桂西南马尾松人工林微量元素积累及其分布特征

Microelements accumulation and distribution of Pinus massoniana plantations in Southwestern Guangxi

[目的]探究桂西南不同林龄马尾松人工林微量元素积累及其分布的变化过程,为马尾松人工林林地土壤管理提供依据。[方法]以广西宁明县马尾松人工林为研究对象,通过测定不同林龄(5、10和15年生)马尾松人工林不同组分生物量和5种微量元素(Fe、Mn、Zn,Cu和B)含量,对不同林龄马尾松人工林养分积累量、年净积累量及其分配格局进行了比较和分析。[结果](1)马尾松各器官微量元素含量(除Fe外)以树叶最高、干材最低,各器官微量元素含量以Mn或Fe最高,其次是Zn和B,Cu最低;各微量元素在不同器官的含量存在差异且随林龄变化而变化。(2)5、10和15年生马尾松人工林微量元素积累量分别为10.165、25.343和41.128 kg·hm^(-2),其中乔木层微量元素积累量分别占78.93%、85.50%和88.90%,灌草层分别占10.85%、5.72%和3.43%,凋落物层分别占10.24%、8.78%和7.67%。(3)3个林龄林分微量元素年净积累量分别为1.605、2.167和2.397 kg·hm^(-2)·a^(-1),随林龄的增加而增加。不同微量元素年净积累量以Fe最高,其次是Mn、Zn和B,Cu最低。[结论]桂西南马尾松人工林微量元素积累量和年净积累量均随林龄增加而增大,不同林龄间微量元素积累增长量为:5~10年生(15.178 kg·hm^(-2))>10~15年生(14.890 kg·hm^(-2))。

[Purpose]By exploring the microelements accumulation and annual net accumulation changes of Pinus massoniana plantations in Southwestern Guangxi,the study provides a basis for soil management of P.massoniana plantations.[Method]The 5,10 and 15-year old P.massoniana plantations were chosen as research object in Ningming County of Guangxi,and the microelements(Fe,Mn,Zn,Cu and B)accumulation,annual net accumulation and distribution characteristics of different forest stands were studied through sample plots survey and sampling analysis.[Result](1)The content of microelements(except for Fe)in various organs of P.massoniana was the highest in leaves and the lowest in stem.The content of different microelements in each organ was highest in Mn or Fe,followed by Zn or B,with the lowest value in Cu.The microelement contents varied among organs and stand ages.(2)The total micronutrient accumulations reached 10.165,25.343 and 41.128 kg·hm^(-2)in 5,10 and 15-year old plantations,respectively,of which the tree layer accounted for 78.93%,85.50% and 88.90%,the shrub and layer for 10.85%,5.72% and 3.43%,and the ground litter layer for 10.24%,8.78% and 7.67%,correspondingly.(3)Annual net accumulative amounts of microelements in 5,10 and 15-year old plantations were 1.605,2.167 and 2.397 kg·hm^(-2)·a^(-1),respectively,which increased with stand age.The annual net accumulation of different microelements was highest in Fe,followed by Mn,Zn,B,and Cu.[Conclusion]The accumulation and annual net accumulation of microelements of P.massoniana plantations increased with stand age.The microelement increment was 15.178 kg·hm^(-2)for plantations of 5-10 years old,higher than that of 14.890 kg·hm^(-2)for plantations of 10-15 years old.