Data-based wildfire risk model for Mediterranean ecosystems – case study of the Concepción metropolitan area in central Chile

Edilia Jaque Castillo,Carolina G Ojeda,Rodrigo Fuentes Robles,Alfonso Fernández

doi:10.5194/nhess-21-3663-2021

Abstract

Abstract. Wildfire risk is latent in Chilean metropolitan areas characterized by the strong presence of wildland–urban interfaces (WUIs). The Concepción metropolitan area (CMA) constitutes one of the most representative samples of that dynamic. The wildfire risk in the CMA was addressed by establishing a model of five categories (near zero, low, moderate, high, and very high) that represent discernible thresholds in fire occurrence, using geospatial data and satellite images describing anthropic–biophysical factors that trigger fires. Those were used to deliver a model of fire hazard using machine learning algorithms, including principal component analysis and Kohonen self-organizing maps in two experimental scenarios: only native forest and only forestry plantation. The model was validated using fire hotspots obtained from the forestry government organization. The results indicated that 12.3 % of the CMA's surface area has a high and very high risk of a forest fire, 29.4 % has a moderate risk, and 58.3 % has a low and very low risk. Lastly, the observed main drivers that have deepened this risk were discussed: first, the evident proximity between the increasing urban areas with exotic forestry plantations and, second, climate change that threatens triggering more severe and large wildfires because of human activities.

Highlights

In the last few decades, the world has seen an increasing trend in wildfires affecting large populations (Moritz et al, 2012), generally being attributed to atmospheric warming fueled by anthropogenic climate change (Spies et al, 2014)and extreme weather events (Stott, 2016) creating a riskier environment
Wildfire hazard is a product of interlinked socio-environmental processes including the proximity between wildland–urban interfaces (WUIs) and urban areas (Kumagai et al, 2004; Kolden and Henson, 2019; Goldman, 2018; Sarricolea et al, 2016); unregulated extractive economic activities in fire-prone landscapes (Castree, 2008; Spies et al, 2014; Freudenburg, 1992; Gago and Mezzadra, 2017); traditional cultural practices which increase the availability of flammable material – in construction, forestry, or agriculture (Harari, 2013; Frene and Nuñez, 2010); and the traditional practice of clearing land called “slash and burn” (Shahriar et al, 2019, p. 1)
This policy favored plantations of exotic fast-growing species across the region, with staggering consequences: in 1974, the surface area of forestry plantations was 480 000 ha, and during the 1990s it was close to 2 × 106 ha (Aguayo et al, 2009), reaching nearly 5 × 106 ha in 2015 (INFOR, 2017, p. 49). This 10-fold increase in plantations motivated by public policy contrasts with the little attention paid to restoring native forests, which have historically contributed to the local population’s livelihoods (Reyes and Nelson, 2014; Frene and Núñez, 2010), requiring that the rural and indigenous communities must compete for the use of the land against the plantations and inciting environmental conflicts (INDH, 2015)

Summary

Introduction

In the last few decades, the world has seen an increasing trend in wildfires affecting large populations (Moritz et al, 2012), generally being attributed to atmospheric warming fueled by anthropogenic climate change (Spies et al, 2014)and extreme weather events (Stott, 2016) creating a riskier environment. In the last few decades, the world has seen an increasing trend in wildfires affecting large populations (Moritz et al, 2012), generally being attributed to atmospheric warming fueled by anthropogenic climate change (Spies et al, 2014). Windy and dry conditions with steep slopes rapidly lead to quick fire spread and burn large areas of forest within a short time Experiences with fire in underdeveloped countries are radically different from those in developed countries, which have controlled burns, a strict forestry policy, and solid territorial planning and usually take advantage of the ecological benefits of the fire for ecosystems and livelihoods (Hutto, 2008; González, 2005; González-Mathiesen and March, 2018; Adams, 2013)

Objectives

Methods

Findings

Discussion

Conclusion