Impact of fires on soil properties, runoff generation and sediment transport

Notes on session Session SSS 9.6/GM 6.7/HS 12.6 (EGU2013)

Conveners: Lee MacDonald; Jonay Neris; Stefan Doerr; Artemi Cerdà; J. Jacob Keizer

Wildfires are increasingly recognized as the primary cause of geomorphic change in forests and brush lands, and climate change is expected to further increase both the amount and severity of wildfires. Recent studies have provided an increasing amount of data on how fires can affect runoff and erosion rates, but there is still much to be done on the underlying causes of the observed increases, and how fire affects vary across vegetation types, climates, and spatial scale.

Post-wildfire landscape.
Post-wildfire landscape.

Dr. Scott Woods at the University of Montana was taking a leading role in this process-based research until his career was tragically ended by lung cancer. The Soil System Science sponsored a session in his honor during the 2013 EGU meeting, and this was entitled Impact of fires on soil properties, runoff generation and sediment transport.  The main aim of this session was to discuss the recent studies on the effects of fires on soil properties, the resultant changes in runoff and erosion rates, and the effectiveness of different post-fire treatments to mitigate these effects.

Impact of fires on soil properties, runoff generation and sediment transport oral session.
Impact of fires on soil properties, runoff generation and sediment transport oral session.

Twenty-four papers were submitted to this session.  The morning oral session in the morning began with a brief summary of Scott’s career, and this was followed by eight talks.  The session then shifted to a different room where a series of short presentations summarized many of the 16 poster papers.    The afternoon poster session then provided a lively venue for further discussions, and in the evening many of the presenters attended the special dinner for all those working on topics related to soil erosion.  Discussions are being held regarding the possible publication of the papers in a special issue of a peer-reviewed journal.

Biogeosciences: Soil CO2, CH4 and N2O fluxes from an afforested lowland raised peatbog in Scotland: implications for drainage and restoration

Soil CO2 CH4 and N2O fluxes from an afforested lowland raised peatbog in Scotland: implications for drainage and restoration. S. Yamulki, R. Anderson, A. Peace, and J. I. L. Morison. Biogeosciences, 10, 1051-1065, 2013


The effect of tree (lodgepole pine) planting with and without intensive drainage on soil greenhouse gas (GHG) fluxes was assessed after 45 yr at a raised peatbog in West Flanders Moss, central Scotland. Fluxes of CO2 CH4 and N2O from the soil were monitored over a 2-yr period every 2 to 4 weeks using the static opaque chamber method in a randomised experimental block trial with the following treatments: drained and planted (DP), undrained and planted (uDP), undrained and unplanted (uDuP) and for reference also from an adjoining near-pristine area of bog at East Flanders Moss (n-pris). There was a strong seasonal pattern in both CO2 and CH4 effluxes which were significantly higher in late spring and summer months because of warmer temperatures. Effluxes of N2O were low and no significant differences were observed between the treatments. Annual CH4 emissions increased with the proximity of the water table to the soil surface across treatments in the order: DP < uDP < uDuP < n-pris with mean annual effluxes over the 2-yr monitoring period of 0.15, 0.64, 7.70 and 22.63 g CH4 m−2 yr−1, respectively. For CO2, effluxes increased in the order uDP < DP< n-pris < uDuP, with mean annual effluxes of 1.23, 1.66, 1.82 and 2.55 kg CO2 m−2yr−1, respectively. CO2 effluxes dominated the total net GHG emission, calculated using the global warming potential (GWP) of the three GHGs for each treatment (76–98%), and only in the n-pris site was CH4 a substantial contribution (23%). Based on soil effluxes only, the near pristine (n-pris) peatbog had 43% higher total net GHG emission compared with the DP treatment because of high CH4 effluxes and the DP treatment had 33% higher total net emission compared with the uDP because drainage increased CO2 effluxes. Restoration is likely to increase CH4 emissions, but reduce CO2 effluxes. Our study suggests that if estimates of CO2 uptake by vegetation from similar peatbog sites were included, the total net GHG emission of restored peatbog would still be higher than that of the peatbog with trees.

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Biogeosciences (BG) is an international scientific journal dedicated to the publication and discussion of research articles, short communications and review papers on all aspects of the interactions between the biological, chemical and physical processes in terrestrial or extraterrestrial life with the geosphere, hydrosphere and atmosphere. The objective of the journal is to cut across the boundaries of established sciences and achieve an interdisciplinary view of these interactions. Experimental, conceptual and modelling approaches are welcome. More at Biogeosciences homepage.

From tailings to soil?

Talitha Santini                                                                                                                                    School of Geography and Earth Sciences, McMaster University

Figure 1 Vegetation cover at sewage sludge treated area.

‘Cap and store’ approaches to tailings management are increasingly being replaced by in situ remediation initiatives, in which plant cover is established directly in the tailings material. In situ remediation involves changing tailings properties (e.g. pH, EC) from very low (pH 1-3) or very high (pH 9-13, EC >4 mS/cm) values to plant-tolerable values, by way of applied treatments and weathering. Pedogenesis is implicit in in situ remediation strategies because establishment of plant cover is usually the end goal. Continue reading

Messy Soil: Spolic Anthroposols

Jess Drake
PhD Candidate, The Australian National University

One soil that I don’t think we talk about enough are Anthroposols: human modified soils. They are all around us; in our backyards, our cities, on highways, and on mine sites. The properties of Anthroposols and how we manage them is really fascinating. In particular, I really love working with Spolic Anthroposols. Continue reading