Fire

La savane africaine occidentale est un des paysages tropicaux les plus largement parcourus par les feux de brousse. Lors de la periode coloniale, relayee par les gouvernements post-coloniaux, des politiques en vue de controler ces feux ont ete mises en place. Elles n'ont pas reussi et ont, en outre, cree un tres long conflit entre les services forestiers et les populations rurales. L'option de lutte contre les feux, qui a persiste pendant presque un siecle, semble s'affaiblir. Le gouvernement a recemment adopte une nouvelle politique. Ce changement permet aux communautes locales de coordonner des mises a feu precoces des savanes. Le Mali venant de mettre en application cette nouvelle politique, il est opportun de reflechir a deux questions primordiales afin d'eviter la repetition des erreurs du passe. Premierement, il est important d'analyser les raisons pour lesquelles une philosophie « anti-feu » a domine la science et la politique du feu dans la region pendant...

Designing a fuel-sampling program that accurately and efficiently assesses fuel load at relevant spatial scales requires knowledge of each sample method’s strengths and weaknesses. We obtained loading values for six fuel components using five fuel load sampling techniques at five locations in western Montana, USA. The techniques included fixed-area plots, planar intersect, photoloads, a photoload macroplot, and a photo series. For each of the six fuels, we compared (1) the relative differences in load values among techniques and (2) the differences in load between each method and a reference sample. Totals from each method were rated for how much they deviated from totals for the reference in each fuel category. The planar-intersect method, which used 2.50 km of transects, was rated best overall for assessing the six fuels. Bootstrapping showed that at least 1.50 km of transect were needed to obtain estimates that approximate the reference sample. A newly developed photoload method,...

Several Melaleuca (Myrtaceae) species are invasive globally. Recently an increase in invasive species from this genus have been reported in South Africa. Here we document the first detailed assessment of the distribution and invasive potential of Melaleuca rugulosa in South Africa. We assess population structure, determine the current and potential future distribution in South Africa using climatic variables, conduct a risk analysis, provide recommendations for management, and consider the feasibility of eradication. We found one naturalising population of »665 individuals covering more than 1.2 hectares. It was first recorded in 1961 invading the native fynbos vegetation in the Table Mountain National Park (TMNP). Two recent fires in 2009 and 2016 likely enhanced spread, this spread happened despite undocumented clearing attempts in the last decade. The south-western Cape is the most climatically suitable for M. rugulosa, with most other wetter areas of the country being only partly suitable regions. The risk analysis indicated a medium risk, and we suggest listing M. rugulosa as category 1a (eradication target) under the South African National Environmental Management: Biodiversity Act (10/ 2004). Given the small area occupied, ease of access and the lack of a soil seed bank, the population can be extirpated from Devil’s Peak within the TMNP. We highlight that serotinous alien species, particular from the Myrtaceae, should receive more attention as potential invasive species in fire-driven ecosystems and that their lack of invasiveness in areas where fire is suppressed, should not be misinterpreted as being a low-risk species.

The development of frameworks for better-understanding ecological syndromes and putative evolutionary strategies of plant adaptation to fire has recently received a flurry of attention, including a new model hypothesizing that plants have diverged into three different plant flammability strategies due to natural selection. We provide three case studies of pyromes/taxa (Pinus, the Proteaceae of the Cape Floristic Region, and Eucalyptus) that, contrary to model assumptions, reveal that plant species often exhibit traits of more than one of these flammability and post-fire recovery strategies. We propose that such multiple-strategy adaptations have been favoured as bet-hedging strategies in response to selective pressure from mixed-fire regimes experienced by these species over evolutionary time.

Large forest fires have repeatedly affected Europe, in particular the Mediterranean countries. It is now crucial to continue the effort to feed the several layers of prediction models and understand how wildfire spreads in order to develop modern preventative and mitigation methods. The present study evaluates the performance of Sentinel 5-P TROPOMI for the monitoring of carbon monoxide (CO) and methane (CH4) during extreme fire events in Portugal, focusing on the Monchique (2018) and Vila de Rei/Mação (2019) wildfires, which devastated 27,154 ha and 9249 ha, respectively. The spatial distribution and trend of CO and CH4 prior to, during, and following the fire event were accessed and linked with in situ data in a qualitative and quantitative exploration. Large CO plumes were observed with CO columns exceeding 4.5 × 1018 and 6 × 1018 molecules/cm2 on 21 July 2019, and 7 August 2018, respectively. CO distribution profiles after consecutive digital processing steps showed the ability ...

