大青山不同林龄榆树林的土壤酶和养分特征

Soil Nutrient Characteristics of Ulmus pumila L.Forest at Different Ages in Daqingshan

为揭示大青山自然保护区榆树林土壤酶活性与土壤养分随林龄增加的变化趋势及其规律,以大青山3种不同林龄(10、25、40 a)榆树林为研究对象,测定0—10、10—20、20—30、30—40 cm土层土壤pH、速效氮、速效磷、速效钾、有机质、蔗糖酶、过氧化氢酶、多酚氧化酶共8个指标,分析不同林龄榆树土壤酶活性与土壤养分含量变化特征及其相互关系。结果表明,随林龄增加榆树林土壤有机质和速效钾含量呈上升趋势;速效氮、速效磷先升高后降低,土壤pH逐渐降低。随着土壤深度的加深,土壤有机质、速效氮、速效磷、速效钾含量均呈现较明显的表聚现象。过氧化氢酶活性随林龄的增加逐渐降低;蔗糖酶、脲酶活性呈现先增加后降低的趋势,随着土层深度的加深酶活性逐渐降低。土壤养分与酶活性之间存在一定的相关性,速效氮和速效磷与蔗糖酶和脲酶存在显著正相关(P<0.05);速效钾和有机质与过氧化氢酶存在显著负相关(P<0.05);主成分分析结果表明,25 a林龄0—10 cm土层土壤肥力最高。研究结果为榆树林可持续经营和土壤肥力提升提供科学依据。

In order to reveal the change trend and law of soil enzyme activity and soil nutrients with forest age in Daqingshan Nature Reserve,3 different forest ages(10,25 and 40 a)at Ulmus pumila L.forest in Daqingshan were selected as the research objects,and a total of 8 indicators of soil pH,available nitrogen,available phosphorus,available potassium,organic matter,sucrose,catalase and polyphenol oxidase in the soil layer of 0—10,10—20,20—30 and 30—40 cm were measured.The characteristics and interrelationships of enzyme activity and nutrient content in soil of Ulmus pumila L.with different forest ages were analyzed.The results showed that with the increase of forest age,the content of soil organic matter and available potassium in soil of Ulmus pumila L.forests showed an upward trend;available nitrogen and available phosphorus were raised first and then decreased,and the soil pH was gradually reduced.With the deepening of soil depth,the contents of soil organic matter,available nitrogen,available phosphorus and available potassium all showed obvious surface aggregation.Peroxidase activity gradually decreased with the increase of forest age;the activities of sucrase and urease showed a tendency of increasing first and then decreasing,and the enzyme activity gradually decreased with the depth of the soil layer.There was a certain correlation between soil nutrients and enzyme activity,and there was a significant positive correlation between available nitrogen and available phosphorus and sucrase and urease(P<0.05);there was a significant negative phase between available potassium and organic matter and catalase(P<0.05).According to the principal component analysis results,the soil fertility of the soil layer of 0—10 cm in the 25 a forest age was the highest.The results of the study could provide scientifsic basis for sustainable management of Ulmus pumila L.forests and soil fertility enhancement.