Francois-Nicolas,

I think that there is greater propensity with thicker forest litter. De Graff (2014) notes that post-fire debris flow depends on the degree of burn and areas subjected to forest fires usually exhibit differential burning. In areas of moderate to high soil burn there is more unshielded soil, thus more susceptibility to erosion and slides. It stands to reason that areas with more forest litter will burn hotter and more completely than areas with insufficient mass. There is likely to also be a correlation between slope and flow as related to forest litter, with steep slopes not accumulating mass while still being susceptible to wasting.

Additionally, I would look into the lubricating effect of the ash residue on the post-fire debris flow, which possibly could be different than a debris/soil flow and more similar to a pyroclastic flow.

https://geoenvironmental-disasters.springeropen.com/articles/10.1186/s40677-014-0005-2

http://landslides.usgs.gov/hazards/postfire_debrisflow/

 Hello Francois, 

 I have a paper under review( Estimating the spatial distribution and locating hotspots of forest biomass from harvest residues and fire-damaged stands in Canada's managed forests) showing the link between forest productivity and  biomass residues available after fire and harvest

 I used the following refs to map and quantify the national woody biomass potentially available from salvage logging of fire-damaged stands and from harvest residues from clearcut areas.

  A. Beaudoin, P.Y. Bernier, L. Guindon, P. Villemaire, X.J. Guo, G. Stinson, T. Bergeron, S. Magnussen, R.J. Hall, Mapping attributes of Canada’s forests at moderate resolution through kNN and MODIS imagery, Can. J. For. Res. 44 (5) (2014) 521-532.

 L. Guindon, P.Y. Bernier, A. Beaudoin, D. Pouliot, P. Villemaire, R.J. Hall, R. Latifovic, R. St-Amant, Annual mapping of large forest disturbances across Canada’s forests using 250 m MODIS imagery from 2000 to 2011, Can. J. For. Res., 44 (12) (2014) 1545-1554.

 I'll be happy to help if you have more questions and' of course the paper will be available once published.

 Cheers Nick

There certainly are relationships like this for post-wildfire wind erosion of soil and dust emission. The amount of dust produced by wind erosion after a fire varies by the vegetation type that covered the soil pre-fire (and was consumed by the fire).

Here are a couple of my papers that have examples of this:

https://www.researchgate.net/publication/228520183_Dust_supply_varies_with_sagebrush_microsites_and_time_since_burning_in_experimental_erosion_events

https://www.researchgate.net/publication/258663425_Quantifying_soil_surface_change_in_degraded_drylands_Shrub_encroachment_and_effects_of_fire_and_vegetation_removal_in_a_desert_grassland

I realize this is not directly related to your question, but it is probably analogous (e.g., sediment supply after fire probably varies by pre-fire landcover/vegetation/biomass for other geomorphic processes too).

Article Dust supply varies with sagebrush microsites and time since ...

Article Quantifying soil surface change in degraded drylands: Shrub ...

Hi guys,

Thanks a lot for your answers. I'll go through those references and hopefully it will be enough to justify the use of forest biomass as a proxy to post-fire debris flow occurrence. As my study is a global scale, with a 0.25deg resolution, I think it should be enough to backup my statement.

Cheers,

F.

From the references I've checked here and there, it seems that the most important recruitment factors of coarse woody debris are the forest age, then the distance to the stream, and the carrying capacity of the stream. This is independent of burned areas, for which I couldn't find any precise measure of pre-fire forest structure, although woody debris flows are more important directly after a fire and then tend to decrease below pre-fire levels.

As there is no global data about forest age, I will use forest height as a proxy. The relationship is not linear, but generally speaking, trees grow in height when the age. I will have to create some subdataset according to forest types, but I think it's a decent proxy. Still have to backup this though.