植物生态学报 ›› 2020, Vol. 44 ›› Issue (3): 192-204.DOI: 10.17521/cjpe.2019.0304

• 研究论文 • 上一篇    下一篇

乔木与木质藤本的水力与光合性状的差异: 以热带森林崖豆藤属和买麻藤属为例

宋慧清,倪鸣源,朱师丹()   

  1. 广西大学林学院广西森林生态与保育重点实验室, 南宁 530004; 广西大学亚热带农业生物资源保护与利用国家重点实验室, 南宁 530004
  • 收稿日期:2019-11-07 接受日期:2020-02-01 出版日期:2020-03-20 发布日期:2020-03-26
  • 通讯作者: 朱师丹 ORCID:0000-0002-9228-368X
  • 基金资助:
    国家自然科学基金(31470468)

Hydraulic and photosynthetic characteristics differ between co-generic tree and liana species: a case study of Millettia and Gnetum in tropical forest

SONG Hui-Qing,NI Ming-Yuan,ZHU Shi-Dan()   

  1. Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning 530004, China; and State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi University, Nanning 530004, China
  • Received:2019-11-07 Accepted:2020-02-01 Online:2020-03-20 Published:2020-03-26
  • Contact: Shi-Dan ZHU ORCID:0000-0002-9228-368X
  • Supported by:
    National Natural Science Foundation of China(31470468)

摘要:

木质藤本是热带森林的重要组成部分, 显著影响森林的结构和功能。已有研究发现木质藤本与乔木的水力结构存在显著差异: 木质藤本的缠绕或攀缘茎细小, 但其木质部具有粗大的长导管, 输水效率高, 抗栓塞能力低。为降低基因型差异对比较结果的影响, 该研究选取热带崖豆藤属(Millettia)和买麻藤属(Gnetum)的乔木和木质藤本, 比较同属内不同生长型植物的水力和光合性状的差异, 分析水分传导效率与抗栓塞能力之间以及水力与光合性状之间的相关关系。结果发现: (1)崖豆藤属植物水力性状的种间差异大, 与生活型和需光性有关。耐阴的木质藤本反而具有较低的水分传导效率和较高的抗栓塞能力。(2)买麻藤属植物是裸子植物较为进化的类群(具有导管和阔叶), 其乔木的水分传导效率很低, 但是其木质藤本的水分传导效率高于其他阳生性的被子植物。(3)不论乔木还是木质藤本, 水分传导的有效性与安全性在枝条和叶片水平上均没有显著的权衡关系。(4)与同属乔木相比, 木质藤本的叶片较枝条的抗栓塞能力更强, 在旱季具有更高的最大净光合速率和气孔导度, 支持了木质藤本的“旱季生长优势假说”。该研究揭示了热带木质藤本水力性状的多样性和重要性, 为阐明环境变化对这一重要植物类群的影响, 需要对它们的水力特征进行更广泛的研究。

关键词: 水力结构, 抗栓塞能力, 权衡关系, 脆弱性分段, 光合速率

Abstract:

Aims Liana is an important component of tropical forest, and exert a significant impact on community structure and function. Previous studies have found significant differences in hydraulic traits between lianas and trees, as indicated that lianas tended to have large and long vessels to compensate hydraulically to their thin stems, resulting in high hydraulic conductivity but low resistant to drought-induced cavitation. In order to reduce the influence of different genotypes on the comparative results, we aimed to compare the differences in hydraulic and photosynthetic characteristics between the two life forms from two genera Millettia and Gnetum.
Methods We measured branch and leaf hydraulic properties, sapwood density, gas exchange rates in the dry season for nine tree and liana species grown in common garden. We compared the hydraulic and photosynthetic traits between each species using one-way ANOVA. In addition, we analyzed hydraulic efficiency-safety trade-off, and the relationship between dry-season photosynthetic rates and hydraulic traits.
Important findings (1) There was a significant variations in hydraulic traits in genus Millettia, which was related to their light requirements and life forms. Compared with trees, the shade-tolerant liana species had lower hydraulic conductivity and higher resistance to cavitation. (2) Despite angiosperm-like characteristics such as vessels and broad pinnate-veined leaves, the Gnetum tree species had the lowest hydraulic conductivity among the nine species. However, the Gnetum liana species had higher hydraulic conductivity, comparable to light-demanding angiosperm species in this study. (3) There was no significant trade-off between hydraulic conductivity efficiency and hydraulic safety in both branch- and leaf-level across all the species, or within each plant group. (4) Compared to co-generic tree species, liana species’ leaves were more resistant to cavitation than branches, as indicated by higher maximum net photosynthetic rates and stomatal conductance during the dry season. These results support the hypothesis of “growth advantages at dry season” for liana species. This study reveals the high diversity and significance of hydraulic functioning in tropical lianas. Extensive measurements of hydraulic properties are needed to promote understanding of tropical species response to environmental change.

Key words: hydraulic function, cavitation resistance, trade-off, vulnerability segmentation, photosynthetic rates