Comparative Study of Soil Microbial Diversity on Different Slope Orientations in Karst Rocky Mountains of Guangxi, China

Background and Research aim: Slope orientations can have a significant impact on the establishment of soil bacterial communities by influencing microclimate, soil properties and hydrological processes such as temperature, water content, pH and soil nutrients. Moreover, soil organic matter in karst ecosystems is more sensitive to environmental changes due to its lower resistance to disturbance.Methods: In this study, we analysed the multiple effects on soil bacterial community structure in karst landscapes at different slope orientations. The chemical properties of the soil of the sunny slope, the shady slope and the hilltop are compared and soil microbial communities are analyzed by high throughput sequencing.Results: We found that soil chemical properties (Total Carbon, Total Nitrogen, Total Phosphorus, Total carbon/Total Nitrogen ratio, Total carbon/Total Phosphorus ratio, Total nitrogen/Total Phosphorus ratio) differed between different slope orientations, but pH didn't differ significantly. In contrast, areas with high carbon to nitrogen ratios showed lower bacterial abundance.Conclusions: This study uncovered distinct soil chemical properties among soils with different slope orientations. At the bacterial and fungal levels, the sunny slope exhibits the properties of having more ASVs. Moreover, although the soil microbial communities exhibited similar structures across these slope orientations, there were substantial variations in species abundance and microbial characteristics. Notably, the abundance of thermophilic bacterial groups increases significantly with increasing altitude, while the bacterial communities with the highest abundance of tree species at low altitude tend to be mesophilic. This study reveals the differences in soil microbial community structure under the influence of different slope orientations, which has practical implications for the overall understanding of soil microbes in karst landscapes and the influence of slope orientation on soil microbial diversity.Implications for Conservation: This study aims to provide a reference and scientific basis for the conservation of karst microbial diversity.