Developing forest vegetation simulator for anatolian black pine stands: a case study of caku research and application forest

This study aimed to develop a Forest Vegetation Simulator for estimating various characteristics of Anatolian Black Pine (Pinus nigra Arn. subsp. pallasiana (Lamb.) Holmboe) stands, a principal tree species with significant distribution in Turkey, within the ÇAKÜ Research and Application Forest. The simulator was implemented using Visual Basic Application (VBA) coded under MS Excel, which provides a current and widely accessible platform. The study utilized data from 61 sample plots measured in 2016 by Şenyurt et al. (2017) and adopted the modeling approach of the Forest Vegetation Simulator (FVS), which originated from the Prognosis simulator first developed in 1973 and has been widely used throughout the United States of America and certain regions of Canada. The simulator was developed based on a distance-independent individual tree diameter growth model (core model) that estimates individual tree diameter increment values. Additional sub-models were developed, including a logistic model for tree mortality, a stand density model, and models for tree diameter-height relationships. The simulator's functionality was achieved through the simultaneous integration of these sub-models. The distance-independent diameter growth model's parameters were all significant at p<0.05 level, with performance metrics of Root Mean Square Error (RMSE) = 0.8140 cm, Percent Root Mean Square Error (RMSE%) = 38.4578%, Percent Bias (Bias%) = 0.2614%, and Coefficient of Determination (R²) = 0.7044. Stand characteristics were simulated for eight different periods starting from 2016, with 10-year intervals (2026, 2036, 2046, 2056, 2066, 2076, 2086, and 2096), to predict various properties of Anatolian Black Pine stands in the study area.