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Leaf and Shoot Water Content and Leaf Dry Matter Content of Mediterranean Woody Species with Different Post-fire Regenerative Strategies

Abstract

ABSTRACT 


Background and Aims

Post-fire regeneration is a key process in Mediterranean shrubland dynamics, strongly determining the functional properties of the community. In this study, a test is carried out to deteremine whether there is co-variation between species regenerative types and functional attributes related to water use.

Methods

An analysis was made of the seasonal variations in leaf relative water content (RWC), leaf dry matter content (LDMC), leaf moisture (LM) and live fine fuel moisture (LFFM) in 30 woody species of a coastal shrubland, with different post-fire regenerative strategies (seeding, resprouting or both).

Key Results

RWC results suggest that the studied resprouters have more efficient mechanisms to reduce water losses and maintain water supply between seasons. In contrast, seeders are more drought tolerant. LDMC is higher in resprouters over the course of the year, suggesting a more efficient conservation of nutrients. The weight of the phylogenetic constraint to understand differences between regenerative strategies tends to be important for LDMC, while it is not the case for variables such as RWC.

Conclusions

Groups of species with different post-fire regenerative strategies (seeders and resprouters) have different functional traits related to water use. In addition to the role of phylogenetical constraints, these differences are also likely to be related to the respective life history characteristics. Therefore, the presence and abundance of species with different post-fire regenerative responses influence the functional properties of the communities.

Key words: Functional traits, leaf dry matter content, Mediterranean plants, post-fire, regenerative strategy, relative water content, resprouter, seeder, woody species

Ano de Publicação: 2007

Holocene fire and occupation in Amazonia: records from two lake districts

ABSTRACT

Abstract

While large-scale pre-Columbian human occupation and ecological disturbance have been demonstrated close to major Amazonian waterways, less is known of sites in terra firme settings. Palaeoecological analyses of two lake districts in central and western Amazonia reveal long histories of occupation and land use. At both locations, human activity was centred on one of the lakes, while the others were either lightly used or unused. These analyses indicate that the scale of human impacts in these terra firme settings is localized and probably strongly influenced by the presence of a permanent open-water body. Evidence is found of forest clearance and cultivation of maize and manioc. These data are directly relevant to the resilience of Amazonian conservation, as they do not support the contention that all of Amazonia is a ‘built landscape’ and therefore a product of past human land use.

Keywords: agriculture, charcoal, fossil pollen, Peru, Brazil, pre-Columbian

Ano de Publicação: 2007

Fuel and fire characteristics in savanna–woodland ofWest Africa in relation to grazing and dominant grass type

Abstract. 

Fuel characteristics, fire behaviour and temperature were studied in relation to grazing, dominant grass type and wind direction inWest African savanna–woodland by lighting 32 prescribed early fires. Grazing significantly reduced the vegetation height, total fuel load, and dead and live fuel fractions whereas plots dominated by perennial grasses had higher values for vegetation height, total fuel load and the quantity of live fuel load. Although fire intensity remained insensitive (P>0.05) to any of these factors, fuel consumption was significantly (P =0.021) reduced by grazing, rate of spread was faster in head fire (P =0.012), and flame length was shorter in head fire than back fire (P =0.044). The average maximum temperature was higher (P<0.05) on non-grazed plots, on plots dominated by annual grasses, on plots subjected to head fire, and at the soil surface. Lethal temperature residence time showed a nearly similar trend to fire temperature.Wind speed and total fuel load were best predictors of fire behaviour parameters (R2 ranging from 0.557 to 0.862). It can be concluded that grazing could be used as a management tool to modify fire behaviour, back fire should be carried out during prescribed burning to lower fire severity, and the fire behaviour models can be employed to guide prescribed early fire in the study area.

Additional keywords: Burkina Faso, fire behaviour model, fuel load, fuel moisture, weather variables.

Ano de Publicação: 2007

Fire, Ecosystems and People: Threats and Strategies for Global Biodiversity Conservation. GFI Technical Report

Executive Summary 

It is widely understood that—as a result of human actions—fire is behaving differently today than at any other time in human history. Fire plays a vital role in maintaining many ecosystems and the communities that depend on them. In order to develop effective conservation strategies, we have to understand the relationships between fire, people and the environment. Only 25% of the terrestrial world assessed exhibits intact fire regimes. Ecoregions with degraded and very degraded fire regimes cover 53% and 8% of the globe, respectively. More than half (53%) of the earth’s ecoregions are fire-dependent, while 22% are fire-sensitive and 15% fire-independent (the remaining 10% have not been assessed). There is a strong link between the degradation of fire regimes and the loss of biodiversity. The top causes of altered fire regimes globally are urban development; livestock farming, ranching and agriculture; fire use and fire suppression; resource extraction (including energy production, mining and logging); and climate change. These threats can be addressed by adopting a framework called Integrated Fire Management. The first step of Integrated Fire Management includes identifying potential environmental, social and economic benefits and consequences of fire. This information helps communities decide how, when and where fire will occur on the land. Specific recommendations for community-based practitioners, country governments and multi-lateral institutions include: 

