應用MODIS影像數據估測台灣陸域初級生產量

Using MODIS Image Data to Estimate the Terrestrial Primary Production of Taiwan

胡瀞予(Ching-Yu Hu)

指導教授 ： 陳朝圳

國立屏東科技大學/農學院/森林系所/碩士(2010年)

https://doi.org/10.6346/NPUST.2010.00175

摘要

淨初級生產量(Net Primary Production, NPP) 為研究全球氣候變遷與陸域生態系之核心資料之一。NPP之估算方式有很多種，而將遙測數據應用於NPP的估算模型中為目前的趨勢。MODIS初級生產量產品(MOD17)為第一個以1 km空間解析力及8天的時間解析力，進行規律的重複監測植被NPP的即時監測(near real-time)資料，該項資料對監測生態環境，自然資源和環境之變化有很大的幫助。本研究以2001年至2006年的MODIS NPP產品，對台灣全島植被之NPP進行不同尺度之時空變異分析探討，並藉由氣象資料於台灣全島劃分氣候生態區，分析氣候因子對各氣候生態區NPP之影響。結果顯示，台灣全島植被的NPP分布於2001年至2006年間大致上並無明顯的變異，且呈現出隨著海拔升高而NPP逐漸降低之趨勢。2001年至2006年之NPP值範圍介於50.40~2,062.30 g C m-2 y-1，全島植被年平均NPP以2005年為最高(1,117.88±286.24 g C m-2 y-1)，2001年為最低(932.44±256.78 g C m-2 y-1)。全島植被6年的年平均NPP最小值為63.37 g C m-2 y-1，最大值為1,922.00 g C m-2 y-1，全島植被6年NPP平均值則為1,035.64±268.71 g C m-2 y-1。2001年至2006年台灣全島植被之NPP組成介於1,000-1,500 g C m-2 y-1之間，約佔全島總面積的24.20%-54.53%。2001年至2006年台灣全島植被年平均NPP有80%
以上之面積呈增加之趨勢，而增加的區域主要分布於山區部份。而呈減少趨勢之區域，則只佔全島植被面積的6%，其多分布於較為接近城市之區域及部分山區。台灣全島有超過60%的面積為IGBP之森林分類型，其中面積最廣的為常綠闊葉林，佔全台灣分類面積的37.47%。2001年至2005年間之IGBP土地覆蓋物類別中，草地類別的轉移率為所有植被類型之土地覆蓋物類別中最大者，主要係轉移至森林(25.93%)及農田(27.76%)。各IGBP林型分類之NPP平均值皆分別與其他分類型具顯著之差異性，其中以常綠闊葉林之6年平均NPP為最高(1083.49±217.12 g C m-2 y-1)，最低者為常綠針葉林(834.78±243.11 g C m-2 y-1)。台灣地區依照IPCC之氣候區與生態區劃分標準，可將台灣分成極地、寒帶山區系統、溫帶山區系統、亞熱帶潮濕林、亞熱帶山區系統、熱帶雨林、熱帶潮濕落葉林與熱帶乾燥林等8種生態區，其中以亞熱帶潮濕林面積最大，佔全台面積約54.00%。熱帶雨林之6年平均NPP為8種氣候生態區中最高(1370.96±426.26 g C m-2 y-1)，最低者為極地(736.39±147.63 g C m-2 y-1)。氣候因子對氣候生態區的影響，以熱帶潮濕落葉林較其他生態氣候區敏感，尤其對溫度之相關性為最高，而溫帶山區系統與溫度之相關性則為最低者；極地與降雨量的相關性較為其他氣候生態區高。台灣重要樹種之NPP，呈現以闊葉樹種高於針葉樹種之趨勢，而針葉樹種中，又以人工林之NPP高於天然林。與前人研究之NPP數據比對，結果顯示本研究所估算之NPP數據仍位於常態之數據範圍內。

關鍵字

MODIS NPP產品 ； 土地利用型 ； 氣候生態區

並列摘要

Estimating the Net Primary Production (NPP) is an important key of global change and terrestrial ecosystems research. There are many methods for estimating NPP that the present tendency is using remote sensing data to estimate NPP. MODIS primary production products (MOD17) are regular at the first, near-real-time data sets for repeated monitoring of vegetation primary production on vegetated land at 1-km resolution and an 8-day interval that is a great benefit to monitor ecological conditions, natural resources and environmental changes. In this research, we used the products of MODIS NPP from year 2001 to 2006 for analyzing and discussing the different scales of spatial and temporal variability on the vegetation of NPP. We demarcated the Ecological Zones of Taiwan by meteorological data and analyzed the effect of Ecological Zones NPP by climatic factors. The results showed that from year 2001 to 2006 the NPP of vegetation was no significant variation, but it showed decreasing trend of NPP by rising elevation. In Taiwan, the range of NPP data is between 50.40-2062.30 g C m-2 y-1, the average NPP of vegetation is the highest (1117.88±286.24 g C m-2 y-1) at year 2005, and the
lowest is (932.44±256.78 g C m-2 y-1) at year 2001. The six years average NPP of vegetation is 1035.64±268.71 g C m-2 y-1, the minimum is 63.37 g C m-2 y-1, and the maximum is 1922.00 g C m-2 y-1. The results showed that the NPP data mainly in the 1000-1500 g C m-2 y-1 interval and the percentage of the total area are from 24.20% to 54.53%. More than 80% of the NPP data area showed a rising trend where mainly located in mountain areas and only 6% of the NPP data area showed a descending trend where mainly located in the area near the city and some part of mountain areas. Using IGBP classification as a base, more than 60% of terrestrial area is forest type in Taiwan, and the most extensive area is evergreen broadleaf forest (37.47%). The transfer rate of savannas type is the highest from year 2001 to 2005 that mainly transfer to forest (25.93%) and croplands (27.76%). The mean of forest type NPP data has significantly different than others. The average NPP of six years in evergreen broadleaf forest is the highest (1083.49±217.12 g C m-2 y-1) and evergreen needle leaf forest (834.78±243.11 g C m-2 y-1) is the lowest. The climate zones and ecological regions were demarcated into eight ecological zones that included polar, boreal mountain systems, temperate mountain systems, subtropical humid forest, subtropical mountain systems, tropical rain forest, tropical moist deciduous forest and tropical dry forest by IPCC classification system. In all of ecological zones, 54% subtropical humid forest is the largest area. In eight ecological zones, the NPP average of six years of tropical rain forest is the highest (1370.96±426.26 g C m-2 y-1) and polar is the lowest (736.39±147.63 g C m-2 y-1). Temperature is significant effect to climatic zone; moreover tropical moist deciduous forest is more sensitive than others. On the contrary, temperate mountains system are the lowest relationship with the temperature, polar are high relationship with rainfall than other ecological zone. The NPP of primary forest species in Taiwan, we find that the broadleaf forest is higher than the needle leaf forest and the artificial forest is higher than the natural forest. We compared the estimating NPP data and previous studies, the results show that the using MODIS to estimate NPP data are within the valid range.

並列關鍵字

MODIS NPP products ； land used type ； climate-ecological zones

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