Objective To study the growth pattern of Liriodendron tulipifera.
Method A 24-year-old L. tulipifera plantation in Jurong of Jiangsu Province was used to study its growth pattern by means of stem analysis, and the age-age correlation of growth traits such as diameter at breast height (DBH), tree height and volume were explored.
Result The results of stem analysis showed that, for DBH and tree height growth, the rapid growth period of L. tulipifera lasted for 12 years (the 6th to 17th year after planting), while the early growth of timber volume of L. tulipifera was slow in the period of the first year to the tenth year. After 12 year, the volume increased quickly, and reached the peak value at 20th year. The results of age-age correlation and early selection efficiency analysis showed that, for the DBH and tree height, the growth in the 6th year were significantly correlated with the growth in the 18th year, while for the volume, the growth in the 6th year were significantly correlated with growth in the 18th year. Setting 24th year as the age of final cutting, the optimum age for early selection in L. tulipifera was the 16th-18th year.
Conclusion The DBH and tree height grow rapidly at early age. The competition and differentiation among individuals increase significantly during half-mature stage. With the increment of stand age, the age of early selection should be postponed. In consequence of this result, the authors propose that early selection should be conducted at the 6th year to accelerate the process of tree breeding. While for the cultivation of large-diameter wood, thinning should be conducted after the 16th year.
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