fire effects on soil biological, physical and chemical

Fire effects on soil biological, physical and chemical properties

Antonio Jordán

University of Seville

MED_SoilResearch Group

A R E Y O U

WO R R I E D

a b o u t

WILDFIRES?

Wildfires in Europe 22/07/2012NASA Earth Observing System

Wildfires in Central Africa 22/07/2012NASA Earth Observing System

Wildfires in the Iberian Peninsula, 8/10/2013NASA Earth Observing System

Wildfires in East Africa and Madagascar, 08/10/2013NASA Earth Observing System

Wildfires in Borneo, Singapore and Malaysia, 08/10/2013NASA Earth Observing System

Map of wildfires (8-17/08/2012). MODIS/NASA.

FIRE AREAS ARE GEOGRAPHICALLY DISTRIBUTED

WHAT IS A

F O R E S T

F I R E ?

Wildfire in Sierra del Algibe (Cádiz, south western Spain), 30/03/2010.

Girona, 22/07/2012. El País.

Wildfire in La Jonquera (Girona, northeastern Spain), 22/07/2012. El País.

WHAT is the

IMPACT of a

F O R E S T

F I R E ?

2-3 months after fire (Santiago de Compostela, NW Spain)

Centuries after recurrent fires (Ejido de Atécuaro, Michoacán, México)

Burned area in Canberra (Australia), 6 years after fire.

Barranc del Tarongers (Alicante, eastern Spain)

Three years after fire (Parque Natural Los Alcornocales, Cádiz, SW Spain)

Six years after fire (Parque Natural Los Alcornocales, Cádiz, SW Spain)

Wildfire in Huelva (south western Spain, summer 2004).

2004 wildfire in Huelva (SW Spain)

8 years after the wildfire of Huelva

Burned grassland 4 (A), 16 (B), 34 (C) and 45 days (D) after fire (Lithuania)Pereira, Cerdà, Úbeda, Mataix-Solera, Martin, Jordán, Burguet (2013

After centuries of using fire for vegetation management (Doñana Natural Park, Huelva, SW Spain)

Two days after fire (Gorga, Alicante, E Spain)

Dzukija National Park (Lithuania)

Long-term effects

Short-term effects

High degradationDisturbed systemSlow recovery

Recurrent wildfires

High degradationDeeply disturbed systemSlow recovery

Fire supression strategies

Low degradationAdaptation of the systemFast recovery

Ocasional low-severity fires

EFFECTS OF FOREST FIRES IN SOILS

Direct effects caused by fire• Chemical changes• Physical Changes• Changes in soil biotaIndirect Effects• Loss of vegetation cover• Deposition of ash and charred debris litter• Hydrological consequences• Increased risk of erosionStrategies for stabilizing soils affected by fires• Spatial analysis of severity index• Short-term measures• Long-term measures

W H A T

HAPPENS

D U R I N G

BURNING?

REQUIRED AGENTS FOR COMBUSTION

FUELTEMPE-RATURE

OXIGENIGNI-TION

Factores involved in soil heating during a forest fire

(modified from Mataix-Solera & Guerrero, 2007)

Relief

Propagation

speed

Type of fire

(crown fire, soil

fire, peat fire)

Wind and humidityVegetation

conditions

Soil conditions

SOIL

TEMPERATURE

Vegetation type

Atmosphere

Water, gases and

solid particles

85-90% of thermal

energy is lost

10-15% of thermal

energy

Convection,

evaporation,

condensation

and conduction

INTENSITY• Fire intensity refers to the fuel

consumption rate on the ground and therefore the rate of energy release.

• Because the rate at which heat energy is transferred through the soil (which is dependent on intrinsic properties), the residence time of high temperature has a great importance regarding the extent of changes induced in the soil.

• It is difficult to determine.• Fire intensity is not a good measure of

the amount of energy transmitted releases to soil, nor a good indicator of the changes that occur in their properties.

FIRE SEVERITY AND FIRE INTENSITY

SEVERITY• Fire severity is a qualitative term.

• It is used to describe the responses of ecosystems to fire and is especially useful for describing the effects of fire on the ground.

