Promoting reforestation through supplementing native forest tree species in northwestern Vietnam
Hoang Van Thang1, Dang Thinh Trieu2, Hoang Van Thanh2, Phung Dinh Trung2, Cao Van Lang1, Nguyen Trong Dien3, Tran Van Do2,4*
1Science and Planning Management Department, Vietnamese Academy of Forest Sciences, Hanoi, Vietnam
2Silviculture Research Institute, Vietnamese Academy of Forest Sciences, Hanoi, Vietnam
3Forest Science Centre of North-Eastern Vietnam, Vietnamese Academy of Forest Sciences, Ngoc Thanh, Phuc Yen Town, Vinh Phuc, Vietnam
4Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Kyoto, Japan
Abstract
Forest enrichment and/or supplement planting is a silvicultural technique to improve number of valuable trees in natural poor forests. In this study, two native species including Canarium album (Lour.) Raeusch and Cinnamomum obtusifolium (Roxb.) Nees were planted in fallow stands by two experiments as planting in clear band of 6 m wide (band planting) and in canopy gaps of >200 m2 (cluster planting). The results indicated that planted trees of both species in both planting experiments had high survival rates (>89%) after planting three years, and more than 75% survival trees had good quality as straight boles without diseases. The difference of stump diameter and stem height between experiments and species was statistically significant. C. obtusifolium in band planting had biggest stump diameter (2.86 cm), while C. album in band planting had tallest stem height (2.69 m) after planting three years. C. obtusifolium had significantly larger crown diameter in band planting (1.09 m) than that in cluster planting (0.92 m). While it was conversely found in C. album as significantly larger crown diameter was found in cluster planting (1.12 m) compared to smaller one in band planting (0.96 m). It is concluded that silvicultural techniques are required to promote growth of planted trees after planting three years, especially for C. album as it requires more sunlight at this age. The techniques must focus on opening forest canopy for sunlight reaching crown of planted trees and on removing bad-growth trees surrounding planted trees to minimize competitions.
