RESEARCH ON THE DISTRIBUTION, ECOLOGICAL CHARACTERISTICS AND REGENERATION OF Sindora tonkinensis A. Chev. Ex K. & S. S. Larsen IN DONG CHAU - KHE NUOC TRONG NATURE RESERVE, QUANG BINH PROVINCE

Abstract

Sindora tonkinensis A. Chev. Ex K. & S. S. Larsen, commonly known as Gụ lau, is a large, rare timber tree belonging to the Fabaceae family, classified under Group I as per TCVN 12919-2:2019 due to its high-quality wood. The research results have shown that S. tonkinensis is sporadically distributed in natural forests at elevations up to 637 m above sea level, with an average slope of 5⁰ - 30⁰. The annual mean temperature varies between 24 and 25⁰C, with an average annual minimum temperature of 16.6⁰C and an average annual maximum temperature of 34.2⁰C. The average annual rainfall ranges from 2,000 to 2,500 mm, and the average annual humidity is between 83% and 84%. S. tonkinensis thrives on yellow-brown feralitic soils developed on granite bedrock, with soil layers exceeding 50 cm in depth. These soils are moderately to strongly acidic (pH_KCl < 4.5) and have a light to medium texture, including sandy loam and loam soils. The species exhibits a relatively high capacity for seed-based regeneration, with an average regeneration density ranging from 160 to 347 seedlings per hectare, averaging 258 seedlings per hectare. The composition of regenerating species retains the dominance of the parent canopy layer. However, the number of promising regenerants of S. tonkinensis is relatively low. Therefore, protective measures, such as safeguarding mother trees for seed dispersal and further research on the species' biological characteristics, propagation potential, and cultivation techniques, are essential for conserving and developing the genetic resources of this rare and valuable species.