Biodiversity is of crucial importance for ecosystem health and functioning. It is thus one of the most important topics in forest ecology. This study focuses on modelling the spatial distribution of vascular plant diversity (H), richness (S) and evenness (E) in the Yukarıgökdere forest district (14667 ha) located in transition zone between Mediterranean and continental climates in the Mediterranean region, Turkey. Species abundance was sampled at 95 sample plots extending from 1000 to 1900 m a.s.l. in order to calculate the response variables (H, S, E). Climatic and topographical data served as explanatory variables. Multiple regression (ML) and classification and regression tree technique (CART) were used to obtain the distribution models of response variables. The better results were provided by CART. That is why visual assessments of the predicted values of the response variables based on (CART) were performed. The explained variances of the model trees were 63.4, 63.1 and 44.5% for H, S and E respectively. Elevation was found to be the most important environmental factor for all response variables. The higher H and S values were found at the east lower part (1000–1150 m a.s.l.) and the west upper part (1500–1800 m a.s.l.) of the district. The evenness (E) shows generally higher relative values in the upper part of the area. The lowest E specifies the area being optimal for tree growing. It is located between 1400 and 1500 m a.s.l., and ranges from the north to the south in the district.