Ecology of Iranian Forest

Extended Abstract

Background: Arbuscular mycorrhizal fungi (AMF) are a crucial component of soil microflora, forming symbiotic relationships with approximately 80% of plant species. These fungi play a significant role in enhancing plant nutrient uptake, improving soil structure, and promoting ecosystem health. The present study aimed to identify the morphology of arbuscular mycorrhizal fungi across three distinct habitats—Shanachir, Ilam, and Malekshahi—each characterized by different climatic conditions. Additionally, the study focused on two aspect slopes, north and south, within the oak forests of Ilam province. Understanding the diversity and distribution of AMF in these varying environments can provide insights into their ecological roles and the factors influencing their populations.
Methods: To collect soil samples, a total of 20 mixed soil samples were taken from each habitat, ensuring representation from both north and south aspect slopes. This resulted in a comprehensive collection of 60 samples across the three habitats, all obtained through a completely random sampling plan from a depth of 0-20 cm during the spring season. The extraction of AMF spores was conducted using a method that involved sieving and centrifugation with sucrose, which is effective for isolating fungal spores from soil. Identification of the mycorrhizal fungi was performed based on morphological characteristics, utilizing identification keys and reliable online resources. The abundance percentage of each fungal species was calculated based on the proportion of spores belonging to each species within the total sample. To analyze the similarity of fungal species across different habitats and aspect slopes, a Venn diagram was employed. This visual representation allowed for a clear understanding of species overlap and diversity among the sampled areas.
Results: The study identified a total of 39 species of arbuscular mycorrhizal fungi belonging to 11 genera across the three studied areas and two aspect slopes. Specifically, 36 fungal species from 11 genera were recorded in the Ilam habitat, while the Malekshahi habitat yielded 37 species from the same number of genera. In contrast, 34 fungal species from 10 genera were identified in the Shanachir area. The genera Acaulospora and Glomus exhibited the highest relative frequency across all habitats and aspect slopes, indicating their dominance in these ecosystems. Among the identified species, Glomus nanolumen and Acaulospora lacunosa were the most abundant, consistently showing high percentages of fungal species abundance across all habitats. The analysis of species similarity revealed that 30 species of mycorrhizal fungi, accounting for 76.92% of the total species identified, were common among the different habitats. Notably, one endemic species, Glomus macrocarpum, was found exclusively in the Malekshahi region. Statistical analysis indicated a significant difference in spore density among the study areas (p=0.000). The highest spore density was recorded in the Malekshahi and Shanachir habitats, surpassing that of the Ilam habitat. Furthermore, the average spore density was consistently higher in the southern aspect slopes compared to the northern slopes. Specifically, the average spore density varied from 111.20 spores per 100 grams of soil in Ilam to 140.25 spores per 100 grams in Malekshahi. Among the aspect slopes, spore density ranged from 105.60 in the northern Ilam to 150.90 in the southern Malekshahi.
Conclusion: The results of this study demonstrate significant variations in the diversity and distribution of arbuscular mycorrhizal fungi across different habitats and aspect slopes. The number of fungal species, their distribution patterns, and spore densities varied considerably, with the highest spore density observed in the southern aspect slope and the Malekshahi region. These findings underscore the importance of environmental factors, such as climatic conditions and soil characteristics, in shaping the composition and abundance of mycorrhizal fungi. Understanding the dynamics of AMF in relation to their plant partners is essential for improving ecosystem management and conservation strategies. The presence of endemic species highlights the need for targeted conservation efforts in specific regions. Future research should explore the functional roles of these fungi within their ecosystems and assess how changes in land use and climate may impact their populations and the overall health of forest ecosystems. By fostering a deeper understanding of arbuscular mycorrhizal fungi, we can enhance our ability to maintain and restore the ecological balance in these vital habitats.