1. 於外太魯閣低海拔地區另覓典型的常綠闊葉林，劃設永久樣區進行監測，以掌握本區植被和生態系的長期變化，做為日後環境教育和經營管理的參考。
2. 於天祥附近山區，針對內太魯閣特殊的太魯閣櫟、青剛櫟和落葉闊葉樹形成的下部山地半落葉闊葉林，劃設永久樣區進行長期監測。

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Abstract

keywords：plant community, permanent plot, Taroko National Park

This research involved a re-survey of three permanent plots in 2024, including He-Ren (lowland evergreen broad-leaved forest), Bi-Lu (upper montane mixed needle-broad-leaved forest), and Xiao-Feng-Kou (subalpine needle-leaved forest), spanning across different elevations in Taroko National Park.

In He-Ren, a landslide destroyed approximately one-third of the area, which was previously a frequently disturbed secondary forest. Now, only a few scattered trees, such as Dendrocnide meyeniana and Melanolepis multiglandulosa, remain, while the shrubs and herbs are covered by debris. In contrast, the remaining two-thirds of the area were less affected by the landslide. By 2024, the secondary forest in this part is dominated by Melanolepis multiglandulosa, Macaranga tanarius, and Broussonetia papyrifera, and is transitioning toward shade-tolerant species, such as fig trees, including Ficus irisana, Ardisia sieboldii, Ficus benjamina, and Ficus variegata var. garciae.

In Bi-Lu, species diversity is higher compared to the other plots. Although species such as Acer morrisonense and Acer kawakamii in the tree layer, along with Pittosporum pentandrum and Berberis kawakamii in the shrub layer, are retreating from the community, the overall composition has been minimally impacted. Over the past 32 years, many small trees have died, significantly reducing density; however, the basal area has steadily increased. Currently, the plot represents a typical mixed needle-broad-leaved forest. The canopy is dominated by the conifer Picea morrisonicola, while broadleaf species, including Cyclobalanopsis morii, Cyclobalanopsis stenophylloides, and Daphniphyllum himalaense subsp. Macropodum, make up the broadleaf canopy.

In Xiao-Feng-Kou, five surveys have been conducted over 32 years. This comprehensive dataset reveals the survival mechanisms and successional trends of Taiwan firs. The self-thinning phenomenon in the regenerating forest is evident, with tree density continually decreasing due to intense competition. Tree growth and survival are strongly influenced by competition and light resource availability. Therefore, competition pressure, average annual diameter growth, and average diameter at breast height (DBH) can serve as useful indicators for evaluating tree survival probability. On the outer edge of the regenerating forest, the growth pattern has shifted from height growth to trunk thickening. However, in the inward sample trees, the growth pattern shifts back to height growth. In contrast, within the inner forest, trees maintain a height growth pattern but grow slowly due to high density and poor light availability.