Site index conversion equations for mixed stands of scots pine (Pinus sylvestris L.) and oriental beech (Fagus orientalis Lipsky) in the Black Sea Region, Turkey

The site index conversion equations are important for estimating the site index of one tree species from the site index of another tree species in mixed stands. In this study, data were obtained from 162 sample plots in mixed stands of Scots pine (Pinus sylvestris L.) and Oriental beech (Fagus orientalis Lipsky) from the Black Sea Region in the north of Turkey. The breast height ages and height of the site trees were measured and the site index was estimated by these data. Geometric linear regression was used to estimate the parameters of a linear model relating to site indices of Scots pine and Oriental beech species. The correlation between the site indices of Scots pine and Oriental beech was 0.818, indicating a good fit to the linear model. Validation procedure showed that conversion equations were suitable for the studied mixed stands. The conversion equations can be applied to mixed species stands with inconsistent stratification or in stand conversion situations for an accurate and reliable evaluation of forest quality

Determination of stand structure in even-aged Oriental Beech Forests in Turkey

The data for this study were obtained from Altun et al. (2012) project. The authors thank all who provided data. This work was supported by the TUBITAK - TOVAG (The Scientific and Technological Research Council of Turkey - Research Committee of Agriculture, Forestry and Veterinary), Project Number: 107O752.This study aimed at developing a stand yield model for even-aged and pure Oriental beech (Fagus orientalis) stands in Sinop Province, located in the north of Turkey. The data used in this study were obtained from 238 sample plots. The sample plots are 24-131 years of stand age range, 19.0-35.9 m of site index range, and 2.2-10.8 of stand density range (relative density index). With the generated equation systems, stand age, site index and density of the three main factors in Oriental beech stands, including the effects of individual, dual and triple factor interactions on the stands were numerically determined. As for even-aged Oriental beech stands, the main stand volume values increase depending on age, site index and density. The number of stems per hectare decreases as the stand grows older, and site index rises; the number, however, increases in parallel with stand density. The current annual volume increment reaches a peak at 3035 years at all site index groups and density levels, and begins to fall afterwards. Mean annual volume increment peaks up at 65-75 years at all site index classes and density levels, before beginning to decline. The results were in arrangement with the acknowledged growth rules. Stand yield models were assessed as Density-Variable Yield Table used for estimation of the remaining, removal and total stands

Estimating diameter at breast height (DBH) from diameter at stump height (DST) in triple mixed stands in the region of Artvin in Turkey

This study was supported by the Scientific Research Projects Unit of Karadeniz Technical University under Project KTU 2009.113.001.6.Diameter at breast height is used as an independent variable in the calculation of most tree or stand parameters because it can be measured easily and has high correlation with tree variables. But, it is necessary to estimate the size of the DBH of the tree concerned to have knowledge of the tree which has been separated from the area. In this study, DST-DBH relationships were investigated on stands where Oriental Spruce (So), Scots Pine (Ps) and Eastern Black sea Fir (Fb) were mixed. For this purpose, 206 trees (69 So, 69 Ps and 68 Fb) were used which were cut from 23 different sample areas taken in fully closed SoPsFb and PsSoFb stands in Artvin. According to the statistics analysis; models that best explain the variability of the DBH are power for spruce, quadratic for pine and linear models for fir. These models can explain the variance of DBH in triple mixed stands by 95.2% for spruce, 96.5% for pine and 96.4% for fir, and standard errors of models are 1.850, 1.598 and 1.643 respectively. As a result, these models, which at a certain height of success in predicting DBH, can be used by practitioners at fully closed triple mixed stands in Artvin.Göğüs çapı, kolay ölçülebilir olması ve diğer ağaç değişkenleriyle yüksek korelasyona sahip olmasından dolayı, tek ağaç veya meşcere parametrelerinin birçoğunun hesaplanmasında bağımsız bir değişken olarak kullanılmaktadır. Ancak ormanlık alandan ayrılmış olan ağaç hakkında bilgi sahibi olabilmek için göğüs çapı büyüklüğünü tahmin etmek gerekmektedir. Bu çalışmada, Doğu Ladini (L), Sarıçam (Çs) ve Doğu Karadeniz Göknarı (G) karışık meşcerelerinde göğüs çapı-kütük çapı ilişkisi araştırılmıştır. Bu amaçla Artvin’de tam kapalı olan LÇsG ve ÇsLG meşcerelerinden alınan 23 farklı örnek alandan kesilmiş olan 206 ağaç (69 adet L, 69 adet Çs ve 68 adet G) verisi kullanılmıştır. Yapılan istatistiksel analizlere göre, göğüs çapındaki değişkenliği açıklayan en iyi modeller Ladin’de power, Sarıçamda kuadratik ve Göknarda ise doğrusal modeller olmuştur. Bu modellerin üçlü karışık meşcerlerde göğüs çapı değişkenliğini açıklama oranları Ladin için %95,2, Sarıçam için %96,5 ve Göknar için de %96,4 ve bu modellerin hataları da sırasıyla 1.850, 1.598 ve 1.643 şeklinde bulunmuştur. Sonuç olarak, göğüs çapını tahmin etmede belli başarı seviyesinde olan bu modeller, Artvin’deki tam kapalı üçlü karışık meşcerelerde uygulayıcılar tarafından kullanılabilir olarak bulunmuştur

