Browsing by Author "Sakici O.E."

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Allometric relationships between above-ground biomass increment and stand characteristics for crimean pine in Taşköprü, Türkiye
(2023-01-01) Sağlam F.; Sakici O.E.
Background: Biomass increment, one of the main components of net primary production (NPP) in forest ecosystems, plays an important role as well as total biomass in the global carbon cycle. In this study, the changes of increments of the above-ground total, stem and branch biomasses depending on stand characteristics (i.e., stand age, stand density, and site index) were investigated, and these relations were modeled for Crimean pine (Pinus nigra J.F.Arnold subsp. pallasiana (Lamb.) Holmboe) stands in Taşköprü region of Türkiye. Data were obtained from 109 sample trees within 74 sample plots representing the wide range of possible stand characteristics. Results: The equations developed for above-ground total, stem and branch biomass increments have quite high coefficients of determination (R2=0.784, 0.684 and 0.780, respectively), whereas low root mean square errors (RMSE=0.749, 0.692 and 0.116, respectively). The results indicated that the biomass increment estimates from the allometric equations developed were decreasing with stand age and increasing with stand density and site index and also stand density is the strongest stand characteristic on biomass increment. Conclusion: The estimates are also consistent with the growth patterns, so the equations can be used for biomass increment estimations and also for carbon storage and NPP projections for Crimean pine stands of the region.
Artificial intelligence applications for predicting some stand attributes using landsat 8 oli satellite data: A case study from Turkey
(2018-01-01) Sakici O.E.; Günlü A.
Forest resources inventory is one of the essential parts of the sustainable forest management. Remote sensing applications have broad usage areas for this aim, since field measurements are costly, time consuming and laborious. Monitoring forest resources with various satellite images has found wide usage areas in forestry. In this study, the relationships between some stand attributes (mean diameter, basal area, stand volume and number of trees) and texture values obtained from Landsat 8 OLI satellite image were investigated for Crimean pine (Pinus nigra J.F. Arnold subsp. pallasiana (Lamb.) Holmboe) stands in Kastamonu region of Turkey. The multiple linear regression analysis and artificial neural networks (ANN) were utilized to fit stand parameters using texture values. To form the ANN architectures, various transfer functions in hidden and output layers and number of nodes ranged from 1 to 20 in hidden layer were used, and a total of 180 architectures were designed for each stand attribute. The results indicated that the regression models had low R2 values (0.399 for mean diameter, 0.337 for basal area, 0.332 for stand volume, and 0.183 for number of trees), and the most of the ANN models were better than the regression models for predicting stand attributes. The model containing hyperbolic tangent transfer functions in both hidden and output layers for mean diameter (R2 = 0.593), logistic transfer function in hidden layer and hyperbolic tangent function in output layer for basal area and stand volume (R2 = 0.632 and 0.650, respectively), and hyperbolic tangent function in hidden layer and linear function in output layer for number of trees (R2 = 0.610) were the best ANN models. This study concluded that the ANN models developed with Landsat 8 OLI were useful to predict stand parameters better than the regression models in Crimean pine stands located in Kastamonu, Turkey.
Comparative study of the analytical hierarchy process, frequency ratio, and logistic regression models for predicting the susceptibility to Ips sexdentatus in Crimean pine forests
(2022-11-01) Sivrikaya F.; Özcan G.E.; Enez K.; Sakici O.E.
The six-toothed bark beetle Ips sexdentatus is one of the most important pests of coniferous trees that can cause extensive tree mortality, and change the structure and composition of forest ecosystems. Many abiotic and biotic factors affect the infestation of bark beetles. Early detection of forest stands predisposed to bark beetle infestations will benefit from reducing the impacts of possible infestations. The study focused on the production and comparison of Ips sexdentatus susceptibility maps using the analytical hierarchy process (AHP), frequency ratio (FR), and logistical regression (LR) models. The research was carried out in the Crimean pine forests of the Taşköprü Forest Enterprise in Kastamonu City in the Western Black Sea region of Türkiye. The eight main criteria used to produce the map were the stand structure, site index, crown closure, stand age, slope, elevation, maximum temperature, and solar radiation. The map of the infested stands was used for the models' validation. Crown closure was determined as the one of the most important factors in all three models. The receiver operating characteristic (ROC) curves and area under the curve (AUC) were used to determine the accuracy of the maps. The validation results showed that the AUC for the FR model was 0.747, for the AHP model was 0.716, and for the LR model was 0.638. The results revealed that the FR model was more accurate than the other models in producing an I. sexdentatus susceptibility map. Besides, the AHP model was also reasonably accurate. This study could help decision makers to produce bark beetle susceptibility maps easily and rapidly so they can take the necessary precautions to slow or prevent infestations.
