林分密度和种植点配置对杨树各器官非结构性碳水化合物的影响

【目的】探究林分密度和种植点空间配置对树木各器官非结构性碳水化合物(NSC)的影响，了解杨树Populus在生长季的碳代谢特征。【方法】试验林分以密度为一级因素，种植点配置为二级因素，采用嵌套设计。于‘南林95’杨P.×euramericana ‘Nanlin 95’生长季(7月)选取叶、枝、树干和粗根4个器官，测定各个器官中NSC (可溶性糖和淀粉)的质量分数。【结果】在生长季，杨树各器官中可溶性糖质量分数从大到小依次为叶、根、枝、干，淀粉质量分数从大到小依次为干、根、枝、叶。不同林分密度和种植点配置的杨树叶中可溶性糖质量分数差异极显著(P<0.01)，根中可溶性糖和淀粉质量分数受种植点配置影响极显著(P<0.01)，总体上枝和树干受林分密度和种植点配置影响差异不显著。尽管林分NSC总储量在2种密度间(278和400株·hm-2)差异不显著，但林分NSC总储量在种植点配置间差异显著(P<0.05)。【结论】在生长季，苏北地区杨树优先将碳资源供给地上部分，其中首要的储存器官是树干。一定密度范围内(278～400株·hm-2)，杨树叶中可溶性糖随林分密度增大而升高。林分...

Effects of stand density and spacing configuration on the non-structural carbohydrate in different organs of poplar

  Objective  With an exploration of the effects of stand density and spacing configurations on the non-structural carbohydrate (NSC) of poplar throughout the growing season, this study is aimed to investigate the NSC concentration in various organs of poplar under different stand conditions.   Method  Employing the nested design with density set as the first factor and plant spacing set as the second factor, foliage, branches, stems, and roots of Populus × euramericana ‘Nanlin 95’ were sampled from the experimental stands, in July, their poplar growing season before the soluble sugar and starch in each of them were measured.   Result  The soluble sugar content in the four organs of poplar followed the order of foliage＞root＞branch＞stem during the growing season whereas the starch concentration followed the order of stem＞root＞branch＞foliage. There was a significant difference in the content of soluble sugar among poplar leaves with different densities and plant spacings (P＜0.01). The contents of soluble sugar and starch in roots were significantly affected by the spacing configurations (P＜0.01), while the influence of stand density and spacing configuration on NSC in branch and stem was not significant and the total NSC content of stand was not significantly affected by stand densities (a comparison between 278 and 400 plants·hm?2), but significantly affected by spacing configurations (P＜0.05).   Conclusion  For poplars in northern Jiangsu Province during the growing season, the carbon resources are generally distributed to the parts above the ground with the stems as the primary storage organ. Within a certain density range (278?400 plants·hm?2), the sugar content in poplar leaves would increase with an increase in density. With the same stand densities, the square configuration would be conducive to the accumulation of NSC in poplar organs, which could in turn promote plant growth and stand development, increasing the carbon sequestration potential of the stand. Ch, 6 fig. 2 tab. 35 ref.]