Increased rainfall variability and N addition accelerate litter decomposition in a restored prairie

Area of Science:

• Ecology
• Environmental Science
• Biogeochemistry

Background:

• Anthropogenic nitrogen deposition and increased rainfall variability are key global change factors.
• These factors are expected to influence ecosystem processes, particularly litter decomposition.
• The interactive effects of nitrogen deposition and rainfall variability on litter decomposition remain largely unknown.

Purpose of the Study:

• To investigate the interactive effects of increased rainfall variability and nitrogen addition on litter decomposition.
• To examine how these factors influence mass and nitrogen loss of litter from two tallgrass prairie species.
• To differentiate the impacts of treatments applied during plant growth versus during litter decomposition.

Main Methods:

• Simulated increased rainfall variability by consolidating rainfall into larger events.
• Simulated chronic nitrogen deposition using slow-release urea fertilizer.
• Assessed mass and nitrogen loss of litter from Schizachyrium scoparium and Solidago canadensis.

Main Results:

• For S. scoparium, litter decomposition was more influenced by treatments during plant growth; increased rainfall variability slowed decomposition and increased nitrogen immobilization, while nitrogen addition accelerated mass loss.
• For S. canadensis, both nitrogen addition and increased rainfall variability (during growth and decomposition) enhanced litter mass and nitrogen loss.
• These findings indicate that combined global change factors alter litter quality and accelerate nutrient cycling.

Conclusions:

• Changes in rainfall variability and nitrogen availability interact to influence litter decomposition dynamics in tallgrass prairies.
• These interactions affect litter quality, environmental conditions, and potentially plant community composition.
• The study suggests an acceleration of nutrient cycling in these ecosystems due to ongoing global change.