Thesis (M. Phil.)--University of Hong Kong, 2000. / 3 folded maps in pocket. Includes bibliographical references (leaves 198-212).

Thesis (M.Phil.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 198-212) Also available in print.

Thesis (Ph. D.)--Universität Göttingen, 2008. / Title from PDF t.p. (viewed July 29, 2010). Includes bibliographical references.

Newspaper article: "A good tree is worth saving”

Newspaper article: "SA tree 250 years old”

A mathematical model has been developed to describe the growth of trees in stands of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) from age ten to age 100 years. An initial square pattern of spacing was assumed. At age ten years the trees were assumed to be open-grown, that is, growing in diameter at breast height at a maximum rate. A regression of d.b.h. on age was obtained from eighteen open-grown, Douglas fir trees measured on the Saanich Peninsula, Vancouver Island. The relationship derived from these data agreed with further data collected elsewhere in the coastal regions of British Columbia and Washington and in the interior of British Columbia. The d.b.h. growth of individual trees was predicted by five-year periods. Relationships between crown width and d.b.h. were calculated from data on 426 open-grown, Douglas fir trees. There was a close correlation between crown width and root spread for open-grown trees. A multiple regression equation was obtained for height of 869 trees on d.b.h. and basal area per acre. All regression equations calculated for use in the model, were highly significant statistically. The model is initiated with a matrix of 15 x 15 trees (or tree "locations”). The initial d.b.h. of each tree is specified and, from the crown width/d.b.h. regressions, the crown width of each tree is calculated. As long as the tree remains free of competition, this calculated crown width is reduced by 40 per cent by the reduction factor "REDFAC", to give the "competitive" crown width. This was because it was found that, in young Douglas fir plantations, there could be considerable overlapping of the crowns before d.b.h. growth was reduced. As soon as competition sets in the original 40 per cent reduction is systematically reduced. The proportion of the circumference of each tree that is occupied by the crowns of surrounding competitors is then calculated. This proportion indicates the amount of competition to which the tree is being subjected and varies between zero, if the tree is open-grown, and one or more, if the tree is completely enclosed by the surrounding competitors. If the reduction is sufficiently great, continued survival of the tree is considered unlikely, and the tree is assumed to have died. The periodic d.b.h. growth of the surviving trees is calculated at five-year intervals to age 100 years. All calculations are performed using am I.B.M. 7090 electronic computer. A summary of the structure of the stand can be printed out at the end of each five-year period if required. Height growth can be described by modifying the stand model by including an appropriate regression equation. Similarly, volume growth can be estimated by modifying the basic stand model. The mathematical model developed here satisfactorily describes the growth of Douglas fir stands on an individual tree basis, over a wide range of site conditions, stand densities, amounts and distributions of mortality and thinning regimes. Field data cannot be secured to evaluate the accuracy of all the tests made. However, there are no gross errors in absolute values and results are accurate proportionately. The model described here can aid the forester in managing Douglas fir stands in the Pacific Northwest. By simulating the growth of his stands from age ten to age 100 years in a few minutes he can study questions that would otherwise require several human generations to evaluate. / Forestry, Faculty of / Graduate

The distribution of the above-ground biomass and macronutrient content of the trees were studied on two sample plots in south coastal British Columbia, near Vancouver. The plots differed in elevation (4,600 and 2,200 feet; 1,500 and 700 m), in soil type and depth. Tree age was similar in both plots, ranging from 150 to 530 years. The tree cover on the high elevation plot consisted of Tsuga mertensiana (Bong.) Carr. (mountain hemlock) and Abies amabilis (Dougl.) Forbes (Pacific silver fir) while the lower elevation plot was occupied by Tsuga heterophylla (Raf.) Sarg. (western hemlock), Thuja plicata D. Don (western red cedar) and Chamaecy- paris nootkatensis (D. Don) Spach (yellow cedar). Twenty-four trees were sampled to determine the biomass and nutrient content of wood, bark, branches, twigs, foliage and cones. Another nine trees were sampled for the biomass and nutrient content of wood and bark only. Multiple regression analysis was used to establish the relationship between d.b.h., tree length, crown length and biomass of the various tree components. The regression equations obtained were used to estimate the total biomass of wood, bark, branches, twigs and foliage contained in the trees on each of the sample plots. The data thus obtained were combined with data on chemical concentration and used to estimate the distribution of macronutrient elements in different above-ground biomass components of the stands. / Forestry, Faculty of / Graduate

Three studies were conducted with Fraser fir Christmas trees to determine the variation in foliar nitrogen (N) , phosphorus (P) , potassium (K), calcium (Ca), and magnesium (Mg) levels among plantation ages, sample locations within the crown, and effects due to seasonal changes. Extensive variation in nutrient concentrations existed with age of tissue collected, sample location with respect to aspect and vertical position, and normal seasonal fluctuation. Tree to tree nutrient variation indicated that greater sampling intensities are required for younger (under four years) plantations as opposed to older (over four years) plantations to achieve comparable confidence and precision levels. The data clearly illustrated that comparisons of foliar nutrient levels without regard to these sampling variables could cause erroneous diagnoses. Recommended foliar sampling practices involved sampling current-year's tissue from 2- or 3-year-old south-facing branches in October or November for routine foliar diagnoses. Another study developed a DRIS application to evaluate N, P, K, Ca, and Mg nutrition on seventy-nine trees in a 3-year-old Fraser fir Christmas tree plantation. DRIS norms and index equations from premium grade Christmas tree were developed. In contrast to most crops where growth and yield are assessed, Fraser fir Christmas tree performance was evaluated by conventional grading procedures based on tree quality. A classification model utilizing several measured growth characteristics to predict Christmas tree grade was also investigated to objectively evaluate tree performance. Satisfactory grade-prediction results using a discriminant model were obtained yielding overall correct classification rates of 80 percent. Preliminary evaluation of DRIS performance suggested that assessments of nutritional balance, rather than examination of individual nutrient concentrations, may be more useful for prescribing fertilizer to improve Christmas tree quality. / M.S.

Call number: LD2668 .T4 1951 L37 / Master of Science

No description available.