水稻田區微氣候與光合作用模式之研究

Abstract

本研究探討水稻田之生態功能，量化其調節微氣候與吸收二氧化碳之效果。本研究首先建立垂直一維多層微氣候模式，計算水稻與大氣、地表土壤之間能量、質量及動量傳輸，模式經由實測資料驗證後，應用於水稻田之熱流模擬，並利用模擬結果評估水稻田調節微氣候之效果，並換算水稻田可節省電量與間接減少之發電二氧化碳排放量，模擬結果顯示關渡地區一公頃水稻田一日之節電量約為21,400度，可節省約58,500元電費。本研究並建立兩種不同之光合作用模式，即大葉模式與光照-陰影模式，比較兩種不同模式之模擬結果，結果顯示光照-陰影模式模擬所得之二氧化碳吸收率有較高之精確度。利用光合作用模式模擬結果與水稻各生長期之光合作用速率變化可推估水稻全生育期之二氧化碳總吸收量，評估水稻田之二氧化碳吸收量對我國二氧化碳減量目標之貢獻，並以各種車輛之二氧化碳排放量量化水稻田吸收二氧化碳效果。分析結果發現關渡地區374.61公頃水稻田之二氧化碳吸收量對我國2003年二氧化碳總排放量之減量貢獻為0.1%，亦為關渡附近台北市北投焚化廠之2003年二氧化碳減量目標之78%。

This study investigates the effects of paddy fields on microclimate and assimilation of carbon dioxide. A vertical one-dimensional multilayer microclimate model is developed to simulate the mass, energy, and momentum transfer between plant, soil, and atmosphere. After verification with field data, the model is applied to evaluate the benefit of paddy fields on regulation of region microclimate, saving of electronic power and reduction of carbon dioxide emission. The result shows that the daily electronic power saving per hectare paddy field in Guan-Du is about 21,400 degrees, and the power costs 58,500NTD. Two different photosynthesis models, namely, the big-leaf model and sun/shade model, are also developed to estimate the assimilation rate of carbon dioxide. According to the simulation results, it is found that the sun/shade model has better accuracy. Integrating the simulated assimilation rate with the variation of photosynthesis rates at different growth stages, the total amount of carbon dioxide assimilation during the whole growth period can be obtained. The carbon dioxide emissions from different types of vehicles and the carbon dioxide reduction goals are used to assess the assimilation effects of paddy fields. It is found that the daily carbon dioxide assimilation per hectare of Guan-Du paddy field can achieve 0.1% contribution of total carbon dioxide reduction goal in Taiwan, or 78% contribution in Bei-Tou incinerator in 2003.