太行山南麓5个林龄侧柏人工林土壤酶活性季节变化

采用时空互代法，以太行山南麓地区20，30，40，50，60年生侧柏人工林土壤为研究对象，研究了土壤蔗糖酶和脲酶活性的季节变化、空间分布特征及其与土壤因子的相关性。结果表明:土壤酶活性有明显的季节变化特征，土壤蔗糖酶的活性呈夏季 > 秋季 > 春季 > 冬季，脲酶活性的季节动态呈夏季 > 春季 > 秋季 > 冬季，两种土壤酶活性均在夏季最高，冬季最低。土壤蔗糖酶和脲酶活性均随土层深度的增加而显著降低（p<0.01），从表层0-10 cm至深层30-40 cm酶活性下降幅度均超过46%。相关性分析表明，土壤蔗糖酶和脲酶均与土壤含水率、DOC含量呈极显著正相关关系，且两者之间也存在极显著正相关关系（p<0.01），但是二者的主要影响因子并不完全一致。逐步回归分析表明蔗糖酶活性的主要影响因子是土壤含水率和砂粒体积分数，二者能解释71.2%的变化；脲酶活性的主要影响因子是DON、土壤含水率、硝态氮含量和土壤容重，四者能解释71.5%的变化，暗示温度和水分可能是该区人工林土壤生物活性的主要控制性因素。

Seasonal Dynamics of Soil Enzyme Activities Under Five Different Ages of Platycladus orientalis Artificial Forest in the Southern Taihang Mountains

We studied seasonal dynamics and spatial transformation of soil sucrase and urease activity as well as their relations with other soil properties under 20, 30, 40, 50 and 60-year-old Platycladus orientalis plantation in mountainous region of southern Taihang Mountains by using the method of time-space mutual substitution. The results showed that both soil enzyme activities had clear seasonal dynamics, with highest value in hot summer and lowest value in cold winter. The trend of soil sucrase activity followed the order:summer > autumn > spring > winter, while the trend of soil urease activity decreased in the order:summer > spring > autumn > winter. Soil sucrase and urease activity appeared significant decrease with the depth of soil layer (p < 0.01), and the decreasing rates of both soil enzymes from the surface layer (0-10 cm) to the deep layer (30-40 cm) were more than 46%. Correlation analysis showed that both soil enzymes had positive correlation with soil water content and dissolved organic carbon concentration, and soil sucrase had a positive correlation with soil urease (p < 0.01), while the main influencing factors for both enzymes were different. Stepwise regression analysis showed that the main influencing factors on soil sucrase activity were soil water content and sand volume fraction, which could explain 71.2% of variation. The main influencing factors on urease activity were dissolved organic nitrogen, soil water content, NO₃^--N and soil bulk density, which could explain 71.5% of variation, indicating that temperature and soil moisture may be the main controlling factors on soil biological activity in this area.