Dynamic base-age invariant site index models based on generalized algebraic difference approach for mixed Scots pine (Pinus sylvestris L.) and Oriental beech (Fagus orientalis Lipsky) stands

Data from stem analysis of 397 dominant trees (198 Scots pine and 199 Oriental beech) were used to evaluate dynamic base-age invariant site index models derived from Bertalanffy–Richards, Hossfeld, and Lundqvist–Korf functions with the generalized algebraic difference approach (GADA) for mixed Scots pine (Pinus sylvestris L.) and Oriental beech (Fagus orientalis Lipsky) stands. These functions were compared with respect to residuals of these models; specifically, the evaluation criteria were bias (– root mean square error (RMSE), absolute mean error (AME), adjusted coefficient of determination (R2 ), and Akaike information criterion. The best results were obtained with generalized algebraic difference equations derived from the base models of Bertalanffy–Richards for Oriental beech and Hossfeld for Scots pine. These selected models accounted for 95%–96% of the total variance in height–age relationships in dominant trees with bias of 0.049841 and 0.00171, RMSE of 1.55624 and 1.353736, AME of 0.940128 and 0.884034, and AIC of 723.55 and 1250.78 for Scots pine and Oriental beech, respectively. These dynamic base-age invariant site index models for the 2 tree species presented more effective and accurate polymorphic site index curves with multiple asymptotes than earlier site index models for Oriental beech and Scots pine. The important differences of height growth trend between developed base-age invariant site index models in this study and earlier site curves were determined by graphical comparisons for site index predictions. Therefore, the new dynamic base-age invariant site index models developed based on GADA methodology can be recommended for dominant height prediction and forest site quality evaluations in the mixed stands of these 2 species

Karadeniz bölgesi sarıçam (pinus sylvestris L.) - doğu kayını (fagus orientalis lipsky) karışık mesçerelerine ilişkin sıklığa bağlı hasılat tablolarının düzenlenmesi

In this study, variable density yield tables were developed for Scots pine and oriental beech mixed stands in Black Sea Region. The data used in this study were obtained from 162 temporary sample plots measured in evenaged Scots pine and oriental beech mixed stands. The sample plots have 31-150 years for Scots pine and 33-117 years for oriental beech of stand age range, 16.2-34.9 m Scots pine and 14.7-32.3 m for oriental beech of site index range, 0.24-0.9 of Scots pine mixture ratio range, 2.9-10.0 of stand density range. With the generated equation systems, stand age, site index, density and mixture ratio of the four main factors in Scots pine -Oriental beech mixed stands, including the effects individual, dual, triple and quadruple of factor interactions on the stands were determined numerically. The results were in arrangement with the acknowledged growth rules.Bu çalışmada, Karadeniz bölgesinde yayılış gösteren Sarıçam-Doğu Kayını karışık meşcerelerine ilişkin sıklığa bağlı hasılat tabloları düzenlenmesi amaçlamıştır. Bu çalışmada, Karadeniz Bölgesi sınırları içerisinde yer alan eşityaşlı Sarıçam (Pinus sylvestris L.) - Doğu Kayını (Fagus orientalis Lipsky) karışık meşcerelerinden alınan 162 adet geçici örnek alandan elde edilen veriler kullanılmıştır. Örnek alanlar, Sarıçam için 31-150 ve Doğu Kayını için 33-117 yaşları, Sarıçam için 16.2-34.9 m ve Doğu Kayını için 14.7-32.3 m bonitet endeksi, 0.24-0.90 sarıçam karışım oranları ve 2.9-10.0 sıklık değerleri arasında değişim göstermektedir. Söz konusu bu veriler kullanılarak elde edilen regresyon denklemleriyle, Sarıçam-Doğu Kayını karışık meşcerelerinin yaş, verim gücü, sıklık derecesi ve karışım oranı olmak üzere dört ana faktörün bireysel etkileriyle, ikili, üçlü ve dörtlü faktör etkileşimlerinin meşcere yapısı üzerindeki etkileri sayısal olarak belirlenmiştir. Elde edilen bulgular temel ormancılık büyüme yasaları ile uyumludu

