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標題: | 南仁山低地雨林凋落物分解及有效性養分之研究 Litter Decomposition and Nutrient Availability in a Lowland Rain Forest of Nanjenshan |
作者: | Chia-Hao Chang 張家豪 |
出版年 : | 2001 |
學位: | 碩士 |
摘要: | 本研究之進行地點位於墾丁國家公園南仁山保護區。前人的樣區調查發現,南仁山山頂與溪穀兩地植物社會在樹種組成上有很大的差異。凋落物分解袋(litter bag)、土壤埋藏袋(buried bag)及離子交換樹脂袋(ion exchange resin bag)這三種實驗技術分別可以監測凋落物養分釋出速率、土壤礦化作用(mineralization)速率、及土壤中養分提供速率(nutrient supply rate)這三個森林生態系中養份循環之重要步驟。目前普遍認為氮和磷是森林發育的重要限制因數,本研究即以上述方法來探討南仁山山頂與溪谷兩森林的有效性養分有何差異。 分解袋實驗中,溪穀與山頂的葉片凋落物交叉置於溪穀及山頂。結果以溪穀葉片凋落物在溪穀分解速率最快,半衰期為131天,山頂葉片凋落物在山頂的分解速率最慢,半衰期為185天。凋落物養分釋出速率與試驗地特性及凋落物特性皆有相關。容易因淋洗作用而釋出的鉀,在淋洗作用旺盛的山頂釋出速率亦較快;置於溪穀的葉片凋落物,氮釋出速率較快;溪穀葉片凋落物的鉀、鎂、磷釋出速率比山頂葉片凋落物快;葉片凋落物的鈣、鎂、磷釋出速率在其各自的生育地較快。由於山頂土壤有機質含量較高,平均土壤礦化作用速率比溪穀快。2000年1?4月的實驗中,山頂溪穀的無機氮、無機磷、鈣、鎂淋洗速率皆較其他時間的實驗為慢,應與雨量有關;山頂的土壤無機氮、無機磷、鈣、鎂提供速率皆比溪穀慢。凋落物養分年輸入量中,無機氮在山頂溪穀差異很小,都是約60kg ha-1 yr-1,其他養分差異較大,相差一?三倍。在土壤養分提供速率部分,山頂溪穀差距與凋落物養分年輸入量類似,無機氮在山頂與溪穀的差異也很小(23、26kg ha-1 yr-1)。山頂溪穀無機氮的流動速率差異不大,可能其他養分對植被限制影響比較大。 Nutrient availability was studied in a lowland rain. forest on Nanjenshan Long Term Ecological Research Site in southern Taiwan. From detailed vegetation surveys, we know that the plant communities between footslope and summit on Nanjenshan are different in species composition. By using litter-bag, buried-bag, and ion-exchange-resin-bag technique, we can determine the rates of three important steps of nutrient cycling in forest ecosystem: nutrient releasing rates of litters, soil mineralization rate, and soil nutrient supply rate. The results showed that the decomposition rates were different between leaf litters collected from footslope and summit, and it also different between litters put on footslope and summit. Their decomposition half-life ranged from 131 to 185 days. Leaf litters collected from footslope showed greater decomposition rate than from summit, and litters put on footslope had greater decomposition rate than on summit. Nutrient releasing rates were different in site characters and in litter quality. Potassium had fastest releasing rate, and it reached a low remaining percentage earlier on summit than on footslope. Nitrogen releasing rate was faster on footslope than on summit. Leaf litters collected from footslope had greater releasing rates of potassium, magnesium, and phosphorus than those collected from summit. Leaf litters collected from both sites had faster releasing rates of calcium, magnesium, and phosphorus on their own sites. Soil mineralization was faster on summit than on footslope. Nitrogen input by leaf litter per year was about 60 kg yr-1 ha-1 on both sites. But other nutrient elements had great difference between the two sites. Soil nitrogen supply rates per year had similar trend of leaf litter input, and the difference between two sites (23, 26 kg yr-1 ha-1) was small, too. The rate of nitrogen flux showed no obvious difference as other nutrient elements, so maybe nitrogen is not the limiting element in making the two plant communities different. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/75203 |
全文授權: | 未授權 |
顯示於系所單位: | 植物科學研究所 |
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