WATER AND NUTRIENT FLUXES IN A COOL TEMPERATE RAIN-FOREST AT THE CORDILLERA DE LA COSTA IN SOUTHERN CHILE

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 degrees 05'S) in southern Chile. Measureme nts 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, NO3-N, to tal-P, K+, Ca2+, Na+ and Mg2+ in all levels of forest Concentration of organic-N, NO3-N, total-P and K+ showed a clear pattern of enrichment in the throughfall, stemflow, effective precipitation and soil infilt ration. For Ca2+ and Mg2+, enrichment was observed in the effective pr ecipitation, soil infiltration and stream flow. Annual transport of K, Na+, Ca2+ and Mg2+ showed that the amounts exported from the forest via stream flow (K+ = 0.95, Na+ = 32.44, Ca2+ = 8.76 and Mg2+ = 7.16 k g ha(-1) yr(-1)) are less than the inputs via precipitation (Kf = 6.39 , Na+ = 40.99, Ca2+ = 15.13 and Mg2+ = 7.61 kg ha(-1) yr(-1)). The amo unts of organic-N and NO3-N exported via stream flow (organic-N = 1.04 and No-3-N = 3.06 kg ha(-1) yr(-1)) were relatively small; however, t hey represented greater amounts than the inputs via precipitation (org anic-N = 0.74 and NO3-N = 0.97 kg ha(-1) yr(-1)), because of the great contribution of this element in the superficial soil horizon, where t he processes of decomposition of organic material, mineralization and immobilization of the nutrients occurs. (C) 1998 John Wiley & Sons, Lt d.