万木林自然保护区不同林分土壤可溶性有机氮含量

Soil soluble organic nitrogen content in different forest stands in Wanmulin Nature Reserve

对福建建瓯万木林自然保护区内细柄阿丁枫天然林(ALG)、米槠天然林(CAC)和35年生杉木人工林(CUL)土壤可溶性有机氮含量(SON)进行了研究.结果表明:3种林分中,ALG0～5cm、5～10cm和10～20cm层土壤SON含量最高,分别为95.3、78.3和72.5mg.kg-1,且与其余林分差异显著(P<0.05);而CAC与CUL各土层SON含量分别为74.5、70.1、65.6mg.kg-1和78.6、68.9、69.1mg.kg-1.CAC、CUL和ALG在0～20cm土层的SON含量分别占可溶性总氮(TSN)组分的79.17%～80.78%、68.64%～74.51%和59.97%～69.66%,随着土层加深,3种林分SON含量占土壤TSN和全氮(TN)含量的比例不断增大;SON与土壤有机碳含量极显著相关(r=0.982,P<0.01),与TSN、TN、铵态氮和硝态氮等土壤养分也存在不同程度的相关性.土壤SON含量与森林类型、地形、海拔以及树龄等因素有关.

An investigation was made on the soil soluble organic nitrogen （SON） in two natural forests Altingia gracilies （ALG） and Castanopsis carlesii （CAC） and an adjacent 35-year-old Cunninghamia lanceolata （CUL） plantation in Wanmulin Nature Reserve in Jianou,Fujian Province.Among the three forest stands,ALG had a significantly higher content of soil SON,being 95.3,78.3,and 72.5 mg·kg-1 in 0-5 cm,5-10 cm,and 10-20 cm soil layers,respectively （P0.05）,while CAC and CUL had lesser differences in their soil SON content,which was 74.5,70.1,and 65.6 mg·kg-1 in the three soil layers for CAC,and 78.6,68.9,and 69.1 mg·kg-1 in the three soil layers for CUL,respectively.The proportion of SON to total soluble nitrogen （TSN） in 0-20 cm soil layer was 79.17-80.78% for CAC,68.64%-74.51% for CUL,and 59.97%-69.66% for ALG.With increasing soil depth,the proportion of soil SON to soil TSN and total nitrogen （TN） for the three forest stands all increased.Soil SON content had a significant positive correlation with soil organic carbon （r=0.982,P0.01）,and also,had definite correlations with soil TSN,TN,NH_4＋-N,and NO_3--N.It also correlated with the factors such as forest type,topography,altitude,and tree age.