Thesis (M.S.)--Oregon State University, 1961. / Typescript. Includes bibliographical references (leaves 32-35). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 1989. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Thesis (M.A.)--Carleton University, 2004. / Includes bibliographical references (p. 134-145). Also available in electronic format on the Internet.

The procedure used to sample crown timber before harvesting in B.C. is designed to estimate net volume per ha using systematically located angle-count plots where trees are selected with probability proportional to basal area. The primary purpose of the sample is to provide information for timber valuation and stumpage appraisal. Timber value is the most important population parameter for stumpage calculation, but it is not explicitly considered in the sampling design. The objective of this study was to modify the current sampling method to increase the efficiency for estimating value using model-dependent sampling theory. Eighteen model-dependent sampling strategies were developed from six subsampling methods using three estimators. The six subsampling methods were used to select trees from angle-count plots to estimate the relationship between cruiser-called and estimated tree value. Three subsampling methods used probability-based selection of trees and three methods used purposive-based selection of trees. Ratio, average ratio, and regression estimators were used with each method. The 18 strategies were tested using Monte Carlo simulation with 2000 samples at each of nine sample sizes in three test populations. The test populations were created by grouping angle-count plot data into mutually exclusive sets reflecting different stand characteristics. The sample sizes were n = 20,40, and 60 plots with m = n, 3n, and 5n subsampled trees. Individual tree value was estimated with regression equations that used variables closely related to the value of each species. The sampling strategies were evaluated for bias, sample variance, achieved subsample size, sampling cost, confidence interval coverage, and relative advantage against the current sampling method. The model-dependent subsampling methods using purposive selection of trees were more efficient than the current sampling method considering cost and variance. The purposive-based methods were biased up to about 5%; the probability-based methods were slightly less biased. The two most efficient methods were: i) purposive selection of trees with the highest estimated values in a plot; and ii) purposive selection of trees with estimated values within a given range to give a second-stage sample balanced on the auxiliary variable. The greatest efficiency was always achieved with one sample tree per plot. The current sampling method was unbiased for estimating value but required approximately twice as many plots to estimate value to the same level of precision as net volume. / Forestry, Faculty of / Graduate

Volume and taper studies in Pinus patula and Cupressus lusitanica trees growing in Kenya forest plantations are discussed. The ultimate objective of the study was to find suitable models for estimating volumes and taper rates using two approaches for each parameter (i.e. volume and taper). These included producing volume models in the traditional way and by integrating taper models. Taper models derived from the best of the volume models were compared to the taper models produced from taper data in the traditional way to find out the efficiency of each approach. Data from the two species were used to fit a few popular volume and taper models. Trials were also made to develop new models. Of the popular volume models tested the logarithmic volume model was found to be giving very good estimates. Weighted models conditioned through the origin, by a technique proposed in the study, were also giving similar good estimates. Models weighted by current approach were, however, giving relatively poor estimates. Volume-based taper models were found to be giving biased diameter estimates along the tree profiles. However, when integrated for total volume, the volume estimates given seemed to be better than those given by the other taper models tested. Because of their bias in estimating the diameters and other points along the tree profile, volume-based taper models are not recommended for estimating volumes to any other points along the tree profiles. Other popular taper models were also giving biased diameter estimates. They lacked inflection points. When integrated for volumes, they were giving very poor estimates. Two fairly simple taper models have been proposed which have most of the characteristics needed in a taper model to give proper profile description. They have been recommended for constructing the inside volume tables and taper tables for the two species. They should also apply well in other conifers. One model describes profiles of trees with butt swell while the other describes trees with smooth stem forms. / Forestry, Faculty of / Graduate

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