• Fire intensity is not necessarily related to the total amount of energy produced during the fire.

• Fire severity can be classified according to certain criteria such as:– The amount of fuel consumed,

– The properties of these fuels (height, diameter or loppers, water content and mineral content)

– The impact of these fuels on fire during the different phases of fire or

– Heat transfer and its aftermath (ash color, textural changes and loss of organic matter).

SOIL HEATING

Experimental burn in Sierra de Algeciras (SW Spain)

Higher peaks at thesurface

Two hours afterburning, soil is still hot

Fire starts

The surface starts coolingand temperature is higher2 cm below the surface

Granged, Zavala, Jordán & Bárcenas-Moreno (2011)

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0 5 10 15 20 25 30 35

Tem

pe

ratu

re (

oC

)

Time (minutes)

NS1 NS2 NS3 NS4 NS5 NS6 S1 S2 S3 S4 S5 S6

SOIL HEATING

Effect of stones

Stones delay peaking

Cooling is slower in stone-covered areas

Fire starts

Peaks are smallerwhen there are no stones

Gordillo-Rivero, García-Moreno, Jordán, Zavala, Granja-Martins (2013)García-Moreno, Gordillo-Rivero, Gil, Jiménez-Morillo, Mataix-Solera, González-Peñaloza, Granged, Bárcenas-Moreno, Jiménez-Pinilla, Lozano, Jordán, Zavala (2012)

High severity burn Low severity burn

Stones increase the heating of subsurface soil layerLengthened residence of temperature peaks is alsoobservedHigh degree of SWR

Stones protect soil fromheating

Low or unaffected SWR isobserved

Heated soil

Cold soil

SOIL HEATING

SOIL HEATING

High severity burn

Heating and smouldering betweenneighbour stones may occur in

areas with high stone cover

Uncontinuous gradient of heatingis observed in areas with low stone

cover

H E A T

MATTERS

TEMPERATURE THRESHOLDS

Modified from several authors

T (oC) MINERAL COMPONENTS ORGANIC MATTER

1400 Sand and silt melt (>1400 oC)

1300

1200 Ca volatilizes

1100

1000

900

800 Clays melt (>800 oC) Lost of S (>800 oC)

700 Clay structure collapses Lost of P (>700 oC)

600 Maximum lost of K and P Lost of 50% N (300 – 600 oC)

500 Fe and Al oxides transform (400 – 500 oC) Ash

Black carbon (250 – 500 oC)

Destruction of water repellency (450 – 580 oC)

400 Lost of structural water in clays(>420 oC) Combustion (400 – 450 oC)

300 Lost of organic compounds associated to clays (>300 oC) Distillation of organic matter (200 – 315 oC)

200 Changes in organic matter(200 – 250 oC)

Water repellency is induced

150 Death of seeds, bacteria and fungi (50 – 120 oC)

100 Dehydration Dehydration (60 – 100 oC)

50 Death of plants (40 – 70 oC)

EFFECTS ON

S O I L

CHEM I CA L

PROPERTIES

0

0.5

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1.5

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2.5

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3.5

4

Pre-fire Im.afterfire

1 year 2 years 3 years

Org

anic

carb

on

(%)

Jordán, González and Zavala (2010)Granged, Zavala, Jordán and Bárcenas-Moreno (2011)

Granged, Jordán and Zavala (2011)

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8

May Jun Jul Aug Sep Oct Nov

FI0 FI1 FI2 FI3

Granged, Zavala, Jordán, Muñoz-Rojas and Mataix-Solera (2011)

Soils under eucalypts (Australia)Mediterranean soils (Cádiz and Huelva)

EFFECTS ON ORGANIC MATTER

EFFECTS ON ORGANIC MATTER

• Dramatic decrease (combustion )

• Increase:– Mineral soil incorporation of little or no residue affected by the fire , therefore, are

better protected from decomposition (Johnson and Curtis , 2001).

– Fresh organic matter transformation in recalcitrant forms (Almendros et al. , 1984 ) .

– Appearance in the burned areas of nitrogen -fixing species (Johnson and Curtis , 2001 ) .

– Decrease in the rate of mineralization (Fernandez et al. , 1999).

