Long term carbon export from mountain forests driven by hydroclimate and extreme event driven landsliding

Area of Science:

• Earth and Environmental Sciences
• Geochemistry
• Climate Science

Background:

• Terrestrial organic carbon export influences geological carbon cycle and climate.
• Modern river sampling limits understanding of long-term carbon export dynamics.
• Hydroclimate and extreme events impact erosion and carbon yields over millennial timescales.

Purpose of the Study:

• To reconstruct past organic carbon yields from terrestrial ecosystems.
• To investigate the influence of extreme events and hydroclimate on carbon export.
• To assess the role of organic carbon export in the geological carbon cycle.

Main Methods:

• Volumetric reconstruction of lake sedimentary fills.
• Generation of time-series data for sediment and organic carbon yields.
• Analysis of data from two catchments in the Southern Alps, New Zealand, over the last millennium.

Main Results:

• Earthquake-induced landslides significantly increase sediment and organic carbon yields (~40% of total).
• Organic carbon export doubled during wetter centuries between extreme events.
• Pulsed export events driven by landslides are a major component of carbon export.

Conclusions:

• Hydroclimate variability and extreme events (landslides) are critical drivers of organic carbon export.
• Organic carbon export linked to hydroclimate may act as a negative feedback in the long-term carbon cycle.
• Lake sediment records provide valuable insights into millennial-scale carbon dynamics.