1992, Fang and Bailey 1998, Robinson and Wykoff 2004, Sharma and Parton 2007). Height-diameter relationship models are developed using the trees measured for both height and diameter (e.g., Curtis 1967, Wang and Hann 1988, Huang et al. Therefore, dbh is conventionally measured for all trees in sample plots (permanent and temporary) established for forest resource inventories, but height is measured for only a subsample of trees selected across the range of observed diameters ( Huang et al. The dbh of a tree can be measured quickly, easily, and accurately, but measuring total tree height is relatively complex, time-consuming, and expensive. Nonlinear least-squares regression, mixed-effects modeling, boreal tree species, height-diameter equationsĪll growth-and-yield models used in forest management planning rely on accurate measures of dbh and estimates of total tree height. The magnitude and nature of the effect of stand origin, however, varied among species. These results indicated that the height-diameter relationship of plantation-grown trees differed from that of trees grown in natural stands. For all species, predicted heights at given values of dbh differed between stand origins. Heights were also predicted for different values of dbh for each species and stand origin. The test was highly significant for all species. To examine the effects of stand origin on height-diameter relationships for each species, a sum of squares reduction test was conducted. The height-diameter model presented by Sharma and Parton (2007) was fitted using a nonlinear mixed-effects method. For each species, the initial comparisons between stand origins were made by visually examining tree heights plotted against corresponding diameters. Height-diameter relationships of trees grown in two different stand origins-plantation and natural-were compared for jack pine ( Pinus banksiana Lamb.), red pine ( Pinus resinosa Ait.), black spruce ( Picea mariana B.S.P.), and white spruce ( Picea glauca Voss) in the boreal forest of Ontario, Canada. However, the height-diameter relationship depends on the growing environment and stand conditions. Traditionally, tree dbh is measured for all trees in sample plots established for forest resource inventories, and the height is estimated using height-diameter relationship models. Growth-and-yield models used in forest management planning rely on accurate measures of dbh and estimates of total tree height.
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