• Chemical changes (González -Pérez et al., 2004 ) :– Overall loss of external oxygen groups favoring the appearance of materials with a

relatively low solubility.

– Reduction of chain length alkyl compounds, such as alkanes, fatty acids and alcohols.

– Flavoring sugars and lipids.

– Formation of heterocyclic nitrogen compounds .

– Condensation of humic substances .

– Production of an almost unchanged component, black carbon, which originates at temperatures between 250 and 500 ° C as a result of incomplete combustion ( carbonization ) of the waste.

Lost of organic

matter by

combustionInput of charred

organic residues

Erosion of fine

sediments

EFFECTS ON SOIL ACIDITY

SOIL pH

DENATURALI-ZATION OF

ORGANIC ACIDS

(Certini, 2005)

RELEASED CATIONS

(Gil et al., 2010)

LOST OF HYDROXYLS

AND FORMATION OF

OXIDES

(Giovannini et al., 1990)

EFECTS ON SOIL ACIDITYBurned soil in Las Minillas (Córdoba, SW Spain)

Soil acidity (pH) in burnedand unburned soils

Gil, Zavala, Bellinfante and Jordán (2010)

Jordán, González and Zavala (2010)Granged, Zavala, Jordán and Bárcenas-Moreno (2011)

Granged, Jordán and Zavala (2011)Granged, Zavala, Jordán, Muñoz-Rojas and Mataix-Solera (2011)

EFFECTS ON SOIL ACIDITY

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1

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5

6

7

8

0 5 10 15 20 25 30 35 40

pH

Months after burn

(not always)

EFFECTS ON THE CATION EXCHANGE CAPACITY

Organic matter

Clay

Exchangeable cations(Ca2+, Mg2+, K+ and Na+)

Moderate intensity fire(<500 oC)

Al3+

CEC

Saturation

Combustion

Release of Fe and Al oxides

Ash

Lost of organic matter

EFFECTS ON THE CATION EXCHANGE CAPACITY

Unburned soil Burned soilCIC cmol (+) kg-1 14.10 ± 5.63 2.11 ± 0.80Ca2+ cmol (+) kg-1 6.43 ± 3.37 0.64 ± 0.30Mg2+ cmol (+) kg-1 1.13 ± 0.71 0.17 ± 0.20Na+ cmol (+) kg-1 0.45 ± 0.46 0.09 ± 0.04K+ cmol (+) kg-1 0.38 ± 0.24 0.04 ± 0.03V% 59.8 ± 16.4 48.6 ± 23.6

Gil, Zavala, Bellinfante and Jordán (2010)

Leaching or erosion of ash maycontribute to a decreasedsaturation of the cation exchangecomplex in burned soils.

EFFECTS ON

S O I L

P H YS I C A L

PROPERTIES

pH

Organic matter

(%) Sand (%) Clay (%) CND

Bulk density

(g/cc)

Prefire 6.2 ± 0.2 a 3.1 ± 0.2 c 41.9 ± 3.7 a 19.5 ± 3.2 c 101.5 ± 3.9 d 1.4 ± 0.0 a

Inmediately after fire 7.5 ± 0.2 c 1.1 ± 0.1 a 52.7 ± 5.7 b 10.8 ± 1.6 d 66.6 ± 1.6 a 1.5 ± 0.1 b

1 year 7.1 ± 0.2 d 1.3 ± 0.1 a 58.8 ± 5.4 bc 5.6 ± 1.0 a 69.8 ± 1.3 b 1.5 ± 0.1 b

2 years 6.7 ± 0.2 b 1.5 ± 0.2 b 59.7 ± 7.8 bc 5.8 ± 0.3 a 74.0 ± 2.6 c 1.5 ± 0.1 b

3 years 6.3 ± 0.2 a 1.5 ± 0.1 b 61.7 ± 9.1 c 5.7 ± 0.3 a 73.8 ± 2.0 c 1.6 ± 0.1 b

Kruskal-Wallis p 0.0000 0.0000 0.0000 0.0000 0.0000 0.0001

Granged, Zavala, Jordán and Bárcenas-Moreno (2011)Granged, Zavala, Jordán, Muñoz-Rojas and Mataix-Solera (2011)

