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Possible land management uses of common cypress to reduce wildfire initiation risk: a laboratory study
Abstract
Accurate determination of flammability is required in order to improve knowledge about vegetation fire risk. Study of the flammability of different plant species is essential for the Mediterranean area, where most ecosystems are adapted to natural fire but vulnerable to recurrent human-induced fires, which are the main cause of forest degradation. However, the methods used to evaluate vegetation flammability have not yet been standardized. Cupressus sempervirens is a native or naturalized forest tree species in the Mediterranean area that is able to tolerate prolonged drought and high temperatures. The aim of this study was to characterize the flammability of C. sempervirens var. horizontalis at particle level by using different bench-scale calorimetry techniques (mass loss calorimeter, epiradiator and oxygen bomb) to determine the main flammability descriptors (ignitability, sustainability, combustibility and consumability) in live crown and litter samples. Our findings indicate that this variety of cypress is relatively resistant to ignition because of the high ash content, the high critical heat flux, the high time to ignition displayed by both crown and litter samples and the ability of the leaves to maintain a high water content during the summer. We also discuss the possibility of exploiting some morphological, functional and ecological traits of the species to construct a barrier system (with selected varieties of cypress) as a promising complementary land management tool to reduce the fire spread and intensity in a Mediterranean context.
... Região atingida pelo incêndio com as árvores de cipreste quase intactas(Rocca, et al., 2015). O texto bíblico de Gênesis 11:1-9 relata que os descendentes de Noé habitaram a Planície de Sinar, onde eles fizeram tijolos através da técnica de cozimento. ...
... Para entendermos esta analogia, fiquemos atento no seguinte fato científico. No mês de junho de 2012, a área de reserva florestal conhecida como Barranco de Herbasana, localizada no município de Jérica, em Valência, na Espanha, foi atingida por um incêndio de grandes proporções(Rocca, et al., 2015). O fogo destruiu todas as reservas de Q. ilex (azinheira), Quercus faginea (carvalho português), juniperus oxycedrus (cedro-de-espanha) e de P.halepensis (pinheiro-de-alepo). ...
... Porém, apenas 1,27% das árvores de cipreste foi queimada, 37,09% foi desidratada e 61,64% não foi atingida. A Figura 1 mostra a região atingida pelo incêndio(Rocca, et al., 2015). Este acontecimento despertou o interesse deRocca et al. (2015). ...
A Bíblia Sagrada relata as tecnologias de sua época, mostrando o avanço das civilizações antigas. A Bíblia Sagrada, além de seu valor religioso e moral, é também um registro histórico que reflete o desenvolvimento tecnológico das civilizações antigas. A engenharia avançada empregada na edificação da Torre de Babel, do Templo de Salomão e dos muros de Jerusalém revela um conhecimento sofisticado de materiais e técnicas. A metalurgia, evidenciada pela fabricação de armas, utensílios e ferramentas, reflete a evolução dos processos de fundição e trabalho com metais como ferro e bronze. Além disso, os métodos de escrita, incluindo tábuas de argila, pergaminhos e inscrições em pedra, demonstram a importância da comunicação escrita para a preservação do conhecimento e da cultura. As tecnologias mencionadas na Bíblia Sagrada contribuíram para o avanço das sociedades antigas, sendo fundamentais para o desenvolvimento econômico, militar e religioso, além de ter sido um marco fundamental que colaborou de maneira significativa para que houvesse a disseminação de diferentes áreas do conhecimento atual. As tecnologias mencionadas na Bíblia Sagrada tiveram um papel fundamental no desenvolvimento do mundo moderno, pois muitas delas serviram de base para avanços na engenharia, na escrita, na navegação e nas demais áreas do conhecimento atual. Sendo assim, e dentro desse contexto, o objetivo do presente artigo foi relatar as principais tecnologias mencionadas nas Escrituras Sagradas, com a finalidade de mostrar a sua importância para o mundo moderno.
... Consequently, accurately assessing the flammability of various plant species is not only crucial for fire prevention, fire risk assessment, and fire behavior prediction, but is also an important aspect of fire ecology studies [12,13]. Plant flammability has four components-ignitability (the ease of ignition), combustibility (the strength of plant combustion), sustainability (the duration of plant burning), and consumption (the amount of plant burned) [14][15][16][17]. These flammability components vary substantially across different species [18][19][20] and are influenced by multiple plant traits, including plant physiological, morphological, and chemical characteristics [21][22][23][24]. ...
... Plants serve as the primary fuel in nature, and their flammability characteristics directly influence the ease of fire ignition and fire behavior, such as fire spread speed and fire intensity [9,10]. Moreover, plant flammability is an important property that affects plant A total of 220 articles related to plant flammability measurements were retriev from the Web of Science and Google Scholar databases (Supplementary Materials File S [14][15][16][17][18][19][20][21][22][23][24]27,28,30,31,. The earliest research related to plant flammability measu ment was published in 1964 [205]. ...
... Table 1). Ignition time and rate of spread are commonly used to assess ignitability [14,15,17]. Specifically, 65.13% of studies used ignition time, 20.41% used rate of spread, and 14.29% used both ignition time and rate of spread. ...
In recent years, the frequency of wildfires worldwide has been gradually increasing, posing significant threats to global ecosystems and human society. Given that plants serve as the primary fuel in natural environments, accurately assessing the flammability of plants is crucial for wildfire management and fire ecology studies. Plant flammability is a multifaceted trait influenced by various physiological, physical, and chemical characteristics of plants. Currently, there is no universally accepted standard for quantifying plant flammability. By analyzing published research over the past few decades, this study found that 17.27% of studies assessed plant flammability by measuring flammability-related characteristics, such as moisture content, leaf size, bark thickness, oil content, and terpene content; a total of 34.55% of studies assessed plant flammability through burning experiments by measuring burning parameters, such as ignition time, duration of combustion, and flame spread rate. The remaining studies, approximately 50%, used a combination of burning experiments and flammability-related characteristic measurement to assess plant flammability. This study outlined the current status of plant flammability measurements, discussed the merits of each measurement method, and proposed suggestions for enhancing the assessment of plant flammability, with the aim of contributing to the standardization of plant flammability measurements.
... In addition, a thermocouple (type K, range 50-1000 °C) connected to a data logger is placed 8 cm above the epiradiator disk to record flame and heat temperature during complete combustion (Blackhall and Raffaele 2019). This type of method was used in 16 tests, where on 13 occasions, small leaves and branches were used (Núñez-Regueira et al. 1996;Bianchi and Defosse 2015;Della Rocca et al. 2015;Fenesi et al. 2016;Gibson et al. 2016;Essaghi et al. 2017;Ganteaume 2018;Bianchi et al. 2019;Blackhall and Raffaele 2019;Guerrero et al. 2021Guerrero et al. , 2022Batista et al. 2021;Rosavec et al. 2022). The three remaining Epiradiator 500 W The epiradiator consists of an electrical heating resistor that reaches a standard surface temperature of 500 °C. ...
... Núñez-Regueira et al. 1996;Curt et al. 2011;Bianchi and Defosse 2015;Della Rocca et al. 2015;Kauf et al. 2015;Fenesi et al. 2016;Simpson et al. 2016;Essaghi et al. 2017;Ganteaume 2018;Bianchi et al. 2019;Blackhall and Raffaele 2019;Franzese et al. 2020;Batista et al. 2021;Guerrero et al. 2021;2022;Rosavec et al. 2022) Yes Fonda method This method involves placing the sample on a stainless steel platform and placing cotton threads soaked in xylene on it, which are ignited in different parts until ignition is initiated.(Kane et al. 2019, 2022; Barnes et al. 2022) No Idealized Firebrand Ignition Test (I-FIT method) This heater consists of a 5-cm-long cylindrical radiator with an operating range of up to 260 V. ...
... c Direct ignition lighter(Fuentes-Ramirez et al. 2016). d Epiradiator method(Della Rocca et al. 2015) ...
Background
Vegetation plays a crucial role in the ignition, propagation, and severity of fire, and understanding the relationship between plants and fire through flammability attributes has become a useful tool that is increasingly used in studies on fire dynamics worldwide. However, in the southern cone of South America, rather few studies have systematically and specifically addressed the flammability of vegetation, and yet fewer have compared native and non-native species. Given the increasing interest in knowing the flammability characteristics of vegetation, this review aims to assess the potential differences in flammability between native and non-native plant species that inhabit the southern cone and to identify the main methodologies and experiments used to analyze vegetation flammability.
Results
Twenty-eight species were identified, 18 native to the region and 10 non-native. Additionally, 64 experimental tests were revised to evaluate plant flammability. It was found that Cryptocarya alba , Acacia dealbata , Eucalyptus globulus , and Pinus ponderosa are the species with a high flammability index. By contrast, the species Araucaria araucana , Austrocedrus chilensis , Embothrium coccineum , and Persea lingue showed low flammability. The methodologies used to evaluate vegetation flammability were highly variable, with the use of epiradiators being the most frequent.
Conclusions
Our review indicates that the geographic origin of vegetation (native vs. non-native in South America) is not a decisive factor in determining species-level differences in flammability. Other relevant factors that contribute with the degree of plant flammability include fuel moisture, the morphology of the species, and its internal chemical compounds. We highlight the necessity of continuing the study of plant flammability and advance in the standardization of protocols and measurements, using uniform criteria and increasing comparative studies between species, particularly in the southern cone of South America where catastrophic wildfires are increasing.
... Different methods exist for studying samples along this range. For studies that burn smaller samples (e.g., individual leaves), such as those using epiradiator-based methods (e.g., [5,6]; see Figure 1a,b), flat-flame burners ( [7]), or oxygen bomb calorimetry (e.g., [8,9]), differences in flammability may be easier to link to specific mechanisms due to the controllable environment and limited variation between samples. However, challenges arise when applying these conclusions to broader scales due to the lack of realism regarding fuel morphology, as critics of laboratory flammability testing have noted [10]. ...
... On six occasions, methods were utilized that were not seen in any other study, so these methods were aggregated into an 'other' group. There were 19 studies that utilized more than one method to test different aspects of flammability or different fuels, with a few using more than two methods [9,12,27]. ...
... Tests were most commonly conducted at 50 kW/m 2 . [9,12,13,50,59,67,[123][124][125][126] Oxygen Bomb This is a calorimetry method commonly used to measure gross energy content and heat of combustion. It operates by having a reaction occur in a container (referred to as the 'bomb') with a fixed volume, so that changes in temperature can be attributed to the energy flux of the reaction rather to any changes in volume. ...
Increased wildfire frequency and size has led to a surge in flammability research, most of which investigates landscape-level patterns and wildfire dynamics. There has been a recent shift towards organism-scale mechanisms that may drive these patterns, as more studies focus on flammability of plants themselves. Here, we examine methods developed to study tissue-level flammability, comparing a novel hot-plate-based method to existing methods identified in a literature review. Based on a survey of the literature, we find that the hot plate method has advantages over alternatives when looking at the specific niche of small-to-intermediate live fuel samples—a size range not addressed in most studies. In addition, we directly compare the hot plate method to the commonly used epiradiator design by simultaneously conducting flammability tests along a moisture gradient, established with a laboratory benchtop drydown. Our design comparison addresses two basic issues: (1) the relationship between hydration and flammability and (2) relationships between flammability metrics. We conclude that the hot plate method compares well to the epiradiator method, while allowing for testing of bigger samples.
... Fire management policies that focus on fire suppression rather than preventive measures in land management can further accelerate fire hazard increase (Fernandes 2013). With respect to fire regime changes, fire management strategies should give priority to fire hazard assessment and define the flammability of wildland fuels (Dimitrakopoulos 2001a;Della Rocca et al. 2015). ...
... Studies on plant flammability are, therefore, important for fire management and planning (Liodakis and Kakardakis 2006;Fares et al. 2017). In fact, in recent years, the use of less flammable plants in afforestation areas and for zonal planting in the wildland-urban interface is regarded as a promising option (Della Rocca et al. 2015;Curran et al. 2018;Blackhall and Raffaele 2019). In some countries (e.g. ...
... Many researchers have studied the differences in flammability between Mediterranean plant species using different methods and test standards (Valette 1990;Dimitrakopoulos and Papaioannou 2001;Etlinger and Beall 2004;Hachmi et al. 2011;Liodakis et al. 2011;Mitsopoulos 2011;Ganteaume et al. 2013;Della Rocca et al. 2015;Molina et al. 2017). The assessment of flammability under laboratory conditions is limited to the scale of the experiment (White and Zipperer 2010), because the way plants are exposed to heat may differ from that of a forest fire (Fernandes and Cruz 2012). ...
Vegetation is the only component that can be directly managed to reduce the negative consequences of wildland fires. Flammability indexes provide information about plant flammability characteristics and are commonly used in wildland fuel management. However, previous flammability indexes were usually based on only two or three flammability components. We propose an advanced approach for leaf flammability index estimation that integrates all four flammability components (ignitability, combustibility, sustainability and consumability) using cluster and linear discriminant analyses. We measured time to ignition, ignition temperature, maximum flame height, combustion time, mass loss percentage and fuel moisture content of 15 plant species most affected by forest fires in Turkey (every two weeks, from May to September). Species were divided into different flammability classes and ranked according to their flammability index (FI) values. Classifications and FI rankings showed seasonal variations for some of the species. During May and June, fuel moisture contents explained ~50–60% of variation in leaf flammability but this relationship steadily decreased towards September (13%) when weather conditions became drier. The proposed approach for FI estimation offers a more detailed flammability assessment and comparison between plants. It can be used to identify less flammable plants for fuel breaks and landscaping in the wildland–urban interface.
... By contrast, other conifers such as Cupressus spp. produce litter with a relatively high bulk density that is more combustible but less ignitable than Mediterranean pines (Della Rocca et al., 2015). Similar physical properties have been observed in other species of Cupressaceae such as Chamaecyparis sp. ...