1. Evaluate whether the effects of fire will be detrimental, beneficial or benign; 

2. Weigh the relative benefits and risks of fire and human actions; and 

3. Implement appropriate policies, increase fire management capacity, educate citizens about the role of fire, and learn and adapt along the way

Ano de Publicação: 2007

Fire, ecosystems and people: Threats and strategies for global biodiversity conservation1

Abstract

Fire plays a major role in shaping our environment and maintaining biodiversity. When fire regimes are altered, they can contribute to climate-changing greenhouse gases into the environment, provide a pathway for harmful invasive species, alter the hydrology of a site, and present a direct risk to biodiversity and human habitation. Effective biodiversity conservation requires, among other things, that fire is allowed to play a natural role and at the same time that it does not pose a threat to biodiversity or human well-being. The Global Fire Partnership (GFP) includes The Nature Conservancy, World Conservation Union (IUCN), University of California at Berkeley Center for Fire Research and Outreach, and the World Wildlife Fund (WWF). The GFP implemented 3 expert workshops between January and July 2006 covering four broad biogeographic realms to establish scientifically credible data consistently at coarse ecoregional levels for global biodiversity conservation. Results revealed that 25 percent of terrestrial area is intact relative to fire regime conditions. Ecoregions with degraded fire regimes cover 53 percent of global terrestrial area while ecoregions with very degraded fire regimes cover 8 percent. Assessment continues of the remaining 13 percent. Globally, boreal forests and taiga are the most intact systems relative to fire regime conditions, and Mediterranean forests, woodlands and scrub are the most degraded. Based on regional expert workshops, the top threats to maintaining an ecologically-acceptable role of fire include ecosystem conversion (e.g., livestock ranching, agriculture, urban development), resource extraction (e.g., energy production, mining, logging and wood harvesting), and human-caused fires or fire suppression. Effective biodiversity conservation depends on building global to local constituencies and partnerships focused on abating the leading causes of altered fire regimes, enabling public policies and local capacities to make a difference at ecologically-relevant scales, educating practitioners and policy- and decision-makers about the ecological role of fire and the ecological and social costs of altered fire regimes, implementing Integrated Fire Management, creating economic incentives for maintaining intact fire regimes, monitoring fires and changes in land use and land cover, enforcement of laws that support ecologically-appropriate fire prevention and fire use, and being adaptive to changing knowledge, social and political contexts, and ecological conditions.

Ano de Publicação: 2007

Soil organic carbon and black carbon storage and dynamics under different fire regimes in temperate mixed-grass savanna

We quantified the effects of repeated, seasonal fires on soil organic carbon (SOC), black carbon (BC), and total N in controls and four fire treatments differing in frequency and season of occurrence in a temperate savanna. The SOC at 0–20 cm depth increased from 2044 g C m2 in controls to 2393–2534 g C m2 in the three treatments that included summer fire. Similarly, soil total N (0–20 cm) increased from 224 g N m2 in the control to 251–255 g N m2 in the treatments that included summer fire. However, winter fires had no effect on SOC or total N. Plant species composition coupled with lower d13C of SOC suggested that increased soil C in summer fire treatments was related to shifts in community composition toward greater relative productivity by C3 species. Lower d15N of soil total N in summer fire treatments was consistent with a scenario in which N inputs > N losses. The BC storage was not altered by fire, and comprised 13–17% of SOC in all treatments. Results indicated that fire and its season of occurrence can significantly alter ecosystem processes and the storage of C and N in savanna ecosystems.

