| 摘要: | 森林在維繫地球生命系統的平衡中具有不可替代的作用。由於森林與氣候之間存在著密切的關係，森林還能作為生產活動以及生活提供休憩的場所；長期的觀察與調查森林的變遷，可以做為為來森林管理與維護的重要依據。傳統上，植物的分布情形都是以人為方式到現地調查獲取資料，但是近年來科技進步，可以更容易地取得衛星影像進行分析，藉以評估植物的生長特性。植被指數是衡量植被生長和覆蓋程度的指標，而氣候因素則是影響植被生長和分布的重要因素之一。本研究以蘭陽溪流域的原生林和人工林為對象，探討氣候變化對其植被指數的影響因此，分析不同植群條件下，各項植生指標的變化特徵。研究中利用USGS提供2000-2020 的Landsat 衛星影像依照四個季節每季各挑選兩張雲量50%以下的衛星影像作為研究資料，並以原生林，經改造天然林、半天然林、生產性人工林及保護性人工林等五種森林類型進行分析；同時，探討不同植物指標的表現，以作為後續相關研究的探討，本研究以蘭陽溪流域中上游為主要的研究區區域。本研究以宜蘭陽溪區域內2000年至2020年的衛星影響進行分析，評估不同林相隨時間變化情形，研究以NDVI與SAVI植生指數進行評估。
透過本研究透過分析，宜蘭蘭陽溪地區的半天然林、原生林、生產性人工林、保護性人工林與經改造天然林之NDVI與SAVI數值與溫度之間相關性指數發現兩者之間的相關性接近0，顯示它們之間的關係很弱或不存在，這些發現顯示在這段時間序列的觀測期間植被指數呈現出明顯的變化這可能會因為颱風、暴雨，乾旱等等自然災害或是其他人為影響而在這20年各個林相的NDVI與SAVI的數值變化，儘管從研究結果未並去研究NDVI與SAVI數值變化的原因，但這也為未來更深入的研究提供了啟示，以進一步探討植被生長與氣候條件之間可能存在的複雜關係，非單一限性關係，未來可檢視如何將植物生長的趨勢量與溫度變化量能有更具體量化區隔的方法。
Forests play an irreplaceable role in maintaining the balance of Earth's life systems. Due to their close relationship with climate, forests serve as both producers and recreational spaces, crucial for sustaining life. Long-term observation and study of forest changes provide essential insights for forest management and preservation. Traditionally, plant distribution has been surveyed manually, but recent technological advancements allow easier access to satellite imagery for analyzing vegetation growth characteristics. Vegetation indices, such as NDVI and SAVI, are used to measure vegetation growth and coverage, while climate factors significantly influence vegetation growth and distribution. This study focuses on the primary forests and plantations in the Lanyang River Basin to investigate the impact of climate change on their vegetation indices. Using Landsat satellite imagery provided by USGS from 2000 to 2020, two images with cloud cover below 50% per season were selected for analysis. The study analyzes five forest types: primary forests, natural forests modified by human activities, semi-natural forests, productive plantations, and protective plantations. It explores the performance of different vegetation indices to inform future research.
The study area primarily covers the upper reaches of the Lanyang River Basin. Analysis of NDVI and SAVI values between semi-natural forests, primary forests, productive plantations, protective plantations, and modified natural forests reveals a Pearson correlation coefficient close to zero regarding temperature, indicating a weak or nonexistent relationship between them. This suggests that temperature variations may not significantly influence vegetation coverage within our study area, possibly due to other influencing factors.
Through this study, the correlation index between NDVI and SAVI values of semi-natural forests, native forests, productive plantations, protective plantations, and transformed natural forests in the Lanyang River area of Yilan and temperature was found to be close to zero, indicating a weak or non-existent relationship between them. These findings suggest that vegetation indices showed significant changes during the observation period of this time series, possibly due to natural disasters such as typhoons, heavy rain, droughts, or other human influences over the past 20 years. Despite studying the reasons for the changes in NDVI and SAVI values from the research results, this also provides insights for future more in-depth studies to further explore the complex relationships that may exist between vegetation growth and climate conditions, which are not simply linear. In the future, it can be examined how to quantify the trends in plant growth and temperature changes more specifically. |
