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  • 1990-1994  (2)
  • 1
    ISSN: 1432-2285
    Schlagwort(e): Allometry ; Eucalyptus ; Height prediction ; Diameter prediction ; Mechanistic models
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Previous work has suggested that tree stems are structured dimensionally to resist the forces to which they are subjected by the weight of the crown and the action of wind, snow and other loads on the crown. This proposition has been used to develop allometric relationships relating diameter at breast height or height of individual trees growing in even-aged monoculture to their above-ground fresh biomass. These models have practical application as estimators of tree diameters or heights from tree biomass as extensions of mechanistically based models of forest tree growth which predict tree biomasses. The present work applied these models to Eucalyptus regnans F. Muell, E. delegatensis R. Baker, E. nitens (Deane: Maiden) Maiden and E. grandis Hill ex Maiden trees, growing in plantation or regrowth stands, aged between 1.5 and 20 years, at eight geographically diverse sites extending from temperate to sub-tropical regions of Australia. While the models held for the various species at the various sites, their parameter values differed significantly between sites and/or species. This suggested there may be some inadequacy in the models. However, the differences were small and it was found reasonable to fit single models across all species and sites for practical use in estimating diameter or height. The errors about predicted values of height and diameter from these models were quantified. The models were also found to estimate diameter or height with little loss of precision when dry biomass was used in place of fresh biomass.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    ISSN: 1573-5095
    Schlagwort(e): atrazine ; establishment ; eucalypt plantations ; nitrogen-fertiliser ; phosphorusfertiliser ; triazine herbicides ; weed control
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract A factorial experiment was established in a plantation of Eucalyptus nitens in southern Tasmania on a site which had formerly carried native eucalypt forest. Before planting, the site had been cleared of weeds with foliar translocated and pre-emergence herbicides. The first factor of the experiment examined the effects on tree growth of no post-planting weed control, control by hand or with three levels of application of granulated atrazine, 0.9, 1.8 and 8 kg ha−1. The second factor examined the effects of no fertiliser application or the application of nitrogen as urea at 200 kg ha−1 N plus triple superphosphate at 120 kg ha−1 P. Tree growth responses to treatments were examined at 11, 16, 23 and 29 months of age. Fertiliser application increased tree height and diameter growth. Application of atrazine generally reduced height and diameter growth, but this was statistically significant only at the highest rate of application. Growth reduction occurred even though atrazine reduced post-planting weed cover on the site and hence potential competition with the tree crop for site resources. Hand weeding reduced the weed crop on the site even more than atrazine, but this did not increase growth of the tree crop. Given satisfactory establishment practices which include the use of herbicides pre-planting, it was concluded that post-planting weed regeneration was not sufficiently vigorous to warrant post-planting weed control on these sites. The use of atrazine for post-planting weed control could even be deleterious to eucalypts.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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