Jordán, González-Peñaloza and Zavala (2010)

Soils under heath (Cádiz, SW Spain)

Fuel

(kg/m2)

Temperature

peak (oC) pH

Organic

carbon (%) Sand (%) Clay (%) CND MWD (mm)

0 ND 4.6 ± 0.8 a 5.4 ± 1.3 d 59.1 ± 4.7 a 13.8 ± 4.2 c 113 ± 10 c 0.77 ± 0.15 c

2 142 5.2 ± 0.8 b 6.3 ± 1.2 c 55.0 ± 4.3 b 14.9 ± 4.6 b 125 ± 8 b 0.84 ± 0.04 a

4 317 5.5 ± 0.9 c 3.2 ± 1.8 b 63.7 ± 5.1 c 13.1 ± 4.1 b 102 ± 13 a 0.80 ± 0.08 b

8 525 5.7 ± 1.0 c 2.5 ± 1.7 a 68.5 ± 5.7 d 12.1 ± 4.0 a 126 ± 10 c 0.81 ± 0.15 b

Soils under eucalypts (Australia)

EFFECTS ON SOIL TEXTURE

pH Organic matter (%) Sand (%) Clay (%)

Burned 6.2 ± 0.1 3.0 ± 0.6 42.9 ± 2.4 23.7 ± 3.4

Control 6.2 ± 0.1 3.2 ± 0.3 41.9 ± 3.7 19.5 ± 3.2MW-U, p 0.012612

Soils under heath (Cádiz, SW Spain)

Month FL0 FL1 FL2 FL3

OC (%) May 6.0 ± 0.8 cd 6.2 ± 0.9 a 6.5 ± 1.0 a 5.8 ± 1.4 a

Jun 7.0 ± 0.8 b 6.4 ± 1.3 a 3.7 ± 0.8 b 2.0 ± 1.0 c

Jul 5.3 ± 0.8 e 6.0 ± 1.0 a 2.6 ± 0.7 c 1.9 ± 0.8 c

Aug 7.5 ± 1.1 a 5.8 ± 0.8 a 3.9 ± 0.7 b 2.0 ± 1.0 c

Sep 6.3 ± 0.8 c 5.1 ± 1.0 b 2.3 ± 1.2 cd 2.8 ± 1.4 b

Oct 6.0 ± 1.3 cd 4.0 ± 1.1 a 2.1 ± 0.7 d 1.5 ± 0.9 c

Nov 5.6 ± 0.9 de 4.6 ± 1.2 b 1.6 ± 1.0 e 1.7 ± 0.9 c

K-W, p <0.0001 <0.0001 <0.0001 <0.0001

pH May 5.7 ± 0.7 a 4.6 ± 0.6 a 5.0 ± 0.6 cd 4.8 ± 1.1 a

Jun 5.1 ± 0.7 c 5.1 ± 1.0 b 6.0 ± 0.5 b 6.6 ± 0.7 a

Jul 5.3 ± 0.7 bc 5.3 ± 0.7 b 6.5 ± 0.6 a 6.2 ± 0.8 a

Aug 5.0 ± 0.7 cd 4.3 ± 0.6 a 6.0 ± 0.5 b 6.3 ± 0.9 a

Sep 4.7 ± 0.6 de 4.3 ± 0.7 a 5.3 ± 0.9 b 5.6 ± 1.0 b

Oct 4.7 ± 0.9 d 4.4 ± 0.8 a 4.9 ± 0.6 a 5.3 ± 0.7 bc

Nov 5.6 ± 0.8 ab 4.4 ± 0.8 a 5.2 ± 0.7 b 5.2 ± 0.7 cd

K-W, p <0.0001 <0.0001 <0.0001 <0.0001

EFFECT ON SOIL TEXTURE

DIRECT EFFECTS

• Dehydration (100 oC)

• Lost of organic compounds(300 oC)

• Lost of structural water(400 oC)

• Clay melting (800 oC)

• Sand and silt melting(1000 oC)

INDIRECT EFFECTS

• Erosion of fine particles

• Increase of fine particles(ash)

