Forest Fires In Portugal Research Articles

A Neural Network Approach to Forest Fire Burned Area Prediction

Worldwide ecosystems and economies are seriously threatened by forest fires, which can result in extensive damage and financial losses. Strategies for managing and preventing wildfires depend heavily on the accurate prediction of burned areas. To create a predictive model for the burned areas caused by forest fires in Portugal's northeast, this study uses a machine learning technique, namely Neural Network. The model integrates meteorological and spatial-temporal data and makes use of regression algorithms. To maximize the performance of the model, data preprocessing, exploratory data analysis, model building, feature selection, and assessment are done. The results show that burned area is greatly influenced by meteorological factors, including temperature, humidity, and wind speed. The created model shows a respectable level of prediction accuracy of 97.11%, offering insightful information for efficient fire management and early warning systems. The potential for reducing the destructive effects of wildfires is enormous when machine learning is incorporated into the prediction of forest fires.

ECMWF Lightning Forecast in Mainland Portugal during Four Fire Seasons

The study evaluated the ECMWF model ability in forecasting lightning in Portugal during four fire seasons (019–2022). The evaluation was made based on lightning data from the national lightning detector network, which was aggregated into resolutions of 0.5° and 1° over 3 h periods and analyzed from statistical indices using two contingency tables. The results showed that the model overestimates the lightning occurrence, with a BIAS greater than 1, with a success rate of 57.7% (49%) for a horizontal resolution of 1° (0.5°). The objective analysis was complemented by the spatial lightning distribution analysis, which indicated a time lag between the two data, i.e., the model started predicting lightning before its occurrence and finished the prediction earlier. Furthermore, such analysis revealed the lightning distribution being consistent with some weather patterns. The findings of this study provide insights into the applicability of the ECMWF lightning forecast data in the context of forecasting natural forest fires in Portugal.

Study of Building Vulnerabilities to Forest Fires in Portugal

Nowadays with disorderly urban growth into forested areas and climate changes becoming more pronounced, the number of buildings affected by forest fires is increasing. Forest fires are becoming more destructive and socially threatening. However, it is irrefutable that the probability of a forest fire to reach a structure is dramatically reduced by implementing good construction practices and proper fuel management procedures in the environment. Aiming to evaluate the behavior of construction elements of a structure facing a forest fire with testing close to reality, a demonstrative test was performed by the authors in a small house located in a forest environment, in the municipality of Miranda do Corvo, in Portugal. The test consisted of burning a plot of land, with a high forest fuel load, where the house was exposed to a high heat flux originating from the flame front. The separation strip between the fuels and the house was 50cm. With the observation of the results, it was verified that even though the house had an incombustible structure, the construction elements such as window glass, door, thermal insulation and exhaust fans presented vulnerabilities to be considered when it is assumed that a house can serve as shelter in case of fire. It is important to emphasize that the study and research on the vulnerability of buildings in the face of a wildfire at an urban-forest interface must be integrated with all the constraints and variables that surround this theme.

Pyrolysis of burnt maritime pine biomass from forest fires

Forest fires in Portugal give rise to a large amount of burnt wood, a waste, and as such with few applications. Its energy recovery can be seen to manage these residues with advantages for the environment and as a source of income for the populations that depend on the primary sector of the economy. Burnt pine wood was evaluated as raw material for pyrolysis. The collected biomass samples, from the maritime pine trunk, were cut to separate the burnt part (external layer) from the part not affected by the fire, giving rise to the two distinct biomass samples, raw and burnt. The lignocellulosic composition was assessed by thermogravimetry and the differences in composition arise from the fact that the raw sample is sapwood, whereas the burnt sample is mainly cambium. Biomass pyrolysis kinetics evaluated by the KAS method led to an activation energy of 192 kJ/mol for raw and 169 kJ/mol for burnt biomasses. Biomass was pyrolyzed in a fixed bed pyrex reactor for temperatures in the 673–773 K range corresponding to the maximum thermal degradation rate assessed by thermogravimetry. The burnt biomass showed lower bio-oil yields (maximum 31%), which increase with the pyrolysis temperature. Besides, burnt biomass bio-char yield was always greater than the analog produced from raw biomass over the entire temperature range. The catalyzed pyrolysis tests using carbonate catalysts (limestone, CaCO3, Na2CO3, and Li2CO3) showed improved pyrogas which are compatible with the gasification role of alkali carbonate catalysts reported in the literature.