... Another interesting trait of these forests is the contrasting flammability of the species involved. Cupressaceae are reported (in laboratory studies) as being slow to ignite but develop high energy (Della Rocca et al., 2015), whereas several Mediterranean oak species, belonging to the 'fast flammable' group as defined by Pausas et al. (2017), generally burn more rapidly but release less heat. It would therefore be interesting to evaluate the occurrence of non-additive effects of the fuel mixtures on the flammability components, as has been done for litter (van Altena et al., 2012). ...
... An adapted Mass Loss Calorimeter (MLC) device was used, as reported in previous studies on the flammability of forest fuels (Madrigal et al., 2009(Madrigal et al., , 2011(Madrigal et al., , 2013Della Rocca et al., 2015;Dehane et al., 2017). Tests were performed using the MLC arranged in the standard horizontal configuration, according to criteria established by White and Zipperer (2010) to determine the main flammability descriptors (ignitability, sustainability, combustibility, and consumability). ...
In the Mediterranean region, wildfires are a major disturbance, determined by ecosystem and forest species characteristics. Both the flammability and resistance to fire of a mixed forest may vary from those of the individual species. Two mixed Mediterranean woodlands, a Cupressus sempervirens and Quercus ilex stand in Italy; and a Juniperus thurifera and Quercus faginea stand in Spain were investigated. Laboratory flammability tests were conducted on live foliage, litter samples and on litter beds from individual and mixed species to evaluate: (i) the flammability traits of the mixtures of live foliage and litter samples; (ii) whether the flammability of the two-species mixtures are non-additive, i.e., differ from expected flammability based on arithmetic sum of the single effects of each components species in monospecific fuel; (iii) the ignition success and initial fire propagation in litter beds. Flammability tests were also conducted on bark samples to estimate the resistance of the tree species to fire. The ignitibility of live foliage was lower and the combustibility was higher in Cupressaceae than in Quercus. Non-additive effects were observed in some flammability components of live foliage and litter, especially in the mixtures of C. sempervirens and Q. ilex. Ignitability and combustibility were higher and lower than expected, respectively, and tended to be driven by Quercus), while the consumability was lowered more than expected by both Cupressaceae. The ignition success in the litter beds was low, especially for the presence of Cupressaceae that increase the bulk density of the mixtures. Cupressaceae, which have a thinner bark, suffered more damage to the cambium after shorter exposure to the heat source than Quercus species. In all the species studied, time to reach lethal temperatures in the cambium was dependent on thickness rather than on flammability of the bark. The study findings revealed that tree species may influence flammability of mixed fuels disproportionately to their load. The studied species showed to exert a contrasted effect on flammability of the mixtures, increasing ignitability and decreasing combustibility and consumability well out of their proportion in the mixture. This may potentially influence fire dynamics in mixed forests.
... At the 8 th day, an additional series of ignition test was performed for each species on oven dried (to constant weight) fuel samples (sixth step, FMC = 0). The IP was evaluated at a low radiant flux using an epiradiometer, simulating a lowmoderate fire condition (Cruz & Alexander 2010), according to the methodology proposed by Della Rocca et al. (2015). A low radiant flux was adopted following Petriccione et al. (2006) to more effectively discriminate the flammability of components and to better explore differences among species. ...
... Flammability tests were carried out on live fuel and litter samples of the 5 species (Tab. 1, Tab. 2), using an epiradiometer set as described in the previous experiment to simulate a low fire condition (Della Rocca et al. 2015). Forty 1 g subsamples were tested from each collection site, totalling 560 assays on LFF and 440 assays on litter samples. ...
... Our results also showed that common cypress leaves have to lose a much greater proportion of water content before ignition started, compared to the Mediterranean pines, confirming a relative ignition resilience (initial thermal inertia) of cypress LFF when samples are subjected to a relatively low heat flux (25 kW m -2 -Della Rocca et al. 2015). ...
One of the major factors influencing forest fuel combustion are terpenoids, a fraction of flammable Biogenic Volatile Organic Compounds (BVOCs) produced and stored by most Mediterranean species. The qualitative and quantitative effect of terpenoids on flammability has been only partially explained. In this study several major terpenoid-storing Mediterranean species (common cypress and three pines) were considered and compared to Holm oak as a reference non-storing species. The terpenoids were quantified via gas chromatography (GC-MS) analysis from both live fine fuel (LFF) and litter samples, and the relations between flammability and the terpenoids content were investigated by categories (Monoterpenoids, oxygenated Monoterpenoids, Sesquiterpenoids). The effect of fuel moisture content and species on ignition probability of LFF was also explored. A very different ignition probability was observed at the same fuel moisture content for the different species (Pinus spp. > C. sempervirens > Q. ilex). The stored terpenoids explained 19% to 50% of the whole flammability of both LFF and litter. Fuel moisture content (FMC) did not substantially change the relative effect of terpenoids on flammability, except in C. sempervirens. Monoterpenoids do not seem to significantly affect flammability, while sesquiterpenoids greatly influenced most flammability components, though their relative effect varied among species. A relation between storing structure of terpenoids and flammability was suggested. The results of this study indicate that isoprenoids should be included in physical models of the prediction and propagation of wildfire in Mediterranean vegetation as significant factors in driving flammability.
... Some bench-scale studies have been carried out using different approaches and methods to characterize and compare the flammability of both live and dead fine fuel in Mediterranean species (e.g. Valette 1990;Alessio et al. 2008;Madrigal et al. 2011;Ganteaume et al. 2013;Pausas et al. 2015;Della Rocca et al. 2015;Jervis and Rein 2016). Comparison of the results obtained among studies is rather difficult, indicating that a standardized method for determining flammability must be developed and a common classification established for the test results (e.g. ...
... Two series of tests were carried out using both fresh and dried fine fuel samples, from the ten selected species, according to the methodology proposed by Madrigal et al. (2013). A Mass Loss Calorimeter (MLC) device (FTT®) was used, as reported in previous studies concerning flammability of forest fuels (Madrigal et al. 2009;Madrigal et al. 2011;Madrigal et al. 2013, Della Rocca et al., 2015. This apparatus is the complete fire model of the cone calorimeter, which has assumed a dominant role in bench-scale fire testing of building materials (more details in Madrigal et al. 2009). ...
... The species T. articulata and common cypress (Cupressus sempervirens L.) showed great similarities. Both species, which are closely related, displayed high values of TTI (low ignitability) and also of PHRR and AEHC (Della Rocca et al. 2015;Ganteaume et al. 2013). Juniperus oxycedrus is recognized as a highly flammable species in the Mediterranean (Madrigal et al. 2011) because of its very high surface area-to-volume ratio and low FMC during the summer (Valette 1990;Elvira and Hernando 1989). ...
Key message: The high flammability of some companion species inQuercus suberforests, estimated in laboratory tests, could potentially generate an increase in fire vulnerability and in fire risk. Context: Recurrent wildfire is one of the main causes of forest degradation, especially in the Mediterranean region. Increased fire frequency and severity due to global change could reduce the natural resilience of cork oak to wildfire in the future. Hence, it is important to evaluate the flammability of companion species in cork oak forests in the particularly dry bioclimatic conditions of North Africa. Aims: This study aimed to assess and compare flammability parameters at laboratory scale among ten companion frequent species in cork oak forests. Methods: Fuel samples were collected in a cork oak (Quercus suber L) forest in the southern part of the mountains of Tlemcen (Western Algeria). A series of flammability tests were carried out using a Mass Loss Calorimeter device (FTT ®). A cluster analysis to classify flammability of the selected species was conducted using the K-means algorithm. Results: The results revealed differences in the four flammability parameters (ignitability, sustainability, combustibility and consumability), in both fresh and dried fine fuel samples from Quercus suber, Pinus halepensis, Quercus ilex, Quercus faginea, Erica arborea, Arbutus unedo, Pistacia lentiscus, Calicotome spinosa, Juniperus oxycedrus and Tetraclinis articulata. Application of the K-means clustering algorithm showed that C. spinosa, T. articulata, J. oxycedrus and P. halepensis are highly flammable because of their high combustibility and sustainability. Conclusion: The findings identify species that could potentially increase the vulnerability of cork oak forests to forest fires.
... Cork oak or Quercus suber L. (Q.s.L.) and Cupressus sempervirens L. (C.s.L.) are abundant Mediterranean forest species with distinctive morphological characteristics. C.s.L. species which possess foliar monoterpene storage compartments (resin ducts) (Hamidpour et a. 2011) are recognized for their high thermotolerance characteristics and are being considered in silviculture measures as green barriers against wildfires (Della Rocca et al. 2015). ...
... A cypress plantation in Spain (Valencia), was slightly affected by a wildfire that burnt all trees arounds whereas only 12.7% of the cypress trees were burned, 37.1% were dehydrated and 61.6% were not affected (Della Rocca et al. 2015). Although, this same species is dangerous as a house hedge because when it is regularly cut to form a clean hedge, dead fuel accumulates inside the trees. ...
O período entre 2018 e 2022 mostrou-nos que o problema dos incêndios à escala global não está a diminuir, antes pelo contrário. Parece que as consequências das alterações climáticas já estão a afectar a ocorrência de incêndios florestais em várias partes do Mundo, de uma forma que só esperaríamos que acontecesse vários anos mais tarde. Em muitos países do Sul da Europa, bem como em algumas regiões dos EUA, Canadá e Austrália, onde estamos habituados a enfrentar a presença de incêndios muito grandes e devastadores, continuamos a ter eventos que quebram recordes. Alguns países, como os da Europa Central e do Norte, que não estavam habituados a ter grandes incêndios, experimentaram-nos durante estes anos. Os anos anteriores foram muito exigentes para todo o Mundo, também noutros aspectos que nos afectaram a todos. Referimo-nos às restrições impostas pela pandemia que limitaram as nossas reuniões e viagens, afectando em muitos casos a saúde dos membros da Comunidade Científica Wildfire. Felizmente, conseguimos encontrar novas formas de comunicação, ultrapassar essas limitações e manter-nos em contacto uns com os outros. Durante semanas e meses, para muitos de nós, as reuniões pessoais e o trabalho de grupo foram substituídos por ligações em linha. Apesar da economia de dinheiro e tempo, e da facilidade de reunir uma grande variedade de pessoas que estas reuniões desde que nos apercebêssemos de que não substituem as reuniões presenciais, que trazem consigo outras dimensões inestimáveis, que fazem parte da comunicação pessoal e ajudam a construir uma comunidade científica.
... Passo 1) Análise junto a base secundária de instituições internacionais sobre áreas prioritárias para conservação da biodiversidade (CEPF, 2022 Passo 1) Levantamento na literatura científica sobre tipos de florestas que contribuem como barreira para incêndios (Della Rocca et. al., 2015;Xanthopoulos (2015); Passo 2) Análise dos tipos vegetacionais predominantes na Flona de Altamira para saber se correspondem a tipo de floresta que exerce papel relevante como barreira a incêndios (ICMBio, 2012a). ...
... espécies de florestas mediterrâneas, como carvalho, zimbro e pinheiro. Adicionalmente, por cada das dimensões reduzidas, as folhas de cipreste caídas no chão são muito compactas, o que faz com que a circulação de ar em seu interior seja menor que em outras espécies. A camada densa e compacta de folhas caídas atuam como esponja que retêm a umidade (Della Rocca et. al. 2015;Xanthopoulos, 2015). Assim sendo, as florestas sob a Flona Altamira, e consequentemente as UMFs I e II não são florestas que fornecem barreiras críticas contra incêndios. ...
Florestas são áreas medindo mais de 0,5 ha com árvores maiores que 5 m de altura e cobertura de copa superior a 10%, ou árvores capazes de alcançar estes parâmetros in situ. Isso não inclui terra que está predominantemente sob uso agrícola ou urbano (FAO, 2018). Todas as florestas tem algum tipo de valor ambiental, social ou econômico diverso para a sociedade. As florestas constituem um recurso essencial para a subsistência de cerca de 20% da população do planeta (Cheng, et. al., 2018). Em termos econômicos, a contribuição das atividades do setor florestal é expressiva porque ativa diversos setores da economia que são desde extração, passando pelo processamento, transporte e geração de insumos para outras indústrias e segmentos econômicos (Timko et. al., 2018). Ambientalmente, florestas são elementos chave em estratégias de conservação da biodiversidade e esforços de atenuação das mudanças climáticas (Näyhä, 2019). Adicionalmente, florestas podem ser consideradas de valor excepcional. Quando além dos benefícios já citados, áreas de florestal são essenciais, por exemplo, para proteção de bacias hidrográficas, presença de espécies raras ou ameaçadas de extinção, áreas de uso costumeiro e imprescindível para os meios de vida de comunidades locais, tais florestas são consideradas como de Alto Valor para Conservação (HCVF ). Altos Valores de Conservação foram inicialmente definidos pelo Forest Stewardship Council (FSC) para serem utilizados na certificação florestal. Porém, este conceito tem sido aplicado para outros propósitos, incluindo conservação, planejamento e advocacia de recursos naturais, mapeamento de paisagens, e na política de compras de grandes empresas. Este conceito começou a aparecer recentemente nas discussões e nas políticas de organizações governamentais e patrocinadores institucionais (Proforest, 2003). A chave para o conceito de Florestas de Alto Valor de Conservação é a identificação da presença de atributos, particularidades, qualidades e características que são próprias da floresta, ou seja, atributos de alto valor de conservação. Quando identificados, esses valores devem ser mantidos e ampliados. Portanto, a identificação de HCVF é o primeiro passo para o manejo apropriado dos recursos florestais e valor excepcional das florestas (Proforest, 2003). Este documento tem o propósito de apresentar a identificação da presença ou ausência de atributos de alto valor de conservação da floresta, bem como dissertar sobre a localização, status e contexto da paisagem, bem como estratégias implementadas ou planejadas de manutenção e ampliação dos atributos documentadamente existentes. Nos casos em que a presença seja apenas possível considerando com indícios, mas sem evidências concretas, serão apontadas pesquisas adicionais de averiguação sobre tais possibilidades de atributos presentes.
... A group of methods, approaches and technologies utilizing liquid spraying systems were developed to contain and suppress the thermal decomposition and flame combustion of woodland [1][2][3]. These systems facilitate the containment of flame combustion and thermal decomposition of materials [4][5][6][7]: high heat capacity of water and energy-consuming endothermic phase transition decrease the temperature in the combustion zone and in the layers of pyrolyzing material; thermal decomposition products are displaced by water vapors; liquid droplets and vapors block the heated oxidizer access to the pyrolysis and combustion zone. ...
