The regeneration of vegetation at disturbed sites in Guandaushi forest ecosystem

• Main Authors: Sheng-Kuo Lin, 林勝國
• Other Authors: Ming-Yih Chen
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/88209654177586276799

碩士 === 國立中興大學 === 生命科學系 === 91 === During the process of succession in forest ecosystem, landslide and fire are important disturbances. The soil seed bank and seedling bank are the beginning of the dynamic change after disturbance, and play important roles in the process of regeneration and succession. This study aims to realize the change of vegetation and regeneration after disturbance by investigating the soil seed bank, seedling bank and upper canopy composition of 921 landslide plots, burned areas of Song-Fong Shan and Du-Jan Lin in the Guandaushi forest ecosystem. In the landslide plots and unlandslided check plots, the seed bank consists of abundant seeds of Melastomataceae and Scrophulariaceae; shrub seeds are more than those of tree, herb, and vine. At landslide plots, most seedlings are herb (Miscanthus floridulus, etc.) and tree (Litsea cubeba, etc.); shade-intolerant species (Litsea cubeba, Miscanthus floridulus, etc.) are dominant in the early stage, and gradually displaced by shrub (Eurya acuminata, Melastoma candidum, etc.) and tree (Schima superba); the seedling density and fluctuation are affected by soil stability, top-soil persistence and surrounding vegetation. In the unlandslided check plots, seedlings of tree (Litsea cubeba) and shrub (Melastomataceae) are most abundant; the dominant species of seedling are tree (Cinnamomum subavenium, Syzygium buxifolium, etc.) and shrub (Blastus cochinchinensis, Pachycentria formosana, etc.). The seedling density at unlandslided check plots shows seasonal change and is lower in dry season (December to next April). For all plots, the seed germinating concentrates during April to October, especially in the early rain season (June). The death rate of seedling of landslide plots increases during April to August (rain season). Seedlings of herb and tree show higher proportion of death. During February 2002 to March 2003 study period, monthly average temperature of all plots decrease with the increase of elevation. Monthly average relative humidity of unlandslided check plots is higher than that of landslide plots, and all are changed with seasons. Monthly average light of landslide plots (830.2 lux) is significantly higher than that of unlandslided check plots (313.8 lux). In landslide plots, the dispersion of seedling species is affected by aspect and altitude. The species of seedlings at the southwestern aspect (L3) and at the highest altitude plots (L4) are different from that of other landslide plots. The seedlings of shade-intolerant species, for example Litsea cubeba, Miscanthus floridulus etc., are randomly appeared in most landslide plots. Comparing the similarity of soil seed bank, seedling bank and upper canopy composition in landslide plots and unlandslided check plots, we presume that plant regeneration at landslide plots is mainly by seeds outside disturbance area, but that at undisturbed plots is mostly from seedling bank under canopy. In burned areas of Song-Fong Shan and Du-Jan Lin, ground vegetation is mostly shade-intolerant (Miscanthus floridulus, Mallotus japonicus, etc.) and sprouting species (Brainea insignis, Lindera aggregata, etc.); overstory is dominated by fast-growing shade-intolerant species (Litsea cubeba, Mallotus paniculatu, etc.), sprouting broad-leaved tree (Lindera aggregata and Rhododendron breviperulatum), and Pinus taiwanensis. In unburned areas, ground vegetation is mostly Lindera aggregata and Ardisia cornudentata, upper canopy is mostly Lindera aggregata, Pasania glabra etc. As canopy is getting closer, shade-intolerant species, Pinus taiwanensis, Brainea insignis are decreasing. If no more fires, these species would be eliminated and succeed to climax of broad-leaved trees.