High fire-derived nitrogen deposition on central African forests

Area of Science:

• Environmental Science
• Ecology
• Biogeochemistry

Background:

• Atmospheric nitrogen (N) deposition influences ecosystem N availability and biogeochemical cycles globally.
• Remote tropical forests are often assumed to receive low N deposition due to limited anthropogenic activities.
• Anthropogenic N deposition can disrupt ecosystem stoichiometry and functioning.

Purpose of the Study:

• To quantify atmospheric nitrogen deposition in the central Congo Basin.
• To characterize the organic fraction of atmospheric N deposition.
• To identify the sources of atmospheric N deposition in this region.

Main Methods:

• Field-based measurements of N deposition.
• Ultrahigh-resolution mass spectrometry for organic N characterization.
• Satellite data and modeling for atmospheric N source apportionment.

Main Results:

• Central Congo Basin forests receive 18.2 kg N hectare⁻¹ year⁻¹ via wet deposition, with significant dry deposition.
• Approximately 50% of the total N deposition is in organic forms.
• The primary source of atmospheric N is intensive seasonal biomass burning.

Conclusions:

• Tropical forests, like the Congo Basin, receive substantial atmospheric N deposition, contrary to previous assumptions.
• The significant organic N fraction and biomass burning source have critical implications for regional ecology.
• Findings necessitate re-evaluation of N deposition impacts on tropical ecosystems and global biogeochemical cycles.