... the forest fuel sample mass (m f ) was recorded using an electronic analytical balance, it was about 20 g; the aluminum cuvette mass: m sub ≈6 g, the sample bulk density: ρ f ≈13.5 kg/m 3 (corresponds to the mean range of the real forest floor density); a liquid composition with a regulated component concentration was injected into the forest fuel sample (1). For that we used a spraying nozzle, generating water aerosol with the radius of droplets R d =0.01-0.12 ...
Typical fire extinguishing agents were considered: water; bischofite solutions (with a mass fraction of 5% and 10%); bentonite slurries (with a mass fraction of 5% and 10%); foaming agent emulsions (with a mass fraction of 5% and 10%). The heating temperature range of 150-400?? was chosen to correspond to the conditions of rapid thermal decomposition of forest fuels. The experimental research findings suggest that the rates of moisture release depend exponentially on the heating temperature. It was established that the rates of moisture release in the above temperature range may differ significantly for the forest fuels and fire extinguishing agents under study. Conditions were identified when the general approximation equations, presented in this paper, can be used to predict the vaporization characteristics of firefighting liquids.
... The flammability of the live crown of plants of C. sempervirens has already been studied extensively [42][43][44][45][46][47]; nevertheless, the flammability descriptors (ignitability, sustainability, combustibility and consumability) of healthy and diseased cypress clones selected for CCD resistance have not yet been assessed. This work explores the links between diseased trees and wildfire, comparing the flammability of canker-resistant and susceptible common cypress clones, artificially infected by S. cardinale, in comparison to healthy ramets of both clones. ...
... An adapted Mass Loss Calorimeter (MLC) device was used [47,[49][50][51]. The tests were performed using the MLC arranged in the standard horizontal configuration, to determine the main flammability descriptors [52]: ignitability (time to ignition, TTI), combustibility (peak of heat release rate, PHRR), sustainability (average effective heat of combustion, AEHC) and consumability (percentage mass lost, PML). ...
To explore the possible relationship between diseased trees and wildfires, we assessed the flammability of canker-resistant and susceptible common cypress clones that were artificially infected with Seiridium cardinale compared to healthy trees. This study explored the effect of terpenoids produced by the host plant in response to infection and the presence of dead plant portions on flammability. Terpenoids were extracted and quantified in foliage and bark samples by gas chromatography–mass spectrometry (GC–MS). A Mass Loss Calorimeter was used to determine the main flammability descriptors. The concentration of terpenoids in bark and leaf samples and the flammability parameters were compared using a generalized linear mixed models (GLMM) model. A partial least square (PLS) model was generated to predict flammability based on the content of terpenoid, clone response to bark canker and the disease status of the plants. The total terpenoid content drastically increased in the bark of both cypress clones after infection, with a greater (7-fold) increase observed in the resistant clone. On the contrary, levels of terpenoids in leaves did not alter after infection. The GLMM model showed that after infection, plants of the susceptible clone appeared to be much more flammable in comparison to those of resistant clones, showing higher ignitability, combustibility, sustainability and consumability. This was mainly due to the presence of dried crown parts in the susceptible clone. The resistant clone showed a slightly higher ignitability after infection, while the other flammability parameters did not change. The PLS model (R²Y = 56%) supported these findings, indicating that dead crown parts and fuel moisture content accounted for most of the variation in flammability parameters and greatly prevailed on terpenoid accumulation after infection. The results of this study suggest that a disease can increase the flammability of trees. The deployment of canker-resistant cypress clones can reduce the flammability of cypress plantations in Mediterranean areas affected by bark canker. Epidemiological data of diseased tree distribution can be an important factor in the prediction of fire risk.
... Forest fires are traditionally considered the most large-scale natural disasters in the world (Blanco et al., 2015;Le Goff and Sirois, 2004;Reilly et al., 2018;San-Miguel-Ayanz et al., 2013). One of their main features is high propagation rate and, as a result, large areas of forest burning (Chetehouna et al., 2015;Della Rocca et al., 2015;Kawahara et al., 2016;Rakowska et al., 2017). The world statistics shows that in most cases the localization and suppression of forest burning occur only in rainfall. ...
... This leads to the need for simultaneous use of a large number of aircraft. For countries (e.g., Russia, Canada, the USA, Australia, etc.) with vast areas of forests, it is impossible to use 10-15 vehicles with a total capacity of 100-200 tons of water in one area or close regions (Della Rocca et al., 2015;Kawahara et al., 2016;Le Goff and Sirois, 2004;Rakowska et al., 2017). So there is a topical problem of determining the minimum volume of water and rational schemes of its supply to the zone of the barrier line. ...
The article presents the results of experimental research, determining the conditions for suppressing the combustion front of forest fuels (FF) with the use of a protective water line. Integral parameters, velocities and other characteristics of the main interrelated heat and mass transfer processes, phase transformations and chemical reactions are studied. The conditions for suppressing the combustion front of typical forest fuels (needles; leaves; a mixture of needles, leaves and branches) are established. The experimental conditions are designed to be the utmost close to those of ground forest fires and parameters of fire lines: in terms of temperature, wind velocity, the forest fuel layer thickness, the size of water droplets, etc. The rational dimensions (width, length, depth) of the protective water lines, the density of water irrigation of the material surface, the volume of liquid, the time of spraying are determined. It is shown that effective conditions for forest burning localization can be achieved at almost complete thermal decomposition of a small layer of FF near the barrier line. It is established that necessary and sufficient conditions of FF combustion localization can be reliably predicted using the obtained dependences of specific water flow rate on FF volume.
... Cupressus sempervirens (var. pyramidalis) had a large amount of dead leaves within its crown, owing to its fastigiated form (Ganteaume et al. 2013b;Della Rocca et al. 2015), resulting in a high combustibility, thus burning with a far greater intensity when reached by the flames. This result highlights the need to assess, along with the flammability, the proportion of dead and fine particles that comprise each species' crown (as in Ganteaume et al. 2013b). ...
... This result highlights the need to assess, along with the flammability, the proportion of dead and fine particles that comprise each species' crown (as in Ganteaume et al. 2013b). In their work, Della Rocca et al. (2015) suggested planting barrier systems of C. sempervirens var. horizontalis in the WUI to reduce the fire spread because of this species' low leaf flammability, but without assessing litter flammability (the most flammable fuel scale for C. sempervirens according to the present work) nor the amount of dead fuel in the canopy. ...
The increasing concern regarding fire in the wildland–urban interface (WUI) around the world highlights the need to better understand the flammability of WUI fuels. Research on plant flammability is rapidly increasing but commonly only considers a single fuel scale. In some cases, however, different fuel scales (e.g. leaf and litter bed) have greater influence on fire, for instance, when it spreads from the litter bed to the lower canopy. Examining fuel flammability at these different scales is necessary to better know the overall flammability but also provides insights into the drivers of flammability. To investigate if leaf and litter bed flammability differed, laboratory experiments were conducted on 15 species (native or exotic) commonly found in the WUI of south-eastern France. Species were ranked and the association of fuel characteristics with flammability sought at both scales. For most species, leaf and litter bed flammability differed because of strong fuel characteristics (e.g. leaf thickness or litter bulk density), entailing differences in rankings based on fuel scale and potentially leading to a misrepresentation of flammability of the species studied. Favouring species with lower flammability at both scales in the WUI, especially near housing, may help reduce undesired effects during wildfires.
... Madrigal et al. (2013) have developed a bench-scale method with a mass loss calorimeter to estimate flammability attributes (time to ignition, peak heat release rate, mass loss rate, average effective heat of combustion, and total heat release) and a moisture analyzer to evaluate fuel moisture content. Both epiradiators and mass loss calorimeters have been used by Della Rocca et al. (2015) to characterize the flammability of Cupressus sempervirens. ...
... This effect, especially at higher moisture contents, was weaker than that predicted by theoretical formulations and from studies in mixtures of dead and live fuel, thus suggesting that live fuel affects fire spread rate through properties other than moisture content. Fernandes and Cruz (2012) also highlighted that the assessment of flammability in the laboratory is limited by various factors: scale, Fig. 3 a Epiradiator used to test cypress flammability by Della Rocca et al. (2015). b Mass loss calorimeter used by Madrigal et al. (2009) to evaluate forest fuel flammability and combustion properties. ...
Key messageFuel moisture and chemical content affecting live plant flammability can be measured through laboratory and field techniques, or remotely assessed. Standardization of methodologies and a better understanding of plant attributes and phenological status can improve models for fire management. ContextWildland fire management is subject to manifold sources of uncertainty. Beyond the difficulties of predicting accurately the fire behavior, uncertainty stems from incomplete understanding of ecological susceptibility to fire. AimsWe aimed at reviewing current knowledge of (i) plant attributes and flammability: fuel moisture and chemical content in leaves; (ii) experimental evaluation of flammability in the laboratory and in the field; and (iii) proxy evaluation of flammability: vegetation cover assessment at large scale, fuel seasonality, and biomass distribution using remote sensing and Light Detection and Ranging (LiDAR) techniques. Methods
We conducted a review of scientific literature from the last two decades on the three selected issues, with a specific focus on the Mediterranean region. ResultsWe have evidenced important knowledge gaps: (i) developing standardized methodologies for laboratory- and field-scale assessment of vegetation flammability; (ii) introducing reliable approaches to test the impact of biogenic volatile organic compounds on fire spread; (iii) improving the analysis of spatiotemporal changes in vegetation dynamics, acknowledging distinctive vegetation phenological status as a relevant driver affecting leaf biomass and moisture contents; and (iv) further exploring the processes that shape fuel dynamics to understand how fuel characteristics change over time and space. Conclusion
We propose some improvements in the current knowledge of vegetation science and wildland fire ecology, aiming to generate more realistic models and effective planning in support of fire management in the Mediterranean basin.
... The recent events that occurred in Portugal in 2017 [5], then in Greece and California in 2018 [6], and more recently in Australia [7] revealed unexpectedly severe fires caused by changes in climatic conditions as well as changes in forestry zones and wildland-urban interfaces (WUI). Algeria is the most affected country by wildland fires in the region of Maghreb, with a recent increase of outbreaks in the region of Kabylie [8]. The topography of this region (mainly composed of mountains) has made it very difficult to fight against fire spread. ...
To seek a fire‐resistant fuel, the reaction to fire of Algerian Phoenix dactylifera leaves known for their thermal resistance was compared to that of three highly flammable Algerian fuel particles: Eucalyptus globulus leaves and Pinus halepensis and Pinus canariensis needles. By using a small‐scale cone calorimeter, their thermal properties were investigated under a low irradiance of , while their ignition and combustion properties were examined with irradiances of and . Eucalyptus globulus leaves were found the most ignitable fuels with the largest released heat, while Phoenix dactylifera leaves were found by far the least ignitable fuels with the smallest released heat, particularly under large heat flux intensities. Based on a theoretical analysis of thermal and ignition properties, a new flammability/spreading index combining the ignitability and combustibility metrics was proposed to rank these fuels. This index was compared with the fire retardancy index used for polymer composites and adapted to these plants because it uses a cone calorimeter. A similar ranking order was obtained between the two indices for the considered fuels, where Eucalyptus globulus leaves were found by far the most fire‐spreading fuels particularly at large fire intensity. On the other hand, Phoenix dactylifera leaves appeared by far the least fire‐spreading fuels particularly at large fire intensity. The possible use of Phoenix dactylifera trees as extreme fire retardants in wildland fuel management, as well as their use at the wildland–urban Interface, are discussed, but these results should be confirmed at a large scale.
... The oxygen bomb calorimeter was utilized to measure the gross heat of combustion, offering additional insights into the flammability of the samples. The heat content of the analyzed samples was consistently higher in the oxygen bomb tests compared to the mass loss calorimeter tests [8], aligning with the statements in [7]. Additionally, the results in [9] show that the effective heat of combustion is between 18% and 44% lower than the gross heat of combustion. ...
The purpose of this review is to examine key findings in the fundamental research of wildfire flammability characteristics. The review begins with a brief introduction, highlighting the growing need for more detailed research into the development of forest fires due to increasingly pronounced climate changes. This is followed by an overview of the application of devices operating on the principle of calorimetry, emphasizing additional possibilities for setting and adjusting these devices. Upon reviewing the literature, it becomes evident that the majority of research on the flammability of forest vegetation is primarily focused on the moisture content levels in fuels. For this reason, the third part of this paper is dedicated to exploring the influence of moisture content on the flammability of forest vegetation. Towards the end, an overview of the types and possibilities of igniting forest fuel is provided, with a particular emphasis on the creation of firebrands as a source of ignition for vegetative fuel.
... El ciprés del mediterráneo (Cupressus sempervirens var. horizontalis) dado su elevada resistencia a la inflamabilidad (Rocca et al. 2015), ha sido utilizado en la región mediterránea de Europa como una alternativa económica y ecológicamente factible para la implementación de barreras cortafuegos verdes. Actualmente existen ensayos en nueve países como parte del proyecto CypFire financiado por la Unión Europea (Rocca et al. 2014). ...
Este documento se ha desarrollado en el marco del proyecto “Adaptación al Cambio
Climático en la Actividad Forestal, Productividad y Reducción de Impactos”, mandatado por la Corporación Nacional Forestal (CONAF) y ejecutado por la Universidad Austral de Chile, con financiamiento del programa Bienes Públicos con Adaptación al Cambio Climático de la Corporación de Fomento de la Producción (CORFO) y cofinanciado por las empresas Forestal Mininco SpA y Forestal Arauco S.A.
El documento tiene por objetivo discutir los elementos a considerar para diseñar e implementar estrategias de adaptación al cambio climático en plantaciones de Pinus radiata en Chile.
