- 期刊
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福山闊葉林生態系的土壤養分庫及其有效養分動態
Soil Nutrient Pool and Available Nutrient Dynamics in the Fushan Mixed Hardwood Forest Ecosystem
摘要
本研究的目的是在估算福山森林生態系的土壤養分儲存庫，並監測其有效養分季節變動。在福山森林試驗集水區內研究養分流動路徑的樣區及附近範圍，設置5個取樣區，每2個月取0~15、15~30、30~60公分深的土壤樣本，分析有效P、N、K、Ca、Mg的含量。在第一次取樣時，同時推估土壤養分庫的總量及其組成分。 目前結果顯示此福山森林生態系土壤養分主要集中在0~30cm的土層。0~60cm土層的N、P、K、Ca、Mg的總量分別為6,946kg/ha、l,769kg/ha、73,840kg/ha、803kg/ha及13,650kg/ha。P及Ca的總量很低，但是P的有效量低(0.81kg/ha)，而Ca的有效量卻頗高(42.7kg/ha)，不利於Ca土壤的留存。Ca、Mg留存在土壤的機制主要為土壤膠體周圍的吸附，但K除此之外，尚有膠體內層或夾層的吸附。以有效態含量估算，福山森林生態系的N仍大部份存在於土壤，而P、K、Ca、Mg則在地上部佔有極大的比例。但是以全量估算，則除Ca以外，其他測定的養分之土壤養分庫幾乎佔全森林生態系的98%以上。因此，枯落物的分解及土壤礦質化的速率是影響福山森林植群生長的重要因素。在土壤中NO3(上標 -)-N平均為5~15mg/kg，大約為NH4(上標 +)-N的兩倍。NH4(上標 +)-N的季節性變動不大，但NO3(上標 -)-N在春至秋末間比冬季高出1/2~1倍；其他有效養分的季節性變動很少。
並列摘要
The purpose of this study is to estimate the soil nutrient pool and to monitor the seasonal dynamics of major nutrients in the Fushan hardwood forest ecosystem. Five sampling areas were established in and around a plot of a nutrient pathway study in a gauged watershed at Fushan. Every 2 months, soil samples were taken from depths of 0-15cm, 15-30cm, and 30-60cm, and available N, P, K, Ca, and Mg were determined. In the 1st samples, the soil nutrient pool and its composition were estimated. The results indicate that the major nutrient pool in the soil of the Fushan forest ecosystem was in the 0-30cm depth. Total amount of N, P, K, Ca, and Mg of the 0-60cm soil depth were 6,946, 1,769, 73,840, 803, and 13,650kg/ha, respectively. Total P and Ca were low. Available P (0.81kg/ha) was also low, but available Ca (42.6kg/ha) was high which was not advantageous for its retention. In the soil, Ca and Mg were retained mainly by edge adsorption, but K was retained not only at the edge but also among the interlayed spaces of soil colloids. Eased on the estimation of the available nutrient forms, the soil was the major N pool, but the vegetation contained the major portions of the available P, K, Ca, and Mg pools in the Fushan ecosystem. On the contrary, except for Ca, the soil was composed of greater than 98% of the total nutrient amount by the total nutrient estimation. Thus, the rate of litter decomposition and soil mineralization would be the most important factors in determining the productivity of the Fushan mixed hardwood forest ecosystem. On an annual basis, NO3(superscript -)-N averaged 5-15mg/kg, which was about 2 times higher than NH4(superscript +)-N. Soil NH4(superscript +)-N concentrations did not fluctuate much seasonally, but soil NO3(superscript -)-N concentrations from spring to late fall were 1/2 to 1 times higher than those in winter.