School of Ecosystem and Forest Sciences - Theses
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ItemThe dynamics of growth in even-aged stands of Eucalyptus obliqua (l'herit)( 1968)The genus Eucalyptus contains a large number of species suitable for the commercial production of timber, but the history of their forest management is comparatively recent, being initially founded on traditional European experience. Despite this tradition and the fact that many species have certain silvicultural properties in common distinguishing them from other timber producing genera (Jacobs, 1955), there already exists a diversity in silvicultural systems, even for the one species or species association in a single region. This diversity appears to be associated with the development history of the forest region, because there has been a general tendency to perpetuate the characteristic forest structure of a particular area at the time that planned management was commenced. This structure has varied from extensive areas of even-aged stands of a single species to intimate mixtures of species of all ages and sizes in association. The variation in forest structure appears to have developed largely from a diversity in the history of settlement and early exploitation. Fire history, access history, intensity and frequency of past utilization have all played a prominent role in forming the characteristic forest structure of a particular area. Regardless of whether growing in regular or irregular forests, the determination of tree and stand age for the majority of eucalypts is extremely difficult or even impossible. The identification of annual rings is reasonably reliable only for those species growing in subalpine and alpine climatic zones of Australia. Therefore, in the absence of adequate compartment and stand history records, management planning in the eucalypts must be based on methods which do not require precise knowledge of tree and stand age. While age is not normally required for the management of irregular forests, it has been fundamental to the planned management of even-aged forests. The ability to distinguish sites of differing productive capacities is an important aid in forest management. The most popular method of site classification is the site index, which gives stand height at a particular reference age. If age is unknown this method cannot be used and alternative methods of site quality determination have not yet been developed for the eucalypts. (From Introduction)