以多時期衛星影像及樹冠高程模型分析崩塌植生復育與影響因素

崩塌復育是具高度空間異質性的地景，也是林分替代干擾後植群隨時間再植被的連續動態過程，其涉及物理環境與生物因素的交互作用，釐清關鍵的影響因素有助於山坡地保育的策略管理。光學遙測影像在監測森林干擾恢復方面具有低成本、高時間頻率的優勢，但對植被結構的恢復仍缺乏明確的推論關係。多時期光達資訊可直接獲取地面植被結構的三維變化，提供檢測植生結構恢復差異的機會。地形會導致崩塌表面的微棲地特徵差異，進而影響不同坡地位置的恢復進程。本研究旨在分析六龜試驗林莫拉克崩塌的自然復育過程，比較不同地形變化區的植生恢復差異，並探討影響復育的重要條件。研究結果顯示，災後12年約87%崩塌面積有顯著的植生復育，光譜恢復軌跡推算植生量已達64%～67%的災前水準，冠層覆蓋率恢復至0.42，平均冠層高度恢復到2.72公尺。相對植生比的比較結果顯示光譜的恢復速率為冠層高度的3倍，等於冠層覆蓋率的1.38倍，結構的恢復速率遠低於光譜。在地形變化不明顯的穩定區，植被的光譜及結構增長恢復表現更好，堆積區有利短期生長的草本植物發展，因此有更明顯的光譜增長恢復，侵蝕區則因初期定殖的木本植物生長，結構增長恢復顯著高於堆積區。坡向、海拔及種源距離是影響崩塌復育的重要因素，地形特徵造成日照、溫濕度等環境條件差異，結合可利用的種子或繁殖體能迅速萌芽定殖，促成一系列的演替過程。整合不同特性的多時序遙測資料能協助剖析植被恢復的動態過程，補充當前崩塌復育研究的洞見。

關鍵字

多時序衛星影像；植生指標；光達；冠層結構；崩塌復育

並列摘要

Landslide restoration landscapes were highly spatial heterogeneity. The restoration was the sequential dynamic process in that plant communities regenerated over time following stand-replacing disturbance, and it involved the interaction of the physical environment and biological factors. Identifying the key influencing factors is helpful to develop strategic management for mountain conservation policies. Optical satellite imagery has the advantages of low cost and highly captured frequency in monitoring forest restoration, but there is still a lack of robust inference relationships between spectral recovery and vegetation structure. The multi-temporal LiDAR measurement could directly obtain the three-dimensional changes of vegetation structure on the ground, providing an opportunity to detect recovery differences compared to spectral information. Topography could lead to diverse microhabitat characteristics on the landslide surface, which affected the restoration process at different slope locations. The purpose of this study was to analyze the natural landslide restoration following Typhoon Morakot in the Liukuei Experimental Forest (LEF), to compare the differences in vegetation recovery between different topographic change areas, and to explore the important factors in the restoration process. According to spectral trend statistics, about 87% of the landslide area had significant vegetation regeneration in 12 years' time after the disturbance. The spectral recovery trajectory estimated that vegetation had reached 64%-67% of the pre-disturbance level, while the canopy cover ratio (CCR) and mean top-of-the-canopy (TCH) had recovered to 0.42 and 2.72 (m), respectively. The comparison results of the relative vegetation ratio showed that the spectral recovery rate was 3 times as fast as the TCH, which was equal to 1.38 times as much CCR, indicating that the structural recovery was much slower than spectral recovery. In the stable area where the topographic changes were non-significant, both the spectral and structural vegetation recovery were better. The accumulation area was favorable for the development of short-term growing herbs, so there was more obvious spectral growth recovery, while the erosion area was significantly higher structure recovery than the accumulation area due to the growth of woody plants which colonized in the early successional stage. Aspect, altitude, and distance from seed pools were important factors affecting landslide restoration. Topographical features could lead to differences in environmental conditions such as solar radiation, temperature, and humidity. Once suitable seeds or propagules arrived, they could quickly sprout and colonize, and promote a series of successional processes. The multi-temporal data acquired from different remote sensing approaches can help to analyze the restored dynamic and supplement the insights into current landslide restoration research.

並列關鍵字

Multi-temporal satellite imagery ； Vegetation index ； LiDAR ； Canopy structure ； Landslide restoration

參考文獻

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