Landscape metrics quantifies structural features of the landscape. One of the advantages of these metrics is a possibility to use them in fast cumulative assessment of the development activities in the environment. In this paper, the cumulative effects of road network expansion on the tree cover of Gorgan, Kordkuy, Aliabad townships in Golestan province were investigated. To prepare the required land use map, images of the Landsat TM (1987) and ETM+ (2002) sensors were employed. Based on previous studies in this area and towards cumulative effects assessment, seven related classes related were defined and distinguished in a supervised manner (maximum likelihood). Then, the effects of road network expansion and the cumulative effects of land use development on the tree cover were analyzed, using metrics of patch area, perimeter to area ratio, shape, fractal dimension, contiguity, proximity, and Euclidean nearest neighbor distance. With applying cross tabulation method, the amount of cumulative effects of development, and the road effects on the tree cover were calculated for a period of 15 years. Results showed that most patches which need protection from cumulative development are located 684-342 meters from the road. It was also determined we can assess the cumulative effects of development activities on tree patches, using landscape metrics. We also prioritized tree patches for protection and mitigation measures.