福衛二號光譜土壤調整植生指數與地測葉面積指數於光蠟樹材積推估之比較

面對全球暖化日趨嚴重，人工造林地木材積蓄積量具有碳吸存環境效益，應用遙測技術連結地面樣區調查資料，精確量測大面積平地造林地的林木材積蓄積量，是一個國際的重要課題。本研究以花蓮縣光復鄉台糖大農及大富農場平地造林光蠟樹林地為試驗區，應用福衛二號光譜土壤調整植生指數(SAVI)分級，進行分層目的取樣法，選取60個具空間獨立的地面樣區。於每一樣區上進行每木調查獲取材積蓄積量，並使用孔隙率透光分析法(gap light analyzer, GLA)測量地面樣區的兩個葉面積指數及樹冠鬱閉度。應用曲線估計迴歸統計分析方法，建立SAVI指數、葉面積指數及樹冠鬱閉度指數對材積推估最適迴歸式；另建立SAVI指數推估葉面積指數及樹冠鬱閉度最適廻歸式，比較各類最適推估模式的關係及優缺點。研究結果顯示經本研究所得之最適迴歸式，推估可解釋的變異量達94%以上。連結福衛二號光學遙測SAVI植生指數與GLA地面量測的葉面積指數，可用來推估光蠟樹人工林蓄積量、葉面積指數及樹冠鬱閉度；所得成果可繪製大面積空間異質性分布圖，具有相當的可應用性。未來一部分每木調查樣區可用GLA法量測的葉面積指數取代，連結樣區的SAVI進行多重取樣的林木蓄積量調查與估算，將可節省地面樣區調查的人力與時間成本。

關鍵字

植生指數；葉面積指數；林分材積；平地造林地；福衛二號

並列摘要

To mitigate the impacts of global warming, afforested plantations have a considerable amount of wood stock volume with environmental benefits for carbon sequestration. Applying remote sensing technology linked to ground plot data has been an important international topic to precisely measure wood volume in large areas of afforestation. This study focused on Fraxinus griffithii (Fg) plantations, owned by Danong and Dafu Farms of the Taiwan Sugar Company, in Guangfu Township, Hualien County, Taiwan. The soil-adjusted vegetation index (SAVI) from a FORMOSAT-2 (FS2) satellite image acquired on February 13, 2009 was classified into 5 separate grades to perform a stratified purposive sampling scheme for the setting up of 60 spatially independent ground plots. In each plot, the Fg wood volume (VOL) was determined by a field survey of each tree, and 2 leaf area indices (LAI4 and LAI5, i.e., LAIs) and a canopy closure index (CCI) were measured by utilizing gap light analyzer (GLA) method. SAVI and LAIs or CCI were adopted as independent variables in curve regression analyses to establish optimal regressions on the VOL estimation. In addition, the SAVI was used in curve regression analyses to estimate LAI and CCI. The advantage of these 2 optimal equation sets was saving time and labor in the field for ground plot surveys and VOL mapping. Results showed that the optimal regressions could explain more than 94% of the variation of the estimations. Linking SAVI derived fromthe FS2 image or ground measurements of LAI5 or the CCI to the VOL from ground plots is well suited to infer the VOL, LAIs, or CCI of Fg plantations. Using these optimal regressions has the benefit for mapping the VOL, CCI, and LAIs by providing their distributions of spatial heterogeneities. In the future, the time and labor required to investigate, estimate, and map of the Fg stand volume should be greatly reduced by using the LAI calculated from the GLA and linking it to multiphase sampling derived from the SAVI.

並列關鍵字

vegetation index ； leaf area index ； stand volume ； afforestation ； FORMOSAT-2

國際替代計量

福衛二號光譜土壤調整植生指數與地測葉面積指數於光蠟樹材積推估之比較

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