MYCOSOCIOLOGY IN NATIVE FORESTS OF NOTHOFAGUS AND PLANTINGS OF PINUS-RADIATA OF THE X-REGION OF CHILE - DIVERSITY AND ECOLOGICAL ROLE

We have done a mycosociological and taxonomical comparative study of t he Agaricales s. l. that fructify in Nothofagus forests and Pinus radi ata plantations from the Cordillera de la Costa, the Depresion Interme dia and the Cordillera de los Andes, X Region, Chile. In the forests o f Nothofagus the percentage of mycorrhizal species changed from 30.6 % to 52.2 % and the saprophytic one changed from 47.8 % to 69.4 %. In a ll the native forests studied, we found the following mycorrhizal spec ies: Amanita diemii, Cortinarius magellanicus, Russula fuegiana and Tr icholoma fusipes, all of them associated to different species of Notho fagus. The species of the genus Boletus and Stephanopus associated to Nothofagus dombeyi, N. obliqua and N. alpina were only found in the na tive forests of the Cordillera de la Costa, while Amanita aurantiovela ta and Russula nothofaginea associated to N. dombeyi and N. obliqua we re only found in the forests situated in the Depresion Intermedia. In Nothofagus forests of the Cordillera de los Andes we have not found an y characteristic mycorrhizal Agaricales. No species of Lactarius genus were recorded in native forests, but in those with some kind of anthr opic disturbance or situated near Pinus radiata plantations, we found the mycorrhizal species Amanita rubescens and Xerocomus rubellus assoc iated to N. obliqua. The species of the genus Mycena dominated among t he saprophytic Agaricales in all the Northofagus forests, We also dete cted the presence of the genus Armillariella, Gymnopilus, Hypholoma, P holiota, Pluteus and Psathyrella that fructify on stems and stumps. We did not find any species of pathogenic Agaricales which indicates tha t the forests are healthy. In the Pinus radiata plantations, the perce ntage of mycorrhizal species varied from 62.5% to 77.8% and it compris es species of the genus Amanita, Hebeloma, Laccaria, Lactarius, Russul a, Suillus and Xerocomus, none of them being dominant. The percentage of saprophytic species varied from 22.2 % to 37.5 %. The low percentag e of saprophytic versus mycorrhizal species indicates the poor degrada tion of the plant remains rendering an accumulation of them, an absenc e of returning of basic elements and immobilization of nutrients, sinc e the saprophytic native species belonging to Agaricales apparently ca n not do that function.