CESAM Centro de Estudos do Ambiente e do Mar
2.ºSeminário Ibérico “Intervenções Raianas no Combate à Desertificação
Castelo Branco, 22-23/02/2013
Incêndios e recuperação dos solos
emergency measures for mitigating soil erosion following wildfires
J. Jacob Keizer
Sergio Prats A.
Martinho A.A. Martins
António J.D. Ferreira
Celeste O.A. Coelho
CESAM CERNAS
Centre for Environmental and Marine Studies Centro de estudos de Recursos Naturais , Ambiente e Sociedade
University of Aveiro Escola Superior Agrária de Coimbra
Dpt. Ambiente Dept. Ambiente
2SIIRCD, Castelo Branco, 22-23/02/2013
hectares
450.000
400.000
350.000
Long-term average area of burnt forest stands & woodlands
300.000
> 100.000 ha/year
(“povoamentos e matos”; © AFN)
250.000
200.000
150.000
100.000
50.000
2007
2008
2009
2010
0
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
CESAM Centro de Estudos do Ambiente e do Mar
In Portugal, wildfires have: (i) occurred frequently
(ii) affected large areas
2SIIRCD, Castelo Branco, 22-23/02/2013
and the rest of the world
CESAM Centro de Estudos do Ambiente e do Mar
In Portugal, wildfires can increase: (i) runoff generation
(ii) soil erosion
“window-of-disturbance” = post-fire erosion > pre-fire erosion
wildfire
© Shakesby & Doerr (2006: review paper “Wildfire as a hydrological and geomorphological agent”)
2SIIRCD, Castelo Branco, 22-23/02/2013
CESAM Centro de Estudos do Ambiente e do Mar
In Portugal, “window of disturbance” can last: (i) 2-5 years (Shakesby et al.)
(ii) ???
soil loss
(g m-2 mm-1 rain)
Soil
© Shakesby et al. (1993, 94, 96)
- north-central Portugal
- pine and eucalypt stands
- 16 m2 erosion plots
window-of-disturbance
2 year
5 year
background erosion
time-since-fire
(years)
2SIIRCD, Castelo Branco, 22-23/02/2013
CESAM Centro de Estudos do Ambiente e do Mar
Post-fire erosion looks like …..
2SIIRCD, Castelo Branco, 22-23/02/2013
CESAM Centro de Estudos do Ambiente e do Mar
Post-fire erosion looks like ……… that in USA, California
2nd year after wildfire
and …… after “heli-mulching”
79 ha burnt
catchment
Video footage courtesy
Devore resident
Mr. Davis
© P. Robichaud, Forest Service, USDA, USA
2SIIRCD, Castelo Branco, 22-23/02/2013
CESAM Centro de Estudos do Ambiente e do Mar
“heli-mulching” is ………
2SIIRCD, Castelo Branco, 22-23/02/2013
CESAM Centro de Estudos do Ambiente e do Mar
“heli-mulching” is ……… spreading, by heli, of organic layer on soil surface
- straw (Devore example)
- forest logging residues
- pine needles
- “hydro-mulch”
In the USA: - post-fire mulching is a common practice (but not always succesful)
- ,,
,,
is exhaustively tested by field trials
In Portugal: - post-fire mulching is rarely applied but ……..
is contemplated under PRODER 2.3.2.1
(Sub-acção Estabilização de Emergência Após Incêndio”)
- ,,
,,
is poorly tested by field trials
2SIIRCD, Castelo Branco, 22-23/02/2013
CESAM Centro de Estudos do Ambiente e do Mar
Field trials of effectiveness of mulching in reducing post-fire erosion?
- north-central Portugal
- principal forest types: eucalypt and pine plantations
2007 => P. do Vouga
2008 => Colmeal
2010 => Ermida
2012 => Várzea
next: 2 examples
2SIIRCD, Castelo Branco, 22-23/02/2013
CESAM Centro de Estudos do Ambiente e do Mar
example 1: hydro-mulching in Maritime Pine plantation, following logging
- mixture of fibers, seeds, fertilizer, colorant and water
- expense, also in terms of application (water is heavy!!)