Citation: Ansley, R. J., T. W. Boutton, and J. O. Skjemstad (2006), Soil organic carbon and black carbon storage and dynamics under different fire regimes in temperate mixed-grass savanna, Global Biogeochem. Cycles, 20, GB3006, doi:10.1029/2005GB002670

Ano de Publicação: 2006

Global distribution and seasonality of active fires as observed with the Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) sensors

We describe a new global multiyear satellite fire product designed to meet the needs of the global modeling community. We use the new data set to analyze the global distribution of biomass burning using five different temporal metrics derived from 5 years of high-quality satellite data acquired with the Moderate Resolution Imaging Spectroradiometer (MODIS), on board NASA’s Terra satellite. The global distributions of fire pixel density, peak month, season length, and annual periodicity are described. As part of our analysis we show, for the first time, the global distribution of the fire radiative power (FRP), a relatively new remotely sensed quantity. We find that low FRP tends to be associated with areas of cropland burning. In the tropics and much of the subtropics, low FRP is also associated with more heavily forested areas, while higher FRP tends to occur in areas of grassland burning. In boreal forests this trend is reversed, with higher FRP occurring in areas of greater tree cover. We next combine 3 years of Terra and Aqua MODIS observations to show that a strong diurnal fire cycle is prevalent at tropical and subtropical latitudes. We also consider the consistency of the fire time series recorded by the two MODIS instruments, and find the month of peak burning and fire season length observed by each to be in good agreement in most areas. However, significant discrepancies with respect to seasonality do occur in some relatively small areas, and are most pronounced in tropical rain forest.

Citation: Giglio, L., I. Csiszar, and C. O. Justice (2006), Global distribution and seasonality of active fires as observed with the Terra

and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) sensors, J. Geophys. Res., 111, G02016,

doi:10.1029/2005JG000142.

Ano de Publicação: 2006

Convivendo com o Fogo— Manutenção dos Ecossistemas & Subsistência com o Manejo Integrado do Fogo

Iniciativa Global para o Manejo do Fogo - Junho 2006

web site: http://nature.org/fire, http://tncfuego.org

Síntese

A percepção do fogo como ferramenta útil surgiu com os primeiros humanos quando estes, há milhares de anos, passaram a se beneficiar dos efeitos do fogo para alterar a vegetação e a vida selvagem nas savanas africanas. É muito provável que a ameaça, representada pelo fogo, à segurança e à subsistência desses povos já lhes fosse óbvia, de modo que, à medida que a humanidade foi se espalhando pelo planeta, novos regimes de fogo foram criados, os quais moldavam e modificavam sucessivamente a paisagem. Há também os incêndios que destroem as casas, as lavouras, os animais e os outros recursos. Portanto, “as duas faces do fogo” — o fogo benéfico e o fogo maléfico — sempre existiram. Durante o século XX, o fogo passou a ser visto como uma ameaça à população e aos recursos naturais, e muitos países desenvolveram programas sofisticados de prevenção ao fogo e criaram organizações de supressão ao fogo para proteger a população e os recursos naturais. Algumas dessas medidas foram tão eficazes e determinantes na prevenção e na supressão dos incêndios que a sociedade perdeu a noção da utilidade do fogo como ferramenta importante para o processo de modelagem da paisagem. O resultado foi o grande acúmulo de combustível modificando a vegetação e desta forma tornando-se mais propensa a incêndios mais intensos durante os anos atipicamente secos, associado com a perda de espécies que evoluíram em paisagens mais abertas que queimavam com mais freqüência e com menor intensidade. Para agravar ainda mais esse cenário, um contingente cada vez maior de pessoas vem há anos construindo suas casas em áreas onde o programa de supressão tem evitado o fogo por muito tempo, e a vegetação continuou a crescer e acumular. O resultado global, desta “bem-sucedida” exclusão do fogo, são as incidências de incêndios cada vez mais danosos à vegetação, ao solo e às bacias hidrográficas, que geram um custo econômico cada vez maior com a perda de propriedades e com o combate a esses incêndios. Em muitas partes do mundo, as pessoas continuam a utilizar o fogo da forma tradicional, mas as pressões impostas pela sociedade vêm causando mudanças no uso da terra, migração para novas áreas e aumento das fontes de ignição em todo o mundo. Para as vegetações propensas ao fogo, como as savanas e as florestas, que atualmente queimam anualmente resultando na diminuição da densidade de árvores. Nas áreas florestais há a expansão das áreas de savanas antropogênicas e de pastos em detrimento das florestas, mesmo em ambientes em que o fogo era um evento historicamente raro.  O fogo tornou-se um tema de conservação, pois muitas áreas do planeta denominadas ecossistemas dependentes do fogo, dependem do fogo para preservar as espécies nativas, os habitats e a paisagem. Contudo existem também outras áreas, estas chamadas de ecossistemas sensíveis ao fogo, onde o fogo pode levar à destruição ou à extinção de espécies nativas e à destruição de seus habitats. De fato, o fogo pode afetar de maneira tanto negativa quanto positiva, os benefícios proporcionados pelos ecossistemas, tais como ar limpo, água limpa e solos saudáveis e produtivos, dependendo da adaptação de cada espécie e, de outras características do meio ambiente, além da freqüência e intensidade da queima de uma determinada área. Uma nova ciência, ecologia do fogo, está começando a esclarecer sobre esses fatos. Todavia, o papel exercido pelo fogo em muitos ecossistemas em todo o mundo continua sendo pouco compreendido pela comunidade científica, e geralmente ignorado por quase toda a sociedade. Nos locais onde os benefícios do fogo são reconhecidos, o regime de fogo ecologicamente apropriado pode ser desconhecido.  O fato de o fogo ter duas faces — as funções benéficas e os impactos maléficos, dependendo das circunstâncias —, tem sido, em grande parte, ignorado pelas sociedades e pelos governos que buscam e desenvolvem tecnologias cada vez mais sofisticadas de supressão do fogo e campanhas de prevenção contra o fogo. As conseqüências indesejáveis da exclusão do fogo em algumas paisagens e o fato dessa exclusão resultar em custos elevados e retornos bem mais modestos passaram a ser reconhecidos por alguns governos nestes últimos quinze anos. Os governos e  as sociedades urbanas também não reconhecem ou compreendem a necessidade do uso do fogo por diversas comunidades rurais. As políticas e os programas foram criados com base na premissa de que a população rural é a causa dos problemas do fogo. No entanto, essas políticas deveriam olhar para as comunidades rurais como parte da solução, oferecendo-lhes incentivos e tecnologias que possam ser agregados ao conhecimento tradicional do uso do fogo, e desta forma manejar o fogo de uma maneira mais eficaz, tanto com as queimadas que são necessárias quanto as que acontecem naturalmente. O manejo do fogo refere-se ao espectro de decisões técnicas e ações disponíveis para evitar, preservar, controlar ou utilizar o fogo em uma determinada paisagem. A premissa básica deste documento é que as tecnologias mais sofisticadas de manejo do fogo dificilmente solucionarão os problemas dos incêndios destrutivos e nem serão eficazes em restabelecer os regimes de fogo ecologicamente apropriados em locais onde as queimadas são necessárias. Para manejar as queimadas, é inevitável que haja a integração de realidades socioculturais e as necessidades ecológicas com abordagens tecnológicas. Este documento expõe uma estrutura que denominamos Manejo Integrado do Fogo, que considera as abordagens ecológica e socialmente apropriadas para manejar o fogo e as ameaças do fogo relacionados à conservação de terras.