... El ciprés del mediterráneo (Cupressus sempervirens var. horizontalis) dado su elevada resistencia a la inflamabilidad (Rocca et al. 2015), ha sido utilizado en la región mediterránea de Europa como una alternativa económica y ecológicamente factible para la implementación de barreras cortafuegos verdes. Actualmente existen ensayos en nueve países como parte del proyecto CypFire financiado por la Unión Europea (Rocca et al. 2014). ...
Management challenges and opportunities in Radiata Pine plantations facing climate change.
... The entire experiment was conducted within a chamber under a laboratory fume hood to control for humidity, air movement and ambient temperature . During tests, 0.4-0.6 g of plant material (shoot(s) and leaves) were placed directly atop the epiradiator surface (Della Rocca et al., 2015;Pausas et al., 2016;Valette, 1990). This sample mass was used to follow previously established epiradiator-based methods and to minimize variation in live fuel moisture and branch architecture present within larger branches. ...
In semi‐arid regions where drought and wildfire events often co‐occur, such as in Southern California chaparral, relationships between plant hydration, drought‐ and fire‐adapted traits may explain landscape‐scale wildfire dynamics. To examine these patterns, fire scientists and plant physiologists quantify hydration in plants via mass‐based metrics of water content, including live fuel moisture, or pressure‐based metrics of physiological status, such as xylem water potential; however, relationships across these metrics, plant traits and flammability remain unresolved.
To determine the impact of hydration on tissue‐level flammability (leaves and stems), we conducted laboratory dehydration tests across wet and dry seasons in which we simultaneously measured xylem water potential, live fuel moisture and flammability. We tested two widespread chaparral shrubs, Adenostoma fasciculatum and Ceanothus megacarpus.
Live fuel moisture showed a threshold‐type relationship with tissue flammability (increased ignitability and combustibility at specific hydration levels) that aligned with drought‐response traits (turgor loss point) and fire behaviour (increased fire likelihood and spread) identified at the landscape scale. Water potential was the better predictor of flammability in linear statistical models.
A. fasciculatum was more flammable than C. megacarpus, and both species were more flammable during the wet growing season, suggesting seasonal growth or drought‐related tissue characteristics other than moisture content, such as lignin or chemical content, are critical for determining flammability.
Our results suggest a mechanism for landscape‐scale increases in flammability at specific levels of drought stress. Integration of drought‐related traits, such as the turgor loss point, might improve models of wildfire risk in drought‐ and fire‐prone systems.
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... Plant-trait-based flammability approaches have been shown to provide relevant information on wildland fire behavior that can be implemented at the wildland-urban interface (Simeoni et al., 2012;Ganteaume, 2018) and particularly for species selection for green firebreaks (Krix et al., 2019). Few studies have emphasized the importance of identifying the fire-sensitive species in WUI fire management (Romero et al., 2019) and establishing effective buffer zones based on suitable varieties (Della Rocca et al., 2015). A study of roadside vegetation indicated that trait-based flammability can be a useful component of road projects for fire spreading prevention (Molina et al., 2019). ...
The occurrence of large and recurring forest fires has long been associated with fire-prone environments, but this perception has been shifted rapidly in recent decades as Earths' landscapes have become increasingly threatened by severe and unpredictable fires as a result of climate changes. In this regard, the flammability of trees is a topic of great interest for ecology, management, and the development of sustainable restoration and rehabilitation plans. Tree species differ in regard to flammability, and many plant functional traits contribute to flammability at species, community and vegetation level. The relationship between plant traits and flammability at species level is important for a broader understanding of the vegetation-fire dynamic at the local and landscape scales. This review summarizes the current state of knowledge regarding the impact of individual plant traits of tree species on flammability components. By keywords-based searching of academic databases, 85 research papers were collected and analyzed. The literature synthesis shows: i) main issues addressed in studies on plant trait-based tree flammability, ii) general research output and biogeographic regions studied, iii) inventory of tree taxa investigated, iv) relationships between plant traits and flammability components, v) the most relevant plant traits that determine the flammability-related differences between species.
... According to Kovalsyki et al. [12], parameters such as the ignition time (TTI) and aming duration (FD) provide the characteristics of the ammability of biofuels. The procedure to determine these variables requires an epiradiator, which radiates heat to the tested samples [13][14][15]. Mu e furnace equipment, commonly found in laboratories, also releases heat and can be used for the same procedure. Gill and Moore [16] tested a mu e furnace at 400°C to measure the TTI; however, the study was not published. ...
Measuring the energy characteristics of solid biofuels can help to determine the most suitable species for combustion. The objective of this study is to propose a new methodology for determining the ignition time and flaming duration in lignocellulosic biomass. A muffle furnace was used, instead of an epiradiador, to measure the variables. The optimal oven temperature was defined according to the average time-to-ignition of biomasses in the literature. Ten biomasses were analyzed to obtain their high heating value, volatile matter, fixed carbon content, ash content, time-to-ignition, and flaming duration. The results showed a high correlation between the biomass volatile content, time-to-ignition, and flaming duration. In the literature, it is described that high levels of volatile materials accelerate the ignition of the material. Thus, the association between the volatile matter and the variables analyzed justifies the use of the muffle furnace methodology. Furthermore, biomasses with high levels of volatile matter have longer flaming durations than other solid biofuels.
... Los incendios forestales se consideran como los desastres naturales de mayor escala en el mundo (San Miguel-Ayanz, Moreno, & Camia, 2013, Reilly, et al., 2018. Una de sus características principales es la alta tasa de propagación y, como resultado, grandes áreas de quema de bosques y selvas (Della Rocca et al., 2015, Rakowska, et al., 2017, dando lugar a la degradación y deforestación (Morfin, Jardel, Alvarado, & Michel, 2012). En México, los incendios forestales son de alto impacto para los ecosistemas (Ávila-Flores, Pompa-García, & Vargas-Pérez, 2010). ...
El municipio de Cintalapa se localiza dentro de la región Valle-Zoque, el cual tiene alta presencia de incendios en el estado de Chiapas. Es por lo que la presente investigación se planteó como objetivo determinar las causas de la alta frecuencia y recurrencia de incendios forestales en algunos ejidos críticos de Cintalapa, además de analizar los cambios de cobertura e impacto de los incendios sobre la vegetación forestal, a determinada escala de tiempo. Para la identificación de las causas de incendios, se aplicaron cuestionarios en ocho localidades en función a un mapeo de ejidos críticos con antecedentes de incendios. En una segunda fase, se delimitaron los cambios de cobertura y vegetación a través del procesamiento de imágenes Landsat de las series 2,3,5 y 6, correspondientes a los años 1993, 2002, 2011 y 2014 y se generó un mapa de los incendios más críticos durante los años 1998, 2012 y 2019 en el municipio de Cintalapa. Los resultados mostraron que la causa principal de incendios corresponde a las quemas agropecuarias; el 45 % de los agricultores desconoce las técnicas y procedimientos para realizarlas de acuerdo con la NOM-015 SEMARNAT/SAGARPA-2007. Se cuantificaron pérdidas de cobertura en el bosque de encino-pino (2 363 hectáreas) y selva mediana y alta perennifolia y subperennifolia (1 873 hectáreas), ocasionadas por incendios. La información obtenida contribuye a la generación de conocimiento respecto al papel que juegan las comunidades en la gestión de incendios, a través de prácticas agropecuarias irregulares y sus impactos en la pérdida de cobertura forestal.
... The knowledge of the effect of plant biochemical response to fire contributes to understanding the patterns of postfire recovery of native vegetation in burnt forests. Besides, it could provide tools to post-fire management strategies [9,12,35,41,42]. ...
Resprouting is one of the main regeneration strategies in woody plants that allows post-fire vegetation recovery. However, the stress produced by fires promotes the biosynthesis of compounds which could affect the post-fire resprouting, and this approach has been poorly evaluated in fire ecology. In this study, we evaluate the changes in the concentration of chlorophylls, carotenoids, phenolic compounds, and tannins as a result of experimental burns (EB). We asked whether this biochemical response to fire could influence the resprouting responses. For that, we conducted three EB in three successive years in three different experimental units. Specifically, we selected six woody species from the Chaco region, and we analyzed their biochemical responses to EB. We used spectrophotometric methods to quantify the metabolites, and morphological variables to estimate the resprouting responses. Applying a multivariate analysis, we built an index to estimate the biochemical response to fire to EB per each species. Our results demonstrate that photosynthetic pigment concentration did not vary significantly in burnt plants that resprout in response to EB, whereas concentrations of secondary metabolites (phenolic compounds and tannins) increased up to two years after EB. Our main results showed that phenolic compounds could play a significant role in the resprouting responses, while photosynthetic pigments seem to have a minor but significant role. Such results were reaffirmed by the significant correlation between the biochemical response to fire and both resprouting capacity and resprouting growth. However, we observed that the biochemical response effect on resprouting was lower in tree species than in shrubby species. Our study contributes to the understanding of the biochemical responses that are involved in the post-fire vegetation recovery.
... An explanation of the scarcity of the finds could be that C. sempervirens var. horizontalis is characterized by peculiar and lower flammability traits compared to other Mediterranean species [90,91]. Moreover, the very scarce amount of charcoals in FONT2 is probably due to this specific behavior during wildfires, as well as to the more open forest structure defining (and defined also in the past) this south-facing slope. ...
The cypress (Cupressus sempervirens) is characterized by a very ancient history linked to the wide employment for the technological properties of its wood and for its symbolic value. Although this tree was often considered as a species introduced in Italy, the first genetic studies showed, instead, the presence of an autochthonous population of C. sempervirens in the forest of Fontegreca (Matese massif, Southern Italy), which constitutes the unique autochthonous cypress woodland present in Southwestern and Western Europe. Therefore, investigations were carried out in selected (using geomorphological criteria) areas of the forest, through soil chemical analysis, identification and ¹⁴C dating of soil charcoals. Indeed, we hypothesize that these analyses allow clarifying the history of this woodland characterized by the dominance of the cypress in the forest cover. Areas at medium-low (17–29°) slope gradient on the eastern and southern slopes of the forest were investigated and sampled, following pedological criteria (soil horizons order). Soil morphological and chemical analysis showed humus-rich surface horizons, thin (15–30 cm) and poorly developed (young) soils, overlapping the bedrock limestones. The first soil charcoal analysis data highlighted the presence of a previous landscape characterized by several species (e.g., Pistacia, Ostrya carpinifolia, Juniperus sp. and Pinus sp.) and, probably, by a different forest structure. Ongoing charcoal identification and ¹⁴C dating will likely give a better understanding of both (1) the cypress history and (2) the development of this forest landscape.
... In spite of the content of resin, that is a characteristic of Cupressaceae family, the flammability of A. chilensis leaves was much lower than N. dombeyi. Similar results were reported by Della Rocca et al. (2015) in relation to another Cupressaseae. ...
The overlapping zone between urbanization and wildland vegetation, known as the wildland urban interface (WUI), is often at high risk of wildfire. Human activities increase the likelihood of wildfires, which can have disastrous consequences for property and land use, and can pose a serious threat to lives. Fire hazard assessments depend strongly on the spatial scale of analysis. We assessed the fire hazard in a WUI area of a Patagonian city by working at three scales: landscape, community and species. Fire is a complex phenomenon, so we used a large number of variables that correlate a priori with the fire hazard. Consequently, we analyzed environmental variables together with fuel load and leaf flammability variables and integrated all the information in a fire hazard map with four fire hazard categories. The Nothofagus dombeyi forest had the highest fire hazard while grasslands had the lowest. Our work highlights the vulnerability of the wildland-urban interface to fire in this region and our suggested methodology could be applied in other wildland-urban interface areas. Particularly in high hazard areas, our work could help in spatial delimitation policies, urban planning and development of plans for the protection of human lives and assets.
... [95][96][97]. Further temperature tolerance mechanisms may be gleaned from Antarctic plants, or plants that have survived dramatic events such as forest fires and prolonged flood(98)(99)(100). Some plant extremophiles have evolved to accumulate certain specialized metabolites at very high levels as part of their unique adaptive strategies, with a few already harnessed for human uses, including UV protection, food, and beverage(101)(102)(103). ...
Planet Earth has experienced many dramatic atmospheric and climatic changes throughout its 4.5‐billion‐year history that have profoundly impacted the evolution of life as we know it. Photosynthetic organisms, and specifically plants, have played a paramount role in shaping the Earth's atmosphere through oxygen production and carbon sequestration. In turn, the diversity of plants has been shaped by historical atmospheric and climatic changes: plants rose to this challenge by evolving new developmental and metabolic traits. These adaptive traits help plants to thrive in diverse growth conditions, while benefiting humanity through the production of food, raw materials, and medicines. However, the current rapid rate of climate change caused by human activities presents unprecedented new challenges to the future of plants. Here, we discuss the potential effects of modern climate change on plants, with specific attention to plant specialized metabolism. We explore potential avenues of future scientific investigations, powered by cutting‐edge methods such as synthetic biology and genome engineering, to better understand and mitigate the consequences of rapid climate change on plant fitness and plant usage by humans.
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... The presence of internal fire scars in several of our cypress samples demonstrates the fire-tolerance of this tree, which together with its ability to slow fire progression, could be important for forest and land management in the Mediterranean. For example, planting fire-breaks with cypress could help prevent the rapid spread of wildfires (Della Roca et al. 2015). ...
In the Mediterranean region, stone and clay have long been the basic materials for buildings, crafts, and manufacturing. Wood plays a secondary, frequently hidden, role but is almost always present. Commonly considered a ‘less important’ building component, wood has been one of the first materials replaced and frequently discarded during restoration works. In this study, we apply dendrochronological techniques to timbers from Preveli Monastery on the island of Crete in the south Aegean (Greece). Samples were mainly collected from piles of building components discarded during renovations, as well as from standing features like ceiling beams and floorboards. A total of 74 samples from 59 different elements were collected and measured. Four different tree species were identified but by far the majority are fir (Abies sp.) and cypress (Cupressus sempervirens). Tree-ring correlations indicate that the fir timbers are Abies alba from the Alps. Cypress timbers were difficult to date because most samples had multiple false rings. Nevertheless, we were able to date about one-fifth of our cypress samples through comparison with a local cypress chronology. Our findings show that both local and imported timber were used for the Monastery’s restorations during the 18th and 19th centuries AD.