EFFECT ON SOIL TEXTURE


Mes FI0 FI1 FI2 FI3Sand (%) May 54.9 ± 3.8 bc 59.0 ± 4.1 bc 63.7 ± 4.8 bc 68.6 ± 5.3 bcd

June 56.2 ± 3.5 cd 60.4 ± 3.7 cd 65.2 ± 4.1 cd 67.6 ± 7.0 abcJuly 57.2 ± 3.6 d 61.5 ± 3.8 d 66.2 ± 4.6 d 67.0 ± 6.0 ab

August 55.8 ± 3.3 cd 59.8 ± 3.6 cd 64.5 ± 4.3 cd 65.4 ± 5.3 aSeptember 54.3 ± 5.3 abc 58.5 ± 5.9 abc 63.1 ± 6.2 abc 69.6 ± 4.7 bcd

October 53.5 ± 4.8 ab 57.5 ± 0.5 ab 61.8 ± 5.3 ab 70.2 ± 4.2 cdNovember 52.7 ± 4.3 a 56.7 ± 4.7 a 61.1 ± 5.0 a 71.3 ± 4.9 d

Clay (%) May 14.9 ± 4.5 14.8 ± 4.5 b 14.2 ± 5.0 b 13.2 ± 3.3 bJune 15.1 ± 3.6 15.2 ± 4.4 b 14.0 ± 3.6 b 13.1 ± 3.5 bJuly 15.1 ± 4.6 13.8 ± 4.8 ab 12.8 ± 3.8 ab 11.7 ± 3.6 ab

August 13.9 ± 4.9 14.0 ± 4.2 ab 14.2 ± 3.6 b 12.9 ± 4.4 bSeptember 14.5 ± 5.1 14.0 ± 3.7 ab 12.9 ± 3.4 ab 13.0 ± 4.9 b

October 15.8 ± 4.7 12.6 ± 3.3 a 11.7 ± 4.5 a 10.0 ± 2.1 aNovember 15.0 ± 4.8 12.3 ± 4.4 a 11.9 ± 3.7 a 10.8 ± 4.5 a

CND May 124 ± 6 125 ± 7 c 103 ± 9 b 124 ± 11 bJune 126 ± 7 111 ± 10 b 103 ± 9 b 132 ± 8 dJuly 124 ± 7 113 ± 8 b 127 ± 8 c 131 ± 7 cd

August 126 ± 8 112 ± 7 b 97 ± 6 a 127 ± 9 bcSeptember 124 ± 7 114 ± 8 b 94 ± 10 a 123 ± 12 b

October 127 ± 11 112 ± 6 b 95 ± 6 a 126 ± 8 bNovember 126 ± 7 101 ± 8 a 97 ± 7 a 118 ± 7 a

MWD May 0.85 ± 0.04 0.95 ± 0.04 f 0.90 ± 0.04 f 1.00 ± 0.05 gJune 0.85 ± 0.04 0.96 ± 0.04 f 0.87 ± 0.04 e 0.95 ± 0.04 fJuly 0.84 ± 0.03 0.87 ± 0.03 e 0.85 ± 0.03 d 0.90 ± 0.04 e

August 0.85 ± 0.03 0.72 ± 0.03 d 0.83 ± 0.03 c 0.85 ± 0.05 dSeptember 0.84 ± 0.02 0.65 ± 0.04 c 0.75 ± 0.04 b 0.73 ± 0.05 c

October 0.84 ± 0.04 0.62 ± 0.05 b 0.71 ± 0.03 a 0.65 ± 0.06 bNovember 0.85 ± 0.04 0.60 ± 0.04 a 0.70 ± 0.04 a 0.61 ± 0.04 a

Increase during the wet season

Lost of clay increases with fireseverity

Small decrease or increase afterfire, and progressive decrease• Selection of aggregates?• Erosion?• Lost of water-repellent

particles?

Decrease with time• More stable aggregates?• Destruction of selected

aggregates?

