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چکیده
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Soil bacteria are integral to ecosystem functioning, significantly contributing to nutrients cycling and organic matter decomposition, and enhancing soil structure. This research considered the composition and dynamics of soil bacterial communities under different vegetation types (native Quercus brantii Lindl. and Amygdalus scoparia Spach, and non-native Pinus eldarica Medw. and Cupressus arizonica Greene.) in Zagros mountain area of Iran. This study involved a comparative analysis of soil culturable heterotrophic bacterial communities in spring (wet season) and summer (dry season) to clarify the effects of seasonal changes and vegetation on the dynamics of soil microorganisms. Soil samples were randomly collected under the canopies of various tree species and a control area, yielding a total of 48 composite samples analyzed for bacterial composition. Results indicated that 11 Gram-negative (e.g., Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, etc.) and 2 Gram-positive (Staphylococcus epidermidis and Staphylococcus aureus) bacteria were identified, showing significant seasonal variation. Specifically, 53.85% of bacterial species were common to both seasons, with notable shifts in community composition observed between spring and summer, highlighting a higher abundance of Gram-negative species in spring. Bacterial community structure was significantly influenced by vegetation type, with various tree species shaping distinct microbial assemblages. Moreover, Pearson's correlations revealed that soil properties, particularly pH, phosphorus, and moisture content, were critical drivers of bacterial diversity and abundance. Our findings underscore the dynamic nature of soil bacterial communities in response to seasonal and vegetation changes, emphasizing the importance of repeated temporal sampling for accurate assessments of microbial diversity. Understanding these microbial dynamics is essential for improving soil management strategies and enhancing ecosystem resilience, particularly in arid and semi-arid areas where environmental fluctuations play a pivotal role. This research not only confirms our hypotheses but also enhances our understanding of soil biogeochemical processes and informs future vegetation management practices.
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