Global comparison shows that soil bacterial communities in extreme pH soils are more structured by deterministic...

Area of Science:

• Microbial Ecology
• Soil Science
• Community Ecology

Background:

• Understanding the ecological principles governing microbial community variation is a key goal in microbial ecology.
• Previous studies indicated soil pH influences the balance between stochastic and deterministic processes in bacterial communities.
• Neutral pH soils were previously found to be more influenced by stochastic processes than low or high pH soils.

Purpose of the Study:

• To definitively determine if soil pH is a dominant factor in structuring bacterial communities.
• To analyze bacterial community structuring across a global dataset of 237 soil samples.

Main Methods:

• Utilized a global database of 237 soil samples for analysis.
• Employed the beta-nearest taxon index (beta-NTI) to quantify the relative importance of stochastic versus deterministic processes.
• Examined community structuring at both global and continental scales.

Main Results:

• Globally and continentally, low pH soils showed dominance of deterministic processes.
• Neutral pH soils consistently exhibited dominance of stochastic processes.
• High pH soils showed global stochastic dominance, but continental-scale determinism was observed in some regions.
• A consistent pattern emerged: determinism at low pH and stochasticity at neutral pH.

Conclusions:

• Soil pH strongly and predictably affects bacterial community structuring.
• The most consistent finding is the contrast between deterministic processes at low pH and stochastic processes at neutral pH.
• Further research, including hypothesis testing, is needed to elucidate the mechanisms behind these pH-driven trends, potentially involving resource exploitation and niche-based competition.