The effects of planting density to the growth of some acacia species 2 year old in Quang Ninh province
Keywords:
Acacia mangium, Acacia auriculiformis, Acacia hybrid, planting density, Quang Ninh provinceAbstract
Density of plantation is an important silviculture treatment for intensive forest planting, that contributes improves productivity and quality of plantation, especially intensive plantation of Acacia hybrids, Acacia mangium, and A. auriculiformis for the large timber production purposes. In this study, four different density levels were used include: i/ 1,660 trees/ha (2 × 3m); ii/ 1,110 trees/ha (3 × 3 m); iii/ 830 trees/ha (3 × 4 m); iv/ 625 trees/ha (4 × 4 m). After 2 years, the growth of Acacia hybrids in four density levels are significant difference in both of Diameter at Breast Height (DBH) and Height (H): The highest average DBH reached 8.25 cm with the density of 625 trees/ha, DBH gradually decreasing when density increasing and the smallest DBH is 7.08 cm with density of 1,660 trees/ha; the highest average Height reached 7.96 m with the density of 1660 trees/ha, average Height gradually decreasing when density decreasing and the smallest Height is 7.37 m with density of 625 trees/ha. The growth of Acacia mangium of four density levels are significant difference in both of average Diameter at Breast Height (DBH) and average Height (H): The highest average DBH reached 7.27 cm with the density of 625 trees/ha, DBH gradually decreasing when density increasing and the smallest average DBH is 6.39 cm with density of 1,660 trees/ha; the highest average Height reached 6.14 m with the density of 1660 trees/ha, Height gradually decreasing when density decreasing and smallest average Height is 5.99 m with density of 625 trees/ha. The growth of A. auriculiformis of four density levels are significant
difference about average Diameter at Breast Height (DBH): The highest
average DBH reached 6.86 cm with the density of 625 trees/ha, DBH gradually decreasing when density increasing and the smallest average DBH is 5.25 cm with density of 1,660 trees/ha; Height are not significant different with the average Height from 6.37 - 6.96 m. However, average height also tends to increase from low density to high density. That results just an initial results in the period new forest closure canopy, further investigation is required in the next 1 - 2 years for more accurate conclusions.
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