... Genetic engineering greatly reduces the long-breeding cycle typical in forestry, leading to an increase in biomass yields, addressing yield-reducing factors, and enhancing drought, wildfire and cold tolerance (National Academies of Sciences, Engineering & Medicine, 2016). For example, since certain Mediterranean cypress trees were found to be resistant to wildfire (Rocca et al., 2015), there exists an opportunity to develop GM growing stock for planting in BC that has the potential to deter wildfire in the future. ...
... This may be particularly useful where residents at the WUI favour retention of a natural appearance of surrounding vegetation (Nelson et al. 2004) or are financially unable (Penman et al. 2017) or unwilling to clear land to create defensible spaces around homes . Green firebreaks (Della Rocca et al. 2015;Curran et al. 2018) or garden plantings consisting of low-flammability species may also be incorporated into garden design to provide a balance between aesthetic values and lowered fire risk in urban gardens . ...
Leaf flammability is a multidimensional plant functional trait with emerging importance for wildfire risk management. Understanding relationships among leaf flammability attributes not only provides information about the properties of leaves as fuels in the wildland–urban interface (WUI), it can also offer an effective way to identify low-leaf-flammability species. We examined relationships between leaf ignitibility, sustainability and combustibility among 60 plant species of the WUI of eastern Australia. We found that leaf ignitibility and sustainability worked in opposition to each other as dimensions of flammability. Species with leaves that were slow to ignite were those with leaves that sustained burning for the longest, whereas species with leaves that were fast to ignite had leaves that burned for the shortest periods of time. Low leaf combustibility was related to short leaf burning sustainability but not to ignitibility. We created an overall leaf flammability index (OLFI) to rank species on emergent properties of ignitibility, sustainability and combustibility attributes in combination. We found that low-leaf-flammability species with low OLFI values had small leaf area, high leaf mass per area and high leaf water content. Our findings have implications for species selection for green firebreaks in the WUI.
... The purpose of using the tree is mainly for shading, air-barriers, wood and in recreation parks for renovation. They are also used as green barriers as silviculture method to manage fires as a complementary method to suppress fires (Della Rocca et al., 2015). Most plants are proliferated with seeds. ...
Cypress tree is primarily used for shading, air-barriers, wood and in recreation parks for renovation. The tree is propagated by seeds which vulnerable to several plant pathogens. Damping off fungi inhabited in soil or associated with seeds are considered major impediment to produce Cypress seedlings. Chemical soil treatment although paid attention worldwide but it is still a keystone to manage many plant pathogens including damping off fungi. Despite of that, these chemicals could not eliminate all seedling pathogens. In a greenhouse experiment, three chemicals represented in Ridomil G, Topsin and formalin, and two organic matters comprising peatmoss amended with the commercial product of Trichoderma harzianum (Biocont-T) and sole peatmoss were used. Continuous monitoring and sampling were resulted in isolating several major soil borne pathogens which were Rhizoctonia solani, Phytophthora sp., Pythium sp., Helminthosporium sp., Alternaria alternata, and Stymphylium sp.. The results showed that formalin, as pre-planting treatment, was the best to promote seedling emergence and lowering the number of pre and post-emergence damping off. The other two chemicals were also worked but in lesser efficiency. None of the chemicals used in the experiment were eliminated the pathogens associated with Cypress damping off. The use of amended and non-amended organic matter were not as efficient as the chemicals. It can be concluded that the management seedling of damping off could not be achieved with a solitary method and the integration of several methods would be of optimum option.
... Opinions on the species' flammability could vary according to previous works, which could differ in terms of methodology or fuel type studied. Regarding cypress, some works concluded that leaf samples were moderately flammable (Valette 1990;Ganteaume et al. 2013b) and even that this species could be used as a firewall (Della Rocca et al. 2015). By contrast, Dimitrakopoulos and Papaiannou (2001), as well as Liodakis et al. (2002), considered this species at leaf and ground sample scales among the most flammable species. ...
South-eastern France is strongly affected by wildfires mostly occurring in the wildland–urban interfaces (WUIs). A WUI fire is often initiated in dead surface fuel, then can propagate to shrubs and trees when the lower canopy is close to (or touches) the ground. Whereas a previous study assessed the fire propagation from the fuel bed to the lower canopy of different species used as ornamental vegetation in this region, the objectives of the current work consisted of checking if the modelling of this fire propagation was possible using WFDS (Wildland–Urban Interface Fire Dynamical Simulator) in comparing experimental and modelling results. Experimental and modelling constraints (i.e. branch geometric definition, branch motion due to convection) showed differences in some of the recorded data (such as time to ignition, ignition temperature, mass loss and maximum temperature), but comparisons of variation in mass loss and temperature over time showed that modelling the fire propagation at the scale of a branch was possible if the branch fuel-moisture content remained lower than 25%. For both experiments and modelling, the ranking of species according to their branch flammability highlighted identical groups of species.
... The effective use of water or other composition on its basis in the suppression of combustion of various materials plays a decisive role in the conditions of significant restrictions on the simultaneously supplied volumes of the latter [1][2][3]. Usually small number of aircraft is involved in the suppression of forest burning [4][5][6]. The air fleets of many countries often have few aircraft [4,5]. ...
The article presents the results of experimental studies of water droplets propagation through the sample of typical forest fuel materials: needles, leaves, and their mixture. Different conditions are considered: without any additional energy supply, with heating, in the course of intensive thermal decomposition and flaming combustion. Three methods of registration are applied: thermocouple measurements, control of the weight of the sample as a whole and of its individual layers, and high-speed video recording. Water-based compositions with special additives (bentonite, bischofite, and foaming agents) typical for forest fire extinguishing systems are used. The experiments are carried out using aerosol and single water drops, as well as a small group of the latter. It is shown that the mechanisms, conditions and characteristics of droplet propagation through the layers of needles, leaves and their mixtures differ significantly. The scientific novelty of the work is the determining of the values of all the key characteristics of these processes in the conditions of intensive pyrolysis of the material, as well as through its inert layers.
... On the other hand, vegetation management taking into account high fire occurrence zones could help to decrease the ease of ignition or stop high-speed fire spread. An example could be the use of high water content species, as cypress, strategically placed to avoid new fires or decrease the spread rate [207,141]. ...
Forests cover over a third of the total land area of Europe. In recent years, large forest fires have repeatedly affected Europe, in particular the Mediterranean countries. Fire danger is influenced by weather in the short term, and by climate when considering longer time intervals. In this work, the emphasis is on the direct influence on fire danger of weather and climate. For climate analysis at the continental scale, a daily high-emission scenario (RCP 8.5) was considered up to the end of the century, and a mitigation scenario that limits global warming to 2 °C was also assessed. To estimate fire danger, the Canadian Fire Weather Index (FWI) system was used. FWI provides a uniform numerical rating of relative fire potential, by combining the information from daily local temperature, wind speed, relative humidity, and precipitation values. The FWI is standardised to consider a reference fuel behaviour irrespective of other factors. It is thus well suited to support harmonised comparisons, to highlight the role of the varying climate in the component of fire danger that is driven by weather. RESULTS. Around the Mediterranean region, climate change will reduce fuel moisture levels from present values, increasing the weather-driven danger of forest fires. Furthermore, areas exhibiting low moisture will extend further northwards from the Mediterranean, and the current area of high fuel moisture surrounding the Alps will decrease in size. Projected declines in moisture for Mediterranean countries are smaller with mitigation that limits global warming to 2 °C, but a worsening is still predicted compared with present. There is a clear north-south pattern of deep fuel moisture variability across Europe in both climate change scenarios. Areas at moderate danger from forest fires are pushed north to central Europe by climate change. Relatively little change is expected in weather-driven fire danger across northern Europe. However, mountain systems show a fast pace of change. ADAPTATION OPTIONS. Key strategies to be considered may include vegetation management to reduce the likelihood of severe fires, as well as fuel treatments to mitigate fire hazard in dry forests. These measures should be adapted to the different forest ecosystems and conditions. Limited, preliminary knowledge covers specific but essential aspects. Evidence suggests that some areas protected for biodiversity conservation may be affected less by forest fires than unprotected areas, despite containing more combustible material. Specific typologies of old-growth forests may be associated with lower fire severity than densely stocked even-aged young stands, and some tree plantations might be more subject to severe fire compared with multi-aged forests. Particular ecosystems and vegetation associations may be better adapted for post-fire recovery, as long as the interval between fires is not too short. Therefore, deepening the understanding of resistance, resilience and habitat suitability of mixtures of forest tree species is recommended. Human activity (accidental, negligent or deliberate) is one of the most common causes of fire. For this reason, the main causes of fire should be minimized, which includes analysing the social and economic factors that lead people to start fires, increasing awareness of the danger, encouraging good behaviour and sanctioning offenders. LIMITATIONS. Bias correction of climate projections is known to be a potential noticeable source of uncertainty in the predicted bioclimatic anomalies to which vegetation is sensitive. In particular, the analysis of fire danger under climate change scenarios may be critically affected by climatic modelling uncertainty. This work did not explicitly model adaptation scenarios for forest fire danger because ecosystem resilience to fire is uneven and its assessment relies on factors that are difficult to model numerically. Furthermore, a component of the proposed climate-based characterization of future wildfire potential impacts may be linked to the current distribution of population, land cover and use in Europe. The future distribution of these factors is likely to be different from now.
... As expected, attributes related to ignitability, combustibility and consumability were all higher in grass than eucalypt litter fuels, and sustainability was lower. Callitris intratropica litter had particularly low consumability, consistent with findings for Callitris glaucophylla (Scarff & Westoby, 2006), and similar to some other gymnosperms (Cornwell et al., 2015;Della Rocca et al., 2015). Similar observations, that fires within patches of C. glaucophylla are less intense, and C. glaucophylla survival is higher, than in neighbouring eucalypt forest, have been made in southern Australia (Cohn et al., 2011). ...
We studied the effects of fuel type, fuel load and their associated flammability attributes on growth and survival of Callitris intratropica saplings. Callitris intratropica is a fire‐sensitive conifer that is widespread across northern Australia, but its range is contracting because of frequent and intense fires.
A small‐scale field experiment was used to compare the effect of three fuel types (grass, eucalypt litter and C. intratropica litter), and a mix of grass and eucalypt litter by varying fuel loads within their naturally occurring bounds, and measuring multiple flammability attributes.
Fuel type had the strongest influence on flammability attributes and hence sapling survival. Grass burnt rapidly, producing high temperatures, while duration of flaming was longer for eucalypt litter. Grass–eucalypt litter mixtures had flammability attributes more like grass, while C. intratropica litter was difficult to burn. Fuel load had a secondary effect, with strong interactions between fuel type and load.
Differences in sapling survival could be attributed to temperatures at 5 cm height; there was no additional effect of fuel type or canopy temperature. Sapling size variables were also important, and strongly correlated with bark thickness, so we could not identify the protective mechanism.
Synthesis . Mortality of Callitris intratropica saplings was consistent with damage to the lower stem, because of the direct relationship with temperatures at 5 cm height. Our results demonstrate the existence of a grass–fire cycle in C. intratropica stands, whereby hot fires damage the stands and allow grass to invade, increasing the stand ignitability and combustibility and promoting further fires. Interrupting this cycle by reducing grass fuel loads and hence the frequency of hot fires should therefore be a management priority to safeguard C. intratropica populations. Our findings also highlight that, under a common climate, vegetation type can shape fire regimes, because fuel type strongly influences flammability attributes, which in turn act as a powerful filter of plant populations.
... The lower flammability of the Ligustrum genus was previously reported by Batista and Biondi (2009). Even though C. sempervirens showed a higher TTI than P. halepensis and other forest species, similar to other studies (Della Rocca et al., 2015), it was not one of the less flammable species according to its TTI and FD. This flammabil- ...
Forest fires in the wildland urban interface (WUI) are a widespread and growing problem due to changes in land use and climate. The impacts of WUI fire depend on the exposure of homes to dense vegetation (both natural and ornamental), as well as fire intensity, which is determined by meteorological, topographical, and vegetation conditions. In this study, our goal was to identify the ignition index in one risky Mediterranean WUI based on the potential flammability of the main intermix species at the particle level. The flammability of 18 species (natural and ornamental) commonly found in southern Spain was analyzed at the particle level. Flammability experiments ranked the flammability of the different species from moderately flammable to extremely flammable. Flaming duration (a variable related to fire suppression difficulty) and the ignition coefficient of the surrounding vegetation helped to complete the ignition risk for each vegetation aggregation. Thuja orientalis and Ligustrum vulgare showed the greatest individual potential to mitigate fire spread, and are recommended for planting and use as landscaping hedges in the Mediterranean WUI. We concluded that this methodological procedure is a useful tool for prioritization and budget allocation of fire risk reduction treatments. Furthermore, the development of technical guidelines for public urban landscaping as well as landscaping on private residences is required to adequately address and mitigate fire impacts both on homes and the surrounding landscapes.
... In spite of the content of resin, that is a characteristic of Cupressaceae family, the flammability of A. chilensis leaves was much lower than N. dombeyi. Similar results were reported by Della Rocca et al. (2015) in relation to another Cupressaseae. ...
... More recently, thanks to its ecological qualities, this cypress has been used in forest protection against desertification and soil conservation in hot areas, where the soil is shallow and degraded and no other forest tree species could grow 16, 17 . Its deep and dense litter and the crown are difficult to ignite, so it can be used as a firebreak 18 , even if regeneration is scarce after wildfires 12 . Mediterranean cypress also tolerates salty winds, so it is used as a coastal windbreak. ...
Cupressus sempervirens L., known as Mediterranean or common cypress, is a medium-sized evergreen coniferous tree characterised by a very variable crown shape, from columnar to spread, dark green foliage and small ovoid brown cones. Its natural habitats are the semi-arid mountains around the eastern Mediterranean basin and Middle East. However, as it has had a long tradition of cultivation since the time of ancient civilizations, its natural range is still not clear. It is a pioneer species, growing quickly when young on most types of soils, including rocky and compact ones, adapted to the Mediterranean climate with dry and hot summers and rainy winters. It can form pure forests or be the dominant tree in pine forests or maquis vegetation. This cypress is widely planted as an ornamental tree, especially the columnar and conical forms, making a characteristic feature of the Mediterranean landscape. Its wood is also appreciated for its durability and scent. Main pests of this cypress are fungal cankers, caused by Seiridium cardinal and Diplodia pinea, and the sap-sucking aphid Cinara cupressi.