The occurrence of inorganic contaminants in ‘tronchuda’ cabbage (Brassica oleracea L. var. costata DC.) after large forest fires in Portugal

ABSTRACT European Mediterranean countries have been affected by unhealthy pollutants released by wildfire smoke. This work aims to determine the inorganic elements, present in the vegetable widely consumed by the rural population, provided by burned areas. Two groups composed the sampling plan; group one before forest fires and group two after forest fires under three campaigns: 1) immediately after forest fires; 2) after rainfall; 3) during springtime. ICP-MS analysed all the samples to evaluate the contents of As, Br, Cd, Co, Cr, Pb, Se, Sr, and Zn. The amounts of trace elements founded were the following Pb < Cd < Co < As < Cr < Se < Zn < Br < Sr. Hierarchical Cluster Analysis evidenced 4 clusters; the first with the highest contents of Cr and Pb, the second cluster was marked by the highest amounts of As, and Br, higher values of Se characterised the third cluster, and the fourth cluster presented the highest values of Zn and Cd. The contents of contaminants in group one is not a matter of concern. The results obtained in group two identified a hazard, decreasing one year after the fires and maintaining these patterns afterwards. Occurrence data from local foods is a pioneer to study the impact of forest fires on human health through food consumption.

Large Scale Shrub Biomass Estimates for Multiple Purposes.

With the increase of forest fires in Portugal in recent decades, a significant part of woodlands is being converted into shrubland areas. Background: From an ecological point of view, woodlands and shrublands play an essential role, as they not only prevent soil erosion and desertification, but also contribute to soil protection, habitat preservation and restoration, and also increased biodiversity for carbon sequestration. Concerning the shrublands, the assessment of their biomass is essential for evaluating the fuel load and forest fire behavior and also beneficial for obtaining estimates of carbon and biomass for energy use. Methods: In this study, we collected data about the potential shrub biomass accumulation along fifteen years in former burnt areas within North Portugal. Results: The achieved results showed that for a post-fire period ranging from one to 15 years, the accumulated shrubs’ biomass ranged from 0.12 up to 28.88 Mg ha−1. The model developed to estimate the shrub biomass using the time after a fire (age) as a predictor variable presented a high adjustment to data (p-value of the F statistic <0.01 and R2 = 0.89), allowing estimating shrub biomass regeneration within former burnt areas with an RMSE of 3.31 Mg ha−1. Conclusions: This paper provides practical information on the availability and assessment of shrub biomass in North Portugal, highlighting the suitability of shrubs as potential sources of biomass.

Mapping the Causes of Forest Fires in Portugal by Clustering Analysis

This paper presents a spatial characterization of the distribution at district level of the forest fire events that occurred in mainland Portugal between 1996 and 2015 and whose causes were investigated. We further examine the breakdown of the causes of these forest fires over this period. Results supported by relevant validated statistics show that of the total fire events recorded, 94.4% were identified as an effective occurrence, of which 22.2% had burned an area greater than 1 ha, and of these only 42.1% were investigated. False alarms or fires without a recorded burning area are more significant in the districts of Aveiro, Lisbon and Porto, the biggest municipalities. Of the fires whose causes were investigated, the largest number of recorded events were in NE regions (49.0%), followed by NW regions (41.7%), and finally in the rest of the country (9.3%). Taking into account the ratio between the investigated fires and the total number of fires and the behavior profile produced for cluster analysis, a different panorama is brought to light, with the center and south regions showing greater effort to investigate the fires. A thorough analysis of the causes and motivations of the ignition of these forest fire occurrences showed that human activity, either deliberate (20.4%) or negligent (29.9%), outweigh natural phenomena (0.6%). Reactivations (14.6%) and Unknown (34.5%) causes decreased as time passed, whereas negligent and deliberate causes increased. However, these results could change if the percentage of unknown information in relation to the origin of the forest fires is considerable. The outcome of this research will support an efficient management related to fire mitigation and suppression including establishing preventive actions to reduce the occurrence of forest fires and emphasize the need to improve the procedure for recording forest fire events in Portugal, especially in relation to identifying their cause.

