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平地長期林地之土壤性質與有機碳量蓄積

Soil Properties and Organic Carbon Sequestration in the Long-Term Afforested Stands of Plain Areas

摘要


平地造林是目前積極推動的政策之一,不過,我們對平地經長期造林後的土壤性質與土壤有機碳的蓄積所知仍甚少,也無實際的例子可證明。本研究藉由調查長期果園廢耕地與造林地,以實際林地資料協助評估平地長期林地可能的土壤性質與碳蓄積量,同時並比較鄰近長期耕作農地土壤,利用土壤有機物粒徑分離及粘土礦物鑑定等分析方式,探討林地土壤有機碳量的蓄積機制及其相較於農地土壤的增加碳量。研究結果顯示長期林地與鄰近農地土壤性質間呈現顯著性差異,林地土壤一般有較低的土壤pH值與總體密度,較高的有機碳(氮)濃度、單位面積碳(氮)儲存量與碳氮比。不過,個別農地的管理與施肥,特別是水稻田土壤本身的較低土壤總體密度與較高有機碳(氮)濃度與碳氮比,則會改變這樣的趨勢;農地的肥料施用,也會造成個別樣區土壤交換性鹽基、陽離子交換容量與有效性磷含量的改變。若以調查樣區為基準,長期林地表層0-20cm土壤平均可較鄰近農地增加7.8 ton C ha^(-1)土壤有機碳儲存量,但增加儲存碳量以活性大的土壤有機碳為主,僅有部分林地土壤有機碳可轉變至穩定且活性低的惰性土壤有機碳。林地土壤平均每年約可增加土壤有機碳量為0.34 ton C ha^(-1)y^(-1),這樣的結果相當接近全球農地轉作林地的年平均增加土壤有機碳量(0.3 ton ha^(-1)y^(-1))。在現有平地造林政策下,二萬五千公頃的平地造林面積預期將可增加1.9×10^5噸土壤有機碳量。

並列摘要


Afforestation in the marginal cultivated lands of plain areas is positively implemented in Taiwan. However, the information of long-term afforestation effects on soil properties and soil organic carbon (C) sequestration is still scarce, and no field data exists. In this study, the long-term abandoned orchards and afforested sites were examined as the proxies to assess the long-term afforestation effects on soil properties and soil organic C sequestration. Soil organic C size fractionation and clay mineral identification were also conducted to elucidate the mechanisms of soil organic C sequestration. Our results showed that afforestation could result in lower pH and bulk density and higher soil organic C and nitrogen content and storages compared to the adjacent cultivated stands. However, this general trend can be deflected by the specific management of the individual cultivated stand. For example, afforestation on the paddy rice soil could have opposite results due to the lower bulk density and higher C and N content and storages in the paddy rice soil. Fertilization in the adjacent cultivated stands may also increase exchangeable cations, cation exchange capacity and available phosphorus and abate the effect of afforestation. Average soil organic C storages at 0-20 cm depth in the afforested stands was 7.8 ton C ha^(-1) higher than that in the cultivated stands, while most of these sequestrated C storages belonged to the labile C pools and only a few amount of sequestrated C storages can be stored in the recalcitrant C pools. Annual soil organic C accumulation was 0.34 ton C ha^(-1) y^(-1), which was close to the mean value of global afforestation (0.3 ton C ha^(-1) y^(-1)). We estimate that present afforestation policy over 25,000 ha afforested areas can then sequestrate 1.9 × 10^5 ton C in soils.

被引用紀錄


蔡佩蓉(2017)。長期施用不同有機質肥料對設施內蕹菜連作障礙機制研究〔碩士論文,國立臺灣大學〕。華藝線上圖書館。https://doi.org/10.6342%2fNTU201703270
曾寒莓(2017)。氮鉀肥不同施用量對萬能薯生長及機能性成分含量之影響〔碩士論文,國立臺灣大學〕。華藝線上圖書館。https://doi.org/10.6342%2fNTU201702911
林苡涵(2017)。臺灣農地廢耕造林對土壤有機碳儲存量及形態劃分的影響〔碩士論文,國立臺灣大學〕。華藝線上圖書館。https://doi.org/10.6342%2fNTU201700742
張金鳳(2015)。不同旱作輪作系統對土壤化學性質、微生物活性及群落結構之影響〔碩士論文,國立臺灣大學〕。華藝線上圖書館。https://doi.org/10.6342%2fNTU.2015.00780

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