The Construction of Variable Density Yield Table for Scots Pine and Oriental Beech Mixed Stands in Black Sea Region

Bu çalışmada, Karadeniz bölgesinde yayılış gösteren Sarıçam-Doğu Kayını karışık meşcerelerine ilişkin sıklığa bağlı hasılat tabloları düzenlenmesi amaçlamıştır. Bu çalışmada, Karadeniz Bölgesi sınırları içerisinde yer alan eşityaşlı Sarıçam (Pinus sylvestris L.) - Doğu Kayını (Fagus orientalis Lipsky) karışık meşcerelerinden alınan 162 adet geçici örnek alandan elde edilen veriler kullanılmıştır. Örnek alanlar, Sarıçam için 31-150 ve Doğu Kayını için 33-117 yaşları, Sarıçam için 16.2-34.9 m ve Doğu Kayını için 14.7-32.3 m bonitet endeksi, 0.24-0.90 sarıçam karışım oranları ve 2.9-10.0 sıklık değerleri arasında değişim göstermektedir. Söz konusu bu veriler kullanılarak elde edilen regresyon denklemleriyle, Sarıçam-Doğu Kayını karışık meşcerelerinin yaş, verim gücü, sıklık derecesi ve karışım oranı olmak üzere dört ana faktörün bireysel etkileriyle, ikili, üçlü ve dörtlü faktör etkileşimlerinin meşcere yapısı üzerindeki etkileri sayısal olarak belirlenmiştir. Elde edilen bulgularIn this study, variable density yield tables were developed for Scots pine and oriental beech mixed stands in Black Sea Region. The data used in this study were obtained from 162 temporary sample plots measured in even- aged Scots pine and oriental beech mixed stands. The sample plots have 31-150 years for Scots pine and 33-117 years for oriental beech of stand age range, 16.2-34.9 m Scots pine and 14.7-32.3 m for oriental beech of site index range, 0.24-0.9 of Scots pine mixture ratio range, 2.9-10.0 of stand density range. With the generated equation systems, stand age, site index, density and mixture ratio of the four main factors in Scots pine - Oriental beech mixed stands, including the effects individual, dual, triple and quadruple of factor interactions on the stands were determined numerically. The results were in arrangement with the acknowledged growth rules

A novel approach to selecting a competition index: the effect of competition on individual-tree diameter growth of Calabrian pine