Forest fires in Portugal - case study, 18 june 2017

Forest fires that occurred in Portugal on June 18, 2017, caused several tens of human casualties. The cause of their emergence, as well as many others that occurred in western Europe at the same time remained unknown. Taking into account consequences, including loss of human lives and endangerment of ecosystem sustainability, discovering of the forest fires causes is the very significant question. The heliocentric hypothesis has indirectly been tested, according to which charged particles are a possible cause of forest fires. We must point out that it was not possible to verify whether in this specific case the particles by reaching the ground and burning the plant mass create the initial phase of the formation of the flame. Therefore, we have tried to determine whether during the critical period, i. e. from June 15-19 there is a certain statistical connection between certain parameters of the solar wind and meteorological elements. Based on the hourly values of the charged particles flow, a correlation analysis was performed with hourly values of individual meteorological elements including time lag at Monte Real station. The application of the Adaptive Neuro Fuzzy Inference System models has shown that there is a high degree of connection between the flow of protons and the analyzed meteorological elements in Portugal. However, further verification of this hypothesis requires further laboratory testing.

Applied vegetation science addresses emerging global issues

In this Editorial, the Chief Editors examine how vegetation science addresses emerging global issues

Local fractality: The case of forest fires in Portugal

The research deals with a study of local fractality in spatial distribution of forest fires in Portugal using the sandbox method. The general procedure is the following: (a) define a circle centred in each and all events with increasing radius R; (b) count the number of other events located within the circle of radius R, N(R); (c) plot the growth curve which is the functional dependence of N(R) versus R; and (d) estimate the local fractal dimension as the slope on log[N(R)] versus log[R]. The computation is carried out by using the location of every fire event as a centre but without the final averaging over all the fires for a given R, which is usually performed to get a global fractal dimension and to estimate global clustering. Sandbox method is widely used in many applications in physics and other subjects. The local procedure has the ability to provide the most complete information regarding the spatial distribution of clustering and avoiding non-homogeneity and non-stationarity problems. Most of the analysis was performed using the National Mapping Burnt Area (NMBA) database which accounts for 32 156 fires during the 1975–2013 period. The results of local analysis are compared with a randomly generated pattern in forest zones (validity domain). The results demonstrate interesting local spatial patterns of clustering. Some results on global measures are reported as well.

Forest fires in Portugal - the connection with the Atlantic Multidecadal Oscillation (AMO)

The data on forest fires in Portugal in the period 1980–2015 were used in the research: the annual number of forest fires, the annual burned area and the average burned area per fire. Increasing trend of the annual number of forest fires (statistically significant at p≤0.01), non-significant increasing trend of the annual burned area and decreasing trend of the average burned area per fire (statistically significant at p≤0.01) were recorded. Portugal is the most endangered country by forest fires in comparison with the other European countries. During the research period, fires in Portugal covered 23.6% of the total burned area in five the most affected European countries (Portugal, Spain, France, Italy and Greece). In the research of the connection between forest fires and the Atlantic Multidecadal Oscillation (AMO) Pearson correlation coefficient (R) was used. Monthly, seasonal and annual values of the AMO index were used in calculations. All R values recorded for the annual number of fires were positive and statistically significant at p≤0.01. The highest values were recorded for August (0.543) and for summer (0.525). With the annual burned area all R values were also positive and the highest one on the seasonal level was for summer (0.359). With the average burned area per fire all R values were negative (−0.428 was recorded for winter). The results of the research could be applied in the fire danger forecast for periods of several months. Other climate indices should also be considered in future research.

Electrons or protons: What is the cause of forest fires in western Europe on June 18, 2017?

Forest fires in Portugal (June 17–24, 2017) destroyed 64 lives and caused considerable material damage. The coronal hole CH807 and the energy region S5710 were in the geoeffective position on the Sun immediately before the outbreak of fires. In the period that preceded it, as well as at the time of the fires, increased values of the solar wind (SW) parameters (temperature, speed and density of particles) were recorded. In addition, a geomagnetic disorder was recorded. The shape and size of the burning areas, as well as the low air pressure over Portugal indicate the possibility of the effect of positively charged particles that came from the area south, i.e. southwest of Portugal. Nevertheless, it is a specific case that would have to be investigated in more detail.

Evolution of forest fires in Portugal: from spatio-temporal point events to smoothed density maps

