北京山地4种阔叶林土壤酶活性及动力学特征

为研究北京山地阔叶林土壤酶特征及其与土壤理化性质的关系，探讨土壤酶活性与动力学参数作为评价土壤肥力指标的可行性，选取刺槐Robinia psedoacacia，山杨Populus davidiana-白桦Betula platyphylla，槲树Quercus dentata和板栗Castanea mollissima等4种阔叶林林型，利用方差分析、相关分析和主成分分析方法对0~20，20~40，40~60 cm土壤脲酶、过氧化物酶、多酚氧化酶和过氧化氢酶的活性和动力学特征及与土壤理化性质的关系进行了研究。结果表明:脲酶和过氧化氢酶活性，酶促反应的最大速度（V_max），酶促反应速度反映指标（V_max/K_m）都随土壤深度的增加而减小（P < 0.05），米氏常数（K_m）变化无规律；土壤酶促反应效率不仅取决于土壤酶活性，动力学特征对其也有重要影响；评价土壤肥力的指标，除了有机质、全氮、速效钾、速效磷和有效铁外，土壤脲酶活性，V_max，V_max/K_m，过氧化物酶活性与K_m也可作为北京山地阔叶林土壤肥力的评价指标。

Soil enzyme activity and their kinetics in broadleaf forests of Beijing mountainous areas

To study the relationship between characteristics of soil enzymes and soil physicochemical properties of broadleaf forests in the Beijing mountainous area and to determine the feasibility of using soil enzyme activity as well as kinetic parameters as the evaluation indexes of soil fertility, soil from Robinia pseudoacacia, mixed Betula platyphylla-Populus davidiana, Quercus dentata, and Castanea mollissima, four kinds of broadleaf forests in Beijing, were selected as the research objects. Variance, correlation analysis, and principal component analysis (PCA) were used for analysis of four soil enzymes activity (urease, peroxidase, polyphenol oxidase, and catalase) and kinetic characteristics in the 0-20 cm, 20-40 cm, and 40-60 cm soil depths. Results showed that enzyme activity, maximum rate of enzymatic reaction (V_max), and the indicator of enzymatic reaction rate (V_max/K_m) (where K_m is Michaelis constant) of urease and catalase significantly decreased (P < 0.05) with an increase of soil depth. However, K_m had not significant variation. Soil enzymatic reaction efficiency depends not only on enzyme activity but also on its kinetics. Enzyme activity, V_max, and V_max/K_m of urease as well as enzyme activity and K_m of peroxidase could be used to reflect soil fertility in the Beijing mountain forests with other important indexes to evaluate being soil organic matter, total N, available K, available P, and available Fe.