Fine-scale landscape heterogeneity drives microbial community structure at Robinson Ridge, East Antarctica

Area of Science:

• Environmental Science
• Microbiology
• Ecology

Background:

• Antarctic ecosystems are vulnerable to climate change.
• Soil microbial communities are vital but understudied in East Antarctica.
• Previous research focused on vegetation, neglecting microbial responses.

Purpose of the Study:

• To establish baseline data for soil microbial communities at Robinson Ridge, East Antarctica.
• To investigate the fine-scale heterogeneity of soil environmental and microbial properties along a hillslope.
• To identify environmental drivers shaping microbial community structure and distribution.

Main Methods:

• Established triplicate 300-m transects across a hillslope with varying soil moisture and vegetation.
• Assessed soil environmental properties (fertility, moisture) and microbial community composition.
• Utilized Gradient Forest modeling to identify critical environmental thresholds influencing microbial communities.

Main Results:

• Moist, low-lying soils showed higher fertility and unique biodiversity (Tardigrada, Phloroplastophyta, Chloroflexi, Fibrobacterota, Mucoromycota, Cyanobacteria).
• Elevated, arid soils were dominated by metabolically diverse phyla (Actinobacteriota, Ascomycota).
• Significant microbial differences were found at hillslope (50-300 m) and fine (0.1 m) scales, with vertical heterogeneity suggesting biocrust formation.

Conclusions:

• Microbial community structure is strongly influenced by topography, soil moisture, and nutrient gradients.
• Environmental thresholds (ammonia, manganese, sulfur) drive significant community shifts.
• Finer-scale investigations are essential for understanding Antarctic microbial ecology and predicting ecosystem responses to climate change.