SEVERAL STRUCTURAL CHARACTERISTICS OF FORESTS AND NATURAL FOREST REGENERATION OF Sindora tonkinensis A. Chev. ex K. & S. S. Larsen IN QUANG TRI PROVINCE

Abstract

Sindora tonkinensis is a rare native species listed in Vietnam's Red Book, known for its economic value. However, due to over-exploitation in recent years, the distribution of this species in natural forests has significantly declined.The study on the forest structure and natural regeneration of Sindora tonkinensis in several natural broadleaf evergreen and semi-deciduous forest types in Quang Tri province reveals that the density of the tree layer varies between 496 trees/ha and 692 trees/ha, with the number of species ranging from 36 species to 52 species. The density of Sindora tonkinensis trees fluctuates from 8 to 16 trees/ha, accounting for 1.34% to 2.72% of the total tree population, with a standing volume ranging from 1.80 m³/ha to 13.92 m³/ha. In the natural forest states, Sindora tonkinensis does not play a significant role in the forest composition, and its IV index is very low, ranging from 1.8% to 3.2%. The density of regenerated trees shows considerable variation, ranging from 6,640 trees/ha to 10,240 trees/ha, with regeneration quality predominantly ranging from good to medium. Seed-origin regeneration accounts for a substantial proportion, varying from 85.8% to 95.4%. The regeneration density of Sindora tonkinensis is very low, ranging from 80 trees/ha to 320 trees/ha, with good to medium quality, and all regeneration is seed-origin. The number of regenerating tree species in the sample plots ranges from 17 to 29 species, with 5 to 9 species significantly contributing to the forest composition. Regenerating Sindora tonkinensis does not play a dominant role in the forest structure, with its Ki% index ranging from 1.1% to 3.0% in plots where Sindora tonkinensis is present. The number of regenerated trees decreases with increasing height class, but the regenerated trees are expected to provide a sufficient quantity for forest recovery.