不同采伐年限马尾松人工林伐桩的胡敏酸和富里酸动态特征

摘要

The turnover of humic acid (HA) and fulvic acid (FA) during stump humification plays crucial roles in sequestering carbon and maintaining soil fertility in plantation ecosystems,but little related information has been available.A field experiment was conducted in Masson pine (P.massoniana) plantations in Sichuan Basin.The decaying stumps were sampled based on the local log file records from 1999 to 2013,and the stump system was further divided into stump wood (SW),stump root (SR),bark (B),and linked roots (Rn) with different diameters.After 15-year decomposition,HA concentration and HA/FA in the stump system increased significantly,while the stocks of HA and FA and FA concentration in the stump system decreased significantly.The stocks of HA and FA in the stump system ranged from 1 688.35 to 4434.99 kg·hm-2 and from 822.86 to 6 159.29 kg·hm-2,respectively,in the Masson pine plantation.SR had higher HA and FA stocks than SW and B.Moreover,the roots with larger diameter had higher HA and FA stocks than those with smaller diameters.In conclusion the stump system in the Masson pine plantation has high stocks of HA and FA and the humification degree increases in decaying process.The results provide basic information for understanding the processes of coarse wood debris decomposition and carbon sequestration in the plantations.%伐桩腐殖化中胡敏酸和富里酸的周转是人工林土壤碳吸存和地力维持等关键生态过程的重要途径,尚缺乏必要关注.根据地方采伐档案,以1999-2013年四川盆地马尾松人工林采伐剩余的伐桩为研究对象,用年龄序列分解实验研究伐桩系统中木桩(SW)、根桩(SR)、树皮(B)和不同径级的根系(R1:0mm＜径级≤10 mm,R2:10mm＜径级≤25 mm,R3:25 mm＜径级≤100 mm,R4:径级＞100 mm)的胡敏酸与富里酸的动态特征.结果表明:经过15年的腐解,伐桩的胡敏酸含量增加,但储量减少;富里酸含量和储量都减少;胡敏酸/富里酸增大.伐桩系统的胡敏酸和富里酸储量分别介于1 688.35～4 434.99 kg/hm2和822.86～6 159.29 kg/hm2之间.相对于其他组分,根桩的胡敏酸和富里酸储量大于木桩和树皮,大径级根系的胡敏酸和富里酸储量大于小径级根系.可见,马尾松人工林伐桩系统具有较高的胡敏酸和富里酸储量,随腐解进行,其腐殖化程度逐渐增加.这些结果对于理解粗木质残体分解及人工林碳吸存过程具有重要意义.