Structure changes of the subalpine Taiwan fir (Abies kawakamii (Hay.) Ito) forest from 2008 to 2018

ABSTRACT Abies kawakamii (Hay.) Ito is an endemic species mainly distributed in Taiwan’s subalpine region with an elevation of 3,000–3,600 m above sea level. It is a significant ecological indicator species in high subtropical mountains regarding plant geography and climate change. Taiwan is an island in the Asian-Pacific region. Typhoons cause forest gaps belonging to small-scale disturbances in the forest ecosystem, which is critical in maintaining species diversity and forest regeneration. We set up seven long-term monitoring plots of Ab. kawakamii forest to investigate the stand structure, species composition, and environmental factors of Mount (Mt.) Xue in Shei-Pa National Park. Comparing tree numbers between two surveys in a decade. Most of the population structure of Ab. kawakamii showed a similar positive skewness distribution between the two surveys, indicating that the population of Ab. kawakamii forest in Mt. Xue would be stable. According to principal component analysis (PCA), population structure of Ab. kawakamii correlated with dominant understory species and saplings of Ab. kawakamii but may be related to their habitat condition, such as elevation. Death trees released space and resources as gaps in the subalpine forest, which initiated micro-succession in the Ab. kawakamii forest.