Study of Single Selection Method with Administering Function on Tree Species Diversity in Siyahkal Shenroud Forests

To reach a dynamic forest and preserve the original species in forest and help the natural life restoration the exploitation method of close to nature can be the most essential technique in preserving the north forests of the country. In this study the diversity of tree and grassy species was considered in the gaps made due to single selection cutting in the seventh series Siyahkal shenround forests parcel 704. At the beginning by spryer forest 35 gaps in three groups with the menstruations 100- 200, 200- 300, 300- 400 square meters were assigned and randomly from each group 5 gaps and totally 15 gaps were selected on account of inventory. In order to consider the grass covering along the length of two diameters of gaps, the pieces with size of 2´2 meters, and one meter distance from each other were performed systematically. The study showed that with increase of gaps surfaces the number (richness) and quantity (evenness) of the tree species increases but it doesnt have a specific order. Also, 20 botanical species in the gaps of 1-2R, 21 botanical species in the gaps of 2-3R, 23 botanical species in the gaps of 3-4, was observed. To measuring the different diversity indexes showed that in the gaps with 300- 400 square meter, the shannon winner index with the amount 2.799 had the highest value and according to the calculated value and importance of each species (SIV) in each of the gaps the most importance was allocated to the fagus species and the lowest importance was allocated to, Honey locust, malus and pyrus species.