Characterizing forest fuel properties in terms of their distribution and flammability behaviour offers useful information for effective fire management. Satellite images provide synoptic images capturing the vegetation state and their change including burn area loss, enabling stratification, and narrowing down the search for further investigation on ground or laboratory. The study investigated the flammability of various forest fuels including sal, teak, bamboo and grass species, by analysing different fuel variables such as moisture content (MC), volatile matter (VM), ash content (AC), fixed carbon (FC), higher heating value (HHV) and minimum ignition temperature (MIT), and exploring the intrinsic relationships between and among them. The teak wood showed low MC (5.08%), high VM (81.91%), low AC (1.1%), high HHV (19.93 MJ/kg), high CF (93.82) indicating high sustainability, combustibility and consumability characteristics. Teak indicated higher flammability characteristics compared to sal, while grass indicated higher sustainability and combustibility characteristics compared to bamboo. Overall woody species (sal and teak) indicated high ignitability and sustainability characteristics over grass and bamboo. Among the plant components, leaves indicated high ignitability, wood indicated high sustainability, combustibility and consumability, and barks indicated low flammability characteristics. This study registers a maiden and early attempt using satellite and laboratory-based analysis to characterize the flammability properties of dominant species of tropical dry forests in eastern India.
The paper presents the results obtained in experimental studies of the processes of localizing the combustion of typical forest fuel materials (needles, foliage, and their mixtures with twigs) using a control line (firebreak) of a wetted layer of such materials formed before the fronts of their thermal decomposition and combustion. Water, bischofite solution, OS–5 solution, bentonite suspension and a foaming agent emulsion were used as fire-extinguishing agents. Relative mass and volume concentrations of water impurities were selected in accordance with ranges that are typical of modern fire-extinguishing systems. The possibility is shown for localizing the combustion of the said materials by reducing their temperature through heat accumulation by water, which has a high heat capacity and undergoes endothermic phase transformations, and blocking the access for the oxidizer and pyrolysis products to the flame combustion zone by forming a buffer zone from relatively cold water vapors and reducing the concentration of the products of materials' thermal decomposition as a result of the fire-extinguishing agent spreading on their surface and pores. The conditions are determined for guaranteed localization of the burning of a forest area by supplying its control line with a liquid composition in the form of a massive water drop, a jet and aerosol. It is shown that the supply of an aerosol cloud to the control line is the most efficient method in terms of minimal liquid consumption and guaranteed combustion localization.
Increasingly, architects are embracing "biomorphic urbanism," a design ideology that takes inspiration from nature to develop more sustainable cities that reduce the environmental impact of urban life. At the moment, plants are incorporated into biomorphic urban designs for conservation or aesthetic reasons. Here, I argue the role of plants in building more sustainable cities can be augmented by integrating plant sciences, ecology, and urban design. I propose that we can develop synthetic Function-Specific Plant Systems (FSPSs) which harness the genetic and metabolic diversity of plants to perform specific services that benefit society and the environment as a whole. FSPSs can contribute to three broad categories of urban life: Urban Landscape and Infrastructure; Biodiversity and the Environment; and Human Health. Across the three categories, FSPSs can be designed to provide nine key services: flood control, soil stabilization, fire control, climate control, water treatment, habitat for endangered flora and fauna, pest control, air purification, and modulation of human immune systems. The plants included in each FSPS are based on several considerations, including (1) functional traits, (2) biogeography, and (3) cultural concerns. In the future, synthetic biology could improve, expand and diversify these services. This approach harnesses plant biodiversity to transform urban spaces while meeting key UN Sustainable Development Goals.
Sixty modern surface samples collected from mosses in different cypress forest communities (Cupressus sempervirens L.) on the island of Crete (Greece) were analysed for their pollen content. The samples were taken from six different cypress phytosociological associations between 23 and 1600 m asl, and fall within distinct rainfall and temperature regimes. The aims of this paper are to provide new data on the modern pollen rain from the Aegean islands, and to perform these data using multivariate statistics (hierarchical cluster analysis and canonical correspondence analysis) and pollen percentages. The discrimination of pollen assemblages corresponds to a large extent to the floristic differentiation of Cupressus sempervirens forest vegetation and indicates the existence of three new associations. Discriminación fitosociológica y ecológica de las comunidades de ciprés (Cupressus sempervirens) en Creta (Grecia) mediante análisis polínico Resumen. Sesenta muestras de lluvia polínica actual recolectadas en cepellones de musgos, procedentes de distintas comunidades de ciprés (Cupressus sempervirens L.) en la isla de Creta (Grecia), fueron analizadas palinológicamente. Las muestras proceden de seis asociaciones fitosociológicas dominadas por el ciprés entre 23 y 1600 m asl, bajo regímenes de precipitación y temperatura diferentes. El objetivo de este trabajo es prover datos novedosos acerca de la lluvia polínica actual en las islas del Egeo, así como tratar éstos mediante análisis multivariantes (análisis de cluster jerárquico y análisis de correspondencias canónicas) y a partir de sus porcentajes polínicos. La discriminación de los espectros polínicos corresponde en gran medida a la diferenciación florística de la vegetación de los bosques de Cupressus sempervirens e indica la existencia de tres nuevas asociaciones.
Conocimiento tradicional sobre el comportamiento de las especies arbóreas ante el fuego, para de esta manera conocer que especies son resistentes al fuego, cuales tienen capacidad de rebrote después de un incendio.
[From the introduction] In Europe, 33 % of the total land area (215 million ha) is covered by forests, with a positive trend of increase for the forested areas. Other wooded lands cover an additional area of 36 million ha.
113 million ha are covered by coniferous forests, 90 million ha by broadleaved ones and 48 million ha by mixed forests. Forest resources should not be considered as a monolithic entity. Instead, they play a multifaceted role, with complex patterns and relationships among forests and other wooded lands, their usage and their interaction with other natural and anthropic systems.
Wood is a primary source of renewable energy in Europe. At the same time, primary feedstocks for wood-based biofuels frequently compete for a variety of non-energy uses. […] However, monetary value alone does not provide a complete picture of the real impact of forest resources in Europe.
Recreational and tourism aspects play an important role. 90 % of forest and other wooded land has been reported as available for recreational purposes. Although data are incomplete, at least 1.25 million cultural sites are located in European forests, of which around three-quarters classified as ‘Cultural heritage’. Cultural services are part of the rich set of ecosystem services provided by forests, the value of which reverberates far outside the forest sector. For example, considering only the protective functions of forests, they affect soil resources, water resources and biodiversity. 30 million hectares of European forests have been protected with the main objective to support biodiversity or landscape conservation, and a large majority of European countries (more than 90 %) have specific objectives in relation to biodiversity. Forests can offer a key contribution to mitigate the effects of climate change. European forest biomass adsorbs a remarkable amount of atmospheric CO2. This service of forest resources amounts in Europe to an average (from 2005 to 2015) annual carbon sequestration of 719 million tonnes, which is about 9 % of the net greenhouse gas emission in the region (414 million tonnes in the EU-28). In addition, carbon is also stored in long-lasting structures (e.g. wooden buildings) and another “carbon sink” is constituted by wood products which replace more energy-demanding materials or industrial processes/sectors. Wood-based biofuels also help to reduce the necessity to use fossil fuels, thus contributing to decrease greenhouse gas emissions.
A significant share of European forests (more than 110 million ha) is designated for protecting water, soil, ecosystem and infrastructures. Forests protect soil resources by significantly reducing soil erosion. This role is especially relevant in mountainous areas and areas with extreme climates. Ultimately, the soil-protection services offered by European forests reverberate also as climate change mitigation. In particular, this may be appreciated by considering that the larger proportion of overall forest carbon pools is constituted by forest soils (54.1 %), compared to the living above ground biomass (leaves, branches, trunks, etc.) with 28.5 %, the litter with 9.0 % and the living below ground biomass (roots, etc.) with 7.1 % of the total.
However, not all types of forest can provide the same level of functions, services, biodiversity and sustainability. They also interact with other natural resources, bioclimatic and anthropogenic aspects, some of which are introduced in the next section. In this respect, details on the forest ecology, composition and age structure may be relevant. […]
Unfortunately, almost 3.7 million ha of the overall forested areas in Europe are affected by forest damage, frequently due to biotic causal factors (1.9 million ha damaged by insects and diseases). Among the abiotic factors, fire causes the damage of 0.5 million ha forests while storm, wind and snow damage have been estimated to affect 0.8 million ha of forest resources (estimation based on reports covering 73 % of the forested area).
This brief overview of facts and statistics aims to provide a descriptive picture of the multifaceted aspects of forests in Europe. However, a deeper understanding of the structure and functional relationships among forest resources and other natural and anthropic systems requires some underpinning concept to be considered in an integrated way.
This may be essential even at the science-policy interface in order to provide policy-making with a robust science-based support. In the recent Forest Strategy of the European Union, one of the four strategic orientations explicitly recommends “advanced research and modelling tools to fill data and knowledge gaps to better understand the complex issues around social, economic and environmental changes related to forests” within a general strategy which “promotes a coherent, holistic view of forest management, covers the multiple benefits of forests, integrates internal and external forest-policy issues, and addresses the whole forest value-chain”. This could be achieved by integrating diverse data, information systems and models in a modular way, considering forests in relation with natural disturbances like fires and pests, the bio-economy (see the next chapter), climate change and ecosystem services. […]
Fuel flammability is defined as the relative ease with which a fuel will ignite and burn with a flame. Different forest types have different intrinsic “baseline” flammabilities, depending on the susceptibility to burn of the main tree species that build up the forest cover. In this perspective, we apply a forest-type based approach to classify and map the flammability level of the forests in Italy. Baseline forest type-based flammability values provided at European level have been assigned to a national forest types map, derived from Corine Land Cover 2006. Flammability values have been then further calibrated against the Burned Area Selection Ratio, a measure of the actual incidence of wildfires among different forest types. Accordingly, a calibrated flammability index was derived by simple linear regression, so that predicted flammability reflects more accurately the observed fire incidence among different forest types in Italy. Findings show that the flammability of forest types ranges from low to high: on average, the 17% of the forest cover has medium to high flammability, with wide regional variability. Notably, in four Regions (Sardegna, Sicilia, Puglia, Calabria) over one third of total forest area has medium to high flammability. Large scale mapping of forest flammability is crucial to define long-term priorities among forest areas as to how to distribute fire management effort. Areas falling into medium to high flammability classes should be given priority for implementing fuel management treatments in order to mitigate fire hazard from the stand to the landscape scale.
The objectives of this paper are to assess in laboratory conditions the flammability of undisturbed litter sampled beneath plants of seven species that are among those most frequently planted in hedges in Provence (south-eastern France). The variability in litter flammability recorded during burning experiments was partly explained by the proportions of the different litter components of each species. Phyllostachys sp. and Nerium oleander litters were the quickest to ignite whereas Prunus laurocerasus litter had the lowest bulk density and long time-to-ignition, but high flame-propagation. Photinia fraseri litter ignited frequently and had a high flame spread whereas Pittosporum tobira litter ignited the least frequently and for the shortest duration. Cupressus sempervirens litter had the highest bulk density and the longest flaming duration but the lowest flame propagation. Pyracantha coccinea litter was the slowest to ignite and flame propagation was low but lasted a long time. Co-inertia analysis identified species with the same flammability characteristics according to the composition of their litter. Hierarchical cluster analysis ranked the seven species in four distinct clusters from the most flammable (Photinia fraseri and Prunus laurocerasus) to the least flammable (Pittosporum tobira), the other species displaying two groups of intermediate flammability. These latter species should not be used in hedges planted in wildland–urban interfaces in south-eastern France.
Over 2.5 million people and 1 million structures risk destruction from wildland fires in California. One way to mitigate this risk is the manipulation and/or selection of landscape vegetation. In this study, six species were studied for their intrinsic characteristics and tested with a newly-developed laboratory fire protocol at 150 kW to determine heat release rate (HRR). The plants were 2–3 years old and obtained from a local nursery. Whole plants were subjected to desiccation in a dry kiln at 50°C, which was found to be much more effective than simulating fire weather in a greenhouse. This is apparently the first study that has measured plant variables, burned them in a natural vertical position, and related HRR to the plant characteristics. Multiple regression showed the overwhelming importance of foliage and moisture content to peak HRR. Chemical variables were not significant and high moisture contents were found to obscure other plant characteristics.
The chemical and physical pyric properties of several species, dominant in the Mediterranean Basin, are quantified and compared with each other. Heat content and total and mineral (silica-free) ash content are measured and analysed for 13 species, while surface area-to-volume ratio and particle density are measured for 8 species.
Eight dominant Mediterranean species were classified into similar groups according to their expected flammability, by applying multivariate statistical methods (Hierarchical Cluster Analysis and Canonical Discriminant Analysis) on the values of their most significant pyric properties (heat content, total and mineral ash content, surface area-to-volume ratio, particle density). Based on the statistical classification, meaningful explanations of the flammability differences among individual species were deduced. The results were in good agreement with similar rankings based on laboratory tests. Further validation may render the method widely applicable for the assessment of species potential flammability without laboratory flammability tests.
Leaves from three species of Eucalyptus were combusted in a mass-loss calorimeter to characterise the effect of fuel moisture on energy release and combustion products for this genus. Increasing moisture content reduced peak heat release and the effective heat of combustion in a negative exponential pattern while simultaneously increasing time-to-ignition. Estimates of the probability of ignition, based upon time-to-ignition data, indicated that the critical fuel moisture content for a 50% probability of ignition ranged from 81 to 89% on a dry-weight basis. The modified combustion efficiency of leaves (the ratio of CO2 concentration to the sum of the CO2 and CO concentrations) decreased exponentially as fuel moisture increased. This was because CO2 concentrations during combustion declined exponentially while CO concentrations increased exponentially. However, CO2 mixing ratios were always greater by at least one order of magnitude. Emission factors for CO2 declined exponentially with increasing fuel moisture content while CO emission factors increased exponentially to a maximum. The emission factors for volatile organic compounds increased in a pattern similar to that for CO with increasing fuel moisture content. The empirical relationships identified in this study have implications for fire-behaviour modelling and assessing the effect of fire on air quality and climate.
