From wildfires to prescribed fires: resilience of heathlands under different fire regime parameters

https://fireseves.blogspot.com/ SEFIRECYL (LE001P17)

Leonor Calvo*, Reyes Tárrega, Susana Suárez-Seoane, Luz Valbuena, Angela Taboada, Elena Marcos

Area of Ecology. Faculty of Biological and Environmental Sciences.University of Leon, Spain. E-mail:leonor.calvo@unileon.es

MINECO AGL2017-86075-C2-1-R https://sefirecyl.unileon.es/

“Applied Ecology and Remote Sensing group”

http://ecologiaaplicadayteledeteccion.blogspot.com/

Fire ecology

Wildfires Prescribed fires

Resilience

From wildfires to prescribed fires

The main objective: to compare the resilience of the same type of ecosystems (heathlands) under two scenarios-wildfire vs prescribed fires.

Propose management tools to reduce the damage caused by wildfires

1. Why are wildfires a problem?

2. Which are the environmental drivers of burn severity?

3.- How resilient are the fire-prone ecosystems after wildfire vs prescribed fires?

4.- Are prescribed fires a possible solution to reduce the burn severity of wildfires?

From wildfires to prescribed fires

Dimensions of forest fire impacts

Serious economic damage Loss of human lives

3. Ecological impacts

2. Economic impacts1. Social impacts

1. Why are wildfires a problem?

California= 81 Portugal= 62 Galicia= 4

GIF (2007-2017)

Doerr SH, Santın C. 2016. Global trends in wildfire and its impacts: perceptions versus realities in a changing world. Phil. Trans. R. Soc. B 371: 20150345.

Human relationship with wildfires

Bowman et al., 2011. The human dimension of fire regimen on earth. J. Bigeogr. 38: 223-2236

Arson fires

Dimensions of forest fire impacts1. Why are wildfires a problem?

1.-Rural abandonment results in the expansion of forest

2.- Lack of forest management results in an increase in fuel loads and continuity

Fire regime: severity

3.- Climate change: increase of temperature and decrease of precipitation

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The resilience of ecosystems after fire depends on:

1.- Fire regime attributes: BURN SEVERITY2.- Vegetation traits: Regeneration ability3.- Post-fire conditions: abiotic factors

1. Why are wildfires a problem?

Ryan (2002)

1. Why are wildfires a problem?

2. Which are the environmental drivers of burn severity?

3. How resilient are the fire-prone ecosystems after wildfire vs prescribed fires?

4. Are prescribed fires a possible solution to reduce the burn severity of wildfires?

From wildfires to prescribed fires

La Cabrera= 9,960 ha burned in August 2017

Heathland 65%Pastureland

GrasslandForest

2. Which are the environmental drivers of burn severity?

Keeley, 2009

Heathlands with large shrub skeletons retaining small twigsindicative of fire severity.

BURN SEVERITY

2) Field burn severity: Minimum Twig Diameter of Erica australis1) Spectral burn severity: dNBR

2. Which are the environmental drivers of burn severity?

Pre-fire vegetationstructure

Physical properties

Weather conditions

Fire history

Severity

Severity: conditions---- Pre-fire management

Topography-Slope-Aspect

Garcia Llamas et al., 2019. Forest Ecology and ManagementGarcía Llamas et al., 2019. International Journal of Wildland Fire

Random Forests

-Composition: SIOSE-Heterogenity: LIDAR

-Recurrence- Time since last fire

-Spring rainfall-Summer rainfall

Severity: conditions---- Pre-fire management

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Fire severity variance explained by Random Forest models using different categories of predictors: pre-fire vegetation structure, weather conditions, fire history and physical properties. The figure alsoshows the results of both the most parsimonious model and the full model.

Pre-fire vegetation structure is the main factor driving burn severity in fires occurred in heathlands

Partial dependence plots showing the relationship between fire severity (dNBR) and the most significant explanatory variables included in the mostparsimonious model. Numbers within each plot show the normalized importance of each variable in the model measured as % IncMSE (imp =).

Severity: conditions---- Pre-fire management

1) High shrub (fuel) accumulation= high severity2) High spatial heterogeneity= low severity

Prescribed fires could be an appropriated management tool to increase heterogeneity

Heterogeneity

Among Pre-fire vegetation structure we identified:Shrub cover area

1. Why are wildfires a problem?- Dimensions of wildfires

2. Which are the determining factors of burn severity?

3.- How resilient are the fire-prone ecosystems after wildfire vs prescribed fires?

4.- Are prescribed fires a possible solution to reduce the burn severity of wildfires?

From wildfires to prescribed fires

Zone B

020406080

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Years after burning

Mea

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Annual HerbsPerennial herbsWoody species

3.- How resilient are our fire prone ecosystems after wildfire vs prescribed fires?

Prescribed fires

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Original 1 year 3 years 4 years 5 years 9 years 12 years 15 years

Mea

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Erica australis

31%

Erica australis heathlands

Total cover

Wildfires

29%

45%

15%

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Control Low severity Moderate severity High severity

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Control Low severity Moderate severity High severity

Mea

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Erica australis

1 year after fire

1 year after fire

Erica australis heathlands

3.- How resilient are our fire prone ecosystems after wildfire vs prescribed fires?

1. Why are wildfires a problem?

2. Which are the determining factors of burn severityosystems?

3.- How resilient are the fire-prone ecosystems after wildfire vs prescribed fires?

4.- Are prescribed fires a possible solution to reduce the burn severity of wildfires?

From wildfires to prescribed fires

4.- Are prescribed fires a possible solution to reduce the burn severity of wildfires?

- We need a new vision about wildfires, where the focus is shifted from fire suppression tofire prevention: managing our forestry systems to be more resilient.

Proposal: prescribed fires to create a more heterogeneous landscape and enhance theresilience of ecosystems

- New challenges associated with the problematic of wildland-urban-interfaces (WUI)

Proposal: in areas with low population density plus abandonment of traditional land use, weshould consider the application of prescribed fires to reduce the fuel loads around thevillages to prevent the negative social, economic and ecological impacts of larges wildfires

4.- Are prescribed fires a possible solution to reduce the burn severity of wildfires?

Thank you for your attention

L. CalvoS. Suárez R. Tárrega L. Valbuena E. MarcosA. Taboada

“Applied Ecology and Remote Sensing group”

http://ecologiaaplicadayteledeteccion.blogspot.com/

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