Variable carbon losses from recurrent fires in drained tropical peatlands

Area of Science:

• Environmental Science
• Climate Change Research
• Remote Sensing Applications

Background:

• Tropical peatland fires are a major source of greenhouse gas emissions contributing to global warming.
• Current understanding of carbon loss and peat consumption from these fires is limited, with few studies quantifying peat mass loss.
• Spatial and temporal variations in burn depth, a key factor in carbon loss, have not been previously quantified.

Purpose of the Study:

• To conduct the first spatially explicit investigation of fire-driven tropical peat loss and its variability.
• To quantify burn depth and analyze its relationship with fire frequency and proximity to drainage canals.
• To revise existing estimates of peat and carbon loss from recurrent fires in drained tropical peatlands.

Main Methods:

• Utilized an extensive airborne Light Detection and Ranging (LiDAR) dataset to develop a pre-fire peat surface modeling methodology.
• Enabled spatially differentiated quantification of burned area depth across the entire burned landscape.
• Analyzed the interdependence between burned area depth, fire frequency, and distance to drainage canals.

Main Results:

• Observed a strong relationship between burned area depth, fire frequency, and distance to drainage canals.
• Demonstrated that relative burned area depth decreases with the first four fire events and remains constant thereafter.
• Quantified peat fuel consumed, with values decreasing from 206 t ha⁻¹ for initial fires to 23 t ha⁻¹ for successive fires, significantly lower than IPCC default values.
• Calculated carbon losses ranging from 114 t C ha⁻¹ for the first fire to 13 t C ha⁻¹ for the fourth fire.
• Showed that proximity to drainage canals increases both burned area depth and the probability of recurrent fires.

Conclusions:

• Revised peat and carbon loss estimates for recurrent fires in drained tropical peatlands are substantially lower than current IPCC Tier 1 default values.
• Developed equations relating burned area depth to distance from drainage canals, improving spatial accuracy.
• Enhanced understanding of tropical peatland fire dynamics supports more accurate emissions accounting and facilitates IPCC Tier 2 reporting.