Assessment of dimensional relations and early production in fast-growing deciduous tree species

This thesis presents results from a series of investigations on biomass estimation (BE) procedures in short rotation forestry (SRF). It also includes an evaluation of a SRF experimental trial in which new non-coppice SRF systems were studied. Time consumption and costs often strongly limit non-destructive BE procedures in various research areas. To investigate the effects of using time-saving, generalised allometric equations the allometric variation within and between some SRF species was studied. The relation between tree weight and stem diameter was found to vary between species, clones, trees of different age, stands and degrees of competition. It was concluded that under certain conditions allometric equations can be generalised at the clone or stand level (given species and tree age). When sampling, measuring personnel tend to sample around an "ocular mean". To reduce such bias, the sampling unit should be a unit of ground area (containing several individuals) rather than an individual tree. This reduces the risk for obtaining a biased sample and simplifies the estimation of plant density. Whole-tree moisture content frequently is determined in biomass studies. This procedure can be simplified by limiting the analysis to small samples taken from fixed positions along the stem. In Salix and Populus such procedures resulted in estimates of the mean moisture content which differed by up to two percentage units from values of whole-tree moisture content. A computerised system was constructed that reduces the time needed for diameter measurements and mathematical calculation. The total production of six-year-old hybrid poplar (P. trichocarpa x P. deltoides) in southern Sweden was estimated at 45 tonnes stem and branch dry matter ha-1. This probably the highest juvenile growth ever recorded in Sweden from planted, non-fertilised and non-irrigated forest stands. Other stands of Betula pendula, hybrid aspen (P. tremula x P. tremuloides), Alnus incana, Salix fragilis and Salix schwerinii, in pure species or species mixtures, produces 14-27 tonnes ha-1.