- 期刊
恆春地區三至五年生銀合歡林分地上部養分聚積與循環
Aboveground Nutrient Accumulation and Cycling of 3 to 5-Year-Old Leucaena Ecosystems in Heng-Chun, Southern Taiwan
摘要
本研究旨在探討3至5年生銀合歡林分地上部主要養分之聚積量及循環，供為銀合歡林分施肥之養分種類及其施肥量以及維護林地長期生產力之參考。以3年試驗資料分析結果顯示：（一）銀合歡3至5年生林分養分聚積量最高的部分為土壤，其次是立木地上部，枯枝落葉層和地被層植物。土壤所聚積之養分(N, P, Ca, Mg)量佔林分養分聚積量之77%～95%，僅K例外。（二）葉部聚積養分N自3年生佔立木地上部之29.5%降至5年生之14.2%，而幹部則自53.5%增加至63.5%。（三）隨幹部收獲所移除之養分量，不足以影響生育地生產力之降低，因土壤所聚積之養分量與收獲殘留於林地有機物養分之總和高於栽植前土壤所聚積之養分。（四）銀合歡經由共生固氮使林分聚積大量氮素，5年生林分所增添氮量為栽植前土壞氮素含量之34.5%，故毋需再施用氮素肥料。（五）根據年養分需要量與年再循環量，以及年再轉移量相差之不足部分需由土壤提供之養分量(kg•ha^(-1)•yr^(-1))為：第4年生：P7.29, K52.49, Ca129.89, Mg18.88；第5年生：Ca9.6, Mg13.52。
並列摘要
The purpose of this study was to investigate the nutrient accumulation and cycling rates. According to the results, the following conclusions can be drawn: 1. Soil is the largest nutrient pool in Leucaena ecosystem through age 3 to 5. Its accumulation of N, P, Ca and Mg are ranging from 77 to 95% of Leucaena ecosystem, except K which only about 40%. 2. Nitrogen percentage of aboveground tree accumulation is 29.2% in foliage at age 3 and reducing to 14.17% at age 5; and 53.5% in stern at age 3 hut to increasing 63.5% at age 5. 3. The Leucaena ecosystem accumulates large quantity of nitrogen through the process of biological fixation, and increased 34.5% over the preplanting soil. 4. Stem only harvest will remove nutrients which arc N 7.4%, P 11.7%, K 27.5%, Ca 3.6%, and Mg 6.8% of the ecosystem at age 4; and N 10.3%, P 10.6%, K 32.4%, Ca 4.4%, and Mg 12.2% of the ecosystem at age 5. 5. Litterfall is the major aboveground transfer pathway in N, P, Ca and Mg cycle; while in K cycle, canopy leaching is the major transfer pathway through age 2 to 5. 6. Retranslocation of nutrients of annual requirement are: N 39.7%, P12.6%, and-K 10.1% at age 4; and N 53.4%, P52.1%, and K 23.6% at age 5.