Nitrogen deposition and climate: an integrated synthesis.

Area of Science:

• Ecology
• Environmental Science
• Biogeochemistry

Background:

• Human activities have significantly increased reactive nitrogen (N) deposition globally, disrupting natural N cycles.
• This nitrogen enrichment impacts plant, animal, and microbial communities, but responses vary greatly.
• Predicting ecosystem responses is challenging due to variability influenced by local environmental factors.

Purpose of the Study:

• To synthesize the impacts of elevated N deposition on grassland ecosystems.
• To investigate the causes of variation in biotic responses to N deposition across different scales.
• To understand the relative importance of various factors, including climate, soil, and nutrient interactions, in modulating ecosystem responses.

Main Methods:

• Literature synthesis of reported impacts of elevated N on grasslands.
• Analysis of data from the globally distributed Nutrient Network (NutNet) experiment.
• Examination of interactions between N deposition, climate, soil properties, and other nutrient limitations.

Main Results:

• Elevated N deposition and local climate frequently interact, significantly altering biotic responses.
• Edaphic (soil) context plays a crucial role in determining ecosystem sensitivity to N deposition.
• Interactions with other limiting nutrients are widespread and influence biotic responses to N enrichment.

Conclusions:

• Ecosystem responses to nitrogen deposition are complex and context-dependent.
• Climate and soil conditions are key factors mediating the effects of N enrichment on biodiversity.
• Understanding these interactions is vital for predicting grassland ecosystem futures under continued anthropogenic N deposition.