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- Differentiating fire regimes and their biophysical drivers in Central PortugalPublication . Bergonse, Rafaello; Oliveira, Sandra; Zêzere, José; Moreira, Francisco; Ribeiro, Paulo Flores; Leal, Miguel; Santos, José Manuel LimaWe characterize fire regimes in central Portugal and investigate the degree to which the differences between regimes are influenced by a set of biophysical drivers. Using civil parishes as units of analysis, we employ three complementary parameters to describe the fire regime over a reference period of 44 years (1975–2018), namely cumulative percentage of parish area burned, Gini concentration index of burned area over time, and area-weighted total number of wildfires. Cluster analysis is used to aggregate parishes into groups with similar fire regimes based on these parameters. A classification tree model is then used to assess the capacity of a set of potential biophysical drivers to discriminate between the different parish groups. The results allowed us to distinguish four types of fire regime and show that these can be significantly differentiated using the biophysical drivers, of which land use/land cover (LULC), slope, and spring rainfall are the most important. Among LULC classes, shrubland and herbaceous vegetation play the foremost role, followed by agriculture. Our results highlight the importance of vegetation type, availability, and rate of regeneration, as well as that of topography, in influencing fire regimes in the study area, while suggesting that these regimes should be subject to specific wildfire prevention and mitigation policies.
- Promoting low-risk fire regimes: an agent-based model to explore wildfire mitigation policy optionsPublication . Ribeiro, Paulo Flores; Moreira, Francisco; Canadas, Maria João; Novais, Ana; Leal, Miguel; Oliveira, Sandra; Bergonse, Rafaello; Zêzere, José; Santos, José LimaLandscape patterns and composition were identified as key drivers of fire risk and fire regimes. However, few studies have focused on effective policymaking aimed at encouraging landowners to diversify the landscape and make it more fire-resilient. We propose a new framework to support the design of wildfire mitigation policies aimed at promoting low-risk fire regimes based on land use/land cover choices by landowners. Using the parishes of a fire-prone region in central Portugal as analysis units, a two-step modelling approach is proposed, coupling an agent-based model that simulates land use/land cover choice and a logistic model that predicts fire regimes from a set of biophysical variables reported as important fire regime drivers in the literature. The cost-effectiveness of different policy options aimed at promoting low-risk fire regimes at the parish level is assessed. Our results are in line with those of previous studies defending the importance of promoting landscape heterogeneity by reducing forest concentration and increasing agricultural or shrubland areas as a measure to reduce the risk of wildfire. Results also suggest the usefulness of the framework as a policy simulation tool, allowing policymakers to investigate how annual payments supporting agricultural or shrubland areas, depending on the policy mix, can be very cost-effective in removing a substantial number of parishes from high-risk fire regimes.
- A combined structural and seasonal approach to assess wildfire susceptibility and hazard in summertimePublication . Bergonse, Rafaello; Oliveira, Sandra; Gonçalves, Ana; Nunes, Sílvia; da Câmara, Carlos; Zêzere, JoséWildfre susceptibility and hazard models based on drivers that change only on a multiyear timescale are considered of a structural nature. They ignore specifc short-term conditions in any year and period within the year, especially summer, when most wildfre damage occurs in southern Europe. We investigate whether the predictive capacity of structural wildfre susceptibility and hazard models can be improved by integrating a seasonal dimension, expressed by three variables with yearly to seasonal timescales: (1) a meteorological index rating fuel fammability at the onset of summer; (2) the scarcity of fuel associated with the burned areas of the previous year, and (3) the excessive abundance of fuel in especially fre-prone areas that have not been burned in the previous ten years. We describe a new methodology for combining the structural maps with the seasonal variables, producing year-specifc seasonal susceptibility and hazard maps. We then compare the structural and seasonal maps as to their capacity to predict burnt areas during the summer period in a set of eight independent years. The seasonal maps revealed a higher predictive capacity in 75% of the validation period, both for susceptibility and hazard, when only the highest class was considered. This percentage was reduced to 50% when the two highest classes were considered together. In some years, structural factors and other unconsidered variables probably exert a strong infuence over the spatial pattern of wildfre incidence. These fndings can complement existing structural data and improve the mapping tools used to defne wildfre prevention and mitigation actions.