Ano de Publicação: 2006

Blackwell Publishing, Ltd. The global distribution of ecosystems in a world without fire

Summary

• This paper is the first global study of the extent to which fire determines global vegetation patterns by preventing ecosystems from achieving the potential height, biomass and dominant functional types expected under the ambient climate (climate potential).

• To determine climate potential, we simulated vegetation without fire using a dynamic global-vegetation model. Model results were tested against fire exclusion studies from different parts of the world. Simulated dominant growth forms and tree cover were compared with satellite-derived land- and tree-cover maps.

• Simulations were generally consistent with results of fire exclusion studies in southern Africa and elsewhere. Comparison of global ‘fire off’ simulations with landcover and treecover maps show that vast areas of humid C 4 grasslands and savannas, especially in South America and Africa, have the climate potential to form forests. These are the most frequently burnt ecosystems in the world. Without fire, closed forests would double from 27% to 56% of vegetated grid cells, mostly at the expense of C plants but also of C shrubs and grasses in cooler climates.

• C grasses began spreading 6–8 Ma, long before human influence on fire regimes.

Our results suggest that fire was a major factor in their spread into forested regions, splitting biotas into fire tolerant and intolerant taxa.

Key words: climate–vegetation relationships, dynamic global vegetation models, fire ecology, global biomes, plant biogeography.

New Phytologist (2005)  165 : 525–538

New Phytologist (2004) doi : 10.1111/j.1469-8137.2004.01252.x

Ano de Publicação: 2005

Prevenção de Incêndios Florestais na Amazônia: Lições aprendidas no projeto Proteger

RESUMO

O projeto de Mobilização e Capacitação para Prevenção de Incêndios Florestais na Amazônia, denominado Projeto Proteger, é resultado da iniciativa do Grupo de Trabalho Amazônico GTA e do Grupo Sindical do Movimento dos Trabalhadores Rurais - MSTR no contexto da formulação e implementação do Programa de Prevenção aos Incêndios Florestais no Arco do Desmatamento - PROARCO, formulado e implementado pelo Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis - IBAMA.


Ano de Publicação: 2005