The spatial and temporal distribution of forest fires displays a complex pattern which strongly influences the forest landscape and the neighbouring anthropogenic development. Statistical methods developed for spatio-temporal stochastic point processes can be employed to find a structure, detect over-densities and trends in forest fire risk and address towards prevention and forecasting measures. The present study considers the Portuguese mapped burnt areas official geodatabase resulting from interpreted satellite measurements, covering the period 1990–2013. The main goal is to detect whether space and time act independently or whether, conversely, neighbouring events are also closer in time, interacting to generate clusters. To this purpose, the following statistical methods were applied: (1) the geographically weighted summary statistics, to explore how the average burned area vary locally through the investigated region; (2) the bivariate K-function, to test the space–time interaction and the spatial attraction/independency between fires of different size; and (3) the space–time kernel density, allowing elaborating smoothed density surfaces and representing over-densities of large versus medium versus small fires and on north versus south region. The proposed approach successfully allowed finding and mapping spatio-temporal patterns within this large data series. Specifically, medium fires tend to aggregate around small fires, while large fires aggregate at a larger distance and longer times, indicating that the return time following these events is longer than for small and medium fires. The density maps shows that hot spots are present almost each year in the northern region, with a higher concentration in the northern areas, while the southern half of the country counts lower surface densities of fires, which are mainly concentrated in the central period (2000–2007).

Exploring spatial patterns and drivers of forest fires in Portugal (1980–2014)

Information on the spatial incidence of fire ignition density and burnt area, trends and drivers of wildfires is vitally important in providing support for environmental and civil protection policies, designing appropriate prevention measures and allocating firefighting resources. The key objectives of this study were to analyse the geographical incidence and temporal trends for wildfires, as well as the main drivers of fire ignition and burnt area in Portugal on a municipal level. The results show that fires are not distributed uniformly throughout Portuguese territory, both in terms of ignition density and burnt area. One spot in the north-western area is well defined, covering 10% of the municipalities where more than one third of the total fire ignitions are concentrated. In >80% of Portuguese municipalities, ignition density has registered a positive trend since the 1980s. With regard to burnt area, 60% of the municipalities had a nil annual trend, 35% showed a positive trend and 5%, located mainly in the central region, revealed negative trends. Geographically weighted regression proved more efficient in identifying the most relevant physical and anthropogenic drivers of municipal wildfires in comparison with simple linear regression models. Topography, density of population, land cover and livestock were found to be significant in both ignition density and burnt area, although considerable variations were observed in municipal explanatory power.

The role of fire-suppression force in limiting the spread of extremely large forest fires in Portugal

Large forest fires are notorious for their environmental and socio-economic impacts and are assigned a disproportionately high percentage of the fire management budget. This study addresses extremely large fires (ELF, ≥2500 ha) in Portugal (2003–2013). We analysed the effect of fire-suppression force variation on ELF duration, size and growth rate, versus the effect of the concomitant fire environment (namely fuel and weather) conditions. ELF occurred in highly flammable landscapes and typically were impelled by extreme fire weather conditions. Allocation of suppression resources (normalized per unit of burned area or perimeter length) was disparate among fires, suggesting inadequate incident management. Fire-suppression effort did not affect time to containment modelled by survival analysis. Regression tree analysis indicated ELF spread to be negatively affected by higher fire-suppression resourcing, less severe fire weather, lower time to containment and higher presence of <9-year-old fuels, by decreasing order of importance; regional variability was relevant. Fire environment-to-fire suppression ratios of influence were 3:1 for fire size and 1:1 for fire growth rate, respectively, explaining 76 and 60 % of the existing variability. Results highlight the opportunistic nature of large-fire containment. To minimize the area burned by ELF, management and operational improvements leading to faster containment are recommended, rather than higher fire-suppression resourcing; more effective identification and exploration of containment opportunities are preferable to the accumulation of suppression resources.

A look at forest fires in Portugal: technical, institutional, and social perceptions

Forest fires affect Portugal and other southern European countries to a greater or lesser extent every year, causing severe environmental, social, and economic damage. This research is based upon the analysis of the results of a case study on the technical and social perceptions of multiple dimensions of forest fires in Portugal, which brings together the views and perspectives of different entities with expertise in forest management and in forest protection against fires, forest owners, and members of the public. Assessing perceptions of forest fires has proved to be relevant when it comes to a greater involvement of the local population in forest management. The results show that the opinions of local respondents were consensual in identifying crime as the main cause of the forest fires. Additionally, it is the repeated failure to clean the forest biomass which cause the rapid spread of forest fires. Damage caused to the environment was more of an issue with the local forestry technicians, and economic issues were at the forefront for the local community. Various solutions were put forward to mitigate these problems, but everyone agreed that cleaning the forests biomass and punishing arsonists should be at the top of the list of priorities.

