評估機械性壓力對包籜矢竹生物量與生長之影響

Abstract

近年來氣候變遷下，竹類因具有較高的碳吸存潛力而成為碳匯管理的重要對象。然而，竹類以地下莖入侵原生植群與林地，引發生態失衡的風險需透過更完善的管理措施進行預防。為探討機械性逆境是否可抑制竹林擴張，本研究以陽明山包籜矢竹擴張較明顯的推移帶交界處，透過衛星影像判釋與現場勘查設定試驗樣區，針對包籜矢竹地下莖施加束紮壓力(約6–7 kg)，來模擬竹類地下莖受到機械性逆境後，其竹桿地上部生物量與竹筍生長之影響。逆境處理包含60枝竹桿，透過人工測量與光達掃描同步調查基徑與稈高，以異速生長方程式推估生物量。 結果顯示匍匐式地下莖(creeping rhizomes)遭受機械性壓力之竹稈地上部生物量未顯著受影響；但竹筍發筍模式呈現多項顯著的差異、筍地徑及筍高的生長皆低於對照組，且死亡率亦高於對照組，表明推移帶交界地下莖遭受機械性壓力之竹叢，其竹筍發育生長受到抑制。發筍曲線相對於機械性壓力形成的逆境曲線在時間和空間上的互動變化研究結果表明，發筍曲線最終沒有超過逆境曲線，並且遠離了逆境曲線(即遠離樹木)。綜合推移帶交界處的筍因遭受機械性壓力，導致其發育生長受到抑制的效應，整體而論，本研究結果指出，對推移帶交界匍匐地下莖施加機械性壓力雖不影響竹稈碳吸存生物量，但顯著抑制竹筍生長與擴張方向，顯示使用本策略具有控制竹林擴張的潛力，並能提供一個能夠穩定原生林與竹林推移帶的永續管理模式。

In recent years, under climate change, bamboo has become an important target for carbon sink management due to its high carbon storage potential. However, the risk of bamboo invading native vegetation and forests with rhizomes, causing ecological imbalance, needs to be prevented through more comprehensive management measures. To investigate whether mechanical stress can inhibit bamboo forest expansion, this study used satellite image interpretation and field surveys to set up experimental plots at the junction of the ecotone where the expansion of the Pseudosasa usawae was more obvious in Yangmingshan. Binding pressure (about 6-7 kg) was applied to the rhizomes of the Pseudosasa usawae to simulate the effects of mechanical stress on the aboveground biomass of bamboo stems and bamboo shoot growth. The stress treatment included 60 bamboo culms, and the base diameter and culm height were investigated simultaneously through manual measurement and lidar scanning, and the biomass was estimated using the allometric growth equation. The results showed that the aboveground biomass of bamboo culms subjected to mechanical stress on creeping rhizomes was not significantly affected; however, the shoot development pattern showed many significant differences, the growth of shoot diameter and shoot height were lower than those in the control group, and the mortality rate was also higher than that in the control group, indicating that the development and growth of bamboo shoots in bamboo clumps subjected to mechanical stress on the rhizomes at the ecotone were inhibited. The results of the study on the interactive changes of the shoot growth curve relative to the adversity curve formed by mechanical stress in time and space showed that the shoot growth curve did not exceed the adversity curve in the end and moved away from the adversity curve (that is, away from the trees). The shoots at the junction of the comprehensive ecotone are subjected to mechanical stress, which leads to the inhibition of their development and growth. Overall, the results of this study indicate that although the mechanical stress applied to the creeping rhizomes at the junction of the ecotone does not affect the carbon storage biomass of the bamboo culms, it significantly inhibits the growth and expansion direction of bamboo shoots, indicating that the use of this strategy has the potential to control the expansion of bamboo forests and can provide a sustainable management model that can stabilize native forests and bamboo forest ecotones.