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Esfanjani J, Zare Chahouki M A, Mahmoodi S. Assessing the Effect of Environmental Factors on Plant Diversity in Southern Rangelands of Golestan Province, Iran. ECOPERSIA 2024; 12 (3) :205-217
URL: http://ecopersia.modares.ac.ir/article-24-73523-en.html

Aims: The present study aimed to investigate beta and alpha diversities in vegetation types and examine the relationship between the distribution of plant species and environmental factors in the rangelands of southern Golestan Province, Iran.
Materials & Methods: This study was conducted in four vegetation types, namely Artemisia aucheri, Festuca ovina - Astragalus gossypinus, Bromus tomentellus, and Bromus tomentellus - Festuca ovina. The vegetation was sampled using a systematic random sampling approach. Thirty plots measuring one m2 were placed in each plant type along three 50-meter transects to measure the vegetation. In total, 120 plots were placed across the different plant types. Soil samples were collected from a depth of 0-30 cm. The soil depth was selected based on the mountainous terrain and the rooting depth of the plants. The Past software calculated plant species diversity and similarity indices between vegetation types and beta and alpha diversities. The Tukey test was used to compare the diversity indices of the plant functional groups.
Findings: The highest alpha diversity among annual plants was observed in the F. ovina-A. gossypinus type with a Shannon-Wiener index of 0.927 and a Simpson index of 0.554. At the same time, the most remarkable alpha diversity of shrub plants was associated with the same type with a Shannon-Wiener index of 1.316 and a Simpson index of 0.711. Across all four studied types, the highest richness of annual and perennial plants was observed in the A. aucheri type, with a Margalef index of 8.192 and a Menhinick index of 5.774. In contrast, the greatest richness of shrub species was observed in the F. ovina-A. gossypinus type, with a Margalef index of 3.734 and a Menhinick index of 2.677. In addition, beta diversity was calculated using the similarity index for vegetation types. The results indicated a Whittaker similarity index (beta diversity) of 0.3, 0.4, and 0.5 for annual, shrub, and perennial plants, respectively. Canonical Analysis (CA) was performed using the Canoco 4.5 software to examine the effect of environmental factors on plant species distribution. The analysis revealed that soil texture, N, organic carbon, pH, EC, and aspect were the most significant factors affecting the distribution of plant species. 
Conclusion: This research provides valuable information about rangeland plant species for primary livestock grazing and soil protection in the studied vegetation types for better land management.