Regional variability and driving forces behind forest fires in Portugal an overview of the last three decades (1980–2009)

The purpose of this paper was to analyze the evolution and regional distribution of both forest fire ignitions and burnt areas in mainland Portugal and to identify the relationship between biophysical and human variables and the incidence of forest fires at the district level over the last 3 decades (1980–2009). A positive trend can be observed in the number of fires and in the areas burnt by forest fires since 1980. An interesting regional distribution of forest fire ignitions and burned areas was detected, highlighting some districts especially vulnerable to the outbreak of fires and others particularly susceptible to the spread of fire. A stepwise multiple regression methodology was applied to determine the relative importance of each variable in explaining the regional distribution of ignitions and burned area fractions and to address hypotheses regarding human and biophysical influences on the drivers of forest fires.Population density was the primary determining variable in the outbreak of fires at the district level (this factor alone explained 65% of the inter-district variation in the density of fire ignitions), whereas burn areas were influenced by the synergistic effects of topography, changes in land use, and vegetation.The topographic roughness index emerged as the most important variable causing the regional variations observed in the percentage of the district area burnt over the last 30 years, explaining 70% of the observed variance. Variables associated with changes in land use and cover during the second half of the last century explained an additional 17% of the variance. Multiple regression analysis also suggested a positive relationship between the total area burnt and the total uncultivated area, explaining 57% of the variance at the district level. In general, the greatest pressures from fire occur in the districts north of the Tejo River, which are more mountainous, have lower annual temperatures and more rainfall, and produce the most biomass under pressure from agriculture and grazing. In these districts, the decline of traditional agriculture has resulted in important transformations to the landscape characterized by the spread of natural vegetation.

A Review of the European Summer Heat Wave of 2003

This paper reviews the European summer heat wave of 2003, with special emphasis on the first half of August 2003, jointly with its significant societal and environmental impact across Western and Central Europe. We show the pattern of record-breaking temperature anomalies, discuss it in the context of the past, and address the role of the main contributing factors responsible for the occurrence and persistence of this event: blocking episodes, soil moisture deficit, and sea surface temperatures. We show that the anticyclonic pattern corresponds more to an anomalous northern displacement of the North Atlantic subtropical high than a canonical blocking structure, and that soil moisture deficit was a key factor to reach unprecedented temperature anomalies. There are indications that the anomalous Mediterranean Sea surface temperatures (SSTs) have contributed to the heat wave of 2003, whereas the role of SST anomalies in other oceanic regions is still under debate. There are methodological limitations to evaluate excess mortality due to excessive temperatures; however, the different studies available in the literature allow us to estimate that around 40,000 deaths were registered in Europe during the heat wave, mostly elderly persons. Despite previous efforts undertaken by a few cities to implement warning systems, this dramatic episode has highlighted the widespread un-preparedness of most civil and health authorities to cope with such large events. Therefore, the implementation of early warning systems in most European cities to mitigate the impact of extreme heat is the main consequence to diminish the impact of future similar events. In addition to mortality (by far the most dramatic impact), we have also analyzed the record-breaking forest fires in Portugal and the evidence of other relevant impacts, including agriculture and air pollution.

Fire activity in Portugal and its relationship to weather and the Canadian Fire Weather Index System

The relationships among the weather, the Canadian Fire Weather Index (FWI) System components, the monthly area burned, and the number of fire occurrences from 1980 to 2004 were investigated in 11 Portuguese districts that represent respectively 66% and 61% of the total area burned and number of fires in Portugal. A statistical approach was used to estimate the monthly area burned and the monthly number of fires per district, using meteorological variables and FWI System components as predictors. The approach succeeded in explaining from 60.9 to 80.4% of the variance for area burned and between 47.9 and 77.0% of the variance for the number of fires; all regressions were highly significant (P &lt; 0.0001). The monthly mean and the monthly maximum of daily maximum temperatures and the monthly mean and extremes (maximum and 90th percentile) of the daily FWI were selected for all districts, except for Bragança and Porto, in the forward stepwise regression for area burned. For all districts combined, the variance explained was 80.9 and 63.0% for area burned and number of fires, respectively. Our results point to highly significant relationships among forest fires in Portugal and the weather and the Canadian FWI System. The present analysis provides baseline information for predicting the area burned and number of fires under future climate scenarios and the subsequent impacts on air quality.

Forest fires in Portugal: how they happen and why they happen

Forest fires are recurrent phenomena in Southern European countries, due to the nature of Mediterranean forest and climatic characteristics. In Portugal, however, in the recent years, forest fires have become a public calamity and are now endangering the sustainability of the forest itself, as well as several derived economic activities. This paper reviews the past and current situation of forest fires in Portugal, analyses its main causes and consequences and derives recommendations to overcome this problem.