The vegetation of the Wet Tropics bioregion of Far North Queensland is a complex system whose components (mainly tropical rainforests and fire-prone forests and woodlands) have mostly been studied independently from each other. We suggest that many characteristics of the vegetation are consistent with those of a complex, dynamic, spatially heterogeneous system which exhibits alternative stable states. We propose these states are driven and maintained by the interaction of vegetation-specific positive feedback loops with the regions’ environmental parameters (such as topography, steep humidity gradients and seasonality) and result in the rainforest/fire-prone vegetation mosaic that characterises the area. Given the regions’ magnitude, biodiversity and complexity, we propose the Wet Tropics as an important new example and a good testing ground for alternative stable state and resilience theories in large heterogeneous natural systems. At the same time, thinking in terms of alternative stable states and resilience creates a new context for understanding the regions’ biological dynamics.

Aim  There remains some uncertainty concerning the causes of extinctions of Madagascar’s megafauna. One hypothesis is that they were caused by over-hunting by humans. A second hypothesis is that their extinction was caused by both environmental change and hunting. This paper systematically addresses the second hypothesis through examination of two new pollen records from south-eastern Madagascar alongside other published records across the island.Location  South-eastern Madagascar.Methods  We reconstructed past vegetation and fire dynamics over the past 6000 years at two sites in south-eastern Madagascar (Ste-Luce) using fossil pollen and charcoal contained in sedimentary sequences. We investigated drivers of vegetation changes and how these, in turn, influenced faunal species in the south-east, using published climatic, archaeological and faunal records. Further, we also used published records to provide a synthesis of environmental changes on the whole island.Results  Vegetation reconstructions indicate that the mosaic vegetation in the region of Ste-Luce was highly dynamic in response to climatic changes. The open woodland, surrounding the littoral forest, transformed into an ericoid grassland between c. 5800 and 5200 cal. yr bp, possibly in response to a moderate drought recorded during this period. The littoral forest was more stable between c. 5100 and 1000 cal. yr bp, with only some minor compositional changes c. 2800 cal. yr bp and between c. 1900 and 1000 cal. yr bp. Significant forest decline, however, is observed at c. 950 cal. yr bp, coinciding with a drought and a marine surge. A comparison of these results with a synthesis of published vegetation records across the island shows asynchronous vegetation changes in response to various droughts during the Holocene, except for the 950 cal. yr bp drought event, with evidence of widespread vegetation transformations and fires across the island.Main conclusions  Pronounced climatic desiccation between 1200 and 700 cal. yr bp may have been the slow driver framing and triggering vegetation transformations and decline in megafaunal populations. In addition, hunting by drought-impacted human inhabitants and competition with newly introduced cattle would have amplified the impacts on megafaunal populations, leading to numerous extinctions in this period.

Fuel mapping is key to fire propagation risk assessment and regeneration potential. Previous studies have mapped fuel types using remote sensing data, mainly at local-regional scales, while at smaller scales fuel mapping has been based on general-purpose global databases. This work aims to develop a methodology for producing fuel maps across European regions to improve wildland fire risk assessment. A methodology to map fuel types on a regional-continental scale is proposed, based on Sentinel-3 images, horizontal vegetation continuity, biogeographic regions, and biomass data. A vegetation map for the Iberian Peninsula and the Balearic Islands was generated with 85% overall accuracy (category errors between 3% and 28%). Two fuel maps were generated: (1) with 45 customized fuel types, and (2) with 19 fuel types adapted to the Fire Behaviour Fuel Types (FBFT) system. The mean biomass values of the final parameterized fuels show similarities with other fuel products, but the biomass val...

Wildland fuelbeds are exceptionally complex, consisting of diverse particles of many sizes, types and shapes with abundances and properties that are highly variable in time and space. This complexity makes it difficult to accurately describe, classify, sample and map fuels for wildland fire research and management. As a result, many fire behaviour and effects software prediction systems use a generalised description of fuels to simplify data collection and entry into various computer programs. There are several major fuel description systems currently used in the United States, Canada and Australia, and this is a source of confusion for many in fire management. This paper (1) summarises the challenges of describing fuels, (2) contrasts approaches (association, classification and abstraction) for developing fuel description systems and (3) discusses possible future directions in wildland fuel description and science to transition to a universal fuel description system. Most discussio...

