Effects of some intensive afforestation techniques to the growth and productivity of 36 - months - old Acacia auriculiformis plantation in Uong Bidistrict, Quang Ninh province

Abstract

The results of testing applied technical measures for intensive afforestation of Acacia auriculiformis of Clt7 and Clt98 clone in Uong Bi, Quang Ninh in the period of 2016 - 2019 including vegetation treatment, soil preparation, fertilizing and planting density. Monitoring of these experiments after 36 months showed that the diameter at breast height (D1,3) of A. auriculiformis in the experiments reached from 8.76 to 10.11 cm, the total height (Hvn) reached 11.74 - 13.25 m and standing timber volume (M) from 48.58 to 56.31 m3/ha, corresponding to the timber productivity (ΔM) of 16.19 - 18.77 m3/ha/year. In these intensive measures, after 36 months, it
was shown that the experiments on  vegetation treatment and tending have not had a significant effect on the productivity of A. auriculiformis plantation, while the experiments on soil preparation, fertilizing and planting density showed differences between experiments. After 36 months, A. auriculiformis’s highest yield was found in the hole digging formulas with dimensions of 40 u40 u 40 cm, with basal dressing of 1 kg of Song Gianh compost and top dressing of 0.4 kg P2O5+ 0.1 kg K2O in the first 2 years, with a density of 1,666 trees/ha, the vegetation was treated by total clearing and spreading evenly, 3 times tending combined with 0.3 kg of NPK fertilizer, with the yeild from 16.19 to 18.58 m3 /ha/year. These results showed that the productivity of A. auriculiformis plantation in Uong Bi - Quang Ninh was similar to those of the same speices planted in some Southern provinces and is very promising for afforestation for sawlog supply in the Northern provinces.