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1

Identification of driving factors for presence of endemic species in the Aglasun district of the Mediterranean Region, Turke

Ozkan K.

Polish Journal of Ecology

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2012

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Vol. 60, nr 2

291-30

EN

This study was addressed to environmental factors significantly influencing the habitat preferences of endemic species and to obtain a model of their common habitat preferences in the Aglasun district. The district, covering an area of 55,000 hectares, is located in the lakeland subregion of the Mediterrranean region, Turkey. Data were collected from 199 sample plots (20 x 20 m ) and in total 40 endemic taxa was recorded in 124 plots which include minimum one endemic species. Wilcoxon rank-sum statistic and Pearson chisquared tests were used for continuous and categorical explanatory variables, respectively. The factors playing important roles in habitat preferences of endemic species were following: altitude, radiation index, soil texture, landscape position and landform. Generalized additive model was used for modelling the habitat preferences of endemic taxa. To obtain the best model, all significant environmental factors were evaluated by selecting stepwise option. Finally, the best model was obtained (training AUC = 0.816, and crossvalidation AUC = 0.800) by using altitude and landform variables.

2

Key factors in the site selection of Rosa canina (L.) - applying the Generalized Additive Model

Guner S., Ozkan K., Comez A.

Polish Journal of Ecology

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2011

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Vol. 59, nr 3

475-482

EN

Determining suitable sites for species is of great importance in the choice of plant species to be used for ecosystem restoration. The number of plant species to be used in restoration of degraded ecosystems is restricted by climate in arid and semi arid regions. Planting with economically important species in addition to ecological aspects is preferred by decision makers in Mediterrenian countries including Turkey. This study was addressed to determine the significant environmental factors influencing the distribution of dog rose hip (Rosa canina) and to obtain its distribution model. The study was carried out in an area of 26,400 km2 in The Inner Anatolia which has semiarid climate. 106 sample plots, 20 x 20 m in size, were selected from different sites with and without Rosa canina in the summer of 2007. Wilcoxon rank-sum statistic for continuous variables and Pearson Chi-square tests for categorical variables were applied. Altitude, slope degree, available water capacity, soil reaction and soil K, Ca, Mg content as well and total calcium carbonate amount as the continuous variables and northwest-northeast group of aspect, metamorphic group of bedrock as the categorical variables were determined as the significant factors influencing the presence of dog rose. Generalized Additive Model (GAM) was performed for modeling the distribution of the species. To obtain the best model, all significant environmental factors were evaluated. The best model result was obtained (training Area Under Curve (AUC) = 0.902 and cross-validation AUC = 0.841) by means of altitude, slope degree, aspect, and bedrock. Interspecific correlation analysis (ICA) was applied to define indicator species accompanying the dog rose. Dog rose distribution was positively correlated with Cistus laurifolius, Pyrus elaeagnifolia, Lonicera caucasica subsp. orientalis, Quercus vulcanica and Amelanchier rotundifolia subsp. rotundifolia. The results obtained from this study are crucial for estimation of the suitable areas for Dog rose in restoration studies of natural ecosystems in the Mediterranean region, including Anatolia in Turkey.

3

Ecological land classification and mapping based on vegetation-environment hierarchical analysis - a case study of Buldan forest district (Turkey)

Ozkan K., Gulsoy S.

Polish Journal of Ecology

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2010

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Vol. 58, nr 1

55-67

EN

Distinction of the geographic areas intended for hierarchical sequence of vegetation classes involves the hierarchical classification of ecosystems. In this context, it is essential to determine the effective environmental characteristics at each hierarchical level of vegetation distinction. The study was carried out in order to classify and hierarchical mapping the Buldan forest district (area 190,000 km2, altitude 400-1400 m a.s.l. covered in 40% with Mediterranean pine and oak forest, in 60% - by arable and pasture land). 56 sample plots (20 m x 20 m) were taken. At each sample plot, environmental characteristics (56 variables) and vascular plant species (108 species in total) were recorded. The relationships between environmental variables and the distribution of plants (presence/absence) were investigated by two hierarchical approaches for both of floristic data matrix and environment matrix by using cluster analysis, stepwise discriminate analysis and chi square test. Interepecific correlation analysis was also applied to determine the indicator species at each level of divisions. Two subdistricts were distinguised: Ortakci-Cagir subdistrict (characteristic species association with Pinus brutia, Pistacia terebinthus, Nerium oleander, Ficus carica, Olea europea) and Suleymanli subdistrict (species association with Pinus nigra, Cistus laurifolius, Prunus divarcata and Rosa canina). Two sections in Suleymanli subdistrict were distinguished: Kocaalan section with characteristic association of Pinus nigra, Cistus laurifolius, Drypteris pallida and Ericek section - characterized with an association of Creategus monogina, Astragalus sp. and Pistacia terebintus. The altitude was the fundamental variable affecting on site classification at the level of subdistrict. Longitude was the most important variable affecting on discrimination of the sections of Suleymanli subdistrict. This local study offers a model including statistical processes which can be applied to the other forest areas for large scale classification of vegetation and environmental relations. Application of this model based on hierarchical classification of ecosystem units is also important for estimation of the changes of natural vegetation in ecosystems in the future due to global climatic change.

4

Endemic plant species in a karstic canyon (Mediterranean region, Turkey) : relation to relief and vegetation diversity

Ozkan K., Suel H.

Polish Journal of Ecology

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2008

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Vol. 56, nr 4

709-715

EN

Data collected from 85 sample plots in Yazili Canyon Nature Park (deep, limestone valley; length - 6 km, area - 600 ha, height - 100-400 m) located in Mediterranean region (Turkey) yielded 24 endemic vascular plants. The endemic plant diversity and all vascular plant diversity indices were calculated for each sample plot using Simpson index. Regression analysis was performed between environmental factors, plant diversity and canopy closure. Endemic plant diversity showed a positive correlation with vascular plant diversity, and a negative correlation with slope position and altitude. A significant quadric relationship was observed between the endemic plant diversity and aspect variable. RDA (redundancy analysis) and CCA (canonical correspondence analysis) based on linear regressions were applied to determine the environmental factors affecting the distribution of endemic species, and the best model based on total variance explained was selected. According to RDA based on linear regression, habitat selection of endemics is strongly correlated with aspect, slope position and altitude. Lower altitude zone (300-500 m), the north aspect and lower slope including valley bottom of Yazili canyon were observed to be the most suitable areas for endemics.