PURE NATURAL STANDS OF Castanopsis boisii, AN EDIBLE CHESTNUT IN VIETNAM

Castanopsis boisii is a multipurpose forest tree, native to South China and Vietnam. The nut of C. boisii is edible and has been widely used as daily food. The study in North Vietnam indicated that more than 70% of stems and 80% basal areas of C. boisii were found in natural stands, indicating the availability of purely natural forests of C. boisii. Even though, up to 14 other tree species were also found mixing with C. boisii. The density of tree group (diameter at breast height/DBH ≥ 10 cm) of C. boisii ranged 43–51 stems/1,000 m2, sapling density (height > 2 m and DBH < 10 cm) ranged 13–25 stems/225 m2 and seedlings (height ≤ 2 m) ranged 28–101 stems/20 m2. Stem/DBH distributions of the pool of C. boisii had bell-shapes for tree group with peaks in 13–17 cm DBH. Stem/height distributions had bell-shapes with both right and left skews, and in-continuous shape with two peaks at 7–9 cm and 13–15 cm DBH. Meanwhile, crown area/height distributions had all bell-shapes with left skews. It is concluded that for sustainable nut production, stand development and tree diversity conservation, silvicultural treatments must be applied by remaining all found species in the stands, removing diseased and bed growth stems of all species, removing stems of C. boisii in dense areas and ensuring regenerations of C. boisii as seedlings, saplings, and trees. In addition, less than 150 fruited trees/ha must also be considered for high nut production and quality. Silvicultural treatments should forward stand to have stem/DBH distribution of bell-shape.