EFFECT ON SOIL STRUCTURE

N CND/MWD CND/OC MWD/OC

Control 840 0.4644 0.3549 0.4698

FI0 210 0.8856 0.7452 0.7452

FI1 210 0.5588 0.7480 0.7167

FI2 210 0.5848 0.3144 0.8408

FI3 210 0.5404 0.4599 0.6049


Organic matter is not the main bindingagent after fire

Largeraggregates are

more stable


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0 200 400 600

Car

bo

no

org

ánic

o (

%)

Temperatura (oC)

Control Calentado

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80

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120

0 200 400 600Es

tab

ilid

ad e

stru

ctu

ral

(CN

D)

Temperatura (oC)

Control Calentado

Zavala, Granged, Jordán and Bárcenas-Moreno (2010)

EFFECTS ON SOIL STRUCTURE


Month FL0 FL1 FL2 FL3

CND May 124 ± 6 125 ± 7 a 103 ± 9 b 124 ± 11 c

Jun 126 ± 7 111 ± 10 b 103 ± 9 b 132 ± 8 a

Jul 124 ± 7 113 ± 8 b 127 ± 8 a 131 ± 7 ab

Aug 126 ± 8 112 ± 7 b 97 ± 6 c 127 ± 9 bc

Sep 124 ± 7 114 ± 8 b 94 ± 10 c 123 ± 12 c

Oct 127 ± 11 112 ± 6 b 95 ± 6 c 126 ± 8 c

Nov 126 ± 7 101 ± 8 c 97 ± 7 c 118 ± 7 d

K-W, p 0.4203 <0.0001 <0.0001 <0.0001

MWD May 0.85 ± 0.04 0.95 ± 0.04 a 0.90 ± 0.04 a 1.00 ± 0.05 a

Jun 0.85 ± 0.04 0.96 ± 0.04 a 0.87 ± 0.04 b 0.95 ± 0.04 b

Jul 0.84 ± 0.03 0.87 ± 0.03 b 0.85 ± 0.03 c 0.90 ± 0.04 c

Aug 0.85 ± 0.03 0.72 ± 0.03 c 0.83 ± 0.03 d 0.85 ± 0.05 d

Sep 0.84 ± 0.02 0.65 ± 0.04 d 0.75 ± 0.04 e 0.73 ± 0.05 e

Oct 0.84 ± 0.04 0.62 ± 0.05 e 0.71 ± 0.03 f 0.65 ± 0.06 f

Nov 0.85 ± 0.04 0.60 ± 0.04 f 0.70 ± 0.04 f 0.61 ± 0.04 g

K-W, p 0.2923 <0.0001 <0.0001 <0.0001

Organic matter contentdecreases with fire severity

Aggregate stability decreaseswith fire severity

Bulk density in creases withfire severity

Jordán, Zavala, Mataix-Solera, Nava y Alanís (2011)

EFFECTS OF FIRE ON SOIL STRUCTURE

Mataix-Solera, Cerdà, Arcenegui, Jordán and Zavala (2011)

EFFECTS OF FIRE ON SOIL STRUCTURE

Mataix-Solera, Cerdà, Arcenegui, Jordán and Zavala (2011)Mataix-Solera, Cerdà, Arcenegui, Jordán and Zavala (2012)

a) Clayey soil with CO3Ca, Fe/Al oxides and organic matter as binding agentsb) Wettable soil with organic matter

c) Sandy water-repellent soil with organic matter

EFFECTS ON SOIL EROSION RISK

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5

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25

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35

40

45

50

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Tasa

de

esco

rren

tía (m

L m

in-1

)Tiempo (minutos)

RSC RCC R-control

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Conc

entr

ació

n de

sedi

men

tos

(g L

-1)

Tiempo (minutos)

RSC SCC S-control

Unburned and burned areas in Evora, Portugal.

