北京山区不同林分类型土壤肥力的研究

为探讨山地森林土壤酶活性与土壤理化性质的关系，对北京延庆山区6种植被类型下不同层次土壤的脲酶、蛋白酶、转化酶、过氧化氢酶、多酚氧化酶的活性及其与土壤理化性质之间的关系进行研究。结果表明:在各种林分类型之间所测土壤理化性质和土壤酶指标有显著性差异，并且随着土层的加深，均表现出不断减小的趋势。蔗糖酶、脲酶、蛋白酶、过氧化氢酶4种酶活性在不同林分类型中均表现出阔叶林优于针叶林，而多酚氧化酶活性却表现出相反的趋势。所测5种酶活性在6种林分类型A层表现出聚集分布，以脲酶最具代表性。相关分析表明:有机质、全氮、碱解氮、速效钾与所测5种酶活性呈现出不同程度的正显著相关，而有效磷与各种所测酶活性均呈负相关。运用主成分分析可知，土壤酶在第1、2主成分中比重较大，对外界环境变化比较敏感，结合相关分析认为，碱解氮与脲酶可以作为该地区土壤质量评价的首选指标。 

Soil fertility of different forest types in the mountainous area of Beijing

In order to discuss the relationship between soil enzyme activity and soil physioehemical properties in foerest soil, the activity of enzymes (urease, protease, invertase, catalase, polyphenol oxidase) were studied in different soil layers under six vegetation types in the mountainous area of Yanqing, Beijing. The results showed that: the indictors of soil enzymes and soil physiochemical properties were significantly different, and decreased with the deepening of the soil in all kinds of vegetation. The activity of invertase, urease, protease, catalase in this six stands in soil of broadleaved forest was better than that in coniferous forest expect polyphenol oxidase. The activity of five tested enzymes showed "gathering" effects in the A layer among different types, especially for urease. Organic matter, total nitrogen, available nitrogen and rapidly available phosphorus were positively correlated with the detected enzyme activity in different degree, but correlations between available phosphorus and the tested enzyme activity were opposite. According to principal component analysis, it was observed that the soil enzymes accounted for large proportions, and were more sensitive to the changes of external environment than the other indictors. Combined correlation analysis with principal component analysis, nitrogen and urease were regarded as the first choices indictors to assess soil quality in the local areas.