Pyrogenic carbon production during an extreme-intensity heathland fire
Abstract
Pyrogenic carbon (PyC, also known as charcoal or black carbon) is an important player in the carbon balance of areas affected by wildland fires. Detailed quantification of PyC production has been carried out in recent years for key ecosystems such as boreal and temperate forests or tropical savannahs; however, data from other common fire-prone ecosystems is still missing. An accurate assessment of PyC production is challenging, as it requires detailed quantification of fuels (and PyC) before and after fire, and fire conditions representative of wildfire.
We quantified PyC production during an extreme-intensity fire in Atlantic heathland. We utilized the first large-scale (7 ha) experimental burn carried out under extreme fire conditions in NW Spain (Asturias, Oct. 2017). Before the fire, fuel loads were quantified in eight 1x1 m plots and fuel and soil samples taken. Thermologgers were placed in the litter layer and soil (1-2 cm depth). Immediately after fire, uncharred fuels, charcoal and ash loads were quantified in comparable plots, and samples taken. Organic carbon concentrations were measured in pre- and post-fire unburnt fuels, charcoal and ash. Pre-fire fuel loads ranged from 20-48 t/ha with Erica sp. and Ulex gallii being the dominant vegetation. The burn resulted in extreme fire severity with 93-97% of fuel consumed. In the litter, maximum temperatures of 535-1045 °C were recorded (n=32), whereas the soil exceeded 100 °C in only a few places where smouldering occurred. PyC production averaged 2.2 t/ha (±0.5 S.D., n=8) with most in the form of fine charred particles in the ash (2.1 t/ha ±0.5 S.D., n=8) and only a small proportion as charcoal fragments >1 cm (0.1 t/ha ±0.0 S.D., n=8). This translated into ~17% of the carbon affected by fire not being emitted, but transformed into PyC, underscoring the relevance of PyC in carbon budgets from fires and the need of more field data to improve models.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B33G2564S
- Keywords:
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- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0486 Soils/pedology;
- BIOGEOSCIENCES;
- 0496 Water quality;
- BIOGEOSCIENCES;
- 1807 Climate impacts;
- HYDROLOGY