The relevant measures of competition, site characteristics, and stand statistics were also coded. The advantage of this simulator was that we could be sure that no

additional constraint was being imposed on the growth equations. Output from each of the emulated simulators was checked against the respective original simulation selleck chemical model output to verify that the coding was correct. To ensure identical starting conditions, the same tree input data file was used by each of the four simulators. Site factors for Prognaus and Silva were assessed in the field or obtained from the nearest meteorological station. For BWIN and Moses, site index was calculated from the yield table of Assmann and Franz see more (1965) for spruce in Arnoldstein, from the yield table “Fichte Hochgebirge” ( Marschall, 1992) for spruce in Litschau and from the yield table “Kiefer Südtirol” ( Moling, 1993) for pine in Arnoldstein and from “Kiefer Litschau” ( Marschall, 1992) for pine in Litschau. In order not to underestimate site potential

in mixed stands, top height trees were selected independent of the species according to the recommendations of Sterba (1996). In stands where a species was present, but was not part of the top height trees, top heights were derived using equations from the Austrian National Forest Inventory that relate the top height of one species to that of another species ( Vospernik, 2000). Using each of the four simulators, we then simulated stand growth in Arnoldstein and Litschau for the length of the research plot measurements, 15 and 30 years, respectively. In Arnoldstein, a diameter threshold of 10 cm was used; in Litschau the diameter threshold Buspirone HCl was 5 cm. We used the observed removal and mortality and the observed ingrowth during the simulation on all plots to avoid any confounding of diameter increment, height increment, and

crown models with further submodels. We examined both individual tree values and stand values. For the stand values we compared observed and predicted height:diameter ratios of dominant trees (100 largest trees per hectare), and of the mean stem size (quadratic mean diameter and Loreýs mean height weighted by basal area) at the end of the simulation period. Table 6, Table 7 and Table 8 show the observed and simulated dbh, height, and height:diameter ratios of Arnoldstein and Litschau, their mean, standard deviation, and the minimum and maximum values observed and predicted by the growth simulators. Deviations of the average predicted dbh for each of the growth simulators from the observed dbh range from 0.2 to 4.