Potential of sawlog production of the 13.5 year-old Acacia hybrid in Quang Tri province

Abstract

Acacia hybrid is a major planting species for small timber production in Vietnam in recent years. Due to the increasing demand of sawlog in wood industry, Acacia hybrid was considered as a potential species for production of sawlog. This study assessed the potential of sawlog production of the 13.5 year-old Acacia hybrid plantation in Cam Lo district, Quang Tri province to provide information for planting Acacia hybrid for sawlog. There are three treatments in planting density were set up, 1330, 1660 and 2500 trees/ha. The overall survival rate decreased from 91% at 2 year-old to 49 - 56% at 9.5 year-old and 31 - 47% at 13.5 year-old. At 2 year-old, diameter at breast height (DBH) was 6.19cm at the planting density of 2500 trees/ha and 7.17cm at 1330 trees/ha; annual DBH and height increment were 3.1 - 3.6cm/year and 3.5 - 3.6 m/year, respectively. At 9.5 year-old, DBH and height were 15.13 - 17.49cm and 17.52 - 18.64m, respectively; annual DBH and height increment were 1.59 - 1.84 cm/year and 1.84 - 1.96 m/year, respectively. At 13.5 year-old, DBH and height were 17.93 - 18.91cm and 21.06 - 21.98m, respectively; annual DBH and height increment were 1.33 - 1.40 cm/year and 1.56 - 1.63 m/year, respectively. Standing volume at 9.5 year-old was 160.3 - 214.8 m3 /ha and MAI was 16.87 - 22.61 m3/ha/year. Standing volume at 13.5 year-old was 168.1 - 219.4 m3/ha and MAI was 12.45 - 16.26 m3/ha/year. After 9.5 years, the percentages of number of trees which can be used for sawlog (DBH > 18cm) was 16.98 - 37.93%; there are not any trees having DBH > 25cm. After 13.5 years, the percentages of number of trees for sawlog (DBH > 18cm) was 48 - 58%, in which 2 - 7% of trees having DBH > 25cm.