%0 Journal Article %T NON-SYMBIOTIC NITROGEN FIXATION, NET NITROGEN MINERALIZATION AND DENITRIFICATION IN EVERGREEN FORESTS OF CHILO谷 ISLAND, CHILE: A COMPARISON WITH OTHER TEMPERATE FORESTS FIJACION NO-SIMBIOTICA, MINERALIZACION NETA DEL NITROGENO Y DESNITRIFICACION EN BOSQUES SIEMPREVERDES DE CHILOE, CHILE: UNA COMPARACION CON OTROS BOSQUES TEMPLADOS %A C.A. P谷rez %A M.R. Carmona %A J.J. Armesto %J Gayana. Botanica %D 2003 %I Universidad de Concepci車n %X Temperate forests in southern Chile offer unique opportunities for studying biogeochemical cycles in the absence of industrial air pollution. Here we compare three important fluxes of the nitrogen (N) cycle in temperate forests of southern Chile, non-symbiotic N fixation, net N mineralization and denitrification, with data from northern temperate forests more affected by air pollution. We studied five evergreen, old-growth forests and one second-growth forest in Chilo谷 Island, southern Chile. Non-symbiotic N fixation in the litter layer, mineral soil and coarse woody debris was estimated by the acetylene reduction technique. In situ net-N mineralization in the upper mineral soil layer was assessed by the buried bag method. Denitrification rates of mineral soil were assessed by the acetylene inhibition essay in intact soil cores. Results show that in some southern temperate forests a greater proportion of the ecosystem N-fixation occurs in the litter layer (0.23-2.26 kg N ha-1 year-1) and coarse woody debris (1.31-1.34 kg N ha-1 year-1). In contrast, the highest N fixation rates in northern temperate forests occur in mineral soil. Rates of both N mineralization and denitrification were considerably lower in Chilo谷 forests than in northern temperate forests, which are subject to higher N deposition. These findings suggest that southern temperate forests exert a stronger biotic control on N cycling than their northern counterparts Los bosques templados de Chile ofrecen un escenario 迆nico para estudiar los ciclos biogeoqu赤micos debido a su condici車n libre de contaminaci車n industrial. Comparamos tres flujos importantes del ciclo del nitr車geno (N), tales como fijaci車n no simbi車tica, mineralizaci車n neta y desnitrificaci車n, en bosques del sur de Chile con datos de bosques templados del hemisferio norte sujetos a contaminaci車n. Estudiamos cinco bosques siempreverdes maduros y uno secundario en la Isla de Chilo谷. La fijaci車n no simbi車tica del nitr車geno en la hojarasca, el suelo mineral y desechos le osos gruesos, se estim車 mediante el m谷todo de reducci車n de acetileno. La tasa neta de mineralizaci車n del suelo superficial se estim車 con el m谷todo de la bolsa enterrada. La tasa de desnitrificaci車n se estim車 mediante el ensayo de inhibici車n con acetileno en muestras de suelo intactas. Los resultados muestran que en algunos bosques templados chilenos una mayor proporci車n de la fijaci車n no simbi車tica del N ocurre en la hojarasca (0,23-2,26 kg N ha-1 a o-1) y en los desechos le osos gruesos (1,31-1,34 kg N ha-1 a o-1). En cambio, las mayores tasas de fijaci車n de N en los %K Bosques no-contaminados %K bosques templados %K ciclo del N %K desnitrificaci車n %K fijaci車n de nitr車geno %K Denitrification %K nitrogen cycle %K nitrogen fixation %K temperate forests %K unpolluted forests %U http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-66432003000100005