Sediment concentration in runoff during a simulatedrainfall experiment. RSC: burned area, no ash (< 1

mm); RCC: burned area with ash(1-2 cm); R: unburned

Runoff generation rate during a simulated rainfallexperiment. RSC: burned area, no ash (< 1 mm); RCC:

burned area with ash(1-2 cm); R: unburned

Cerdà, Marcos, Llovet, Benito, Úbeda, Pérez-Cabello, Jordán and Zavala (2010)

Tp Tr Pr Runoff rate Runoff coef. Infiltration rate SSIR Tr-TpLitter -0,48 - - - - - - -Plant cover -0,48 -0,45 -0,47 - - - - -Soil depth 0,56 0,35 0,36 - - - - -Organic C -0,44 - - - - - - -Coarse elements -0,54 -0,38 -0,39 - - - - -Sand - 0,73 0,74 -0,77 -0,77 0,77 0,78 0,84Clay - - - 0,40 0,40 -0,40 -0,43 -0,54Bulk density 0,50 0,68 0,68 -0,63 -0,63 0,63 0,67 0,54M0 - - - - - - - -

Correlation between soil parameters and water repellency

Zavala and Jordán (2008)

Tp Tr Pr Runoff rate Runoff coef. Infiltration rate SSIR Tr-TpLitter -0,48 - - - - - - -Plant cover -0,48 -0,45 -0,47 - - - - -Soil depth 0,56 0,35 0,36 - - - - -Organic C -0,44 - - - - - - -Coarse elements -0,54 -0,38 -0,39 - - - - -Sand - 0,73 0,74 -0,77 -0,77 0,77 0,78 0,84Clay - - - 0,40 0,40 -0,40 -0,43 -0,54Bulk density 0,50 0,68 0,68 -0,63 -0,63 0,63 0,67 0,54M0 - - - - - - - -

WDPT -0,43 -0,79 -0,78 0,70 0,70 -0,70 -0,73 -0,73

Correlation between soil parameters and water repellency


Jordán, Zavala, Nava and Alanís (2009)

EFFECTS ON SOIL EROSION RISK


NATURAL SOIL WATER REPELLENCY IS CONDITIONED BY ORGANIC RESIDUES…

Mataix-Solera, Arcenegui, Zavala, Pérez-Bejarano, Jordán, Morugán-Coronado, Bárcenas-Moreno, Jiménez-Pinilla, Lozano, Granged, Gil-Torres (2013)

…SOIL TEXTURE…

…BUT ALSO WILDFIRES >>

HF7

HF8

HF9

HF5

HF6

HF11

HF4

HF10

HF1

HF2

HF3

HF12

8

9

10

11

12

13

14

15

16

15 25 35 45 55 65 75 85

Soilorgan

icm

aer(%

)

Sand(%)

We able SlightWR StrongWR SevereWR ExtremeWR

y=-0.08x+15.794R²=0.5363

ANOVA,p-value:0.0068

Jordán, Zavala, Mataix-Solera, Nava, Alanís (2011)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1SL 1BL 2SL 2BL 3SL 3BL 4SH 4BH 5SH 5BH 6SU 6BU 7SU 7BU

<5 5-60 60-600 600-3600 >3600

S: 0-20 mm B: 20-40 mm

L: low severityburn

H: High severityburn

U: unburned

Short temperature peaks? Long temperature peaks?

EFFECTS ON SOIL WATER REPELLENCY

Zavala, Granged, Jordán and Bárcenas-Moreno (2010)

Lab experiment with soils from Huelva and Cádiz (Spain), Mexico and Australia(40 minutes heating)

Litter

Ash

Water-repellent layer

Wettable layer

Water-repellent

soil

Lowseverity

High severity

Very highseverity

High severity

LowseverityWettable

soil


Field conditionsDepth (cm)

Type n Water-repellent plots (%)

Wettable plots (%)

Cochran Q p

0 Burned 575 42.5 57.5 533 <0.000001Control 42 95.8 4.2

2 Burned 300 70.0 30.0 211 <0.000001Control 89 91.1 8.9

4 Burned 98 90.2 9.8 16 <0.000063Control 114 88.6 11.4

Lab conditionsDepth (cm)

Type Suma Water-repellent samples

(%)

Wettable samples

(%)

Cochran Q p

0-2 Burned 24 97.6 2.4 1 <0.317311Control 25 97.5 2.5

2-4 Burned 41 95.9 4.1 26 <0.000001Control 15 98.5 1.5

4-6 Burned 20 98.0 2.0 12 <0.000532Control 32 96.8 3.2

Under field conditions, the effect of fire on thehydrophobicity is much more important than in thelaboratory.There are large differences between the response ofburned and unburned soils.



