Size Distribution and Morphological Damage to 17-Year-Old Hopea odorata Roxb. Planted in Fast-Growing Tree Stands in Northeast Thailand

Abstract

The size distribution, morphological damage and climbing of lianas were investigated in 17-year-old Hopea odorata Roxb. which were planted in fast-growing tree stands at the Sakaerat Silvicultural Research Station in northeast Thailand. Eucalyptus camaldulensis, Acacia auriculiformis, and Senna siamea were planted as nurse trees in 1987 at spacings of 4 X 8 m, 2 X 8 m, 4 X 4 m, and 2 X 4 m. Seedlings of H. odorata were planted in the nurse tree stands at a uniform spacing of 4 X 4 m in 1990. In 1994, the stem numbers of nurse trees were thinned by half in the stands with spacing 2 X 8 m and 2 X 4 m. The diameter at breast height (DBH) and height of all the H. odorata were measured, and morphological damage to stems and climbing of lianas were checked in 2007. H. odorata grew well in S. siamea stands and the control plots (no nurse trees) showed a wide-ranging and irregular distribution of DBH, whereas the H. odorata remained small in the E. camaldulensis and the A. auriculiformis stands, with DBH showing a narrow bell-shaped distribution. The survival rate of H. odorata varied among replicates, and was high in plots near a forest road. H. odorata in a control plot located closest to the forest road and used for exhibition purposes suffered less damage. This implies that continuous care of a forest plantation is critical for maintaining its health. Morphological damage to H. odorata and climbing of lianas was high in the E. camaldulensis and A. auriculiformis stands, accounting for over 40% of all stems, whereas it was low in the control plots. The ratio of damaged H. odorata tended to decrease as DBH increased, suggesting that larger trees were less vulnerable to damage.

Keywords: climbing plants, forest health, nurse tree, two-storied forest management