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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.
- People & Fire webGIS tool for wildfire risk assessmentPublication . Mileu, Nelson; Zêzere, José Luís; Bergonse, RafaelloPeople&Fire webGIS tool is an application for wildfire risk assessment, focused on obtaining simulating hazard and risk scenarios centred on land use transformation. This tool is a decisionsupport platform created in the context of a research project, which was dedicated to testing a new analytical framework for supporting the development and evaluation of new, integrated, and people-centred policy approaches to wildfires. The simulator used in the tool is based on the wildfire risk model that results from the combination of three components: hazard (H), exposure (E), and social vulnerability (SV). Based on the wildfire risk model and using real data, from a study region particularly susceptible to forest wildfires the as-is and to-be scenarios demonstrate People&Fire webGIS capacity. People&Fire webGIS tool is available for download at https://github.com/nmileu/peopleandfire.
- 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.
- Dinâmica espacial e temporal do ravinamento na margem esquerda da bacia do Baixo Tejo : formas, processos e factoresPublication . Bergonse, Rafaello; Reis, Eusébio Joaquim Marques dos, 1966-O presente trabalho teve por objectivo geral contribuir para o conhecimento da erosão do solo por ravinamento e estruturou-se em três partes. A primeira consistiu numa revisão da literatura publicada, cujos resultados evidenciam o ravinamento como produto da combinação entre a acção do escoamento e a ocorrência de movimentos de massa ao longo do tempo, em contraste com a abordagem baseada em processos hídricos que tem vigorado. O enquadramento conceptual resultante forneceu sustentação teórica ao restante da investigação. Na segunda parte construiu-se uma perspectiva de conjunto sobre a incidência do fenómeno numa área de estudo abrangendo 2912 km2 da margem esquerda da bacia do baixo Tejo. Fotointerpretação e validação de campo permitiram diferenciar oito grandes padrões de ravinamento e estabelecer um contraste claro entre os sectores N e S da área de estudo, respectivamente associados a sistemas de ravinas de dimensões decamétricas a hectométricas em rede e em complexo, e a formas relativamente incipientes de carácter linear. Salientou-se também a relevância das formas associadas a elementos antrópicos. Na terceira parte do trabalho analisou-se em pormenor um dos grandes padrões referidos. Assumindo como área de estudo as bacias das ribeiras de Ulme e do Vale do Casal Velho (área total 151,3 km2), investigou-se a morfologia geral e a localização de um conjunto de 90 complexos de ravinas, bem como os respectivos factores de controlo. Centrou-se depois a análise num sub-conjunto de 30 formas, relacionando-se quantitativamente morfologia, processos evolutivos e potenciais factores, e investigando-se a evolução entre 1970 e 2006. Os resultados indicam o entalhe fluvial como o mais plausível factor de iniciação, mostrando controlos por parte da topografia antecedente sobre os pontos de iniciação das formas, e do escoamento proveniente de montante sobre o seu desenvolvimento. Estabeleceu-se uma sequência evolutiva geral em termos morfológicos e mostrou-se que as formas continuam em expansão, com a dinâmica actual assente em colapsos nas paredes e cabeceiras. Os resultados sugerem um importante controlo por parte dos movimentos de massa no desenvolvimento e diversificação morfológica dos complexos de ravinas, sublinhando o papel desempenhado pela dinâmica nas cabeceiras.
- Fatores biofísicos da variabilidade espácio-temporal dos incêndios rurais na região centro de PortugalPublication . Bergonse, Rafaello; Oliveira, Sérgio; Zêzere, José Luís; Lima e Santos, José Manuel; Moreira, Francisco; Ribeiro, Paulo Flores; Leal, MiguelEste trabalho relaciona os padrões espácio-temporais dos incêndios em 972 freguesias no centro de Portugal com um conjunto de fatores biofísicos, aplicando a regressão logística ordinal. Os incêndios são caracterizados usando três parâmetros (1975-2018): percentagem acumulada de área ardida, um índice de concentração temporal da área ardida (Gini) e frequência de incêndios ponderada pela área. Os fatores biofísicos incluem a topografia, a temperatura e a precipitação sazonais, os tipos de uso/ocupação do solo e a respetiva fragmentação espacial. Os resultados mostram que as características dos incêndios variam substancialmente na área de estudo, sendo sobretudo influenciados pelo uso/ocupação do solo, a precipitação de primavera e a temperatura de verão.
- Água e Território: um tributo a Catarina RamosPublication . Ramos Pereira, A.; Leal, Miguel; Bergonse, Rafaello; Trindade, Jorge; Reis, Eusébio
- 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.