Assessment of red cedar growth (Cedrela odorata) in Vietnam

December 14, 2010 by

Tran Lam Dong1, Nguyen Toan Thang1, Nguyen Xuan Giap1, Bui Thi Trang2

1 :Forest Science Institute of Vietnam

     2  Sub-branch of Forestry University of Vietnam   

Red Cedar is a large timber tree species, naturally distributed in Southern America. It was first introduced to Vietnam in 1986 and widely planted from 2001 on. Despite its great ability for fast growing and being well-adapted to a wide ecological range, there is a very small number of existing Red Cedar plantations in Vietnam. A survey was conducted in plantations of two to five years old in Thai Nguyen, Thanh Hoa, Gia Lai and Dak Lak province representing three ecological regions (the North-East, Central North, and Central Highlands of Vietnam) to identify this issue. It aimed to identify the influence of two major factors, silviculture measures and site conditions, on the growth of Red Cedar. In silviculture, plating density and mixed planting pattern were considered as the main factors, and in site condition, research focused on analysis of soil properties, pH value and some major nutrient potentials.

In silviculture measures, results show that, the scattered planting model demonstrates the highest growth. In pure Red Cedar plantations, intercropping with annual crops such as cassava and sugar cane performed better growth than without intercropping. In the pattern of mixed planting with Acacia hybrid or A. mangium, with a ratio of 50% Red Cedar and 50% Acacia and a planting density of 1100-1660 trees/ha, after three years, the Red Cedars were suppressed by the Acacias. There is still no significant difference in growth of Red Cedars up to 5 years old within a planting density ranging from 1100-1660 trees/ha. However, in the mixed planting pattern with Acacia, it is needed to carry out proper thinning to avoid the suppression of Acacias over Red Cedar.

In site condition requirements, Red Cedar is well-adapted to a wide ecological range in Vietnam except some species specific areas such as wet land, sandy coastal land and extremely high land. The preferable condition for growing has a deep soil layer, high soil moisture, is rich in humus and is lower than 700m a.s.l. Results show that Red Cedar grows well on the soil texture from clay to sandy loam. On low pH value soil, trees grow slowly and do not look vigorous. Therefore, before planting it is essential  to add lime to neutralize the pH value in the soil. In addition, as it is a fast growing species, additional fertilizer to supplement nutrients to meet growing ability of this species is necessary.

Attack of stem and shoot borers was one of the main problems leading to the failure of Red Cedar plantations in Vietnam. Attacks often occur when the trees are 2-3 years old. It could lead to missing the top of trees due to shoot attack or breaking down the trees due to stump attack. During this stage, it is essential to check the plantation frequently to detect the borers. When attacks happen, it can be either removed by hand or destroyed by spraying pesticide at the attacked place.

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