The Research of forest soil carbon and nutrients stock at different elevations in Taiwan

本研究在臺灣地區不同海拔及溫量指數共八個天然林採取表層土壤樣品，以瞭解海拔及其他環境因子對土壤養分及碳庫的影響。選取的海拔涵蓋400-3000m，溫量指數由38-208℃，氣候區由熱帶至冷溫帶，土壤樣品深度為0-20cm，並分析枝葉層及礦質土壤的有機碳、氮、主要養分濃度及基礎物化性質等。結果顯示表層土壤的有機碳濃度隨海拔的上升而增高，在櫟林帶上層森林(溫量指數約72-108℃)土壤有機碳濃度達到最高，而在更高海拔的天然林，有機碳濃度又呈下降的趨勢。不同海拔森林表層碳總量亦以櫟林帶最高。枯枝落葉層所儲存的總碳量占森林表層的比重隨氣候帶而不同，熱帶的壽卡枯枝落葉層的占表層碳庫的比重約為3.8%，在亞熱帶的比重大約在7.0-11.0%之間，海拔上升至溫帶森林其枯枝落葉層占森林表層碳庫的比重大幅增加至30%左右，而在冷溫帶森林其比重則稍為降低至26%。各主要養分部分，土壤中的可交換性陽離子在溫量指數變化上沒有明顯的趨勢，其中鉀濃度與鈉濃度在各樣區之間沒有顯著差異，鈣濃度與鎂濃度依照母岩種類的不同稍有差異。相關分析的結果顯示除了溫量指數以外，土壤pH值與氮濃度和臺灣地區森林土壤的有機碳濃度有顯著的相關，推測影響臺灣地區土壤及枝葉層碳庫存的主要因子包括海拔、土壤pH值與氮濃度。In this research I sampled from 8 forests at different elevation to examine the relationship among climate, vegetation, edaphic conditions and soil carbon stock in Taiwan. The range of elevation covered from 400m to 3000m, and equivalent climates included tropical, subtropical, warm-temperature, temperature and cold temperature. O horizon and soil were sampled to a depth of 20 cm and analyzed for bulk density, clay content, pH, organic carbon, total N, and exchangeable cation capacity. The lowest soil organic carbon concentration occurred at Shoka (390m) , which equivalent climate is tropical , were 3.3% in the upper 5 cm. Concentration of organic carbon reached a maximum (24.0% to 0-5cm depth) in the Anma mountain (2180m) and decreased both higher and lower elevations. Concentration of TN showed a similar trend to that of organic carbon. TN concentration ranged from 0.3% in the Shoka to a maximum of 1.4% in the Bilueh (2200m), with an approximate 4- fold increment. Forest floor carbon stock increased with elevation, from 35.8 ton/ha in tropical forest, 43.1-60.1 ton/ha in subtropical forest, and maximum occurred in temperature forest about 101.1 ton/ha. The ratio of O horizon/floor carbon content differed with climate zontation. The O horizon/floor ratio were about 3.8% in tropic, 7.0-11.0 in subtropics, and increased substantially to about 30% in temperature forest, then decrease slightly in cold-temperature forest to 26%. Soil pH decreased with the elevation and differ about 2 units. Clay content decreased with increasing elevation. Altitudinal trend in CEC were not significant. Exchangeable cation composition followed the trend Ca>Mg>K>>Na at all sites. Concentration of K and Na were not significant different between all sites using Duncan’s test, but concentration of Ca and Mg showed a weak pattern between different parent materials. Base saturation was significant correlated with soil pH. Nutrients of O horizon were mainly governed by parent material and vegetation type, and had no significant relationship with elevation excluding phosphorous. The forest floor carbon stock in Taiwan could be predicted by warmth index (annual mean temperature), soil pH and concentration of soil C and N.中文摘要 I Abstract II 第一章 前言及研究目的 1 第二章 前人研究 3 一、土壤碳庫的定義 3 二、土壤中的養分與有機碳的關係 4 三、土壤物理性質與有機碳的關係 5 四、森林土壤碳庫存的空間分佈變化 6 五、枯枝落葉層的影響 8 六、台灣相關研究 9 第三章 材料與方法 10 一、研究地點概述 10 二、實驗地環境資料 13 三、樣品之採集與處理 16 四、化學分析 16 （一）枯枝落葉層 16 （二）土壤 17 五、統計分析 20 第四章 結果 22 一、土壤基礎物化性質 22 1.枝葉層生物量與土壤容積密度 22 2.土壤pH值 25 二、枯枝落葉層及土壤的碳濃度變化 28 三、枯枝落葉層及礦質土壤的碳總量變化 31 四、枯枝落葉層及土壤的氮濃度變化 35 五、枯枝落葉層及土壤的氮總量變化 38 六、枯枝落葉層及土壤的碳氮比 40 七、各主要養分差異 42 九、相關性分析 54 第五章 討論 57 一、土壤基礎物化性質的變化 57 二、森林表層碳濃度及總量的變化 59 三、森林表層養分變化 64 結論 66 參考文獻 68 附表 80 附圖 9