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40

60

80

100

120

Jun Ago Oct Di Fe Abr Jun Ago Oct

Hu

me

dad

de

l su

elo

(%

)

Pro

po

rció

n d

e m

ue

stra

s h

idro

fób

icas

(%

)

WDPT EPT CA o Humedad (%)


Fire

Irregular behaviour during the drywarm season

After the rainy season, soilmoisture decreases and water

repellency increases again


WDTP Before fire Immediately after fire After 1-year period

Litter layer Charred litter layer Ash-bed Bare soil Litter layer

Mean 647e 84b 6a 197c 517d

St. dev. 109 33 2 61 111

Max 816 138 9 310 686

Min 448 16 2 98 367

Before fire Immediately after fire After 1-year period ANOVA, p

Charred litter Ash-bed Bare soil

Tp (s) Mean 1454.5b 2539.5c 2247.5c 243.0a 1312.2b <0.01

St. dev. 320.6 417.8 628.6 78.5 225.6

Max 1974 3567 3147 359 1691

Min 1076 1839 1048 65 1054

Tr (s) Mean 1553.2b 2825.4c 2646.1c 423.0a 1405.7b <0.01

St. dev. 310.3 492.6 679.7 121.5 221.3

Max 2037 3131 3475 647 1753

Min 1196 1991 1419 246 1106

Before fire Immediately after fire After 1-year period ANOVA, p

Charred litter Ash-bed Bare soil

Runoff coef. (%) Mean 3.9a 5.1a 4.2a 48.7b 5.0a <0.01

St. dev. 2.2 1.4 2.0 18.8 2.3

Max 7.4 7.2 6.8 79.2 1.3

Min 1.3 1.5 0.6 21.4 7.8

Soil loss (g m-2) Mean 3.6a 4.2a 2.6a 162.8b 3.4a <0.000001

St. dev. 1.4 0.9 0.9 200.3 1.5

Max 5.4 5.5 4.0 651.3 1.0

Min 1.5 1.8 1.1 13.0 5.4

After one year, hydrological properties have re-stablishedNatural background water repellency?

Las cenizas y la hojarasca retrasan la formación de la escorrentía

EFFECT ON SOIL WATER REPELLENCY

R coef. N CND/MWD CND/OC MWD/OC

All treatments 840 0.4644 0.3549 0.4698

FL0 210 0.8856 0.7452 0.7452

FL1 210 0.5588 0.7480 0.7167

FL2 210 0.5848 0.3144 0.8408

FL3 210 0.5404 0.4599 0.6049

WDPT (s) FL0 FL1 FL2 FL3

May 55 ± 20 b 61 ± 18 ef 54 ± 18 a 56 ± 16 a

Jun 60 ± 18 b 957 ± 249 d 2 ± 1 b 1 ± 2 c

Jul 41 ± 17 c 2661 ± 501 c 2 ± 1 b 0 ± 1 c

Aug 18 ± 2 b 3726 ± 120 a 1 ± 1 b 5 ± 1 b

Sep 53 ± 14 b 3546 ± 169 b 3 ± 1 b 3 ± 1 bc

Oct 4 ± 1 a 172 ± 50 c 3 ± 1 b 2 ± 1 bc

Nov 85 ± 9 a 16 ± 8 a 1 ± 1 b 2 ± 2 c

K-W, p 0.0000 0.0000 0.0000 0.0000

EFFECTS IN THE VERY LONG-TERM

Jiménez-Morillo, González-Pérez, Jordán, Zavala, de la Rosa, Jiménez-González, González-Vila (2014, submitted)

The increased exposure of compacted surfaces also decreases water retention

Increased evaporation from unprotected areas

Low infiltration rate and increased runoff generation rate on sloping areas

Loss organic layer:Decreased water retention capacity

Reduction of barriers to the flow of runoff

CONCL

USIONS

Only one:

FIRE IS A

S O I L

F ORM I NG

F A C T O R

Medidas de recuperación de zonas quemadas en Galicia (2010)

http://grupo.us.es/fuegored

fire effects on soil biological, physical and chemical

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