摘要:林窗对更新幼苗生物量积累和分配的影响在种群恢复中具有重要作用，尤其是暗针叶林更为突出。以川西亚高山岷江冷杉原始林林窗、林下的岷江冷杉更新幼苗为对象，研究其粗根和细根生物量的积累与分配过程及其异速生长关系。结果表明：随着岷江冷杉幼苗的生长，粗根、细根生物量均不断积累，但根系生物量中分配到粗根的比例逐渐增加、分配到细根的比例逐渐减少，粗根-细根间生物量的异速生长指数由等速生长转变为异速生长。林窗幼苗的细根生物量、粗根生物量和总根生物量中位数均小于林下幼苗，细根生物量分配比例大于林下幼苗；林窗还显著影响细根、粗根生物量随基径增粗的积累与分配过程，细根生物量分配比例随基径增粗的降幅大于林下幼苗；但林窗对粗根-细根生物量间的异速生长指数影响不显著。说明林窗干扰改变了岷江冷杉更新幼苗地下资源的分配方式，优化了资源配置。



Abstract:The effect of forest gap (FG) on regeneration seedlings biomass accumulation and allocation is important for population recovery, especially in dark coniferous forests. The objectives of this study were to explore the effect of FG on accumulation and allocation process of root biomass for Abies faxoniana regeneration seedlings, and provide a reference for understanding of regeneration mechanism of A. faxoniana. The individual samples of A. faxoniana seedlings lived in the FG and under the forest canopy (FC) were harvested from the subalpine natural coniferous forest in western Sichuan and the roots were further divided into fine root (d<2 mm) and coarse root (d ≥ 2 mm). The fine root and coarse root biomass accumulations and allocations changed with basal diameter fitted by a power function as well as their allometric scaling relationships were modeled with standard major axis (SMA) regression. The results showed that the accumulations and allocations of root biomass for A. faxoniana seedling increased with the basal diameter growth, the fractions of roots biomass allocated to coarse roots increased gradually, while fractions allocated to fine roots decreased gradually, and their allometric relationships were adjusted from isometry scaling to allometric scaling. The median values of fine roots biomass, coarse roots biomass and total roots biomass in FG were lower than those in FC, and the fraction of fine roots biomass in FG was greater than those in FC. And the same time, FG significantly affected the accumulations and allocations process of root biomass in fine roots and coarse roots with the increasing basal diameter. The reduction of fraction of fine roots in FG was greater than that in FC, but the FG had minor effect on the allometric scale of between fine roots biomass and coarse roots biomass. Therefore, this study presented the evidence that FG could promote the A. faxoniana seedlings to adapt the FG via optimizing resource utilization such as underground-biomass allocation.





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