Compatible above-ground biomass equations and carbon stock estimation for small diameter Turkish pine (Pinus brutia Ten.)
(2018-05-01) Sakici O.E.; Kucuk O.; Ashraf M.I.
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.
Determination of relationships between leaf area index and stand characteristics in anatolian black pine stands of kastamonu region, Turkey
(2022-04-01) Yer B.M.; Sakici O.E.
Background: Leaf area index (LAI) is an important stand characteristic in terms of forest productivity and stand growth, and it shows significant correlations with other stand characteristics. In this study, it is aimed to reveal the relationships between LAI and some other stand characteristics, i.e. mean diameter, stand age, dominant height, site index, number of trees, stand basal area, stand density, total crown biomass and crown dimensions for Anatolian black pine (Pinus nigra J.F. Arnold subsp. pallasiana (Lamb.) Holmboe) stands in Kastamonu region, which is one of the economically important tree species in Türkiye, and to develop a regression model for LAI estimations by using these relationships. Results: The data obtained from 119 temporary sample plots were used in the study. According to the results, stand basal area, stand density, total crown biomass, dominant height, number of trees, mean diameter, and site index positively correlated with LAI. LAI values were significantly different in terms of stand density and site classes. Among the candidate models for LAI estimations, the model containing site index and stand density as independent variables was the most successful model with the adjusted coefficient of determination (Radj2) of 0,63 and the Akaike information criterion (AIC) of-67,25. Conclusion: The LAI, which is difficult to measure directly in practice, of Anatolian black pine stands in Kastamonu region of Türkiye could be estimated accurately with the help of the equation developed.
Determination of some factors leading to the infestation of Ips sexdentatus in crimean pine stands
(2022-09-01) Özcan G.E.; Sivrikaya F.; Sakici O.E.; Enez K.
Large infestations of bark beetles result in the death of many trees in large forest areas. Ecological-based modeling approaches that include the factors causing infestations are important for accurately predicting whether these infestations will occur, suggesting ways to avoid large infestations, and understanding sustainable forest management. In the present study, the effects of some stand characteristics and topographical and climatological factors on the of Ips sexdentatus infestation at pure and mixed Crimean pine stands were evaluated. Ten factors were considered as important for predicting the predisposition of a pine forest to infestation: stand structure, site index, crown closure, stand age, aspect, slope, elevation, maximum temperature, precipitation, and solar radiation. Ten conditioning layers were overlayed separately with a beetle infestation map using geographic information system (GIS) to investigate how the beetle damage changed according to these factors and how much damage it caused. Binary logistic regression analysis was used to determine how combinations of the 10 factors affected beetle infestations and which of the factors were most damaging. It was found that the stand structure, crown closure, site index, stand age, slope, elevation, maximum temperature, precipitation, and solar radiation were definite factors in I. sexdentatus infestation; the aspect was not found to be a strong factor. The crown closure was the most significant factor affecting I. sexdentatus infestation followed by maximum temperature, elevation, slope, precipitation, solar radiation, stand age, site index, and stand structure. The crown closure, stand structure, maximum temperature, solar radiation, and forest stand area variables were significantly included in the logistic regression model.
Ecoregion-based height-diameter models for Crimean pine
(2022-01-01) Seki M.; Sakici O.E.
Generalized height (h)–diameter (d) models were developed for Crimean pine stands in the Kastamonu Regional Directorate of Forestry, northwestern Turkey. Nine generalized h-d models were fitted and evaluated based on data set consisting of 2697 h-d measurements obtained from 274 sample plots located in three ecoregions of the studied region. The best results were obtained by modified Richards h-d model accounting for the 93% of the total variance in height–diameter relationship. It is a known fact that h-d relationship can vary in ecological conditions, especially for regions with large areas and various ecological conditions such as Kastamonu. To investigate the differences of height–diameter relationship among the ecoregions located in Kastamonu region, nonlinear extra sum of squares method was performed. The test results showed that there were significant differences, especially between coastal and the inland ecoregions. When compared to reduced model with the same set of parameters for the whole region, full model with a different set of parameters for each ecoregion achieved better accuracy in estimating tree height. Besides, applying h-d model fitted for the coastal ecoregion to the others, or vice versa, could lead under- or over-estimates of tree heights by about 1.8%.
Ecoregional Variation of Crimean Pine (Pinus nigra subspecies pallasiana [Lamb.] Holmboe) Stand Growth
(2022-10-01) Seki M.; Sakici O.E.
