亞熱帶亞高山矮竹地上部碳儲存量空間變異及影響因子

Abstract

高山和亞高山地區，矮竹優勢與氣候變遷引起的植被組成改變間的互動極具意義。本論文深入探討矮竹的優勢及碳儲存空間變化的生態意義，內容包含兩個主要研究的關鍵成果。 第一個研究為首次將無人機光達技術(UAV-lidar)與線性模型結合並應用於矮竹，以準確估算矮竹植被中的地上碳儲存（AGC）密度。其中，多變量自適應迴歸樣條（MARS）在AGC密度估算中優於其他模式類型，其測試資料集RMSE為0.15（kgC m-2）且殘差全距最短，因此所估計的AGC密度圖可應用於管理與相關研究。MARS模式亦顯示近冠層底部高度為關鍵變數，有別於傳統僅關注冠層頂部高度的模式型態，另估計出的AGC密度圖顯示出顯著空間變異，並可能與坡度陡峭程度有關。 第二個研究深入瞭解AGC密度與生物及非生物因子間關係，變數包括空間聚集類型、太陽輻射、風和微地形等影響亞高山植被的重要因子。分析結果顯示，空間聚集類型顯著影響AGC密度對環境變數的反應。空間聚集增強環境因子對AGC密度的影響。儘管空間聚集類型內的冷區不受環境因子影響，但熱區對輻射、風型和微地形的變化則呈現出不同的反應，因相同的環境因子卻呈現反差的反應，顯示矮竹AGC密度對這些條件的馴化情形。 本論文將植被AGC密度與環境因子相互關係緊密結合，提供持續暖化的氣候情境中優化保育和管理策略的重要資訊。

In the alpine and subalpine regions, the intricate interplay between vegetation shifts driven by climate change and the dominant presence of dwarf bamboo holds paramount significance. This comprehensive research delves deeply into the ecological implications of dwarf bamboo's prevalence and carbon storage dynamics. This dissertation encapsulates the pivotal outcomes of two primary studies. The initial study pioneers the integration of UAV-lidar technology and linear models. This synergy accurately estimates aboveground carbon (AGC) density in dwarf bamboo vegetation. Notably, multivariate adaptive regression splines (MARS) outperform other models in AGC density estimation, with a root mean square error (RMSE) of 0.15 (kgC m-2) on test data and the shortest residual range. The model identified near-canopy bottom height as a crucial predictor, challenging the conventional focus on canopy top height. The estimated AGC density map unveiled substantial spatial variation, which may be linked to slope steepness. On the other hand, the intricate relationship between AGC density and various factors comes under scrutiny in the second study. These include spatial clustering, solar irradiation, wind patterns, and microtopography. Spatial clustering significantly shapes how AGC density responds to environmental variables. The role of spatial clustering is pivotal, intensifying the effect of environmental conditions on AGC density. While coldspots remain unresponsive, hotspots exhibit distinct reactions to changes in irradiation, wind patterns, and microtopography. This variation in response to shared environmental factors suggests acclimation to these conditions. This research piece weaves together a comprehensive understanding of the interplay between vegetation AGC density and environmental forces. It provides essential information for refining conservation and management strategies amidst evolving climatic scenarios.