تاثیر جهت جغرافیایی بر تراکم و تنوع‌ گیاهی در جنگل‌های سردشت

Abstract
The results showed that Q. infectoria Oliv, Quercus brantii, and Quercus libani oaks had the highest density in the north, south, and east directions, respectively. Hawthorn had the highest density per hectare in the eastern direction. Based on the results, species diversity in the southern direction has the highest value. Geographic direction has a significant relationship with species density and diversity. Based on the results of the present research, in order to carry out management plans, one should pay attention to the spread of species in geographical directions and take necessary measures based on that. Determining and comparing biodiversity in different forest communities is of special importance for accurate knowledge and forest management. This research was conducted with the aim of investigating the effect of geographical direction on species density and diversity in the Lilane oak forests of Sardasht in an area of about 28 hectares. First, a statistical network with dimensions of 45 x 45 meters was implemented in the region in a systematic random way. In this regard, 120 sample plots (30 sample plots for each geographical direction) were established in the research area and the geographical direction, number and type of trees were recorded. According to the density of species in the sample plots, the density per hectare was calculated, and to check and compare the biodiversity from the Simpson and Shannon-Wiener species diversity indices, the species richness was calculated from the Margalf and Ghanai richness indices. Peylo and Hill's uniformity indices were used for mechanistic and species uniformity. Biodiversity index values were determined using Past software. Then, the normality of the data was done using the Kolmogorov-Smirnov test, the homogeneity of variances was done with the Lune test, and the comparison of the averages in four geographical directions was done with the Duncan test in SPSS software. The results showed that Q. infectoria Oliv, Quercus brantii, and Quercus libani oaks had the highest density in the north, south, and east directions, respectively. Hawthorn had the highest density per hectare in the eastern direction. Based on the results, species diversity in the southern direction has the highest value. Geographic direction has a significant relationship with species density and diversity. Based on the results of the present research, in order to carry out management plans, one should pay attention to the spread of species in geographical directions and take necessary measures based on that.

Introduction
Forest ecosystems contain about 70% of the world's terrestrial biodiversity. Forests are vital components of terrestrial ecosystems that provide a set of services and functions with high societal demand and biodiversity (Jenkins and Schaap, 2018). These services and functions include forest services as a primary habitat for species (some of which are critically endangered), support, maintenance and protection of biodiversity, regulation of weather and pest activities, provision food, fodder, energy and other non-timber products for the well-being of a growing population (Brockerhoff et al., 2017; Jenkins and Schaap, 2018; Damptey et al., 2021). It is also expected that with the disappearance of some species with unique traits, the functions of ecosystems will change significantly (Bricca et al., 2020). In fact, diversity is a fundamental issue in environmental protection, and its main goal is to maintain the largest possible amount of native species in an area, and this can only be achieved through understanding diversity and ways to measure it. Ejtehadi et al., 2009), therefore biodiversity protection, as one of the most important goals in the management of forest ecosystems, has a key role in the evaluation of the natural environment.

Methodology د
First, a statistical grid with dimensions of 45 x 45 meters was implemented in the region by a systematic random method. In this regard, 120 sample plots (30 sample plots for each direction) were established in the research field and the geographical direction, number and type of trees were noted. Then the data was organized and saved in Excel software. To investigate and compare biodiversity, Simpson and Shannon-Wiener species diversity indices were used, to calculate species richness, Margalf and Menchnik richness indices were used, and for species uniformity, Pylo and Hill uniformity indices were used. (Bayat, and Heidari Masteali, 2021). Biodiversity index values were determined using Past software. Then, the normality of the data was done using the Kolmogorov-Smirnov test, the homogeneity of variances was done with the Lune test, and the comparison of the averages in four geographical directions was done with the Duncan test in SPSS software.
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Conclusion
It can be said that the geographical direction has an effect on the density and biodiversity of trees and shrubs in the researched area. Considering that the conditions of the northern direction are more suitable in terms of humidity than other directions; Q. infectoria Oliv species, which has higher ecological requirements than other oak species, was more distributed in this direction. Quercus brantii is a light-loving species and has more resistance to soil and humidity changes than other oak species, so it has the highest density in the south direction. Based on the results of the present research, for forest conservation and enrichment, one should pay attention to the spread of species in geographical directions and take necessary measures based on that. Also, the lowest species diversity was seen in the northern direction and the highest in the southern direction. This importance can be due to the light-loving nature of the studied masses in the region. Because with the decrease in the intensity of the sun's radiation in the northern directions, the value of the diversity index decreased, and with the increase in the intensity of the sun's radiation, especially in the south direction, the size of this index increased.
Abstract
The results showed that Q. infectoria Oliv, Quercus brantii, and Quercus libani oaks had the highest density in the north, south, and east directions, respectively. Hawthorn had the highest density per hectare in the eastern direction. Based on the results, species diversity in the southern direction has the highest value. Geographic direction has a significant relationship with species density and diversity. Based on the results of the present research, in order to carry out management plans, one should pay attention to the spread of species in geographical directions and take necessary measures based on that. Determining and comparing biodiversity in different forest communities is of special importance for accurate knowledge and forest management. This research was conducted with the aim of investigating the effect of geographical direction on species density and diversity in the Lilane oak forests of Sardasht in an area of about 28 hectares. First, a statistical network with dimensions of 45 x 45 meters was implemented in the region in a systematic random way. In this regard, 120 sample plots (30 sample plots for each geographical direction) were established in the research area and the geographical direction, number and type of trees were recorded. According to the density of species in the sample plots, the density per hectare was calculated, and to check and compare the biodiversity from the Simpson and Shannon-Wiener species diversity indices, the species richness was calculated from the Margalf and Ghanai richness indices. Peylo and Hill's uniformity indices were used for mechanistic and species uniformity. Biodiversity index values were determined using Past software. Then, the normality of the data was done using the Kolmogorov-Smirnov test, the homogeneity of variances was done with the Lune test, and the comparison of the averages in four geographical directions was done with the Duncan test in SPSS software. The results showed that Q. infectoria Oliv, Quercus brantii, and Quercus libani oaks had the highest density in the north, south, and east directions, respectively. Hawthorn had the highest density per hectare in the eastern direction. Based on the results, species diversity in the southern direction has the highest value. Geographic direction has a significant relationship with species density and diversity. Based on the results of the present research, in order to carry out management plans, one should pay attention to the spread of species in geographical directions and take necessary measures based on that.