溪頭柳杉老齡林生態系統碳貯存量與淨生態系生產力

Assessment of ecosystem carbon stock and net ecosystem productivity of old-aged Japanese cedar plantation in Xitou

洪志祐(Chih-Yu Hung)

指導教授 ： 鄭智馨

國立臺灣大學/生物資源暨農學院/森林環境暨資源學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.01172

摘要

在台灣，柳杉林不僅在國有人工林佔有重要地位且林份逐漸老化，因此估計生態系統碳貯存量與淨生態系統生產量成了近來重要的課題。本研究於溪頭建立一柳杉林時間序列樣區測量林木碳貯存量及生態系統碳貯存量，並且結合前人研究結果配適一林齡-林木碳量預測模式 (Mitscherlich model)。在時間序列樣區中，選取三塊不同林齡林地，利用生物計量方法測量其淨生態系統生產量。研究結果顯示林木碳貯存量介於164.92到272.36 Mg C ha-1 之間，並佔生態系統碳貯存量最大宗 (285.65 – 355.88 Mg C ha-1)。本研究預測模式的結果顯示林木碳量可能最大值為541.3 Mg C ha-1；且在本研究的林齡範圍之下，林木碳量並無達到最大值。此結果顯示柳杉老齡林仍為碳吸存且跟本研究中淨生態系統生產量的結果相符合。淨生態系統生產量的結果中，在37年生、60年生及90年生的柳杉人工林分別吸存5.61, 4.73和1.46 Mg C ha -1 y-1。 同時，本研究發現淨初級生產量隨著林齡上升而下降，且土壤肥力影響著生態系統內不同部分的淨初級生產量分配。在估算淨生態系統生產量上，異營生物呼吸量介於4.95到7.29 Mg C ha-1 y-1之間，且其單一林分內變異高。我們在溪頭柳杉老齡林的研究，可以提供碳收支及森林經營方面十分具有參考價值的結果。

關鍵字

生態系統碳貯存量 ； 淨初級生產量 ； 土壤異營生物呼吸

並列摘要

Ecosystem carbon stock and net ecosystem production (NEP) are two crucial factors in understanding ecological functions of a forest ecosystem. In Taiwan, Japanese cedar (Cryptomeria japonica D. Don) plantations are one of the important plantations. However, their carbon stock and NEP are not well known, especially when the plantations are becoming older and exceeding their normal rotation period. In this study, we measured live tree carbon stock and ecosystem carbon stock in stands selected along an age gradient from 37 to 90 years of age in Xitou, central Taiwan. We incorporated previous published data with our data to develop an age-sequence model by using the Mitscherlich model. We also determined the NEP in three stands with different ages by using biometric based method. The results show that live tree and ecosystem carbon stock ranged from 164.92 to 272.36 Mg C ha-1 and 285.65 to 355.88 Mg C ha-1, respectively, and live tree carbon stock was the largest carbon pool of ecosystem. The Mitscherlich model further indicated that live tree C continually accumulated in current Japanese cedar stands and the final value of live tree carbon was predicted at 541.3 Mg C ha-1. The NEP values of three stands were in agreement with the findings of the model, showing that the Japanese cedar plantations were carbon sinks and sequestrated 5.61, 4.73 and 1.46 Mg C ha-1 y-1 in the 37-year-old, 60-year-old and 90-year-old plantation respectively. We found the values of NPP declined with stand age, while their allocation of net primary production (NPP) was affected by the nutrient availability of stand. Heterotrophic respiration of three stands ranged from 4.95 to 7.29 Mg C ha-1 y-1 and contributed great uncertainty in NEP estimation. The result of this study is of importance in studying carbon budget and forest management of the Japanese cedar plantation in Xitou.

並列關鍵字

Ecosystem carbon stock ； Net primary production ； Soil heterotrophic respiration

參考文獻

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