中文摘要：

以水曲柳和落叶松人工林为研究对象,于2007年和2008年5月（春）、7月（夏）和10月（秋）分别对2个林分土壤线虫进行调查研究,采用淘洗-过筛-蔗糖离心法提取土壤线虫,探讨土壤总线虫和各营养类群线虫密度的土层变化与季节动态,以及它们与土壤温度、湿度和pH值的关系。结果表明：1）水曲柳林总线虫密度显著高于落叶松林,水曲柳林每100g干土中1079条,落叶松林每100g干土394条（2年平均值）,其中植食线虫占比例最高,食细菌线虫次之,杂食-捕食线虫和食真菌线虫密度最少;2）土壤总线虫和各营养类群线虫密度均随土壤深度的加深而逐渐下降,且各土壤深度间差异显著;3）在2林分中,土壤总线虫和各营养类群线虫密度均在秋季（10月）最高,秋季与夏季或春季差异显著;4）土壤水分和pH值与线虫总密度显著负相关,春季和夏季土壤温度与线虫密度显著正相关,这3个因子的综合作用可以解释线虫总密度变异的46%（水曲柳）和49%（落叶松）。这些研究结果对于了解水曲柳和落叶松人工林土壤线虫密度变化,以及与环境因子之间的关系具有重要意义。

英文摘要：

Soil nematodes play an important role in carbon flow and nutrient cycles in forest ecosystems.In this paper,we investigated total nematodes and dynamics of the different trophic groups with seasons and soil depths,and analyzed their relationship with soil temperature,moisture and pH in ash（Fraxinus mandshurica） and larch（Larix gmelinii） plantations during 2007 and 2008.The soil nematodes were collected from soil with Sieving-centrifugation-flotation method.The results showed that：1） the density of total nematodes in ash plantation was significantly higher than that in larch,averaged 1 079 ind.·100 g-1 dry soil in ash,and 394 ind.·100 g-1 dry soil in larch,respectively.Based on trophic groups classification,the majority of soil nematodes in two plantations was Plant-feeding nematodes（PF）,the second-highest was Bacterivores（BA） and the minimum was Omnivores-Predators（OM-PR） and Fungivores（FF）;2） the densities of total nematodes and trophic groups were significantly higher in topsoil than that in deep soil across two-years investigation;3） in the two years,the maximum population of total nematodes and trophic groups both occurred in autumn（October） in both plantations,while the minimum was in summer and spring;4） total nematode densities were significantly and negatively correlated with soil moisture and pH,but positively with soil temperature in spring and summer.Overall,46%（ash） and 49%（Larch） variations of total nematode density were able to be interpreted by combination of these soil factors.These results are important for understanding the relationships between soil nematodes and environmental factors in ash and larch plantations.