- Biophysical controls over fire regime properties in Central PortugalPublication . Bergonse, Rafaello; Oliveira, Sandra; Zêzere, José; Moreira, Francisco; Ribeiro, Paulo Flores; Leal, Miguel; Lima e Santos, José ManuelThe concept of fire regime can be used to describe, with different degrees of complexity, the spatial and temporal patterns of fires and their effects within a given area and over a given period. In this work, we explore the relations between fire regime and a set of potential biophysical controls at a local scale, for 972 civil parishes in central Portugal. The fire regime was characterized with reference to a 44-year period (1975–2018) using three properties: cumulative percentage of parish area burned, area-weighted total number of wildfires, and the Gini concentration index of burned area over time. Potential control variables included topography, seasonal temperature and rainfall, and land use/land cover type and patch fragmentation. Ordinal logistic regression was used to model the relations between the fire regime properties and the potential control factors. Results show that the fire regime properties have important spatial contrasts within the study area, and that land use/land cover distribution, spring rainfall and summer temperatures are the major controls over their variability. The percentage of each parish occupied by shrubland and spontaneous herbaceous vegetation is the single most important factor influencing cumulative percentage of parish area burned and the Gini concentration index of burned area, whereas spring rainfall is the foremost factor regarding area-weighted total number of wildfires. Along with the role of spring rainfall in promoting fuel availability later in the year, our results highlight the importance of the speed of regrowth of shrubland and spontaneous herbaceous vegetation after burning, pointing out the need of tailoring fuel management strategies to the properties of each parish.
- Wildfire mitigation and adaptation: two locally independent actions supported by different policy domainsPublication . Canadas, Maria João; Leal, Miguel; Soares, Filipa; Novais, Ana; Ribeiro, Paulo Flores; Schmidt, Luísa; Delicado, Ana; Moreira, Francisco; Bergonse, Rafaello; Oliveira, Sandra; Madeira, Paulo Miguel; Santos, José LimaThere is a broad consensus in the academic and policy communities over the need to shift the focus from fire suppression to fire prevention. To inform policies that effectively promote this shift, we distinguish between prevention actions aimed at more fire-resilient landscapes and those focused on the protection of people, i.e., wildfire mitigation and adaptation (WM&A), respectively. With the goal of discussing the usefulness of this distinction and identifying local factors and external resources that promote each of those preventive actions, we developed an analysis of collective WM&A actions across 116 parishes in a wildfire-prone region in Portugal, using primary and secondary data. Two principal component analyses were used to explore relationships between variables expressing collective WM&A actions. Random forest, a machine learning technique based on multiple decision trees, was used to model how those actions are related to local factors (land use/land cover, population, institutions) and access to policy funding for wildfire prevention. Our results showed that collective mitigation and adaptation responses to wildfire are locally independent, in coherence with their distinct goals, actors involved, and institutional and policy framing. Mitigation through owners’ collaboration proved to be strongly related to policy funding (notably that exclusively addressed at mitigation), local socioeconomic dynamism, and ownership structure, whereas adaptation responses are related with leadership by local governments. Considering these differences, the incipiency of adaptation actions, and the difficulties in expanding owner’s collaboratives beyond the most favourable local conditions, we conclude that mitigation and adaptation actions are currently supported by two distinct policy domains with unequal consolidation but equally underfunded.
- Fatores biofísicos da variabilidade espácio-temporal dos incêndios rurais na região centro de PortugalPublication . Bergonse, Rafaello; Oliveira, Sandra; Zêzere, José; Lima e Santos, José Manuel; Moreira, Francisco; Ribeiro, Paulo Flores; Leal, MiguelO regime de fogo caracteriza o padrão espacial e temporal dos incêndios rurais e respetivos efeitos, em determinada área e num dado período. Os objetivos deste trabalho foram investigar diferenças nos regimes de fogo em 972 freguesias do Centro de Portugal com base na frequência de incêndios, na área ardida e na respetiva concentração temporal, bem como aferir a capacidade de um conjunto de variáveis biofísicas para discriminar entre regimes. Utilizou-se análise de clusters para identificar grupos de freguesias com regime de fogo semelhante e uma árvore de classificação para aferir a capacidade das variáveis biofísicas para discriminar entre grupos. Os resultados mostram a existência de quatro regimes de fogo, distinguidos predominantemente pelo uso/ocupação do solo, o declive e a precipitação de Primavera.