In this study, we evaluated the performance of 18 competition indices composed of nine distance-dependent and nine distance-independent indices in explaining the variation in individual-tree diameter growth of Calabrian pine (Pinus brutia Ten.) in the central Mediterranean region of Turkey. The data were obtained from 432 sample plots with varying stand age, site index, and stand density. To evaluate the performance of each competition index, the mean square error reduction approach was used relative to the noncompetition. Also, this study compared fixed and mixed effects models to analyze diameter growth. Statistical analyses showed that the best distance-independent competition indices performed as well as the best distance-dependent competition indices. The distance-independent competition index of Schroder and Gadow (1999; Can. J. For. Res. 29(2): 280-283, doi:10.1139/x98-199) performed best and is recommended for use in future growth and yield models to be used in the central Mediterranean region of Turkey. Also, the best selection of competitive neighbors was achieved using the area of influence overlap method, whereas the fixed-radius and angle count sampling methods had no significant improvement in quantifying the competition effects. On the other hand, all mixed effects models provided much better fits than their fixed model counterparts.Dans cette étude, nous évaluons la performance de 18 indices de compétition, comprenant neuf indices dépendants des distances et neuf indices indépendants des distances, pour expliquer la variation de la croissance en diamètre d’individus de pin de Calabre (Pinus brutia Ten.) dans la région méditerranéenne centrale de la Turquie. Les données ont été obtenues de 432 placettes échantillons couvrant une gamme d’âge du peuplement, d’indice de qualité de station et de densité du peuplement. Pour évaluer la performance de chaque indice de compétition, nous avons utilisé l’approche de la réduction de l’erreur quadratique moyenne par rapport à l’absence de compétition. De plus, cette étude compare des modèles à effets fixes et mixtes pour analyser la croissance en diamètre. Les analyses statistiques montrent que les meilleurs indices de compétition indépendants des distances sont aussi performants que les meilleurs indices dépendants des distances. L’indice de compétition indépendant des distances de Schröder et Gadow (1999; Can. J. For. Res. 29(2): 280–283, doi:10.1139/x98-199) est le plus performant et son utilisation est recommandée pour les futurs modèles de croissance et de production qui seront utilisés dans la région méditerranéenne centrale de la Turquie. De plus, la meilleure sélection des arbres voisins concurrents a été réalisée à l’aide la méthode de chevauchement de l’aire d’influence alors que les méthodes à rayon fixe et par balayage sous angle constant n’ont pas significativement amélioré la quantification des effets de compétition. Par ailleurs, tous les modèles à effets mixtes ont produit de bien meilleurs ajustements que les modèles à effets fixes équivalents. [Traduit par la Rédactio

Site index estimation between species for mixed stands

Karışık meşcerelerde karışımı oluşturan türlerden her biri için yeterli sayı ve nitelikte bonitet ağacı bulunmaması durumunda türler arası bonitet endeks tahmini denklemlerinden yararlanılmaktadır. Denklemlere ilişkin parametre tahminlerinde En Küçük kareler Yöntemi (E.K.K.) yerine, Geometrik Ortalama Regresyonu (G.O.R.), Geometric Mean Regression (GMR), önerilmektedir. Bu çalışmada, Bursa Orman Bölge Müdürlüğü, Bursa Orman İşletme Müdürlüğü, Kestel Orman İşletme Şefliği sınırları içerisinde yer alan Karaçam-Kayın karışık meşcerelerinden alınan 50 deneme alanı verileri kullanılarak, Karaçam-Kayın karışık meşcereleri için Türler Arası Bonitet Endeks Tahmin Denklemleri (Site Index Conversion Equations) geliştirilmiştir.The site index estimations can be incorrect for one of tree species in lower crown layer in mixed stands. For this situation, the equations estimating site index for tree species in lower crown layer from tree species in higher crown layer position must be developed to accurate site index estimations. In developing these equations, Geometric Mean Line Regression Technique, GMLR, was proposed to Ordinary Least Squares, OLS. In this study, fifty sample plots from Kestel Forest Enterprise, Bursa Forest District Directorship, were used. Site Index Conversion Equations were developed to estimate site index for tree species in lower crown layer from tree species in higher crown layer position. Also, Geometric Mean Line Regression Technique was particularly explained to estimate the parameters of Site Index Conversion Equations

