不同林龄湿地松林土壤酶活性与土壤养分特征

以大鹤国有防护林场3种不同林龄(15、23、34 a)的湿地松林为研究对象,研究了不同林龄湿地松林土壤酶活性及其养分含量变化特征。结果表明:土壤pH值随着林龄增加呈先降低后升高,随着土层深度的增加逐渐升高。随着林龄的增长,土壤有机质先增加后降低;土壤水解氮、有效磷和速效钾含量逐渐降低。土壤中的脲酶、蔗糖酶、过氧化氢酶和多酚氧化酶活性随林龄的增长逐渐降低;酸性磷酸酶活性仅在表层土随着林龄的增长逐渐降低,而随着土层的加深表现为先增长后降低。土壤养分和酶活性随土层深度的变化均存在显著性变化。相关分析表明,土壤脲酶、蔗糖酶和酸性磷酸酶均与土壤有机质、水解氮、有效磷和速效钾存在极显著正相关(P<0.01),多酚氧化酶与速效钾呈显著负相关(P<0.05)。滨海地区湿地松在林龄较低阶段土壤养分较为充足,随着林龄的增长,土壤肥力逐渐下降,不利于森林可持续发展。

Characteristics of soil nutrient and enzyme activity in Pinus elliottii forests at different ages

Soil enzyme activitiy and nutrient content were studied inPinus elliottiiforests,at different ages(15,23,34 a),of Dahe State-owned Forest Farm.The results showed that the soil pH value increased with the decrease of forest age and increased with the increase of soil depth.With the increase of forest age,soil organic matter increased first and then decreased;available N,available P and available K decreased gradually.The soil activities of urease,invertase,catalase and polyphenol oxidase decreased with the growth of forest age;the activity of acid phosphatase decreased gradually with the increase of forest age in the topsoil,and increased first and then decreased with the deepening of soil layer.Soil nutrient and enzyme activities varied significantly with soil depth.Correlation analysis showed that activity of urease,invertase and acid phosphatase were significantly positively correlated with soil organic matter,available N,available P and available K(P<0.01),and polyphenol oxidase activity was significantly negatively correlated with available K(P<0.05).In the coastal area,soil nutrient is more abundant in the lower stage of forest age while the soil fertility decrease gradually,which is harmful for the sustainable development,with the forest age growing.