The aim of this paper is to provide an overview of the current state-of-the-art on research into the emission of biogenic volatile organic compounds (BVOCs) from vegetation fires. Significant amounts of VOCs are emitted from vegetation fires; including several reactive compounds, the majority belonging to the isoprenoid family, that rapidly disappear in the plume to yield pollutants such as secondary organic aerosol and ozone. This makes determination of fire-induced BVOC emission difficult, particularly in areas where the ratio between VOCs and anthropogenic NOx is favorable to the production of ozone, such as Mediterranean areas and highly anthropic temperate (and fire-prone) regions of the Earth. Fire emissions affecting relatively pristine areas, such as the Amazon and the African savanna, are representative of emissions of undisturbed plant communities. We also examined expected BVOC emissions at different stages of fire development and combustion, from drying to flaming, and from heatwaves coming into contact with unburned vegetation at the edge of fires. We conclude that forest fires may dramatically change emission factors and the profile of emitted BVOCs, thereby influencing the chemistry and physics of the atmosphere, the physiology of plants and the evolution of plant communities within the ecosystem.
A formula to estimate forest fuel flammability index (FI) is proposed, integrating three species flammability parameters: time to ignition, time of combustion, and flame height. Thirty-one (31) Moroccan tree and shrub species were tested within a wide range of fuel moisture contents. Six species flammability classes were identified. An ANOVA of the FI-values was performed and analyzed using four different sample sizes of 12, 24, 36, and 50 flammability tests. Fuel humidity content is inversely correlated to the FI-value, and the linear model appears to be the most adequate equation that may predict the hypothetical threshold-point of humidity of extinction. Most of the Moroccan forest fuels studied are classified as moderately flammable to flammable species based on their average humidity content, calculated for the summer period from July to September.
The present study proposes a new method in order to evaluate the flammability of live plant parts at bench-scale. Flammability parameters were estimated by the use of a mass loss calorimeter, and fuel moisture content was evaluated by the use of moisture analyser. Forest fuels (Pinus pinaster, Cistus laurifolius, Lavandula stoechas and Daphne gnidium) were monitored under field conditions to detect the changes in the fuel moisture contents during the fire risk season. The combination of two different bench-scale devices (moisture analyser and mass loss calorimeter) guarantees fixed conditions for carrying out laboratory tests (constant bulk density and constant sample dry mass), thus resolving problems detected with other devices and methodologies.
Fire has been an important evolutionary influence in forests, affecting species composition, structure, and func- tional aspects of forest biology. Restoration of wildland forests of the future will depend in part on restoring fire to an appropriate role in forest ecosystems. This may include the "range of natural variability" or other concepts associ- ated with fire as a disturbance factor. Yet fire on the forested landscape has not been a constant in either space or time. Its frequency, intensity, seasonality, extent, and other charac- ters-collectively know as a fire regime-varied consider- ably across western forest landscapes. A series of techniques can be used to understand this history, and accurate inter- pretation depends on using the best fire history technique for a given fire regime. The following synopsis of these techniques is based on a more detailed explanation provided in Agee (1993).
The autoignition delay times of some important Mediterranean forest species: Arbutus adrachne, Abies cephallonica, Pinus brutia, Pinus halepensis, Pistacia lentiscus, Cupressus semprevirens, Olea europaea, Cistus incanus were determined in the range 460–600°C under precisely controlled temperature and airflow conditions. Based on these data the forest fuels examined were classified into two groups: the least and the most flammable species. The autoignition delay data were related to the thermal analysis measurements. The themogravimetric analysis in an inert (nitrogen) atmosphere showed that the thermal decomposition of cellulose in the range of 300–400°C as well as the mass residue at 600°C are directly related to the ignition behavior.
An experimental study is conducted on the emission of volatile organic compounds (VOCs) emitted by Rosmarinus officinalis plants when exposed to an external radiant flux. The thermal radiation heats the plant and causes the emission of VOCs. The thermal radiation simulates the radiant flux received by vegetation in a forest fire. The results of the experiments are used in a simplified analysis to determine if the emissions of VOCs in an actual forest fire situation could produce a flammable gas mixture and potentially lead to the onset of an accelerating forest fire. The experiments consist of placing a plant in a hermetic enclosure and heating it with a radiant panel. The VOCs produced are collected and analyzed with an automatic thermal desorber coupled with a gas chromatograph/mass spectrometer (ATD-GC/MS). The effects of the fire intensity (radiant panel heat flux) and the fire retardant on the VOCs emission are then investigated. Two thresholds of the VOCs emission are observed. The first is for plant temperatures of around 120°C and appears to be caused by the evaporation of the water in the plant, which carries with it a certain amount of VOCs. The second one is around 175°C, which is due to the vaporization of the major parts of VOCs. The application of a fire retardant increases the emission of VOCs due to the presence of the water (80%) in the fire retardant. However, the use of the retardant results in a lower production of VOCs than using water alone. The measurements are used to estimate the concentration of VOCs potentially produced during the propagation of a specific fire and compared to the flammability limits of α-pinene. It is concluded that the quantities of VOCs emitted by Rosmarinus officinalis shrubs under certain fire conditions are capable of creating an accelerating forest fire.
Assessment of the flammability of ornamental vegetation (particularly hedges) planted around houses is necessary in light of the increasing urbanization of the wildland-urban interfaces (WUIs) and the high fire occurrence in such areas. The structure and flammability of seven of the species most frequently planted as hedges in Provence (southeastern France) were studied at particle level. Spatial repartition of the different types of fuel particles within plants was assessed by means of the cube method. The leaf flammability was assessed using an epiradiator as a burning device, and measurements of foliar physical characteristics and gross heat of combustion (GHC) helped to explain the results of burning experiments. Co-inertia analysis revealed that species with thin leaves were quick to ignite (Pyracantha coccinea, Phyllostachys sp.) and species with high leaf GHC burned the longest (Pittosporum tobira, Nerium oleander). Species presenting high ignitability (Photinia fraseri, Phyllostachys sp. and Pyracantha coccinea) were characterized by high foliar surface area-to-volume ratio, and species presenting lower ignitability were characterized by high GHC (Pittosporum tobira, Nerium oleander, Cupressus sempervirens). Hierarchical cluster analysis of the flammability variables (ignition frequency, time-to-ignition and flaming duration) categorized the relative flammability of the seven species (including dead Cupressus sempervirens) in five clusters of species from poorly flammable (Pittosporum tobira) to extremely flammable (dead Cupressus sempervirens).This study provides useful information for reducing fire risk in WUIs in the study area.
An adapted bench-scale Mass Loss Calorimeter (MLC) device for evaluating forest fuel flammability and combustion properties is proposed. This fire test apparatus consists of an MLC fitted with a chimney containing a thermopile. After the thermopile output has been calibrated by use of a methane burner, these data are used to quantify heat release, as an alternative to the classical measurement of oxygen consumption due to combustion. The results showed good repeatability and reasonable approximation to HRR values obtained with a cone calorimeter, and also demonstrated that each variable analyzed was significantly affected by the species considered.
Forest ecosystems and other wooded lands are an important component of landscapes in the Mediterranean region, contributing significantly to rural development, poverty alleviation and food security. They are sources of wood, cork, energy, food and incomes, and they provide important ecosystem services such as biodiversity conservation, soil and water protection, recreation and carbon storage. They are crucial for many of the region’s economic sectors, such as food supply, agriculture, soil and water conservation, drinking water supply, tourism and energy. The State of Mediterranean Forests 2013 (SoMF 2013) represents a major effort of the FAO Committee on Mediterranean Forestry Questions-Silva mediterranea and Plan Bleu, FAO’s Forestry Department, Silva Mediterranea member countries, partners and individual experts many of which gave freely their time and expertise.
Field measurements of moisture content of several fine fuels (shrub vegetation and live foliage) were performed in Central Portugal and in Catalunya (NE Spain) for 1–10 years. Seasonal and interannual variation of live fine fuels of several species in two regions of the Iberian Peninsula are analysed. The species were grouped in three sets according to their relatively high, intermediate or low seasonal variability. Meteorological data from nearby stations were collected in each study area and used in the evaluation of some indicators of fuel moisture that are used in the Canadian Forest Fire Danger Rating System, namely the Drought Code (DC). It was found that in the summer season the slow response of live fine fuel moisture content (LFFMC) to meteorological conditions, namely to precipitation, was well described by the DC. Empirical correlations between LFFMC and DC for each species and site are proposed.
Modified, more severe fire regimes are developing in the Mediterranean basin as a result of changes in land use and climate. Current fire management privileges fire suppression and tends to ignore land management issues, which may further accelerate the transition to a more fire-prone future and magnify the problem. Fire-smart management aims to control the fire regime by intervening on vegetation (fuel) to foster more fire-resistant (less flammable) and/or fire-resilient environments. Scientific knowledge supporting the creation and maintenance of fire-smart wildlands is critically reviewed, considering the landscape and the forest stand scales. Fuel management strategies (isolation, structural modification, and type conversion) are discussed in regards to their current and future potential to buffer the effects of global change on the extent and severity of fires. Uncertainty in the outcomes of fire-smart management arises mainly from insufficient understanding of the relative weights of fuel and weather-drought on the fire regime. Likewise, linkage between global change processes and the fire regime is not straightforward. Shrublands and, in general, open and dry vegetation types will prevail even more in future landscapes. Decrease in biomass will limit fire incidence over parts of the Mediterranean. However, the fire regime will be largely driven by weather, advising concentration of fuel management efforts in wildland–urban interfaces and in forests and their vicinity; decrease of landscape fire severity rather than area burned as the objective; prescribed burning as the treatment of choice, except in the wildland-urban interface; and focus on forest types that are fire-resilient irrespective of flammability.
The flammability of living vegetation is influenced by a variety of factors, including moisture content, physical structure and chemical composition. The relative flammability of ornamental vegetation is of interest to homeowners seeking to make their homes ‘fire safe’. The relative importance of the factors influencing fire behaviour characteristics, such as flammability, is unknown. In the present study, oxygen consumption calorimetry was used to obtain selected combustion characteristics of ornamental vegetation. Peak heat release rate, mass loss rate, time to ignition and effective heat of combustion of 100 × 100-mm samples of foliage and small branches were measured using a bench-scale cone calorimeter. Green and oven-dry samples of 10 species were collected and tested seasonally for a period of 1 year. Similar measurements were made on whole shrubs in an intermediate-scale calorimeter. The range of cone calorimeter peak heat release rates for green and oven-dry samples was 1–176 and 49–331 kW m⁻², respectively. Moisture content significantly reduced heat release rates and increased time to ignition. Peak heat release rates for Olea europea and Adenostoma fasciculatum were consistently highest over the year of testing; Aloe sp. consistently had the lowest heat release rate. The correlation of peak heat release rates measured by the cone calorimeter and an intermediate-scale calorimeter was statistically significant yet low (0.51). The use of the cone calorimeter as a tool to establish the relative flammability rating for landscape vegetation requires additional investigation.
Many studies have assumed that plant terpenes favor fire due to their enormous-flammability. However, only a few of them, all performed on green leaves, have demonstrated this. In the present work we investigated the question of whether litter terpene content can be used to estimate flammability and temperatures reached during fire. Epiradiator and burn table tests were used to compare flammability of leaf litter of P. pinaster, P. halepensis, P. pinea, C albidus, C ladanifer, C laurifolius and the mixture of litter of P. pinaster with that of the other five species (e.g. P. pinaster + P. halepensis). Tests with burn table showed increasing spread rates and shorter combustion times under higher terpene contents. Flame height was triggered both with higher a terpene content and bed thickness, whereas the percentage of burned biomass was only significantly correlated to bed height. Epiradiator tests indicated that terpene concentration in leaf litter was positively correlated to flame height and negatively correlated to both flame residence time and ignition delay. Flammability was high for P. pinaster, A halepensis, and hence for P. pinaster + P. halepensis, intermediate for C albidus, P. pinea and P. pinaster combined with each of these species, and low for C laurifolius, C ladanifer and P. pinaster combined with them. Accordingly, their terpene content was high, intermediate and low. We concluded that plants might influence fire intensity, by having stored terpenes in their dead leaves, in addition to having developed traits to survive fire. Thus, a correct management of dead aboveground fuels rich in terpene concentrations, such as those of P. pinaster and P. halepensis, could prove helpful in reducing the hazard of fire.
In the Mediterranean basin, fires are a major concern for forest and shrubland ecosystems. We studied flammability, its seasonality and its relationship with leaf moisture and volatile terpene content and emission in the dominant species of a Mediterranean shrubland and forest in Catalonia (NE Iberian Peninsula). We measured temperatures and time elapsed between the three flammability phases: smoke, pyrolysis and flame, for four seasons. We sampled twice in spring because of an occasional drought period during this season. Flammability had a significant relationship with leaf hydration, in the shrubland and in the forest. Few and only weak correlations were found between terpene content and flammability. In the future, arid conditions projected by climatic and ecophysiological models will increase fire risk through decreased hydration and subsequent increased flammability of the species.
The time-to-ignition of various dominant Mediterranean forest fuels was measured during laboratory tests, in order to develop a relative flammability classification and determine the moisture of extinction of these fuels. The tests were performed with an ignition apparatus manufactured according to the ISO standards (ISO 5657-1986E) and under a wide gradient of fuel moisture contents, ranging from air-dry to fresh foliage. Moisture content was the single most significant factor that affected fuel flammability. Regression models were developed between the time-to-ignition and the moisture content values of all the fuels tested, and subsequently, were used for the relative flammability ranking of these fuels. Fuel moisture of extinction was assessed to have a threshold value ranging from 40% to more than 140% o.d.w. for the species tested. The flammability ranking of natural fuels can be useful in fuel hazard assessment and fire danger rating, thus facilitating the judicial fire management planning in wildlands and at the rural-urban interface.
