The Status of Dipterocarpaceae Plants in Taiwan

The Dipterocarpaceae family is famous for timber productions in Southeast Asia. The Shuangxi tropical arboretum in Taiwan introduced some dipterocarp species in 1935. However, the changes in abundance and regeneration of each dipterocarp species are unknown. This study aimed to investigate their diameters patterns and regeneration ability over a long period. The results showed that only four dipterocarp species were survived in this arboretum. An individual plant of Dipterocarpus gracilis Blume had a diameter of 5.7 cm. A young seedling was 90 cm in height, and some fruits germinated directly on the ground. A few fruits of Dipterocarpus grandiflorus (Blanco) Blanco were collected; however, and no seedlings have been found thus far, and its annual growth rate was 2.82% as the fastest growth speed. The annual growth rate of Rubroshorea polysperma (Blanco) P. S. Ashton & J. Heck was 2.32%, which is the second growth speed among the different species. Moreover, the abundance of R. polysperma increased as the fruits germinated. In particular, an uneven-aged forest of R. polysperma was established near the southwest area of the No. 2225 nature conservation protection forest, and an individual with a 100 cm DBH was also found. The fruits of Rubroshorea palosapis (Blanco) P. S. Ashton & J. Heck. could not be collected, but a young seedling appeared, with a height of approximately 150 cm. Therefore, Taiwan should be considered as the new distribution site for the Dipterocarpaceae family, all four dipterocarp species can grow in this area and need to be protected carefully.