文山林場溪流水化學及森林水源蓄積量

Stream water chemistry and water conservation capacity of Wenshan Forest Station

本研究於國立中興大學文山林場進行溪流水文、水質及土壤基本性質之調查，並進而估算林場蓄積水源的能力。由溪流區段差異可得知環境匯集導致電導度、Na+、K+、Ca2+、Cl-和SO42-的濃度有累積的現象，然而在4月調查時發現NO3-的濃度則相反，因植物的吸收以及多次降雨事件使土壤中的NO3-被淋洗，由於流失後來不及補充使NO3-濃度被稀釋。從時間變化中可發現不同的降雨形式與土壤水源涵養會使溪流總流量在12月顯著高於4月，且Na+、K+、Mg2+、Ca2+、Cl-、NO3-和SO42-的通量也具有相同趨勢。藉由土壤粗孔隙可估算出林場單位面積森林表土可蓄積水量為143.5m3 ha-1，整個林場可以蓄積的總水量為16,920.1 m3，由此可知近年來因氣候變遷所導致的雨量分布集中，降雨天數減少的現象，森林的存在對於水資源涵養絕對具有正面效益。

This is a study of hydrology and water quality of stream and soil property, as well as estimatimation of water conservation in Wenshan forest station, the Experimental Forest District Office of National Chung Hsing University. Electrical conductivity, concentration of Na+, K+, Ca2+, Cl- and SO4 2- in different section of stream were accumulated due to ions converge from the watershed. Except for NO3 - concentration which showed a different trend in April. NO3 - was taken up by plants and leached out from soil by heavy rain resulted in diluted NO3- concentration. Rainfall and soil water conservation resulted in significantly higher streamflow in December than April, output of Na+, K+, Mg2+, Ca2+, Cl-, NO3- and SO4 2- also showed the same trend. The water conservation of the Wenshan forest station estimated based on soil coarse porosity was 143.5 m3 ha-1, and overall the forest station held 16,920.1 m3 of water. Our results indicated that forest absolutely have positive benefit on water conservation under climate change that distribution of precipitation is more concentrated and severe.