Informal settlements (ISs) are a high-risk environment in which fires are often seen. In 2019 alone, 5544 IS fires were reported in South Africa. One of the main problems, when investigating an IS fire, is determining the fire cause. In the last 15 years, approximately 40% of the fire causes were classified as ‘undetermined’ in South Africa. Furthermore, the cases where the fire causes have been determined, do not provide the necessary information to comprehend why the fire started. This paper seeks to gain better insight with respect to fire causes by analysing the fire risk perception of IS inhabitants. To this end, a survey that was conducted in 2017, consisting of data from 2178 IS households, that were affected by a large-scale fire, was analysed. The survey consisted of questions relating to the fire risk perception with regards to the settlement in general, to the inhabitants’ own household, and about measures that could reduce fire risk. The analysis suggests that (a) the su...

Termoplastikler; moleküllerinin bir arada ikinci zayıf bağlarla bir arada tutulduğu bir polimerdir ve ısıya maruz tutulduğunda yumuşar ve soğuduğunda tekrar orijinal durumuna geri döner. Termoplastikler ısı ile yumuşatıldığında, çekme, kalıba dökme veya presleme ile şekil verilebilir. Polimer gibi, bu süreç molekü-ler yapıda bir değişiklik meydana getirmeden çok defa tekrarlana-bilir. Termoplastikler şimdiye kadar endüstri tarafından üretilen en yaygın plastik tipleridir. Düşük yoğunluklu polietilen (yumu-PLASTİKLERİN YANGIN GÜVENLİĞİ 1. GİRİŞ Plastikler; hiçbir malzemenin olmadığı kadar fazla hayatımıza girdiğinden, pratikteki kullanımlarında yanıcılık özellikleri bü-yük önem taşımaktadır. Günümüzde plastik üretimi en büyük endüstrilerden biri olup mobil telefonlarından otomobil tam-ponlarına, şırıngalara kadar plastik malzeme kullanılmaktadır. Plastik malzemeler; farklı ihtiyaçları karşılamak için sert veya esnek, ağır veya hafif, katı veya sıvı formunda üretilebilmek-te ve binanın farklı elemanlarıyla bir arada yer almaktadır[1]. Plastikler; ham polimer, doldurucu, plastik yapıcı ve kat-kı maddelerinden meydana gelir. Reçine malzemenin birbiri-ne tutunmasını sağlar. Doldurucular reçinenin belli özellikleri-ni iyileştirirler. Katkı maddeleri özel olarak belli bir özelliği ge-liştirir ve küçük oranlarla malzemeye dâhil edilir. Genel olarak bu katkılar: sertleştiriciler, katalizörler, fenol veya amin içeren kararlı hale getiren maddeler, şişme araçları, yağlar, boyalar, mantar türevleri, bakteriler ve solventlerdir. Yaklaşık olarak 45 çeşit temel plastik ailesi vardır ve bu ai-lelerin çok sayıda alt bölümleri ve ayırt edici özellikleri bulun-maktadır. Ancak tüm plastikler bir veya iki grupta sınıflandırıla-bilir-termosetler (ısınınca sertleşen) veya termoplastikler (ısı-nınca yumuşayan)[2]. Termosetler; ısındıkları zaman moleküler yapılarında bir de-ğişime giden plastikler olup ısıtıldıkları takdirde dönüşü olma-yan bir şekilde katılaşan veya sertleşen bir polimerdir. Yaygın olarak kullanılan termosetler içinde polyester, silikon, poliüre-tan epoksi ve alkidler sayılabilir[4]. ÖZET Modern dünya; plastik olmadan hayal edilmez. Plastikler herkesin yaşam biçiminin ayrılmaz bir parçası olmuştur. Hafif ve koroz-yona karşı dirençli, farklı renk oluşturulabilen, şeffaf olarak kullanılabilen ve işleme kolaylığı olduğundan, günümüzde tasarımcılar ve mühendisler tarafından tercih edilmektedir. Bu özelliklerinin yanında istenmeyen özelliği ise kolay yanıcılığıdır. Özel ihtiyaçlara ce-vap verecek şekilde, katkı maddeleriyle yangın direnci artırılırken, depolama ve söndürme sistemleri konusunda da yeni çalışmalar yapılmaktadır. Bu çalışmada; plastikler hakkında bilgi verildikten sonra, plastiklerin yanma özellikleri, yangından korunma sistem-leri, söndürme sistemleri açıklanmaktadır.