大安溪事業區巒大杉人工林區塊伐對地被植物之影響

區塊伐屬於一種小面積皆伐，將每個伐採區塊視為同齡林經營管理，並分不同年度進行區塊伐採，不僅保有皆伐的優點，對生態環境的衝擊也較皆伐小。本研究自2018年7月至2020年7月，於大安溪事業區117林班監測40年生巒大杉人工林區塊伐後對地被植物的影響。調查結果顯示，已伐採區地被層之物種組成以現生植物萌櫱、土壤種子庫，以及外源種子傳播等新拓殖植物所構成；生活型以挺空植物最多，其次為半地中植物，且半地中植物和一年生種子植物比例較未伐採區高。新拓殖樹種有山胡椒、食茱萸、裡白楤木等先驅樹種，以及一年生草本植物如昭和草等；其中，新拓殖植物包含18種歸化植物，但監測期間無族群擴大，推測對伐採跡地的生育地衝擊不大。伐採後樣區地被具萌櫱特性的現生物種對於伐採干擾具有良好耐受性，區塊伐後仍維持一定族群量。伐採後的樣區地被α物種多樣性增加，而地被組成隨季節更替的變動，反映於β物種多樣性指數的變化。整體而言，大安溪事業區117林班巒大杉人工林的地被物種多樣性因小面積區塊伐擾動而增加，但需注意外來歸化植物因擾動而出現。就植物社會而言，小面積區塊伐對生態衝擊較小，可能是臺灣提升木材自給率較佳的伐採作業方式。本研究成果可以提供日後林業經營參考。

關鍵字

區塊伐；人工林；次級演替；物種多樣性；巒大杉

並列摘要

Patch cutting is a type of small-scale clearcutting performed as a part of even-aged forest management and harvesting. Patch cutting not only maintains the advantage of clearcutting but also reduces the ecological impact. This study was conducted in the 117th compartment, a 40-year-old Cunninghamia konishii (Luanta fir) plantation in Daanxi Working Circle from July 2018 to July 2020. The effects of patch cutting on the understory were monitored. The results demonstrated that in the patch cutting area, sprouting from the original plants, soil seed bank, and exogenous plants was the main component of the understory. The dominant plant life-form was phanerophytes, followed by hemicryptophytes. The proportion of hemicryptophytes and therophytes in the patch cutting area was higher than that in the uncut area. The newly colonized species were dominated by pioneer tree species, such as Litsea cubeba, Zanthoxylum ailanthoides, and Aralia bipinnata, and annual herbaceous plants, such as Crassocephalum crepidioides; 18 naturalized plants were also included in the study. However, during the monitoring period, no population expansion was observed, and the effect on the study area was not considerable. Overall, the α-species diversity in the postcutting plot increased. The disturbance of patch cutting and the composition of the understory with seasonal changes were comprehensively reflected in changes in the β-species diversity index. Most species exhibited high tolerance to the cutting disturbance, maintaining a certain population after patch cutting. At present, Taiwan's strategies aim to strike a balance between increasing the timber self-sufficiency rate and reducing the ecological impact of cutting. This study analyzed the changes to the understory following patch cutting in a Luanta fir plantation to provide relevant information for future forest management.

並列關鍵字

patch cutting ； plantation ； secondary succession ； species diversity ； Cunninghamia konishii

主題瀏覽