Development stages dynamics of the Hyrcanian reserve stands, Iran

With the aim of identifying the dynamism of the Hyrcanian forests, four reserve compartments were selected in three provinces of Gilan, Mazandaran, and Golestan. In each reserve stand, three plots of one hectare (12 plots in total) were laid out in the initial, optimal, and decay development stages. The first inventory (structural study) was performed in 2008 and in the present study, data were collected again in 2018. All trees with a diameter at breast height larger than 7.5 cm were measured. Based on the results, the mean number of trees naturally removed in the initial, optimal, and decay stages were 78, 48, and 31 per ha (21.1, 16, and 12.6%), respectively. The increase in the average mean diameter of the stands in the initial, optimal, and decay stand was increased in the amount of 3.2, 4.5, and 3.75 cm, respectively. Also, the maximum volume increment within the period was calculated 101 m3ha-1 in the optimal stage. All of the studied stands were placed in the large sizetimber in the structured triangle. Which indicates that they are far from theirregular structure. Over the ten-yearperiod, all stands, except the initial stage in Haftkhal, showed a light displacement in the triangle structure. Accordingly, periodic monitoring and data collection of permanent plots are one of the basic principles of stand conservation and improvement. Recognizing changes in structure over time is the first step in understanding the dynamics of development stages in stands which facilitates close to nature forest management.