Araucaria araucana — Die ökologische Strategie einer Reliktkonifere: The ecological strategy of Araucaria araucana

Abstract

Summary The reproduction and dispersal strategy of the relict conifer Araucaria araucana (M ol .) K och in the Villarrica National Park in Southern Chile is discussed. Mapping based on aerial photographs shows the distribution of the species and of the plant communities in which Araucaria grows. The reproduction of the tree in different forest types is investigated by analysing each vegetation stratus separately. To describe the distributional pattern of young Araucaria and to determine deviation from a random distribution, M orisita ’s index was computed for two different stands. With a χ 2 test the influence of competing species on the reproduction of Araucaria was analysed. It is shown that most of the seedlings grow directly under female adult trees. Nevertheless, only those seedlings which grow under canopy gaps or in exposed areas have a good chance to develop. The young conifers are unable to compete with Chusquea culeou , Nothofagus dombeyi and vital Nothofagus pumilio . Thus most of the Araucaria stands in the park area are forest types with low interspecific competition. Due to its thick fire protecting bark, adult Araucaria araucana is better adapted to allogenic disturbances by volcanic activities and fire than the competing species. Araucaria can achieve advantages if it survives the disturbance and/or colonizes devastated areas shortly after stand destruction. As the intensity of disturbance can be too high for even the most resistant araucarias the species needs an effective strategy for long distance seed dispersal. The parakeet species Enicognathus ferrugineus seems to serve as dispersal agent. Due to the adaptation of Araucaria seedlings to the climatic conditions of open stands their survival rate is high in canopy gaps, devastated areas or above timberline. Thus the phylogenetical ancient species Araucaria araucana is low competitive in undisturbed Nothofagus stands but well adapted to survive abiotical harsh conditions by its strategies of reproduction, resistance and dispersal.