Response of growth to density for a 21-year-old Betula alnoides plantation
[Objective]In order to understand the growth process of Betula alnoides plantation,analytical trees were employed to analyze its growth dynamics.[Method]In Jiangcheng county,Pu'er city,Yunnan province,based on the investigation for a 21-year-old B.alnoides plantation of established by different initial uneven row spacings(2 m×2 m×5 m,2 m×3 m×5 m,3 m×3 m×5 m and 2 m×2 m×10 m),the growth process of the trees with different planting densities was analyzed based upon the 12 standard trees selected from each tree measure.[Result]The mean diameters at the breast height(DBH),tree heights(TH)and timber volume of the different planting densities for 21-year-old stand trees were 16.82-17.52 cm,26.70-28.00 m和 0.274 3-0.333 8 m3,respectively,and the trees were still in vigorous growth stage,in terms of the quantity of trees was not mature.The fast-growing periods of the DBH,TH and volume were presented in the ages for 1-6,1-6 and 6-18 years old with the maximum current annual increment of which 1.61 cm/a,2.67 m/a and 2.807 6×10-2 m3/a,respectively.B.alnoides belongs to tree species of large-diameter timber in the topical and south-subtropical area in Yunnan province.Tending cutting with timely density control is a necessary management measure for cultivating large-diameter timber.The higher the stand density is,the earlier the age of tending cutting.[Conclusion]Its fast-growing period lasts for a long time,and its growth is more sensitive to planting density.The most suitable planting density should be selected for establishing B.alnoides plantation with high-quality and high-efficiency,and dynamically regulate stand density in time.Based on individual timber volume growth,2 m×3 m×5 m could be applied as the planting density of B.alnoides.At the same time,the first tending cutting of density control should be carried out for the B.alnoides plantation in 10 years old.
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万方数据
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