鸡公山国家级自然保护区散孔材、环孔材树种木质部结构和功能的关系

  目的  木质部解剖结构是植物水力功能和水分利用策略的基础。散孔材和环孔材的导管分布和形态存在显著差异，对2种材性树种木质部解剖结构和水力功能的关系进行比较，有助于理解不同材性树种的水分适应机制。  方法  选取河南省信阳市鸡公山自然保护区中的3个散孔材树种(枫香Liquidambar formosana、旱柳Salix matsudana、深山含笑Michelia maudiae)和3个环孔材树种(槲树Quercus dentata、楝Melia azedarach、野核桃Juglans cathayensis)，研究2种材性树种的枝水力功能(比导率和栓塞抗性)和解剖结构的关系。  结果  3个环孔材树种比导率更大，3个散孔材树种栓塞抗性更强；在物种水平上，只有散孔材树种深山含笑比导率和栓塞抗性呈显著负相关(P＜0.05)，存在水力效率-安全权衡。3种散孔材树种相较于3种环孔材树种具有更大的导管密度、导管壁厚度跨度比和更小的导管直径、导管壁厚度。  结论  环孔材树种倾向于通过增大导管直径显著提高其输水效率，从而避免水势下降、降低潜在栓塞风险。散孔材树种木质部结构中的导管壁厚度和导管壁厚度跨度比对植物水分传输功能具有重要影响。图5表1参32

Relationship between xylem structure and function of diffuse-porous and ring-porous wood species in Jigongshan Nature Reserve

  Objective  The anatomical structure of xylem is the basis of plant hydraulic function and water use strategy. There are significant differences in vessel distribution and morphology between diffuse-porous and ring-porous wood species. The purpose of this study is to compare anatomical structure and hydraulic function of xylem of the two wood species, as well as the quantitative relationship between structure and function, so as to understand the water adaptation mechanism of different wood species.   Method  Three diffuse-porous species (Liquidambar formosana, Salix matsudana, Michelia maudiae) and three ring-porous species (Quercus dentata, Melia azedarach, Juglans cathayensis) in Jigongshan Nature Reserve, Henan Province, were selected to study the branch hydraulic function (specific conductivity, K_s and embolism resistance, P₅₀) and anatomical structure, and the relationship between hydraulic function and anatomical structure was quantitatively analyzed.   Result  K_s of the three ring-porous species was higher and P₅₀ of the three diffuse-porous species was stronger. At the species level, K_s of M. maudiae was negatively correlated with P₅₀ (P＜0.05), and there was a tradeoff between hydraulic efficiency and safety. Compared with the three ring-porous wood species, the three diffuse-porous species had higher vessel density, vessel thickness span ratio, smaller vessel diameter and vessel wall thickness.   Conclusion  The ring-porous species tend to significantly improve their water delivery efficiency by increasing vessel diameter to avoid water potential decline and reduce the risk of embolism. The ratio of vessel wall thickness and vessel thickness span in the xylem structure of the diffuse-porous species has important effects on plant water transfer function. Ch, 5 fig. 1 tab. 32 ref.]