata overmature forest, Pinus massoniana Lamb and eucalyptus young growth are the largest. The microbial phosphorus (Pmic) of Cunninghamia lanceolata mature forest, Pinus massoniana Lamb young growth and eucalyptus near-mature forest are the biggest. The Cmic, Nmic and Pmic of Cunninghamia lanceolata plantation present trends that decrease first and then increase as the age of forest varies. There is no obvious principles of the microbial biomass of Pinus massoniana Lamb and eucalyptus plantations as the forest age varies. There is significant fractal relationships between soil Nmic and soil bacterial and fungal amount(P<0.05), and there is no fractal relationship between the rest of microbial biomass and microbial amount.