The objective of this paper is to provide a basic framework for researchers interested in reporting the results of their PLS
analyses. Since the dominant paradigm in reporting Structural Equation Modeling results is covariance based, this paper begins
by providing a discussion of key differences and rationale that researchers can use to support their use of PLS. This is followed
by two examples from the discipline of Information Systems. The first consists of constructs with reflective indicators (mode
A). This is followed up with a model that includes a construct with formative indicators (mode B).
• Introduction
The abandonment of rural areas has led to an increase of the fire-prone European gorse (Ulex europaeus L.) communities in some regions, where prescribed burning is a technique applied to control them. Understanding flammability changes after treatments is crucial for the sustainable use of fire.
• Objectives
The objectives of this study were to evaluate (1) any differences in the flammability of gorse plant parts 1 and 5 years after burning and (2) the flammability of whole plants, assessing complementarities of the results between full-scale and bench-scale tests.
• Results
Results showed the importance of the effect of the different scales and types of methods used to determine the four components of flammability of forest fuels: (1) Ignitability was highly dependent on the type of ignition source. (2) Combustibility was more dependent on the dead fraction than on live plant part characteristics. (3) Sustainability was mainly related to physical characteristics, like air flow interaction with fuel compactness. (4) Consumability, in terms of residual mass fraction, was similar at both scales.
• Conclusions
The results suggest the need for intensive management of gorse shrubland to maintain them at a very young age in order to reduce flammability associated with the rapid physiological and structural changes in this kind of vegetation.
Leaf and woody plant tissue (Pinus ponderosa, Eucalyptus saligna, Quercus gambelli, Saccharum officinarum and Oriza sativa) were heated from 30 to 300 degrees C and volatile organic compound (VOC) emissions were identified and quantified. Major VOC emissions were mostly oxygenated and included acetic acid, furylaldehyde, acetol, pyrazine, terpenes, 2,3-butadione, phenol and methanol, as well as smaller emissions of furan, acetone, acetaldehyde, acetonitrile and benzaldehyde. Total VOC emissions from distillation and pyrolysis were on the order of 10 gC/kgC dry weight of vegetation, as much as 33% and 44% of CO2 emissions (gC(VOC)/gC(CO2)) measured during the same experiments, in air and nitrogen atmospheres, respectively.
The emissions are similar in identity and quantity to those from smoldering combustion of woody tissue and of different character than those evolved during flaming combustion. VOC emissions from the distillation of pools and endothermic pyrolysis under low turbulence conditions may produce flammable concentrations near leaves and may facilitate the propagation of wildfires. VOC emissions from charcoal production are also related to distillation and pyrolysis; the emissions of the highly reactive VOCs from production are as large as the carbon monoxide emissions.
Pyrogenic plants dominate many fire-prone ecosystems. Their prevalence suggests some advantage to their enhanced flammability, but researchers have had difficulty tying pyrogenicity to individual-level advantages. Based on our review, we propose that enhanced flammability in fire-prone ecosystems should protect the belowground organs and nearby propagules of certain individual plants during fires. We base this hypothesis on five points: (1) organs and propagules by which many fire-adapted plants survive fires are vulnerable to elevated soil temperatures during fires; (2) the degree to which burning plant fuels heat the soil depends mainly on residence times of fires and on fuel location relative to the soil; (3) fires and fire effects are locally heterogeneous, meaning that individual plants can affect local soil heating via their fuels; (4) how a plant burns can thus affect its fitness; and (5) in many cases, natural selection in fire-prone habitats should therefore favor plants that burn rapidly and retain fuels off the ground. We predict an advantage of enhanced flammability for plants whose fuels influence local fire characteristics and whose regenerative tissues or propagules are affected by local variation in fires. Our "pyrogenicity as protection" hypothesis has the potential to apply to a range of life histories. We discuss implications for ecological and evolutionary theory and suggest considerations for testing the hypothesis.
To control and use wildland fires safely and effectively depends on creditable assessments of fire potential, including the propensity for crowning in conifer forests. Simulation studies that use certain fire modelling systems (i.e. NEXUS, FlamMap, FARSITE, FFE-FVS (Fire and Fuels Extension to the Forest Vegetation Simulator), Fuel Management Analyst (FMAPlus®), BehavePlus) based on separate implementations or direct integration of Rothermel’s surface and crown rate of fire spread models with Van Wagner’s crown fire transition and propagation models are shown to have a significant underprediction bias when used in assessing potential crown fire behaviour in conifer forests of western North America. The principal sources of this underprediction bias are shown to include: (i) incompatible model linkages; (ii) use of surface and crown fire rate of spread models that have an inherent underprediction bias; and (iii) reduction in crown fire rate of spread based on the use of unsubstantiated crown fraction burned functions. The use of uncalibrated custom fuel models to represent surface fuelbeds is a fourth potential source of bias. These sources are described and documented in detail based on comparisons with experimental fire and wildfire observations and on separate analyses of model components. The manner in which the two primary canopy fuel inputs influencing crown fire initiation (i.e. foliar moisture content and canopy base height) is handled in these simulation studies and the meaning of Scott and Reinhardt’s two crown fire hazard indices are also critically examined.
Knowledge of how species differ in their flammability characteristics is needed to develop more reliable lists of plants recommended for landscaping homes in the wildland–urban interface (WUI). As indicated by conflicting advice in such lists, such characterisation is not without difficulties and disagreements. The flammability of vegetation is often described as having four components (ignitability, combustibility, sustainability and consumability). No standards or generally recognised test procedures exist for evaluating these components in plants. Some measurements of flammability include times for ignition, rate of flame spread, flame height and heat release rate. Often, the fire behaviour characteristics of a plant are derived from its physical and chemical characteristics. Thermogravimetric analysis and other thermal analyses of ground samples have long been used to characterise the thermal degradation of vegetation. More recently, researchers have used the oxygen consumption methodology to measure the heat released due to combustion of the vegetation. Although oxygen consumption calorimetry is an improvement in characterising plant flammability, translation of laboratory results to field conditions can be problematic and tests can be expensive.
In the north-eastern United States, invasive plants alter forest fuels, but their combustion characteristics are largely unknown. We assessed unground samples of foliage and twigs in the cone calorimeter for 21 non-invasive, native species, paired with 21 invasive species (18 non-native). Variables included sustained ignition, peak heat release rate, total heat release, and especially average effective heat of combustion, which is independent of initial sample mass. Heat of combustion was overall slightly lower for invasive species than for counterpart non-invasive species, and was significantly lower for Norway maple, black locust, and glossy buckthorn than for three non-invasive trees. It was low for invasive Japanese stiltgrass, sheep sorrel, and glossy buckthorn, and for non-invasive whitegrass, interrupted fern, grape, sphagnum moss, and three-lobed bazzania. Heat of combustion was high for invasive roundleaf greenbrier (native), scotchbroom, tree-of-heaven, Japanese honeysuckle, Japanese barberry, swallow-wort, and garlic mustard, and for non-invasive plants of fire-prone ecosystems: black huckleberry, pitch pine, bear oak, northern bayberry, and reindeer lichen. Heat content of twigs and foliage interrelates with other factors that affect fire behaviour, yet the cone calorimeter results enabled comparison of combustion properties among many species. These data have potential application as improved inputs for fire behaviour modelling.
In the late 1970s and early 1980s the fire community was pushing for reliable bench-scale tools to measure material flammability based on heat release rate. A measure of heat release rates was thought to be the most reliable and accurate measure of the flammability of a material. Unfortunately, only a few heat release measurement tools were available at that time and they were difficult to operate and the data was very inconsistent. In response, in 1982, the Fire Research Division at NIST (then called the Center of Fire Research at the National Bureau of Standards) introduced the next generation instrument to measure material flammability, the Cone Calorimeter. In, 1988, the Cone was awarded with a “R&D 100 Award”, often called an Oscar on Innovation. This prestigious American award was given to the top 100 innovations of the year. It was thefirst-ever fire testing tool to be recognized by this award to NIST. In the mid-1980s, the Cone became commercially available. Today, there are now more than 300 Cones in-service worldwide and the Cone is THE BASIS OFmore than a half dozen fire testing standards, such as ASTM E1354 and D5485, ISO 5660-1, NFPA 271, and CAN\ULC-S135. The Cone has become a reliable, accurate, and most common place methods to access material flammability. © Society of Fire Protection Engineers 2016. All rights reserved.
Some theory and observations are presented on the factors governing the start and spread of crown fire in conifer forests. Crown fires are classified in three ways according to the degree of dependence of the crown phase of the fire on the ground surface phase. The crown fuel is pictured as a layer of uniform bulk density and height above ground. Simple criteria are presented for the initiation of crown combustion and for the minimum rates of spread and heat transfer into the crown combustion zone at which the crown fire will spread. The theory is partially supported by some observations in four kinds of conifer forest.
The present study is aimed at quantifying the flame radiosity vertical profile and gas temperature in moderate to high intensity spreading fires in shrubland fuels. We report on the results from 11 experimental fires conducted over a range of fire rate of spread and frontal fire intensity varying respectively between 0.04–0.35ms−1 and 468–14,973kWm−1. Flame radiosity, or radiant emissive power, and gas temperatures were measured with narrow angle radiometers and fine wire thermocouples located at three different heights in the flames, 0.6, 1.1 and 1.6m above ground. Measured peak radiosity within the visual flame region (reaction zone and free flame) varied between 41 and 176kWm−2. Measurements within the intermittent flame region above the visually estimated average flame height varied between 10 and 30kWm−2. The flame vertical radiometric profile was characterized by a uniform area within the reaction zone and lower free flame, and a decrease in radiosity with height as the measurements approach the flame tip.
Two highly combustible western grasses, cheatgrass (Bromus tectorum L.) and medusahead (Taeniatherum asperum (Sim.) Nevski) differ greatly in total ash content. Ash contents of cheatgrass and medusahead are 5.04 and 18.49 percent, respectively, but silica-free ash contents are 0.99 and 1.35 percent. Thermoanalyses indicated pyrolytic similarity between the two grasses. Results suggest that the silica fraction should be discounted when relating ash content to pyrolysis and ignition processes of wildland fuels. Forest Sci. 16:64-65.
Plants representing a wide range in mineral content (silica-free) were used to test the possibility that mineral elements in plants act in ways similar to flame retardants. Thermal analyses showed that the maximum rate of weight loss, the amount of volatilization between 175° and 350°C, and the temperature at which these plant materials undergo thermal decomposition are related to the silica-free mineral content. However, tested plant material having more than 12 percent silica-free mineral content did not fit all of these relationships; generally the effect leveled off between 5 percent and 7 percent. There is evidence that only some of the mineral elements present are probably active in the pyrolytic pathways of plant carbohydrates. Forest Sci. 16:461-471.
An adapted bench-scale Mass Loss Calorimeter (MLC) device is proposed for evaluating effective heat of rapid flaming combustion
of fine Mediterranean forest fuels. The MLC apparatus uses a calibrated thermopile to quantify heat release rate (HRR) as
an alternative to the classical oxygen consumption measurement. A porous holder was used to simulate rapid flaming combustion.
Average effective heat of combustion (AEHC) during the flaming phase was related to the classical measurement of gross heat
of combustion (GHC) obtained in oxygen bomb calorimeter. Results showed that the effective heat of combustion (oven-dry basis)
was between 18% and 44% lower than the gross heat of combustion. A linear regression was obtained (r2=0.48; SEE=1.25; p<0.01; n=26) to relate AEHC and GHC values. The simple model developed (AEHC=GHC−6.75) suggests the possibility of
reducing the heat of combustion values used in forest fire behaviour models for Mediterranean forest fuels.
KeywordsCalorimetry–Dead fine forest fuel–Gross heat of combustion–Live fine forest fuel–Rapid flaming combustion
A critical review of the mechanisms that are described in the literature to explain the onset and development of eruption
or blow up in forest fires is presented, given their great relevance for fire safety, particularly in canyons. The various
processes described in the literature that are considered as potential causes of fire eruption are discussed. Some of them
seem more likely to cause the phenomenon and the others seem to have a complementary role in some conditions. The current
review highlights that more research is required to create a classification of Fire Eruption types and to allow the development
of specific Fire Safety procedures for fire fighters to minimize accidents.
KeywordsFire behaviour–Eruptive fire–Blow up–Extreme fire–Fire modelling–Fire safety
"Part I reviews progress at the regional level. This section was developed from six regional reports prepared for discussion in 2006. Part II presents selected issues in the forest sector, addressing the latest developments in 18 topics of interest to forestry."
Consideraciones bot anicas, Ecol ogicas y de Uso del Cipr es Mediterr aneo El " sistema cipr es " de barreras cortafuegos: selvicultura preventiva
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" sistema cipr es " de barreras cortafuegos: selvicultura preventiva. IMELSA,
Valencia, Spain, ISBN 978-84-616-6273-9, pp. 65e75.
Fire hazard and flammability of European forest types Post-fire Management and Restoration of Southern European Forests
- G Xanthopoulos
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- P Fernandes
Xanthopoulos, G., Calfapietra, C., Fernandes, P., 2003. Fire hazard and flammability
of European forest types. In: Moreira, F., Arianoutsou, M., Corona, P., De Las
Heras, G. (Eds.), Post-fire Management and Restoration of Southern European
Forests, Managing Forest Ecosystems, vol. 24. Springer, ISBN 978-94-007-2207-
1, pp. 79e92.
El "sistema cipr es" de barreras cortafuegos: selvicultura preventiva
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- B Moya
- J Moya
- P Raddi
- R Danti
- Della Rocca
Tuset, J.J., 2013. Y por qu e cipreses? In: Moya, B., Moya, J., Raddi, P., Danti, R., Della
Rocca, G. (Eds.), El "sistema cipr es" de barreras cortafuegos: selvicultura preventiva. IMELSA, Valencia, Spain, ISBN 978-84-616-6273-9, pp. 37e53.