2002-08-012024-05-14https://scholars.lib.ntu.edu.tw/handle/123456789/656837摘要：土壤溶液化學組成的動態變化研究，對於了解森林生態系統水分及養份之輸出與輸入間的平衡關係，非常有幫助。土壤溶液的化學性質，可提供土壤中養份或元素隨空間與時間的分布情形，以及養份對於植物的移動性與有效性的重要訊息，溶液組成也有助於提供推算野外的土壤礦物風化速率、元素循環的範圍與速率及蒸發散的速率。本研究計畫選擇南仁山長期生態研究站中，南仁山西北側稜線之一公頃長形溪谷樣帶為研究區域，包括四種地形位置，即麓坡(海拔250-330公尺之間)、背坡(海拔330-450公尺之間)及頂坡(海拔450-470公尺之間)。在不同的季節、不同的地形位置及不同的土層深度依序採集分析土壤溶液的離子組成。結果顯示，在土壤溶液組成的空間分布方面，NO3--N、SO42-、K+、Ca2+、Si4+和Al3+等元素在不同地形位置間達顯著差異(p<0.05)，而鹽基陽離子於背坡處的濃度顯著高於頂坡，主要是因為養分隨雨水挾帶至背坡處短暫停留，而且背坡處植物生長密度及生質量較小，對於土壤溶液中養分的需求亦較小的原因。在土壤溶液組成的時間變異方面，在雨量較多的月份(7-9月)，土壤表層(0-20cm)的離子濃度由於受雨水稀釋效<br> Abstract: The dynamics of soil moisture content and composition of soil solution plays an important role on the nutrient and water cycling in natural forest ecosystem, especially on the nutrient balance between input and output of water and nutrient in the forest ecosystem. The soil moisture content and chemical composition of soil solutions provide to understand the important information of the spatial and temporal distribution of soil nutrients and their mobility and bioavailability for the plants and also to provide the soil mineral weathering rate, the extent and rate of elemental cycling. The study site was located at the River Valley study site of Nanjenshan long term ecological research site. The selected one ha site has three landscape positions including footslope ranging from 250 to 330m, backslope ranging from 330 to 450m, and summit ranging from 450 to 470m, respectively. The results of spatial distribution of soil solution compositions indicated that NO3—N, SO42-, K+, Ca2+, Si4+ and Al3+ were significantly different within three landscape positions (p<0.05). The concentration of basic cations of soils was highest in the backslope position. This result was attributed to the temporal accumulation of soil nutrients mixed with surface water flowing from upslope landscape position and the lower uptake because of the lower vegetation density and biomass of plants distributed in the backslope. The result of temporal variation of soil solution composition of surface soil (0-20cm) suggested that the dilution effect of rain fall was resulted in the lower concentration of soil solution in surface soil (0-20 cm) sampling from July to September during the rainy season. In contrast, the higher concentration of soil solution in surface layer sampling from October to April was resulted in the lower precipitation during the dry season.土壤水分土壤溶液組成空間分佈季節性變動水分平衡模式養分循環模式遲滯效應soil moisture contentsoil solution compositionspatial distributionseasonal changewater balance modelnutrient balance modelhysteresis effect