87-4 台灣檜木林之生態研究及經營管理建議(中北部地區)

摘要:

台灣檜木林(Chamaecyparis forest)百年來的生態及林業經營管理研究，最重大的盲點或弔詭即天然更新(regeneration)議題。本報告駁斥「檜木林無法更新」的謬論，提出檜木更新的基本模式及其演繹，且針對更新機制，以斯馬庫斯(Shumakushu)及鎮西堡(shinshibu)二地區為對象，實施現地調查，以求驗證本模式。
台灣檜木林之所以長期適存，實乃以其單株超過千年壽命、種苗拓殖偏向不耐蔭的遺傳特性，配合台灣地體不定時變動與脆弱性，以及豪雨沖蝕等因素，造成累聚性大小崩塌，而不斷作拓殖性更新，或異地成林。成林之後的在地更新方式，紅檜與扁柏族群有所不同，扁柏在地更新良好，惟其齡級結構不盡然為反J型，基本更新方式為孔隙(gap phase)或「遇缺則補」方式；紅檜族群集中於山坡中、下段及溪澗，藉基質之高度變動而拓殖更新，易在河川向源侵蝕兩側來回成林。成林之後的在地更新需較大孔隙或蝕溝而發生，但常形成二代木、三代木的原地置換，如果基質長期穩定，紅檜族群則有式微傾向，但台灣地體恒處易動，因而確保紅檜於不墜，總結紅檜的更新，可以「女媧補地」作比喻，此外，紅檜與扁柏皆可因火災而再度更新。
本報告將歷來相關研究整理為植物分類學、型態學、植物地理及台灣檜木始源、植被帶(vegetation zone)分類、植物社會單位分類、檜木與環境因子的相關、社會演替、天然更新、林業經營、及保育等十大議題，賦予總評，另提出台檜源自日本說。
針對玉山西向地區(或阿里山區)、郡大山脈兩側、楠梓仙溪、丹大林道、大雪山區、棲蘭山區、新馬庫斯、鎮西堡、溪頭及杉林溪、台14甲公路及新中橫等地，作勘察及樣區調查，並簡述其形相與組成，據此認定台灣檜木最完整純林分，北以棲蘭之扁柏、南以秀姑巒之紅檜最壯觀，理應賦予最高保育層級之對待。
關於今後檜木林之經營管理，本文強調先由觀念革新，主張台灣並無伐木營林的先天條件，林業工業政策理應轉向，力陳天然林為台灣生界今後最根本的維生生態系之依賴，同時，對林相改良、水土保持等技術層次提出批判，最後援提經營管理若干策略或建言，包括發展台灣檜木學，爭取檜木林列入世界自然遺產保護公約行列；林地分類前不宜經營天然林；全國林地管理應予一元化；全面檢討全國檜木林伐採跡地造林等。參考文獻則為檜木林歷來研究之大成，另檢附二套幻燈片作解說教育之範例。
* 靜宜大學教授，通識中心主任，台灣生態研究中心負責人
** 靜宜大學副教授
***研究助理
 

ABSTRACT:

For over one hundred years, the natural regeneration has been the most critical blind spot and paradox issue regarding to the research of ecological and forestry management of Taiwan’s Chamaecyparis forest (cypress forest). This paper rejects and appeals the absurd statement of “cypress stands cannot be regenerated naturally”, and presents a fundamental model of natural regeneration of cypress forest and the process of deduction. Moreover, for the purpose of verifying the said model, we also engaged in two field surveys of cypress stands in Shumakushu, and Chinshibu.
One of the reasons that cypress forest survived for such a long time is the longevity of individual trees that may have life span over a thousand years. Also, cypress seedlings are intolerable to shade, and seeking openings created by landslides or small collapses due to erosion of unstable geographic structure with heavy rainfalls for propagation. The situation leads to cypress seedlings’ continuously colonization or migration to new lands. There are differences in ways of on site regeneration between red cypress (Chamaecyparis formosensis) and Taiwan cypress (Ch. Obtusa var. formosana). Taiwan cypress has better on site regeneration than that of red cypress, but its age structure is not entirely “reverse J” type, and its basic pattern of regeneration is “gap phase” or “filling in openings”. In contrast, relying on the changes of the foundation, red cypress seedlings concentrate on mid-and-lower slope or grow beside mountain streams. The result makes red cypress propagate vigorously over both eroded banks of stream upward erosion. After stands have formed, the next regeneration has to wait for another large opening or erosion ditce created. However, some second or third generation trees grow on the remnants of the first generation, indicating Taiwan cypresses’ on site regeneration. If the ground is constantly stable then the amount of red cypress groups decline. Fortunately or unfortunately, Taiwan earth body is fragile and never quit moving (earthquakes), so it keeps red cypress stands prosperous forever. In sum, red cypress regeneration is likened to a Chinese mythology of “Empress Patches the Sky.” Besides, both Taiwan and red cypresses can regenerate naturally after a fire.
This study has accumulated relevant literature sorted into 10 issues; such as taxonomy, morphology, plant geography & origin of Taiwan cypresses, vegetation zoning, plant community unit classification, relationships between environment factors and cypress trees, succession of plant communities, natural regeneration, forest and cypress trees, succession of plant communities, natural regeneration, forest industry management, and conservation. General comments for each issue are given. Also a concept of Taiwan cypresses originated from Japan was presented.
Reconnaissance survey and sample plot measurements were taken to describe stand structure for the following locations: the west side slope of Yushan District (or Alishan District), both side slopes of chunta Ridge, Nantzusenchi, Tanta Forest Road, Tahsueshan District, Chilanshan District, Shumakushu, Chinshibu, Chitao & Sanlinchi, Tai 14 Chia Highway & New Central Cross-island Highway. Resulting of the stand structure survey, the purest cypress stands were found in the North at Chilanshan with Taiwan cypress and the South, at Hsiukulanchi with red cypress. Hope these pure cypress stands will give high priority of conservation.
As to the future management and administration of cypress forest, this paper stresses that first of all underlying concepts shall be reformed according to the fact that Taiwan is unfit for commercial forest management congenitally. Forest industry shall be steered to right direction emphasizing that the forest of Taiwan is the last line to support survival of biological community. At the same time, critiques at technical level on current practices of forest type improvement, and soil & water conservation were also presented. Finally, several management and administration strategies and suggestions will be made, which may include the development for cypress forest study; the pursuance of being listed in the World Heritage Preservation and Protection Code; the prohibition of managing natural forest stands prior to the completion of forest land classification; all forest lands in Taiwan shall be administrated under a single agency: and overall examination the present situation of artificial forests from logging areas. The list of references is perhaps a complete bibliography related to cypress stands researches. Two sets of picture slides are attached as examples to help instruction.
*Professor, Providence University; Director, General Education Center; Responsible Man, The Ecological Research Center of Taiwan
**Associate Professor, Providence University
***Research assistant