Groei en productie van es in Nederland

In the Netherlands growth and yield research on ash was done from 1949 to 1988. This in-cludes studies by the Dorschkamp/IBN research institute and by Wageningen University. Together with the permanent sample plots from the timber prognosis system HOSP, all this comprises a da-taset of 41 plots with 150 recordings. For the development of top height htop with age t, Cieszewski’s polymorphic model with site index h50 and three additional parameters fitted best.The diameter development up to stand height of 7 m was described with a linear function in htop and tree distance. From a stand height of 7 m and up, the basal area increment (iG) was described by Jan-sen’s et al. model based on a power function with h50, htop, t, year of recording (yor), and the stand density of Hart (S %). For S% > 16.7 the basal area increment strongly decreases non-linearly with in-creasing %. The model contains a correction factor for yor, but this was not significant, nor was htop. The effect of thinning on the diameter after thinning was modelled with a modified La Bastide-Faber model. The models were used to construct yield tables for with five site classes and one thinning in-tensity.