應用溫度植生乾燥指數推測臺灣地區國有林班地不同生態區土壤濕度之時空變異

Using Temperature Vegetation Dryness Index to Estimate the Spatial-temporal Variation of Surface Soil Moisture on the Different Ecological Zones of National Forest Lands in Taiwan

黃雅莉(Ya-Li Huang) ； 吳芝伶(Chih-Lin Wu) ； 陳建璋(Jan-Chang Chen) ； 陳朝圳(Chaur-Tzuhn Chen)

《國立臺灣大學生物資源暨農學院實驗林研究報告》 32卷3期 (2018/09) Pp. 183-198

https://doi.org/10.6542/EFNTU.201809_32(3).0003

摘要

建立林地土壤濕度的長期動態及空間變異，即可提供森林經營的重要資訊。然而以測站或以現地調查的方式，取得地表土壤濕度資料，其資料無法代表長時間、大面積的地表土壤濕度空間分布及動態變化。本研究以全臺灣作為研究區域，使用MODIS衛星影像，選定2008年（2008／03－2009／02）、2010年（2010／03－2011／02）、2012年（2012／03－2013／02）共三年數據，將其分為春（3－5月）、夏（6－8月）、秋（9－11月）、冬（12－翌年2月）。利用地表溫度（Land Surface Temperature, LST）與常態化差異植生指數（Normalized Difference Vegetation Index, NDVI），推導具有空間性的溫度植生乾燥指數（Temperature Vegetation Dryness Index, TVDI），以表達空間性之土壤濕潤程度，再藉由植群生態區及不同季節間之變化，驗證TVDI對於相對土壤濕度的解釋能力。研究結果顯示臺灣地區之LST／NDVI兩變數之散布圖具有固定的分布樣態，且可有效的建立乾燥邊界（Dry Edge），並可推估具有空間性之TVDI。以臺灣地區不同生態區萃取其不同季節之TVDI並進行變異分析，結果顯示相同生態區之土壤濕度具有季節性的時間變異，而相同季節則具有不同生態區之空間變異，且TVDI之時間與空間變異可有效的解釋土壤的濕潤程度。

關鍵字

地表土壤濕度 ； MODIS衛星影像 ； 溫度植生乾燥指數（TVDI） ； 降雨量

並列摘要

Estimating surface soil moisture with a spatial-temporal variation could provide important information for forest management. However, data obtained from surface soil moisture by observatory or field survey could not represent long-term, large-area spatial distribution and temporal change. This research were focus on the Taiwan island by using different times of MODIS images data. The imagery data for year 2008 (2008/03-2009/02), 2010 (2010/03- 2011/02), 2012 (2012/03-2013/02) were selected and divided into spring (May-May), summer (June-August), autumn (September-November), and winter (February 12-February). Land surface temperature (LST) and normalized difference vegetation index (NDVI) were used to estimate temperature-vegetation dryness index (TVDI) purported to express spatial degree of soil wetting. Ecological zone and as well as variation between different seasons were then used to analyzed with relative soil moisture and to verify the ability of TVDI. The results of this study showed that the scatter plots of the LST/NDVI in Taiwan had a fixed pattern, and could effectively establish a dry edge, and could estimate spatial TVDI. The TVDI of different seasons in Taiwan was extracted and subjected to variance analysis. The results showed that soil moisture with same ecological zone had seasonal variations, while spatial variation of different ecological zones occurred during the same season. The TVDI of spatial-temporal variation can effectively to explain the degree of soil moisture.

並列關鍵字

Surface soil moisture ； MODIS satellite imagery ； Temperature Vegetation Dryness Index (TVDI) ； Precipitation