不同林龄杉木人工林细根生物量及分布特征

Fine root biomass and vertical distribution of Chinese fir plantations(Cunninghamia Lanceolata) at different stand ages

为了研究杉木人工林地下细根的碳分配及其随年龄变化规律，于 2014 年 4 月用土壤钻法对湖南省会同县杉木人工林三个不同林龄（7 年生、17 年生和 25 年生）细根生物量变化、垂直分布进行了研究。结果表明：杉木人工林 0 ～ 60 cm 土层内杉木细根生物量随着年龄的增加表现出先增加后减少的趋势，7、17、25 年生杉木林细根生物量分别为 239.79 g·m^-2、271.90 g·m^-2和 191.60 g·m^-2，占杉木细根总生物量的 68.45%、56.39% 和68.64%。而林下植被层地下细根生物量随杉木林年龄的增大而减少，7 年、17 年和 25 年生杉木人工林林下植被层细根生物量为别为 207.20 g·m^-2，54.87 g·m^-2和 39.54 g·m^-2。不同林龄杉木林细根生物量随土层深度的增加而减少，其中 7 年生杉木人工林细根分布主要在表层；利用渐进累积方程分析表明，25 年生杉木人工林向土层深处生长比较明显。不同林龄活细根比根长和比表面积呈现随年龄增长而降低的趋势，组织密度则呈增大趋势。

In order to study the carbon distribution of underground fine roots and theirs vertical distribution varied with forest age of Chinese fir plantation, three plantations （7-year-old, 17-yearold and 25-year-old） in Huitong, Hunan were investigated by using the soil core method. The results show that the fine root biomass in 0-60cm soil layer first increased then decreased after the plantations reached the mature stage, the average biomass values of fine roots in 7-year-old, 17-yearold and 25-year-old forests were 239.79 g·m^-2, 271.90 g·m^-2, 191.60 g·m^-2, respectively, which accounted for 68.45%, 56.39% and 68.64% of the total woody fine root biomass; While the fine root biomass values in under-story vegetation layer （in soil layer of 0-45cm） increased with the increasing of forests age of Chinese fir plantation, the fine root biomass values of 7-year-old, 17-yearold and 25-year-old plantations understory vegetation layer were 207.20 g·m^-2, 54.87 g·m^-2 和 39.54 g·m^-2 respectively; The fine root biomass values with different tree-aged decreased with the increasing of soil depth, of them, the fine root biomass of seven-year-old Chinese fir mainly distributed in the top soil layer; The analysis results by progressive accumulation equation show that the fine roots of 25-year-old Chinese fir plantations obviously grew toward the depths of the soil; With the increasing of forest ages, the root length and specific surface area decreased, the tissue density of the fine roots increased.