Antalya ve Mersin Yöresi kızılçam meşcereleri için ağaç hacim tabloları

In this study, it is proposed to construct single, single based on site index and double entry tree volume equations for the pure Calabrian Pine stands (Pinus brutia Ten.) within the border of Antalya and Mersin Regional Forest Directorates, Turkey. Tree volume equations were developed using totally 486 sample trees and 6083 data obtained from these trees. The coefficient of determination (adj-R-2), total percent error (PE), and mean absolute percentage error (MAPE) were 0.975, 52.84, -0.457 and 9.756 for single tree; 0.978, 44.84, -0.438 and 9.849 for single tree of the first site index class; 0.976, 54.44, -0.464 and 9.501for single tree of the second site index class; 0.969, 52.96, -0.452 and 9.256 for single tree of the third site index class, and 0.992, 41.26, 0.210 and 5.038 for double-entry tree volume equations, respectively. The first (% 6.32) and the second (% 0.45) site index values overestimated single-entry tree table values whereas the third site index values (%-4.28) underestimated the single-entry tree table values. The best fitted single, single based on site index and double entry tree volume equations were tested with independent data set for Calabrian Pine stands within the border of Antalya and Mersin Regional Forest Directorates, and concluded that these equations can be used for these stands at the 0.05 significant level.Bu çalışmada, Antalya ve Mersin yörelerinde yer alan saf ve doğal Kızılçam (Pinus brutia Ten.) meşcereleri için tek, bonitete dayalı tek ve çift girişli ağaç hacim tablolarının düzenlenmesi amaçlanmıştır. Bu amaçla 486 örnek ağaç ve bu ağaçlardan türetilen 6033 adet veri kullanılarak, ağaç hacim denklemleri geliştirilmiştir. Seçilen en uygun hacim fonksiyonlarının düzeltilmiş belirtme katsayısı (RRdddüzz. 2), tahminin standart hatası (Sy.x), ortalama mutlak hata yüzdesi (% OMH) ve toplam hata yüzdesi (% TH) değerleri sırasıyla; tek girişli için 0.975, 52.84, -0.457 ve 9.756; I. bonitet sınıfı tek girişli için 0.978, 44.84, -0.438 ve 9.849; II. bonitet sınıfı tek girişli için 0.976, 54.44, -0.464 ve 9.501; III. bonitet sınıfı tek girişli için 0.969, 52.96, -0.452 ve 9.256 ve çift girişli için ise 0.992, 41.26, 0.210 ve 5.038 olarak hesaplanmıştır. Tek girişli ağaç hacim tablosu değeri, I. (%-6.32) ve II. bonitet sınıflarında (%-0.45) bonitete dayalı tek girişli ağaç hacim modelleri değerinden düşük, III. bonitet sınıfında ise daha büyük değerler (%4.28) vermektedir. Çalışma kapsamında düzenlenen tek, bonitete dayalı tek ve çift girişli hacim tablolarının, bağımsız bir veri grubu ile Antalya ve Mersin ilerindeki Kızılçam meşcerelerine uygunluğu test edilmiş ve her bir hacim denkleminin de meşcerelere uygun olduğu (p>0.05) sonucuna varılmıştır

Single entry raw wood products table construction for calabrian pine (pinus brutia ten.) .in Mersin region

The main purpose of this study was to construct ‘Raw Wood Products Table’ for the pure and nature Calabrian pine stands within the border of Mersin Regional Directorate of Forestry. For this purpose, 488 sample trees were cut and raw wood products which can be obtained as log, mine prop, industrial wood and bark volume ratios were determined. Then, regression models were obtained with relationship of these ratios and diameter at breast. ‘Single-Entry Raw Wood Products Table’ were created by using these models. The coefficient of determination (R2 ) and standard error were respectively 0.840 and 6.771 for log; 0.700 and 7.500 for industrial wood; 0.856 and 10.941 for mine prop and 0.972 and 0.401 for bark.Bu çalışmada, Mersin Orman Bölge Müdürlüğü sınırları içinde yer alan saf ve doğal Kızılçam meşcereleri için ‘Odun Ürün Çeşitleri Tablosu’ düzenlenmesi amaçlanmıştır. Bu amaçla, 488 adet Kızılçam ağacı kesilmiş ve bu ağaçlardan elde edilebilecek odun ürün çeşitleri olan tomruk, maden direği, sanayi odunu ve kabuk oranları belirlenmiştir. Sonra bu oranlar göğüs çapı ile ilişkiye getirilerek regresyon modelleri elde edilmiştir. Bu modellerin kullanılmasıyla da Kızılçam için ‘Tek Girişli Odun Ürün Çeşitleri Tablosu’ oluşturulmuştur. Çalışma kapsamında elde edilen modellere ilişkin belirtme katsayıları (R2 ) ve standart hatalar (Sy.x) sırasıyla; tomruk için 0.840 ve 6.771; sanayi odunu için 0.700 ve 7.500; maden direği için 0.856 ve 10.941 ve kabuk için de 0.972 ve 0.401 olarak hesaplanmıştı