台灣平地造林之碳吸存潛能：以長期果園廢耕地與造林地為例

Carbon Sequestration Potential of Afforestation in the Plain Areas in Taiwan: Examples from Long-Term Abandoned Orchards and Afforested Sites

林映儒(Ying-Ru Lin) ； 鄭智馨(Chih-Hsin Cheng) ； 曾聰堯(Tsung-Yao Tseng)

《中華林學季刊》 44卷4期 (2011/12) Pp. 567-588

https://doi.org/10.30064/QJCF.201112.0007

摘要

隨著全球暖化問題的日益惡化，如何減緩溫室氣體效應的負面危害，成了現今最重要的環境議題。其中，對農地或劣化土地的造林，是減緩溫室氣體效應危害有效且經濟可行的方法之一。台灣自2002年開始積極推動「平地景觀造林及綠美化方案」，此方案預計增加平地造林面積25,100公頃，並期望能夠達到六萬公頃。不過，對平地造林的碳蓄積潛能以及相關蓄積碳量分布，目前仍缺乏直接證據可用以評估。本研究藉由調查面積0.5公頃以上長期果園廢耕地與造林地的碳儲存量，以實際田間林地資料為例子，協助對平地造林可能碳量變化的預估。結果顯示長期林地生態系統碳含量，介於125.2-211.5 ton C ha^(-1)間，且相較鄰近農地，除了水稻田鄰近樣區由於土壤有機碳量的減少，使得林地生態系統碳量沒有明顯較鄰近農地增加外，其它非水稻田鄰近樣區之林地生態系統碳含量均明顯高於鄰近農地。非水稻田鄰近樣區的平均增加碳量為139.1 ton C ha^(-1)，以林木增加碳量為主，約佔生態系統增加碳量的78.9%，土壤有機碳量與死有機物質的增加碳量，分別佔生態系統增加碳量的11.4%與9.4%。就五個調查樣區平均而言，林地生態系統碳儲存量可較鄰近農地增加111.8 ton C ha^(-1)。假設此數值為平地造林的平均碳吸存潛能，那麼在六萬公頃造林願景下，預計將可增加6.7x10^6 ton的蓄積碳量，或是相當於24.6x10^6 ton的二氧化碳吸收量，即6萬公頃的造林將可抵銷7年全台農業、林業與漁業部門經化石燃料燃燒所釋放的二氧化碳量。

關鍵字

造林 ； 碳吸存潛能 ； 生態系統碳含量 ； 林木碳量 ； 死有機物質 ； 土壤有機碳

並列摘要

Global warming mitigation is an important global issue nowadays. Afforestation in the marginal crop lands has been proposed to be one of the economical and effective means to mitigate global warming. In Taiwan, afforestation policy in the marginal crop lands of plain areas is positively implemented since 2002 and plans to afforest 25,100 hectares or even expects to reach the afforested areas to 60,000 hectares. However, information on possible carbon storage potential of afforestation in the plain areas is still scarce, especially no field data existed. In this study, the long-term abandoned orchards and afforested sites with stand areas larger than 0.5 ha were examined as the proxies to help the assessments of carbon storage potential and relative carbon pools distribution of afforestation policy. Our results showed that the ecosystem carbon storages in the studied stands were between 121 and 232 ton C ha^(-1) and were found to have significantly higher carbon storages than these in the adjacent cultivated stands, except for one stand adjoined with paddy rice where its soil organic carbon was significantly depleted through afforestation. Carbon sequestered potential for non paddy rice adjoined stands was 139.1 ton C ha^(-1) and most sequestered carbon came from the accumulation of living tree biomass (78.9%), and the increases in soil organic carbon and dead organic carbon (woody debris and forest litter) accounted for the remaining 11.4 and 9.4%, respectively. The mean carbon sequestration potential over all studied stands was 111.8 ton C ha^(-1). If this value was assumed to be the average amount for carbon sequestration of afforestation in the plain areas, a total of 6.7x106 ton carbon or equal to 24.6x106 ton carbon dioxide would then be stored via afforestation. This implies that 60,000 ha afforested areas may compensate 7 years' carbon dioxide emission from fossil fuel combustion of agriculture, forestry, and fishery sector.

並列關鍵字

Afforestation ； Carbon sequestration potential Ecosystem carbon stocks ； Biomass carbon ； Dead organic matter ； Soil organic carbon