Comparing parameter recovery methods for diameter distribution models of oriental spruce (picea orientalis (L.) link.) and scotch pine (pinus sylvestris L.) mixed stands located trabzon and giresun forest regional directorate

Diameter distributions are important stand characteristic for describing forest stand structure and stand dynamic. The knowledge about diameter distribution has been required to forecast the range of products, which might be expected from a stand in forest management. There are several methods for predicting the diameter distribution of a stand, varying from methods which utilize theoretical distribution functions to non-parametric methods. In these methods, the studies characterizing diameter distributions with probability density functions (pdf) have provided the most successful and predictive results to model diameter distributions. In fitting the probability density functions, percentiles and moments values of diameter distributions have been used successfully to characterize distributions. The parameter recovery methods for calculating the parameters of probability density functions include the different percentiles values for distribution, e.g. 67, 31, 25, 50 or 95% values of the diameter distribution. In this study, 161 sample plots were used to compare some parameter recovery methods using different percentiles and moment values for distribution for fitting 3-paramaters Weibull in Oriental spruce and Scotch pine mixed stands located in Trabzon and Giresun Forest Regional Directorate. The parameter recovery methods were compared by based on Rennolds et al. (1988)’s error index values calculated by difference between observed and predicted diameter distributions. The comparative results have shown that the parameter recovery method using 25%, 50% and 63% values with 2.341615 mean rank has the more successful results for describe different diameter distributions than other recovery methods