Forests play an important role in addressing the effects of climate change and the carbon cycle in the whole world. Estimating the quantitative characteristics of forests is essential in evaluating its role that done by different methods. According to importance of Zagros forests and especially existing forests in Lorestan factors on the distribution of forest species in this province. Some of the province and threatening factors, it is important to investigate the effective competition, coexistence and management factors. Crataegus pontica (Crataegus factors affecting on distribution of forest species are environmental factors such as climatic parameters, topography and biological factors such as In addition to ecological characteristics, it also has economic and commercial pontica) is one of the most important phanrophyte species in Lorestan forests. benefits. In current research, species response curve of Crataegus pontica in presence of given species in study area using forest vegetation map. Climatic relation to environmental gradients was investigated and most environmental factors were determined. We used a random sampling method to collect points of data were extracted from Chellsa database, and used in R to model species occurrence and environmental data using MAXENT, physiographic data such as altitude, slope and direction were extracted from digital elevation map. NDVI index layer derived from MODIS and Terra satellites were extracted from Earth data.nasa database. BIOMOD2 package were of 0.944 and TSS index of 0.994 were selected as the best model and response curve. eHOF, GAM, GBM, CTA, ANN, SRE, FDA, MARS and RF models. Four statistical indices were used to compare the results of the models including; AUC, TSS, kappa and AICc. Random forest model (RF) with AUC of 0.99 and kappa coefficient which were determined and confirmed by different models. Potential distribution Tolerance range of the species and its optimum conditions was extracted using best response curve. The most effective environmental variables affecting province is suitable for occurrence of species. species distribution include maximum temperature (BIO5) and slope topography, maps of Crataegus pontica showed that about 40 to 50% of the area of Lorestan Keywords: Species distribution, Environmental variables, Statistical parameters, Species presence, Tolerance range
