Abstract
The 3-ha Peitungyen forest dynamic plot established in 1995 in a warm temperate evergreen broad-leaved forest was re-measured 12 yr later. In 2007, one species had vanished from this plot, and 5 species were newly recorded, resulting in an increase of species number from 56 to 60. In the 12-yr census interval, stem density increased from 3336.3 to 5769.0 ha-1, and up to 94.5% of recruits were < 5 cm in diameter at breast height (DBH). In spite of the drastic increase in stem density, the basal area dropped from 78.7 to 71.6 m2 ha-1. The considerable decrease in basal area was attributed to the death of many large-DBH trees. Up to 15.7% of large trees (DBH ≥ 30 cm) were recorded as having died in 2007. Comparing the 10 most dominant species (in terms of stem density and basal area) between the 2 censuses, there was a high similarity of species composition, and the ranking only slightly differed. In other words, over the 12 yr, changes in the forest dynamics plot were mainly structural rather than compositional. A marked increment in stem density of small trees, the lack of pioneer species colonization, and little evidence of compositional changes indicate that this plot encountered medium-scale disturbances in the 12 yr. The relatively drastic changes in stem density and basal area in the Peitungyen plot might be attributed to responses of a forest with a relatively low frequency of disturbances to an abrupt increase in disturbances in recent years.