Abstract

Water and nutrient fluxes were studied during a 12-month period in an alerce (Fitzroya cupressoides) forest, located in a remote site at the Cordillera de la Costa (40°05?S) in southern Chile. Measurements of precipitation, throughfall, stemflow, effective precipitation, soil infiltration and stream flow were carried out in an experimental, small watershed. Simultaneously, monthly water samples were collected to determine the concentrations and transport of organic-N, NO 3-N, total-P, K +, Ca 2+, Na + and Mg 2+ in all levels of forest. Concentration of organic-N, NO 3-N, total-P and K + showed a clear pattern of enrichment in the throughfall, stemflow, effective precipitation and soil infiltration. For Ca 2+ and Mg 2+, enrichment was observed in the effective precipitation, soil infiltration and stream flow. Annual transport of K +, Na +, Ca 2+ and Mg 2+ showed that the amounts exported from the forest via stream flow (K + 0.95, Na + = 32.44, Ca 2+ = 8.76 and Mg 2+ = 7.16 kg ha -1 yr -1) are less than the inputs via precipitation (K + = 6.39, Na + = 40.99, Ca 2+ = 15.13 and Mg 2+ = 7.61 kg ha -1 yr -1). The amounts of organic-N and NO 3-N exported via stream flow (organic-N = 1.04 and No 3-N = 3.06 kg ha -1 yr -1) were relatively small; however, they represented greater amounts than the inputs via precipitation (organic-N = 0.74 and NO 3-N = 0.97 kg ha -1 yr -1), because of the great contribution of this element in the superficial soil horizon, where the processes of decomposition of organic material, mineralization and immobilization of the nutrients occurs. Water and nutrient fluxes were studied during a 12-month period in an alerce (Fitzroya cupressoides) forest, located in a remote site at the Cordillera de la Costa (40°05?S) in southern Chile. Measurements of precipitation, throughfall, stemflow, effective precipitation, soil infiltration and stream flow were carried out in an experimental, small watershed. Simultaneously, monthly water samples were collected to determine the concentrations and transport of organic-N, NO 3-N, total-P, K +, Ca 2+, Na + and Mg 2+ in all levels of forest Concentration of organic-N, NO 3-N, total-P and K + showed a clear pattern of enrichment in the throughfall, stemflow, effective precipitation and soil infiltration. For Ca 2+ and Mg 2+, enrichment was observed in the effective precipitation, soil infiltration and stream flow. Annual transport of K +, Na +, Ca 2+ and Mg 2+ showed that the amounts exported from the forest via stream flow (K + = 0.95, Na + = 32.44, Ca 2+ = 8.76 and Mg 2+ = 7.16 kg ha -1 yr -1) are less than the inputs via precipitation (K + = 6.39, Na + = 40.99, Ca 2+ = 15.13 and Mg 2+ = 7.61 kg ha -1 yr -1). The amounts of organic-N and NO 3-N exported via stream flow (organic-N = 1.04 and No 3-N = 3.06 kg ha -1 yr -1) were relatively small; however, they represented greater amounts than the inputs via precipitation (organic-N = 0.74 and NO 3-N = 0.97 kg ha -1 yr -1), because of the great contribution of this element in the superficial soil horizon, where the processes of decomposition of organic material, mineralization and immobilization of the nutrients occurs.