Radial Variation of Wood Anatomical Properties Determines the Demarcation of Juvenile-Mature Wood in Schima superba

Yunpeng Wang,Rui Zhang,Zhichun Zhou

doi:10.3390/f12040512

Abstract

Schima superba is a precious broadleaf tree species that produces excellent timber. Analyzing the radial variation of wood anatomical properties within stems and determining the boundary between the juvenile and mature wood can provide a theoretical basis for the breeding and cultivation of S. superba. Herein, 30 54-year-old trees were used to analyze the radial variation of wood anatomical properties qualitatively. The correlation among wood properties was analyzed. On this basis, four types of model were used to predict the wood properties quantitatively, and the optimal segmentation model was used to determine the boundary between juvenile and mature wood. The results showed that the variation of the early stage (before the 20th year) was larger than that of the later stage (after the 20th year); moreover, the variation of the vessel features (9.56%) was greater than that of the fiber features (7.42%), the vessel lumen diameter (11.94%) and the fiber length (8.00%) had the most variation. There were three radial variation patterns in the wood properties. In the early stage, there was a significant positive correlation between the ring width and wood air-dry density (0.78) and wood basic density (0.89), and a significant negative correlation between the ring width and the fiber characters (−0.79~−0.93) and vessel characters (−0.64~−0.90). The growth models of Logistic and Richards were more suitable (R2 = 84.2%~95.2%) for the radial variation of wood anatomical properties than the nonlinear least square model (R2 = 67.7%~90.9%). The transition wood between juvenile and mature wood of S. superba was from the 11th to the 16th year based on aggregative indicators from the pith to bark at breast height. Finally, when taken together, the wood anatomical properties of S. superba had regular radial variation. Breeding programs need to consider both growth and wood anatomical properties in the early stage, but they can be neglected in the mature stage. The formation of mature wood of S. superba occurred after the 16th year.

Highlights

Wood density is an important property due to its correlation with other wood properties, such as stiffness and ability to resist deformation [1,2]. It is a composite trait affected by the annual ring width, latewood percentage, cell wall thickness and lumen diameter of the fibers and vessels, etc
Fibers and vessels are the main components of the wood anatomical structure in broadleaf trees [4], and their size, quantity and shape are important indicators affecting wood properties [5]
Mvolo et al [15] used the linear mixed model, maximum-quadratic-linear model and piecewise model to estimate transition age in Picea glauca based on tracheid length radial variation and found that transition age ranged from the 11th to the 27th year and juvenile wood proportion ranged from 15.3% to 47.5%

Summary

Introduction

The radial variation of wood properties within plants caused by the xylem formed at different cambium ages is the main source of wood property variation This variation shows a certain pattern with cambial age increasing in different tree species. The wood anatomical properties of S. superba and its variation with increasing age and the demarcation of juvenile-mature wood are still unclear This restricts its wood processing and utilization and the formulation of an improvement strategy. The primary goals of the current study were as follows: (1) determine the wood anatomical features showing the highest variability; (2) reveal the radial variation pattern of wood properties with increasing cambial age; (3) quantify wood properties such as wood air-dry density and wood basic density; (4) evaluate the relationship between wood properties and growth; (5) determine the boundary between juvenile and mature wood

Objectives

Results

Discussion

Conclusion