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Growth models for natural stands of Calabrian pine in the central Mediterranean region of Türkiye
Modeli rasta prirodnih sastojina kalabrijskog bora u središnjem mediteranskom području Turske
Aydn Kahriman, Abdurrahman Şahin, Turan Sönmez, Mehmet Yavuz
Aydn KAHRIMANa* https://orcid.org/0000-0001-9696-1153, Abdurrahman ŞAHINa https://orcid.org/0000-0002-9435-9844, Turan SÖNMEZb https://orcid.org/0000-0001-7041-1479, Mehmet YAVUZa https://orcid.org/0000-0002-1481-2849
Stand growth models are needed for a variety of forestry practices, primarily management plans and silvicultural studies. The goal of this study was to create stand-level models for natural, pure even-aged stands of Calabrian pine in the central Mediterranean region of Turkey. The study area consists of pure and natural Calabrian pine stands located within the boundaries of the Antalya and Mersin Regional Forestry Directorates in the central Mediterranean region of Turkey. Data was collected from 486 temporary plots scattered throughout the region. Two trees (the dominant tree and the tree representing the quadratic mean diameter of the stand) were measured in each plot, yielding 972 trees. The data showed that the age varied from 6 to 135 years, the site index (SI) from 8.5 to 33.5 m, and the density from 0.3 to 12.4. The density-dependent yield tables were generated using regression equations based on stand age, SI, and stand density with individual, two-factor, and three-factor interaction effects. For SI classes I, II, and III, the optimal rotation period that would result in the highest yields for pure Calabrian pine stands is 60, 65, and 75 years, respectively. The stand growth models developed (i.e., density-dependent yield tables) agreed with the fundamental growth principles and data provided in the literature.
Key words: stand models, density-dependent yield table, Calabrian pine, density, Generalized Algebraic Difference Approach (GADA)
Growth models are classified into three categories based on the unit of analysis: whole stand models, size class models, and individual tree models (Vanclay, 1994). The number of trees, basal area, volume, mean diameter, and mean height of a stand can be predicted using whole stand models. The stand characteristics determined by whole stand models are averages and these models do not make predictions at the individual tree level (Vanclay, 1994; Weiskittel et al., 2011; Özçelik and Altınkaya 2019). Yield tables are a tabular representation of whole stand models and generally provide straight forward and accurate predictions. Yield tables are auxiliary tables that are used to calculate growth estimates.
The initial yield experiments in growth models, which have a 250-year history, were carried out in even-aged, pure stands. According to Schwappach, Réaumer proposed the nascent ideas for generated yield tables in the first quarter of