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Taper and volume equations for poplar trees growing on farmland in Sweden

Hjelm, Birger

Abstract

There is growing interest in the use of poplar (Populus spp.) in Sweden. Effective management of poplar plantations would be facilitated by the availability of improved equations for predicting the taper and volume of poplar stems. In a new thesis* a developed polynomial stem taper equation and two volume equations were presented for individual poplar trees growing on former farmland in Sweden. The outputs of the polynomial taper equation were compared with those of five published equations (Kozak et al., 1969; Ormerod, 1973; Max & Burkhart, 1976; Kozak, 1988; Benbrahim & Gavaland, 2003). Statistical evaluation indicated that the variable exponent taper equation presented by Kozak (1988) performed best and can be recommended. The segmented equation presented by Max & Burkhart (1976) and the constructed polynomial equation was second ranked but are less complicated. One of the constructed volume equations is a function of the tree’s diameter at breast height (DBH) and total height (H), (second entry equation). The other equation uses DBH, H and an additional upper height diameter (third entry equation). These equations output were analyzed and compared to those of six published equations. The best overall performance was provided by the newly-constructed third entry equation and can be recommended when precise volume estimations are required. However, because of the measurements of stem diameters high above the ground, this equation is of less practical utility in traditional surveys. Instead the constructed second entry equation or equations developed by Fowler & Hussain 1987 and Opdahl 1992, can be recommended

    UKÄ Subject classification

    Forest Science
    Renewable Bioenergy Research

    Permanent link to this page (URI)

    https://res.slu.se/id/publ/36084