广西大瑶山常见孑遗裸子植物与阔叶树种枝叶性状的比较

Comparison on stem and leaf traits between common relict gymnosperms and broad-leaved tree species in Dayao Mountains, Guangxi

关键词:  叶片低温半致死温度, 水分运输效率, 抗弯强度, 冻害, 水分关系

Key words:  leaf low temperature semi-lethal temperature, water transport efficiency, bending strength, freeze injury, water relationship

摘要:

广西大瑶山山地常绿阔叶林中分布有多种孑遗裸子植物,了解它们对环境的适应性可为其制定合理的保护策略。为对比分析孑遗裸子植物与共存优势阔叶树种的枝叶性状差异,该研究选择山地常绿阔叶林常见的4种孑遗裸子植物和6种阔叶树种,针对山地环境特点,测定叶片低温半致死温度、比叶面积、边材比导率、木材密度、饱和含水量以及抗弯强度等性状。结果表明:(1)测定的10种木本植物枝叶性状的种间差异显著,其中叶片低温半致死温度为-23.13～-9.46 ℃,比叶面积为56.80～154.00 cm²·g^–1,饱和含水量为0.81～1.25 g·g^–1,边材比导率为0.74～1.77 kg·m^–1·MPa^–1·s^–1,木材密度为0.48～0.67 g·cm^–3和抗弯强度为61.55～138.14 N·mm^–2。(2)孑遗裸子植物与阔叶树种相比,所有测定性状的平均值均无显著性差异。(3)除木材密度与饱和含水量外,所测定性状之间无显著相关关系。综上结果表明,孑遗植物与被子植物具有多样化的枝叶性状组合,有利于它们共存于南亚热带山地常绿阔叶林。该研究有助于维持山地生态系统的完整性,进一步为孑遗裸子植物的保护提供理论依据。

Abstract:

A variety of relict gymnosperms are distributed in the evergreen broad-leaved forest in Dayao Mountains, Guangxi. Understanding their environmental adaptations is essential for developing rational conservation strategies. To compare and analyze the differences in stem and leaf traits between relict gymnosperms and the dominant broad-leaved tree species coexisting with them, this study selected four common relict gymnosperm species and six broad-leaved tree species from the local evergreen broad-leaved forest. Considering the characteristics of the montane environment, this study measured the leaf low temperature semi-lethal temperature, specific leaf area, sapwood-specific conductivity, wood density, saturated water content(of leaves and stems), and bending strength. The results were as follows:(1)There were significant inter-specific differences in the stem and leaf traits among the 10 woody plant species. The leaf low temperature semi-lethal temperature ranged from -23.13 to -9.46 ℃, specific leaf area varied from 56.80 to 154.00 cm²·g^-1, saturated water content ranged from 0.81 to 1.25 g·g^-1, sapwood-specific conductivity ranged from 0.74 to 1.77 kg·m^-1·MPa^-1·s^-1, wood density was 0.48-0.67 g·cm^-3, and bending strength was 61.55-138.14 N·mm^-2.(2)There were no significant differences in the means of all measured traits between relict gymnosperms and broad-leaved tree species.(3)Except for the correlation between wood density and saturated water content, there were no significant correlations between the other pairs of measured traits. These results indicate that relict gymnosperms and angiosperms exhibit diverse combinations of stem and leaf traits, which is beneficial for their coexistence in the subtropical montane evergreen broad-leaved forest. This study contributes to maintaining the integrity of mountain ecosystems and provides a theoretical basis for the conservation of relict gymnosperms.