Key drivers of pyrogenic carbon redistribution during a simulated rainfall event

Abstract

Abstract. Pyrogenic carbon (PyC) is produced by the incomplete combustion of vegetation during wildfires and is a major and persistent pool of the global carbon (C) cycle. However, its redistribution in the landscape after fires remains largely unknown. Therefore, we conducted rainfall simulation experiments on 0.25-m2 plots with two distinct Swiss forest soils (Cambisol (clay loam) and Luvisol (sandy silt)). We applied PyC produced from wood (Picea abies) labelled under FACE conditions and C4-grass (Miscanthus sinensis) to the soil surface to study PyC redistribution by runoff and splash, and the vertical mobility of PyC in a 10 cm unsaturated soil column based on the differences in δ13C of soils and PyC. We assessed the effect of soil texture, slope angle and PyC characteristics (feedstock and particle size) on the mobility of PyC during 30 minutes of intense rainfall (102 mm h−1). Our results highlight that PyC is highly mobile. Surface runoff transported between 0.2 to 36.0 % of the total added PyC. Erosion by splash further redistributed 10.3 to 25.3 % of the added PyC. Soil type had a substantial impact on the redistribution of PyC by both runoff and splash: on average, we recovered 10.5 % of the added PyC in runoff and splashed material for the clay-rich Cambisol and 61.3 % of the added PyC for the sandy silt Luvisol combined. PyC feedstock had a clear, but contrasting effect on PyC redistribution: relocation in the runoff and splashed material was greater for wood-PyC (43.4 % of total added PyC) than grass-PyC (28.4 %). However, more wood-PyC (11.5 %; fraction of organic C derived from the PyC) remained where it was initially applied compared to grass-PyC (7.4 %). The results further suggest that the effect of PyC characteristics on its mobility can be highly variable and depend not only on the material from which it was derived, but also on other factors (e.g. particle size, porosity, density). In particular, the mobility of PyC was almost twice as large for fine-grained PyC (

Key drivers of pyrogenic carbon redistribution during a simulated rainfall event

“…Data availability. The data related to this article are available at https://doi.org/10.5281/zenodo.4422514 (Bellè and Abiven, 2021).…”

Wildfire-derived pyrogenic carbon modulates riverine organic matter and biofilm enzyme activities in an in-situ flume experiment

“…Actual amounts would depend on site factors such as fire behavior, amount and type of fuel affected, slope steepness, and size of the hydrological event. 6,8 The filter bags had a mesh size < 50 µm to allow the release of small PyC particles and DOC. In the control flumes, filter bags without PyC were added to account for potential riverine DOM interactions with the filter bag.…”

“…3 In fire-affected landscapes fresh as well as aged PyC, in both dissolved and particulate forms, is mobilized to fluvial ecosystems via water erosion. [4][5][6] Indeed, significant charcoal presence in river bed deposits in fire affected ecosystems have been the subject of investigation decades ago 7 and hydrological events (e.g. stormwater runoff) can transport large quantities of PyC into river ecosystems in short periods of time.…”

“…stormwater runoff) can transport large quantities of PyC into river ecosystems in short periods of time. 6,8 Coppola and colleagues 9 found that globally 15.8 ± 0.9% of riverine particulate organic carbon is of pyrogenic origin.…”

Wildfire-Derived Pyrogenic Carbon Modulates Organic Matter and Microbial Functioning in a Fluvial Ecosystem

“…surface runoff). [3][4][5] Coppola and colleagues 6 found that globally 15.8 ± 0.9% of riverine particulate organic carbon is of pyrogenic origin. Jones and colleagues 7 estimated that PyC accounts for 12 ± 5% of the riverine dissolved organic carbon (DOC, i.e., filtered < 0.45 µm).…”