Zhang Yun-Yu, Sun Xiao-Feng, Zhang Lin-Feng, Li Ying-Chi, Wang Chuan-Kuan, Wang Xing-Chang
School of Forestry, Northeast Forestry University, Harbin 150040, China.
Center for Ecological Research, Northeast Forestry University, Harbin 150040, China.
Ying Yong Sheng Tai Xue Bao. 2021 Sep;32(9):3053-3060. doi: 10.13287/j.1001-9332.202109.001.
Fine roots play an important role in energy flow and substance cycling in forests. How-ever, the estimates of biomass, production and turnover of fine roots remain large uncertainties, and the mechanism underlying local-scale spatial variation in fine roots is still unclear. In a temperate secondary forest in the Maoer Mountain in Northeast China, we investigated the vertical distribution of fine root biomass and necromass at the 0-100 cm profile and the dynamics, production and turnover rate of fine root in 0-20 cm soil layer. The sequential coring (including the Decision Matrix and the Maximum-Minimum formula) and the ingrowth core (3 cm diameter and 5 cm diameter) were compared in estimating production and turnover rate of fine roots. Forest stand variables that might affect fine roots were also explored. The results showed that 76.8% of fine root biomass and 62.9% of necromass concentrated in the 0-20 cm soil layer, and that both decreased exponentially with increa-sing soil depth. The seasonal variation in both fine root biomass and necromass was not significant in 0-20 cm soil layer, which might be related to the negligible snowfall in winter and the extremely high precipitation in summer. There was no significant difference in the results of the estimated fine root production between two diameter ingrowth cores. After log-transformed, fine root production and turnover rate estimated by the Decision Matrix, the Maximum-Minimum formula and ingrowth cores were significantly different among methods. With the increases of soil nutrient concentrations, fine root biomass/fine root necromass ratio significantly increased, fine root necromass significantly decreased, whereas fine root biomass, productivity, and turnover rate were not related to soil nutrient. There was a significant positive correlation between fine root production and aboveground woody biomass increment in the previous-year but not current-year.
细根在森林的能量流动和物质循环中发挥着重要作用。然而，细根生物量、生产力和周转的估算仍存在很大的不确定性，细根局部尺度空间变异的潜在机制仍不清楚。在中国东北帽儿山的一个温带次生林中，我们调查了0-100厘米剖面细根生物量和坏死物质的垂直分布，以及0-20厘米土层细根的动态、生产力和周转率。比较了序贯取芯法（包括决策矩阵法和最大-最小公式法）和内生长芯法（直径3厘米和5厘米）在估算细根生产力和周转率方面的差异。还探讨了可能影响细根的林分变量。结果表明，76.8%的细根生物量和62.9%的坏死物质集中在0-20厘米土层，且二者均随土壤深度增加呈指数下降。0-20厘米土层细根生物量和坏死物质的季节变化均不显著，这可能与冬季降雪量可忽略不计以及夏季降水量极高有关。两种直径内生长芯法估算的细根生产力结果无显著差异。经对数转换后，决策矩阵法、最大-最小公式法和内生长芯法估算的细根生产力和周转率在不同方法间存在显著差异。随着土壤养分浓度的增加，细根生物量/细根坏死物质比值显著增加，细根坏死物质显著减少，而细根生物量、生产力和周转率与土壤养分无关。前一年而非当年的细根生产力与地上木本生物量增量之间存在显著正相关。