- Risco de incêndio florestal: características, perceções e medidas necessáriasPublication . Soares, Filipa Ferreira; Schmidt, Luísa; Delicado, Ana; Bergonse, Rafaello; Zêzere, José; Oliveira, Sandra; Policarpo, VerónicaO projeto de investigação ‘Pessoas e Fogo’ visou desenvolver e testar um quadro analítico de apoio à avaliação e promoção de políticas de gestão florestal e de desenvolvimento territorial que, centradas nas pessoas, levem à redução do risco de incêndio rural-florestal, no Pinhal Interior. Até recentemente tem sido dada prioridade ao combate direto aos incêndios ativos. A sua prevenção, através da gestão de combustível e do ordenamento florestal, e consequente diminuição da exposição e vulnerabilidade das pessoas, têm sido relegadas para segundo plano. Não se tem conseguido, assim, reduzir as áreas ardidas nem os danos causados pelos incêndios, cujo aumento reflete, em larga medida, o declínio da gestão ativa da floresta, a extrema fragmentação da propriedade e a contração da área agrícola. Face a este cenário, o projeto ‘Pessoas e Fogo’ pretendeu, entre outros objetivos, envolver os diversos atores locais e o seu conhecimento local na conceção conjunta de políticas e estratégias para promover práticas de redução de risco.
- Recent trends in fire regimes and associated territorial features in a fire-prone Mediterranean regionPublication . Moreira, Francisco; Leal, Miguel; Bergonse, Rafaello; Canadas, Maria João; Novais, Ana; Oliveira, Sandra; Ribeiro, Paulo Flores; Zêzere, José; Santos, José LimaFire regimes in Mediterranean countries have been shifting in recent decades, including changes in wildfire size and frequency. We sought to describe changes in fire regimes across two periods (1975–1995 and 1996–2018) in a fire-prone region of central Portugal, explore the relationships between these regimes and territorial features, and check whether these associations persisted across periods. Two independent indicators of fire regimes were determined at parish level: fire incidence and burn concentration. Most parishes presented higher values of both indicators in the second period. Higher values of fire incidence were associated with lower population densities, lower proportions of farmland areas and higher proportions of natural vegetation. Higher levels of burn concentration were associated with smaller areas of farmland and natural vegetation. These associations differed across periods, reflecting contrasting climatic and socio-economic contexts. Keeping 40% of a parish territory covered by farmland was effective to buffer the increased wildfire risks associated with different management and climate contexts. The effectiveness of higher population densities in keeping fire incidence low decreased in the last decades. The results can improve the knowledge on the temporal evolution of fire regimes and their conditioning factors, providing contributions for spatial planning and forest/wildfire management policies.
- Monitorização das redes de faixas e mosaicos de gestão de combustível com recurso a deteção remota e índices de vegetaçãoPublication . Ferreira, Marta; Oliveira, Sandra; Bergonse, RafaelloAs redes de faixas e mosaicos de gestão de combustível desempenham um papel fundamental na prevenção de incêndios. A sua gestão, porém, pode ser morosa e dispendiosa. Com o intuito de automatizar o processo de monitorização, recorreu-se ao NDVI para estabelecer um valor limiar a fim de distinguir níveis de densidade da vegetação para cada tipo de ocupação do solo, possibilitando classificar os pixéis conforme o seu nível de intervenção. Os resultados, aplicados aos municípios da Sertã, Figueiró dos Vinhos e Ferreira do Zêzere, demonstraram uma reduzida proporção de faixas geridas, variando entre 19.49% e 36.17%.
- Avaliação de risco de incêndio rural à escala local na região Centro de PortugalPublication . Oliveira, Sandra; Bergonse, Rafaello; Santos, Pedro Pinto; Gonçalves, Ana; Melo, Raquel; Zêzere, JoséUm índice de risco de incêndio foi aplicado às 972 freguesias da região Centro de Portugal Continental, integrando três dimensões: perigosidade, exposição e vulnerabilidade social. As freguesias do setor centro-sul apresentam níveis de risco mais elevados. Os padrões espaciais variam para cada dimensão; a vulnerabilidade mais elevada ocorre nas freguesias dos setores oriental e centro-sul, enquanto a perigosidade mais alta se localiza numa faixa N-S no setor central da região. As estratégias de redução de risco devem ser ajustadas de acordo com a relevância de cada dimensão.