太行山南麓侧柏人工林土壤酶活性和无机氮含量分布特征

为研究人工林生态系统土壤酶活性与活性氮周转的相互关系，以太行山南麓地区15 a侧柏人工林下土壤为研究对象，对比分析不同土层土壤转化酶、脲酶活性及土壤铵态氮（NH₄⁺-N）、硝态氮（NO₃^--N）含量的季节变化特征。结果表明，土壤转化酶、脲酶活性和NH4+-N含量具有明显的季节变化特征（P<0.05），且均在6月达到峰值；土壤转化酶、脲酶活性和NO₃^--N含量均随土层深度的增加显著降低（P<0.05），相较于0~10 cm土层，20~40 cm的年均降幅均超过25%，呈表层富集现象；线性回归分析表明土壤转化酶和脲酶活性与NH₄⁺-N和NO₃^--N含量呈显著线性正相关关系（P<0.05），酶活性与土壤无机氮含量的耦合作用在6月表现最强烈（P<0.05），暗示了土壤转化酶与脲酶活性可作为催化剂间接指示有机氮向无机氮的周转能力。

Distribution Characteristics of Soil Enzyme Activities and Inorganic Nitrogen Content under Chinese Cypress Artificial Forest in the Southern Taihang Mountains

In order to study the correlation between soil enzyme activities and active nitrogen turn over in the artificial forest ecosystem,a 15-year Chinese cypress plantation occurring in Southern Taihang Mountains were selected as research object.Seasonal variation characteristics of soil invertase activity,urease activity,ammonium nitrogen(NH 4+-N)and nitrate nitrogen(NO 3--N)contents from different soil layers were analyzed and compared.The results showed that soil invertase activity and urease activity as well as soil NH 4+-N content all had clear seasonal variation characteristics(P<0.05),all of them reached the peak values in June.With the increase of soil depth,soil invertase activity,urease activity and NO 3--N content all tended to decrease(P<0.05),showing surface enrichment phenomenon.Moreover,compared to 0-10 cm soil layer,the average annual decrease amplitude in 20-40 cm soil layer was more than 25%.Linear regression analysis indicated that the two soil enzyme activities had significantly positive correlation with soil NH 4+-N and NO 3--N contents(P<0.05).The interaction effects between soil enzyme activities and inorganic N showed the most significant correlation in June(P<0.05),indicating that soil invertase activity and urease activity can be used as catalysts to indirectly indicate the turnover ability from organic nitrogen to inorganic nitrogen.