Development of stem taper and stem volume equations for black pine and scots pine mixed stands in Kütahya-Türkmendağı region

In this study, stem taper and stem volume equations models were developed for natural mixed black (Pinus nigra Arnold.) and Scots pine (Pinus sylvestris L.) stands in Kütahya-Türkmendağı region. For this purpose, necessary measurements were made on 75 black pine and 75 Scots pine sample trees collected from different diameter and height classes from natural black pine-Scots pine mixed stands. The piecewise stem diameter model developed by Jiang model was used to estimate stem diameter, tree height, merchantable stem volume and total stem volume. The accuracy of the predictions was evaluated using R2, RMSE (Root Mean Squared Error) and AIC (Akaike Information Criterion). The R2 values for black pine-Scots pine tree species were greater than 98% for stem diameter estimates, 97% for tree height estimates, 98% for merchantable volume estimates and 96% for total volume estimates. RMSE values were less than 1.23 cm, 0.78 m, 0.023 m3 and 0.038 m3, respectively. As a result of the graphical evaluations, it was also seen that black pine trees growing in natural mixed stands have a more cylindrical stem form than Scots pine trees. As a result, it was seen that the Jiang model can be used successfully and reliable predictions can be made for the estimation of stem diameter, tree height, commercial volume and total stem volume for natural mixed black pine-Scots pine stands in the relevant region.