Further reduction in soil bacterial diversity under severe acidification in European temperate forests

Area of Science:

• Environmental Science
• Soil Science
• Microbiology

Background:

• Soil acidification is a persistent issue in European forests despite reduced industrial deposition.
• Intense agriculture and urbanization exacerbate soil acidification, impacting forest health.
• Understanding the effects of extreme soil acidity on microbial communities is crucial for ecosystem management.

Purpose of the Study:

• To investigate the impact of severe soil acidification on bacterial taxonomic diversity and functional implications for nutrient cycling in European forests.
• To identify key soil parameters influencing acidophilic bacterial communities under extreme pH conditions.
• To demonstrate the continuous decline in bacterial diversity with decreasing pH in severely acidic forest soils.

Main Methods:

• Utilized topsoil environmental DNA (eDNA) metabarcoding across 49 forest plots in The Netherlands and Germany.
• Applied functional annotations to assess potential impacts on nutrient cycling processes.
• Analyzed soil parameters to understand their influence on acidophilic bacterial communities.

Main Results:

• Confirmed pH as the primary driver of soil bacterial communities, even in extremely acidic soils (pH <4.5).
• Observed a continuous decline in bacterial diversity with decreasing pH across different forest types.
• Identified a shift in bacterial communities, favoring recalcitrant carbon degradation and diminishing nitrogen cycling taxa.

Conclusions:

• Severe soil acidification continues to reduce bacterial diversity in European temperate forests, impacting ecosystem functioning.
• The observed changes in bacterial communities disrupt crucial nutrient cycling processes (immobilization and mineralization).
• Severely acidified forests require inclusion in conservation and monitoring programs to prevent irreversible soil degradation.