细根是植物吸收水分和养分的主要器官, 细根生物量对盐土地人工绿化植被生态修复具有重要意义。以3种人工林为研究对象, 分别对其细根生物量、垂直分布及各形态指标的变化特征进行分析。结果表明, 响叶杨(Populus adenopoda)林、普陀樟(Cinnamomum japonicum)林和落羽杉(Taxodium distichum)林0-40 cm土层的平均细根生物量分别为1 699.75、498.50和520.06 g·m^-2。3种林分在0-10 cm土层中的细根生物量占整个细根生物量的50%以上, 随着土层的增加细根生物量呈现指数减少(P<0.05)。在生长季节内细根生物量呈双峰变化, 不同月份间存在显著差异。活细根生物量和比根长均表现为普陀樟林<落羽杉林<响叶杨林。将细根各项指标与3种环境因子进行相关分析, 发现土壤含水量与活细根生物量及根长密度呈显著正相关(P<0.01)。CCA分析表明, 土壤含盐量是影响活细根各项指标垂直变化的主要限制因子, 而高盐可能对细根生物量及分布有不利影响。

Fine root is the main organ of plants absorbing water and nutrients. Fine root biomass is important for restoring saline soil. We considered 3 plant communities along a saline reclamation riparian zone in the Lingang district of Shanghai and studied the variation in fine-root biomass, vertical distribution and morphological indicators of fine roots in salinity. The mean fine-root biomass in 3 communities (Populus adenopoda, Cinnamomum japonicum and Taxodium distichum forest) in the 0 to 40 cm soil layer were 1 699.75, 498.50 and 520.06 g·m^-2, respectively. In the 3 forests, fine-root biomass was significantly affected by soil depth, and fine roots at the 0 to 10 cm soil layer accounted for more than 50% of the total fine-root biomass; with increasing soil layer, the fine-root biomass index decreased (P<0.05). The fine-root biomass of different communities showed existential bimodal changes in the growing season, with significant difference between months. The biomass and length of living fine roots were all decreased in the order of P. adenopoda> T. distichum>C. japonicum forest. We found a significant relation between soil moisture content and living fine-root biomass and density (P<0.01). CCA analysis showed that soil moisture content was the main limiting factor of change in various vertical indexes of live fine roots, and high salt may have an adverse effect on fine-root biomass and distribution.