untreated
treated
untreated
treated
treated
untreated
treated
untreated
2SIIRCD, Castelo Branco, 22-23/02/2013
CESAM Centro de Estudos do Ambiente e do Mar
example 2: forest residue mulching in eucalypt plantation, Ermida
- eucalypt biomass for power plants
- 30€/Mg
untreated
treated
treated
untreated
treated
untreated
2SIIRCD, Castelo Branco, 22-23/02/2013
Monthly soil losses
(g m-2)
70
30
(c)
untreated
Control
Hm
treated
25
I30
50
20
40
15
*
30
*
20
10
*
* *
*
10
*
*
*
5
*
*
Oct-10
Oct
10
Sep-10
Aug-10
Jul-10
Jun-10
May-10
Apr-10
Mar-10
Feb-10
Jan-10
Dec-09
Nov-09
Oct-09
Sep-09
Jul-09
Aug-09
hydro-mulching
Jun-09
May-09
Apr-09
Mar-09
Feb-09
Jan-09
0
Dec08
Dec-08
0
© Prats et al. (in prep.) Effectiveness of hydro-mulching to reduce runoff and erosion in a recently burnt
and logged Maritime Pine stand in north-central Portugal
I30(mm h-1)
60
Soil erosion (g m-2)
CESAM Centro de Estudos do Ambiente e do Mar
effectiveness example 1 = erosion with vs. without hydromulching
2SIIRCD, Castelo Branco, 22-23/02/2013
CESAM Centro de Estudos do Ambiente e do Mar
effectiveness example 1 = erosion with vs. without hydromulching
Total soil losses over 19 months
(g m-2)
1000
750
-74%
-90%
-89%
500
untreated
treated
250
treshold “tolerable” soil loss
(1 Mg há-1 y-1)
0
0.25 m2
0.50 m2
plot size
10 m2
2SIIRCD, Castelo Branco, 22-23/02/2013
CESAM Centro de Estudos do Ambiente e do Mar
effectiveness example 2 = erosion with vs. without forest residue mulching
© Prats et al. (in prep.) Polyacrylamide application versus forest residue mulching for reducing post-fire
runoff and soil erosion
2SIIRCD, Castelo Branco, 22-23/02/2013
= mulched
overall reduction of 93 %
100
Soil losses reduction (%)
CESAM Centro de Estudos do Ambiente e do Mar
effectiveness example 2 = erosion with vs. without forest residue mulching
0
-100
0
5
10
15
20
I30 (mm h-1)
25
30
© Prats et al. (in prep.) Polyacrylamide application versus forest residue mulching for reducing post-fire
runoff and soil erosion
2SIIRCD, Castelo Branco, 22-23/02/2013
Total soil losses over 11 months
(g m-2)
2000
Soil losses (g m -2 )
CESAM Centro de Estudos do Ambiente e do Mar
effectiveness example 2 = erosion with vs. without forest residue mulching
1600
= untreated
1200
800
400
treshold “tolerable” soil loss (1 Mg há-1 y-1)
= mulched
0
base
top
© Prats et al. (in prep.) Polyacrylamide application versus forest residue mulching for reducing post-fire
runoff and soil erosion
2SIIRCD, Castelo Branco, 22-23/02/2013
very many
effectiveness => erosion measurements
CESAM Centro de Estudos do Ambiente e do Mar
field
laboratory
runoff samples
sediment samples
2SIIRCD, Castelo Branco, 22-23/02/2013
CESAM Centro de Estudos do Ambiente e do Mar
Take-home messages
1. wildfires can produce strong and sometimes extreme erosion responses,
including in Portugal
1m
2SIIRCD, Castelo Branco, 22-23/02/2013
CESAM Centro de Estudos do Ambiente e do Mar
Take-home messages
1. wildfires can produce strong and sometimes extreme erosion responses,
including in Portugal
2SIIRCD, Castelo Branco, 22-23/02/2013
CESAM Centro de Estudos do Ambiente e do Mar
Take-home messages
1. wildfires can produce strong and sometimes extreme erosion responses,
including in Portugal
and pollution!!! (eg PAHs)
2. mulching can be highly effective to reduce post-fire erosion
easy and cheap: sediment fences
3. “learn by trial and error”,
i.e. monitor - e.g. the PRODER measures - to do better next time
Outlooks for future research
i. what are the high-erosion-risk areas and the values-at-risk worth protecting?
ii. what is cost-effectiveness for “smart” application schemes, especially also
for off-site hazards due to downstream flooding, silting-up , water pollution?
2SIIRCD, Castelo Branco, 22-23/02/2013
CESAM Centro de Estudos do Ambiente e do Mar
Acknowledgements
Projects:
a. IFADAP-funded project
Recuperação de Áreas Ardidas
b. FCT-MCTES/FEDER-funded projects
RECOVER
EROSFIRE-2
FIRECNUTS
c. EU-projects
DESIRE
CASCADE
Grants:
a. FCT-funded
S. Prats (SFRH/BD/33392/2008)
see www.cesam.ua.pt/teamsite