Loss in microbial diversity affects nitrogen cycling in soil

Area of Science:

• Ecology
• Microbiology
• Soil Science

Background:

• Microbial communities are vital for Earth's biogeochemical cycles.
• The link between microbial diversity and ecosystem functioning remains debated.
• Denitrifiers play a key role in nitrogen cycling, a critical ecosystem service.

Purpose of the Study:

• To experimentally assess the functional consequences of soil microbial diversity loss.
• To investigate the relationship between denitrifier diversity metrics and ecosystem processes.
• To determine how resource availability influences the microbial diversity-functioning relationship.

Main Methods:

• Soil microbial communities were manipulated using a dilution approach.
• Denitrifier diversity (richness, evenness, phylogenetic diversity) was assessed via 454 sequencing.
• Potential denitrification activity was measured under varying resource levels (wheat residues).

Main Results:

• Dilution treatments significantly reduced denitrifier richness and diversity.
• A five-order-of-magnitude dilution decreased estimated richness by 75%.
• Reduced denitrifier diversity led to a 4-5 fold decrease in potential denitrification activity.
• Wheat residue addition amplified differences in denitrification between diversity levels.

Conclusions:

• Microbial diversity loss demonstrably alters terrestrial ecosystem processes.
• The importance of functional redundancy in soil microbial communities may be overstated.
• Resource availability modulates the impact of microbial diversity on ecosystem functioning.