- 期刊
- OpenAccess
南仁山森林倒木孔隙三年間的更新動態
Regeneration Dynamics in a Treefall-Gap within 3 Years in Nanjenshan Forest
摘要
墾丁國家公園南仁山森林一株鐵冬青大樹於2000年4月因根腐倒伏，形成約75平方公尺的孔隙。本研究設置36平方公尺的樣區，調查3年間前生樹與新生樹的組成及族群數量的變化。孔隙初形成時記錄到前生樹苗有26種109株，新生苗在調查期間共記錄到32種597株。新生樹苗群落在孔隙形成後第3、10及第20個月的Shannon-Wiener指數分別為128、241及291。然而此物種多樣性指數在孔隙形成後第26及第31個月降至268及208，意味著此更新過程受到某些不利因子的抑制。孔隙形成初期即有蔓性的莎勒竹入侵，10固月後並繁生巨型葉的姑婆芋，嚴重遮阻陽光，可能造成林床值物群落較高的死亡機會。孔隙形成31個月後，有11株稚樹成為優勢值株，其中4株高度超過3m，另7株高度在2-3m間，樹種包括新生樹的山黃麻、白匏仔、蟲屎，以及前生樹的水同木及台灣拓樹。此結果顯示前生樹及新生樹都是南仁山孔隙更新的來源，但孔隙的形成對非耐陰種的生長較有利。
並列摘要
An old-growth tree, Ilex rotunda, in Nanjenshan Forest, Kenting National Park fell in April 2000 due to its rotten roots. This instance created a forest gap of 75 m^2 in size. We monitored the dynamics of the composition as well as the abundance of both advanced regeneration and seedling recruitment in a 36-m^2 plot for 3 yr after gap formation. There were 26 species with 109 advanced regenerations recorded in the beginning of gap formation. Thirty-two species, mostly shade-intolerant species, with 597 new recruits were recorded during the study period. Shannon- Wiener indices, representing species diversity, of the recruitment co mmunity were 1.28, 2.41, and 2.91 at the 3(superscript rd), 10(superscript th) and 20(superscript th) month, respectively, after gap formation. However, these indices declined to 2.68 and2.08 by the 26and 3lstnrnths, respectively, indicating some adverse factors had occurred and retarded the recruitment processes. A climbing bamboo, Schizostachyum diffusum, had encroached in to the gap in the early stage; and a mega-leaved shrub, Alocasia odora, was thriving 10 months after gap formation. Both species created dense shading and in creased mortality of the under-growth community in the gap. By the end of the 31(superscript st) month, there were 11 dominant saplings in the gap. Among them, 7 saplings had grown to 2-3 m high, while 4 saplings had grown to over 3 m. These dominant saplings included Mallotus paniculatus, Melanolepis multiglandulosa, and Trema orientalis of the new recruits, as well as Ficusfistulosa and Maclura cochinchinensis of the advanced regenerations. Although both the advanced regenerations and the new recruits were sources for gap-phase regeneration in Nanjenshan Forest, shade-into lerant species benfited more than others from the gap formation.