林冠环境对润楠幼苗构型和生物量分配的影响

植物幼苗早期适应对策对种群的更新具有决定性的作用.润楠(Machilus nanmu)是国家Ⅱ级保护植物,是重庆缙云山常绿阔叶林优势乔木树种之一.研究润楠幼苗的适应对策对于维持种群更新和保护常绿阔叶林生物多样性具有重要意义.本研究采集了重庆缙云山常绿阔叶林中不同林冠环境(林窗/林下)下不同年龄阶段(阶段1:1～3年;阶...

Effect of canopy condition on Machilus nanmu seedling configuration and biomass allocation

The adaptation strategy of seedlings plays a decisive role in population regeneration. Machilus nanmu is a tree species belonging to Lauraceae, which is national class Ⅱ protected species and one of the dominant species in the evergreen broadleaved forest in Jinyun Mountain, Chongqing. Therefore, it is of great significance to understand the adaptation strategies of M. nanmu seedlings to maintain population regeneration and protect the biodiversity of evergreen broadleaved forest. We studied the temporal dynamics of early adaptation strategy of M. nanmu in Jinyun Mountain in Chongqing and its response to heterogeneous habitats from the perspective of morphology and biomass allocation. The seedlings of M. nanmu were classified into different age stages (stage 1: 1-3 a; stage 2: 4-6 a; stage 3: 7-9 a) under different canopy environments (gap/understory). Stem configurations (except branch angle) and leaf inclination angle of M. nanmu seedlings in the gap were significantly greater than understory at stages 2 and 3. Root configurations (except root diameter) and leaf area were significantly greater than that in the understory at stages 1 and 2. Specific leaf area in the gap was significantly smaller than understory at all three stages. Across all the conditions, biomass distribution was dominated by leaves. From the stage 2, stem biomass distribution of M. nanmu seedlings in the gap was increased, while root biomass distribution was decreased. There was no significant variation in root biomass of M. nanmu seedlings in the understory. The coordination among different organs of M. nanmu seedlings would help their adaptation to different habitats. Root and leaf of M. nanmu seedlings in the gap were significantly correlated, with the correlation changing from positive to negative as the age increased. While in the understory, there was significant positive correlation between root and stem, but no correlation between root and leaf. The slope of SMA equation of branch weight and branch length had significant difference under different canopy environments only at stage 3, while the slope of SMA equation of leaf and root biomass and configuration had no significant difference. Most of the SMA equation intercepts between biomass and configuration differed significantly at stage 2.