The growth-interaction (GI) process is used for the spatiotemporal modeling of measurements of locations and radii at breast height made at three different time points of the individual trees in 10 Scots pine (Pinus sylvestris) plots from the Swedish National Forest Inventory. The GI process places trees at random locations in the study region and assigns sizes to the trees, which interact and grow with time. It has been used to model plots in previous studies and to improve the fit we suggest some modifications: a different location assignment strategy and a different open-growth (growth under negligible competition) function. We believe that the calibration data contain trees that are too small to reflect the open growth properly, which primarily affects the carrying capacity parameter. To better represent the open growth of Scots pines, we evaluate the open growth from a separate set of data (size and age measurements of older and larger single Scots pines). A linear relationship is found between the plot's estimated site indices and the sizes, and this is exploited in the estimation of the carrying capacity. We finally estimate the remaining GI process parameters and test the goodness of fit on simulated predictions from the fitted model.
