研究形成層年齡與樹高對木材解剖特徵的影響規律,有助於增強對木質部導水功能、心材形成及樹木軸向生長的認識。
楸樹是我國本土珍稀環孔材樹種。本研究選取3株楸樹,沿其主幹的六個不同高度(0-11.3米)採集徑向中心條88個,樣品包括邊材、邊心材過渡區、心材。
採用光學顯微鏡、掃描電子顯微鏡觀察、分析樣品中與導管、纖維相關的13個木材解剖特徵指標,採用線性模型分析軸向高度、形成層年齡及其交互作用對木材解剖特徵的影響規律。
結果表明,楸樹早晚材導管直徑相差近10倍,晚材導管直徑隨軸向高度和形成層年齡增加而增大,早材導管直徑與形成層年齡呈正相關,而與樹高無顯著相關性;樹高與早材導管密度呈正相關,與纖維壁厚、壁腔比、長度呈負相關;形成層年齡與紋孔膜直徑、導管分子長度呈正相關;樹幹直徑年增長量隨樹高和形成層年齡增大而降低;早晚材纖維直徑與樹高、形成層年齡無顯著相關性;另外,由邊材到心材細胞壁、紋孔膜、紋孔口的侵填體、瘤狀層數量逐漸增多。
本研究突出了形成層年齡和軸向高度對木質部解剖特徵的顯著影響,再次強調了當分析木材解剖結構和木質部導水功能的時候,要考慮到它們的空間位置。
楸樹邊材(A)與過渡區(B)及心材(C)橫切面木材顯微圖片
楸樹邊材(A、B)與過渡區(C、D)及心材(E-I)弦切面掃描電子顯微鏡圖片
形成層年齡、樹高及交互效應對導管相關解剖特徵的影響規律Influence of Cambial Age and Axial Height on the Spatial Patterns of Xylem Traits in Catalpa bungei, a Ring-Porous Tree Species Native to ChinaStudying how cambial age and axial height affects wood anatomical traits may improve our understanding of xylem hydraulics, heartwood formation and axial growth.Radial strips were collected from six different heights (0–11.3 m) along the main trunk of three Manchurian catalpa (Catalpa bungei) trees, a precious ring-porous tree species native to China, yielding 88 samples including sapwood, transitional zone and heartwood.In total, thirteen vessel and fiber related wood anatomical traits were observed using light microscopy (LM) and scanning electron microscopy (SEM), and linear models were used to analyse the combined effect of axial height, cambial age and their interaction on investigated wood anatomical traits.Our results showed that vessel diameter differed by about one order of magnitude between early- and latewood, and increased significantly with both cambial age and axial height in latewood, while it was positively affected by cambial age and independent of height in earlywood.Vertical position further had a positive effect on earlywood vessel density, and negative effects on fibre wall thickness, wall thickness to diameter ratio and length. Cambial age had positive effects on the pit membrane diameter and vessel element length, while the annual diameter growth decreased with both cambial age and axial position. In contrast, early- and latewood fiber diameter were unaffected by both cambial age and axial height.We further observed an increasing amount of tyloses from sapwood to heartwood, accompanied by an increase of warty layers and amorphous deposits on cell walls, bordered pit membranes and pit apertures.This study highlights the significant effects of cambial age and vertical position on xylem anatomical traits, and confirms earlier work that cautions to take into account xylem spatial position when interpreting wood anatomical structures, and thus, xylem hydraulic functioning.
Shan Li, Xin Li, Roman Link, Ren Li, Liping Deng, Bernhard Schuldt, Xiaomei Jiang, Rongjun Zhao, Jingming Zheng, Shuang Li and Yafang Yin. Influence of Cambial Age and Axial Height on the Spatial Patterns of Xylem Traits in Catalpa bungei, a Ring-Porous Tree Species Native to China. Forests. 2019, 10: 662.
https://doi.org/10.3390/f10080662
編輯:李姍,李萬峰