earticle

영어

Hybrid aspen is a hybrid between Populus tremula L. × P. tremuloides Michx. and is known as a prospective broadleaved species in northern Europe. The usage for pulpwood and bioenergy is expected with vigorous growth characteristics, but the studies on growth and yield modelling based on empirical data are still insufficient. This research aimed to present the main modelling results regarding diameter and height and to provide an extended idea for model application in practice. The materials applied for modelling were collected from the experimental sites located in southern Finland. The selected clones of hybrid aspen were planted on the sites, and at the same time, plots were established during 1997–1999 with proper site preparation and fencing by experiment. The plots were measured repeatedly at 1–3 years interval with 7–12 times in total by experiment. As a result, the diameter distribution and tree height-dbh allometry were figured out over time and appropriate modelling methods were applied using 2-parameter Weibull function and Näslund’s model, respectively. In the Weibull distribution with parameter recovery method, the basal area-weighted mean diameter (DG) with the number of trees per ha (TPH) and stand basal area (BA) presented the best fit compared to other type of stand diameter statistics. The Näslund’s nonlinear mixed-effects model was fitted for tree height estimation with driving variables of age, BA, DG, and basal area-weighted mean height (HG) in addition to tree dbh. Furthermore, it was feasible to simulate these models in combination with the predicted stand characteristics such as BA, DG, and HG based on stand age, site index, and TPH. This will enable one to simulate the growth and yield of hybrid aspen plantations for stand management. Overall, our models were considered to be practical and applicable on a basis of monitoring data of field trials.