Investigating the state of regeneration in natural and exploited stands of Mirabad forests in West Azarbaijan province

Background and objectives: In terms of size, distribution, species diversity and forest products, Zagros forests play a vital role in the lives of a large part of its residents, and at the same time, they are considered one of the most important biological resources and genetic reserves of Iran. The productivity and stability of the Zagros Forest ecosystems are being destroyed due to the excessive grazing of livestock, the excessive cutting of trees for fuel supply, and the collection of tree seeds by people. Therefore, according to the mentioned cases, in order to achieve the importance of protection in Zagros forests, in the present study quantitative characteristics of regeneration in natural and exploited stands were investigated.
Materials and methods: The research was conducted in the forests of North Zagros, specifically in the area around Mirabad city, located in West Azarbaijan province, across two stands with an area of nearly five hectares. To ensure comprehensive data collection, the entire study area was divided into 40 x 40-meter plots, allowing for precise measurement. Each plot was thoroughly examined to identify and measure all instances of regeneration, including both shoots and seeds, within specific diameter and height classes. regeneration s up to a height of 130 cm were categorized into three distinct height classes: 0-45 cm, 45-90 cm, and 90-130 cm. For regenerations taller than 130 cm, the analysis focused on diameter classes, specifically 0-2.5 cm, 2.5-5 cm, and 5-7.5 cm. To assess the normality of the data, the Kolmogorov-Smirnov test was employed. When data were normally distributed, statistical analyses included the Independent-Samples T Test, One-Way ANOVA, and Tukey’s post hoc test. For non-normally distributed data, the study used the Kruskal-Wallis and Mann-Whitney U tests to draw conclusions.
Findings: The results of the measurement of regeneration at the level of natural and exploited stands showed that the number of regenerations in the natural stand is equal to 1933 plants per hectare (623 seed breeding and 1310 branch breeding) and in the exploited plant it is equal to 247 plants. per hectare (88 seed breeding and 159 branch breeding). The average fertility of different species in the natural stand was 42.02 and in the exploited stand was 8.99 stems per hectare, and the difference between the two stands was significant at the 99% confidence level. The five main species that had the highest regeneration and were investigated in the altitude and diameter classes were Quercus infectoria, Quercus libani, Crataegus aronia L, Pyrus spp and Rosa canina, whose average regeneration in the altitude class is equal to 84.33 stems and in the exploited stand was equal to 12.53 stems per hectare, and the two stands had a significant difference at the 99% confidence level. Also, the average fertility in the diameter class of the main investigated species in the natural stand was 40.6 plants and in the exploited plant was 4.8 plants per hectare, and the two stands in this class also had a significant difference at the 99% confidence level.
Conclusion: Knowledge of the quantitative and qualitative state of regeneration of these forests is very important in the management planning of Zagros forests. Considering the state of the natural mass (less disturbed) and realizing the positive effect of protection and non-exploitation of the forests of this area, it can be concluded that if the exploited forests are properly managed, these forests will also have the ability have reconstruction and revival; Therefore, it is necessary to take positive steps by conducting more research and participation of forest dwellers in preserving and reviving these forests before the loss of natural reproductive power.