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Some dynamic site index models based on the generalized algebraic difference approach (GADA) were fitted for Crimean pine (Pinus nigra J.F. Arnold subsp. pallasiana (Lamb.) Holmboe) stands in Taşköprü, Turkey. Data were obtained from 132 dominant trees representing the wide range of site quality in the region. Nonlinear regression analysis and a second-order continuous-time autoregressive error structure were applied. After autoregressive modeling, the fitted models were evaluated both statistically and graphically. The best results were obtained with the dynamic site index model derived from the Bertalanffy–Richards base equation, accounting for about the 99% of the total variance in height–age relationships in dominant trees, with an Akaike information criterion (AIC) value of 119.55 and root mean square error (RMSE) of 0.5446. The selected base-age invariant dynamic site index curves provided the polymorphism with multiple asymptotes and other realistic height growth patterns.

This paper aims to identify the hazelnut characteristics of four different populations (Ağlı-Tunuslar, Ağlı-Müsellimler, Araç-Güzlük and Tosya-Küçüksekiler) in the North Western Black Sea Region of Turkey, one of the most important areas of economic interest for this species. There, the Turkish hazel (Corylus colurna L.) grows in its optimal conditions and reveals relatively high inter-population and intra-population variation in terms of nut characteristics. With the purpose of assessing variation, measurements were performed in four populations in Kastamonu district on 14 different nut characteristics (number of nuts per cluster, nut length (mm), nut width (mm), nut thickness (mm), shell thickness (mm), nut size (mm), nut shape, compression index, nut weight (g), kernel length (mm), kernel width (mm), kernel thickness (mm), kernel weight (g) and kernel ratio (%) of representative samples of the populations. Significant differences were found out among populations with regard to all of nut characteristics (p<0.05). The four populations have created two groups, population of Ağlı-Tunuslar and the others, according to cluster analysis. The closest populations have been Tosya-Küçüksekiler and Araç-Güzlük in terms of nut characteristics. According to the results 670

Stem taper estimations with artificial neural networks for mixed Oriental beech and Kazdaği fir stands in Karabük region, Turkey. CERNE, v. 24, n. 4, p. 439-451, 2018. HIGHLIGHTS The volume of a stem or any part of a tree can be accurately estimated depends on the stem taper estimations. The ANN models and taper equations were compared for estimating stem diameters for a mixed stand in Turkey. The ANN models were superior to taper equations for stem diameter predictions. ANN models offer some advantages to overcome the problems such as multicollinearity and autocorrelation.

Small trees and saplings are important for forest management, carbon stock estimation, ecological modeling, and fire management planning. Turkish pine (Pinus brutia Ten.) is a common coniferous species and comprises 25.1% of total forest area of Turkey. Turkish pine is also important due to its flammable fuel characteristics. In this study, compatible above-ground biomass equations were developed to predict needle, branch, stem wood, and above-ground total biomass, and carbon stock assessment was also described for Turkish pine which is smaller than 8 cm diameter at breast height or shorter than breast height. Compatible biomass equations are useful for biomass prediction of small diameter individuals of Turkish pine. These equations will also be helpful in determining fire behavior characteristics and calculating their carbon stock. Overall, present study will be useful for developing ecological models, forest management plans, silvicultural plans, and fire management plans.