速生阶段西南桦人工林养分积累及其分配特征

Accumulation and Distribution of Nutrients in Betula alnoides Plantation at Fast Growing Stage

对广西天峨县林朵林场速生阶段(12年生)西南桦(Betula alnoides)人工林的N、P、K、Ca、Mg 5种养分元素的质量分数、积累及其分配特征进行了研究。结果表明:1西南桦不同器官养分质量分数由高到低依次为树叶、树枝、干皮、树根、干材;树叶和干材各元素质量分数由大到小依次为N、K、Ca、Mg、P;树枝、干皮和树根中则是K(或Ca)、N、Mg(或P)。2西南桦人工林养分总储量为1 172.85 kg·hm-2,其中乔木层养分储量占87.62%,灌草层和凋落物层养分储量分别占5.91%和6.47%。3西南桦人工林乔木层养分年净积累量为85.64 kg·(hm2·a)-1,不同养分元素年净积累量由大到小依次为N、K、Ca、Mg、P;每积累1 t干物质需要5种养分元素8.40 kg,其中对N的需求量最大,P最小。

We studied the contents,accumulation and distribution of the nutrient elements（N,P,K,Ca and Mg） in B.alnoides plantation at fast growing stage（12-year-old） in Tian＇e Linduo Forestry Farm of Guangxi,China.Changes in nutrient contents for different organs in the same B.alnoides were in the descending order of leaves,branch,stem bark,root and stem wood.The descending order of nutrient element content was N,K,Ca,Mg,P in leaves and stem,and K or Ca,N,Mg or P in branch,stem bark and root.The total nutrient storage in B.alnoides plantation was 1 172.85 kg / hm2.Of the total storage of nutrients,87.62% was distributed in arbor layer,5.91% at herb and shrub layer,and 6.47% at standing litter layer.The annual net accumulation of nutrient elements of B.alnoides plantation was 85.64 kg /（hm2·a）,and the descending order of nutrient storage of five kinds of nutrient elements was N,K,Ca,Mg and P.The net production of organic matter per ton needed five elements of 8.40 kg,N element amount was the biggest,and P element was the smallest among five nutrient elements.