Habitat Determination of Ferula gummosa Boiss. Using Generalized Additive Model in Lar Rangeland, Tehran Province

Knowledge of plants spatial distribution involves understanding and management of ecological factors affecting them which a prominent role in the evaluation, protection, development and regional planning. Due to the ecological and economic importance of Ferula gummosa Boiss, this study aimed to identify potential habitat using GAM model, distribution of this species with environmental factors and economic valuation was selected Lar rangeland custom unit at Tehran province. Identify and collect basic information of the study area, determination of the custom unit boundary by using a topographic and other map, typing of habitat, random sampling and estimation of soil surface cover properties and soil sampling to 30 cm depth, modeling of potential habitat, the prediction of the economic value of market value in the study area has been process of implementation of this study. The results showed that phosphorus factor with decreasing linear relationship and moisture, acidity and silt with 2 degree of freedom were the most important factors affecting density of Ferula gummosa Boiss (R2 is 0.44 and RMSE equals 1.32). Also, aspect, moisture, silt, potassium, organic matter and nitrogen with 1 degree of freedom and elevation with 2 degrees of freedom were major factors affecting canopy cover (R2 is 0.68 and RMSE equals 0.25). Also, from the thirteen factors examined, aspect with 1 degree of freedom and elevation and silt were major factors affecting on distribution Ferula gummosa Boiss 1 degree of freedom (AUC = 0.72 and Kappa coefficient = 0.49). Potential habitat map shows that 7.8 percent of the total study area has a perfect match, 37.9% fit, 44.9% are low and 8.5% inappropriate to predict the distribution of this species.