Investigation and numerical determination of the effects of ecologically different regions on forest growth are important issues to be considered for sustainable forest management. In this study, differences in growth patterns of Crimean pine (Pinus nigra subsp. pallasiana [Lamb.] Holmboe) stands among the ecoregions located in the Kastamonu region of northwestern Turkey were investigated. For this purpose, stand-level growth models for dominant height, number of trees, basal area, and volume were fitted using the data from 274 sample plots and 293 stem analysis in even-aged, pure, and productive Crimean pine stands. The nonlinear extra sum of squares method and graphical examinations revealed that growth characteristics of these Crimean pine stands were affected by ecoregional differences. Ecoregion-based growth models, which are more flexible and have the ability to reflect the ecoregional differences in growth patterns, were found to be superior to regional models. Applying general models without any ecoregional classification resulted in biases of 5.3%, 23.1%, 5.5%, and 6.2% in the estimates of dominant height, number of trees, basal area, and volume of Crimean pine stands, respectively. The results showed that ecological differences must be considered in studies on forest growth modeling and forest management. Study Implications: Investigation and numerical determination of the effects of ecoregional differences on forest growth are important issues to be considered for sustainable forest management. In this study, differences in growth patterns (dominant height, number of trees, stand basal area, and stand volume) of Crimean pine (Pinus nigra subsp. pallasiana [Lamb.] Holmboe) stands among the ecoregions located in the Kastamonu region of northwestern Turkey were investigated. Growth characteristics of the Crimean pine stands in the coastal ecoregion showed significant differences to those in the interior. Therefore, it was found necessary to use ecoregion-based growth models instead of a regional model for the entire region.
The effects of pine mistletoe (Viscum album subsp. austriacum) on the growth of Scots pine and Crimean pine in Turkey
(2023-01-01) Sakici O.E.; Özcan G.E.; Seki M.; Sağlam F.
In this study, the effect of pine mistletoe (Viscum album subsp. austriacum) on basal area increment of Crimean pine and Scots pine was investigated. Dendrochronological data were collected from 223 (71 uninfected and 152 infected) Crimean pines and 195 (77 uninfected and 118 infected) Scots pines located in Kastamonu province of Turkey in 2014. Infected sample trees were classified as light, moderate or severe infection levels. Growth trends and basal area increment loses were compared between uninfected and infected trees for the periods of the last 10, 20 and 30 years. In addition, infection status of forest stands was investigated using temporary sample plots; 27 plots in Crimean pine stands and 26 plots in Scots pine. Results demonstrated that basal area increments were negatively affected by pine mistletoe for both species. Mean basal area increment losses of infected trees for the last decade were determined as 24% for Scots pine and 26% for Crimean pine. Basal area increment losses varied by infection levels (light, moderate and severe) as follows: 25%, 20% and 28% for Scots pines and 20%, 32% and 9% for Crimean pines. Scots pine stands were more severely infected by pine mistletoe than Crimean pine stands. There were negative correlations between number of infected trees and stand density for both species, while positive correlation was detected between the number of infected trees and mean diameter for Scots pine. The results of this study indicate that the pine mistletoe infection has negative effect on radial growth of Scots pine and Crimean pine trees. The results can be an important contribution to the forest management and protection activities in mistletoe-infected stands.
Variations in the attack pattern of Dendroctonus micans and the colonization rate of Rhizophagus grandis in Picea orientalis stands
(2022-09-01) Büyükterzi A.; Özcan G.E.; Sakici O.E.
The great spruce bark beetle, Dendroctonus micans, is an invasive pest that has spread to almost all of the Picea orientalis forests in Turkey, affecting many trees and causing active damage. The species-specific predator Rhizophagus grandis plays an important role in suppressing populations of this pest because it is only found in D. micans galleries. In this study, the attack pattern of D. micans and the colonization rate of R. grandis were investigated according to some stand characteristics, such as aspect, developmental stage, crown closure, and stand type. It was determined that 20.5% of the 2025 sample trees evaluated in 83 sample plots were attacked by the beetle and that active damage from the beetle was currently continuing in 5.8% of the trees. There was no difference in the attack pattern of D. micans between shady and sunny aspects. However, trees showed significant differences in terms of susceptibility to beetle attacks based on developmental stage, crown closure, and stand type. The damage rates of the beetle were 19.8% and 29.6% for the mature and overmature stages, respectively; 28.5%, 18.8%, and 16.4% for low, medium, and full coverage stands, respectively; and 10.5–32.3% for different stand types. The colonization rate of R. grandis was 18.2%. This rate was not affected by the aspect, developmental stage, crown closure, or stand type. However, the rate was higher in the stands heavily infested by D. micans. In addition, there was a moderate correlation between the total number of D. micans individuals in active galleries and the total number of R. grandis individuals in these galleries.