Abstract:
Lebanon, a biodiversity hotspot in the Mediterranean basin, hosts a wide array of endemic taxa and plant species with distinct biogeographical origins. Among its most iconic ecosystems are cedar forests dominated by Cedrus libani, which support distinct microbial communities vital for forest health and ecosystem resilience. Traditional cultivation-based methods are inadequate for capturing the extent of soil microbial diversity. Given these limitations, metagenomic approaches offer a more comprehensive and culture-independent means of exploring microbial diversity and assessing ecological roles within cedar forest soils.
This study employed a metagenomic approach to assess the differences in soil microbial community composition across six major Lebanese cedar forests: Ain Zhalta, Barouk, Bchare, Ehden,Maaser,and Tannourine cedars forests. A total of 36 soil samples were collected, followed by DNA extraction, whole-genome sequencing, and in silico analysis. Taxonomic profiling using KrakenUniq revealed distinct community structures highlighted the dominance of key bacterial phyla Proteobacteria and Actinobacteria along with the genera Streptomyces and Bradyrhizobium.
Alpha diversity analysis using Shannon and Simpson indices demonstrated significant variation in microbial richness and evenness among the forests, with Tannourine exhibiting the highest diversity. Beta diversity analysis using principal coordinate analysis (PcoA) further confirmed the significant difference in microbial composition between forests, with Tannourine’s samples grouped to the right forming a well-separated cluster, while other forests showed distinct shifts, likely due to local environmental factors.
These findings provide new insights into the spatial variation of soil microbial communities across Cedrus libani forests in Lebanon and highlight the ecological importance of microbiomes in sustaining forest health. Understanding these microbial patterns is critical for developing informed conservation strategies and guiding ecosystem management practices in biodiversity-rich forest habitats.
