Spatial distribution mapping of common yarrow (Achilla millefolium and thyme (Thymus kotschianus) using artificial neural network (Case study: Donna rangelands, Mazandaran province)

The purpose of this study was to map the spatial distribution of common yarrow(Achilla millefolium)and thyme (Thymus kotschianus) using artificial neural network model in rangelands Donna, Mazandaran Province.

Sampling was carried out with equal random classification in 29 homogenous units. In each unit, 3 soil samples were harvested from depth of 0-30 cm. In this study, 20 environmental factors were the independent variables and the presence of plant species were the dependent variable. For the preparation spatial distribution map of the species, environmental data were converted to maps in GIS. Then each of these factors was classified using the frequency. In this research, network Multilayer Perceptron that is the most common feed forward neural network was used. Optimal structure for the network was determined 1, 20, and 20. Then distribution maps of studied species were prepared with 4 class absence and low presence, medium presence and high presence in the GIS software. Models were evaluated using ROC curves and Kappa coefficient.

AUC were 96.8 and 84.7 for the species Achilla millefolium and Thymus kotschianus was, respectively  that indicates models are excellent or very good for the prediction.

Also kappa coefficient were calculated as 89.0 and 76.0 for Achilla millefolium and Thymus kotschyanus,  respectively which  indicate very good and good prediction.