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Savanna burning: The ecology and economy of fire in tropical savannas

Tropical savannas are the world’s most fire-prone biome, making fire a key issue for the maintenance of savanna ecosystem function and for the management of savanna biodiversity. Savanna burning also makes a significant contribution to global greenhouse gas emissions, through its effects on emissions of methane and nitrous oxide, and on carbon sequestration. There is growing international interest in reducing the extent and severity of savanna fires in the context of greenhouse gas abatement. Fire management for greenhouse gas abatement is a particularly important issue for northern Australia, where the burning of >400 000 km2 each year contributes on average 3% of Australia’s accountable greenhouse gas emissions.
Most of these emissions are produced by relatively highintensity wildfires that sweep through remote and unmanaged
areas during the end of the dry season, and which seriously threaten iconic biodiversity values such as those of World Heritage-listed Kakadu National Park. Greenhouse gas abatement provides an economic basis for improved fire management in these remote areas. It also presents important livelihood opportunities for remote Aboriginal communities, where traditional knowledge relating to fire remains strong, as does the desire to re-establish traditional fire management practices on their homelands. Savanna burning, therefore, sees an unprecedented meeting of interests relating to biodiversity protection, greenhouse gas abatement, and culturally appropriate economic opportunity for historically marginalized communities. This calls for an interdisciplinary understanding of fire in savanna landscapes, incorporating fuel dynamics and fire behaviour, the effects of fire on biodiversity and ecosystem function, economic analysis, and indigenous livelihood
development. Such is the scope of this Special Issue. The Special Issue begins by addressing the drivers of fire
occurrence in a Neotropical savanna (Hoffmann et al. 2012).This is followed by papers on fire and tree dynamics
in Australian savannas (Bond et al. 2012; Werner 2012), focussing on the peculiar ability of eucalypts to ‘escape the
fire trap’. There is considerable interest in the extent to which long-term fire exclusion can result in a biome shift
from savanna to forest, and this issue is addressed by Scott et al. (2012) in a northern Australian case study. Cook
(2012) addresses fire management in the context of fuel and savanna vegetation dynamics in landscapes undergoing
restoration following broad-scale mining.The effects of fire on soil nitrogen are examined by Richards et al. (2012b), while Andersen et al. (2012) and Radford and Andersen (2012) address fire in relation to fauna conservation in northern Australia.The Special Issue concludes with a spatially explicit economic analysis of fire management for greenhouse gas abatement across northern Australia (Heckbert et al. 2012), and a northern Australian case study integrating the ecological and economic consequences of different fire management options in the context of indigenous livelihood development (Richards et al. 2012a). We are hopeful that this Special Issue will provide an enhanced understanding of the full ecological, economic and social values of fire management in savanna landscapes.

Ano de Publicação: 2012

Savanna burning for biodiversity: Fire management for faunal conservation in Australian tropical savannas

Abstract

Tropical savannas are the world’s most fire-prone biome, and savanna biotas are generally well adapted
to frequent fire. However, in northern Australia there are concerns that recent increases in the frequency and extent
of high-intensity fires are causing substantial declines in regional biodiversity values. In this paper we use two
well-studied and contrasting faunal groups, ants and small mammals, as case studies for reviewing faunal responses
to fire in Australian savannas.The Australian savanna ant fauna is dominated by arid-adapted taxa that are highly
resilient to frequent fire and are not considered to be threatened by prevailing fire regimes. Indeed, frequent fire
promotes ant diversity because it maintains an open habit that makes the dominant arid-adapted taxa feel at home.
Long-term fire exclusion reduces ant diversity due to a marked decline in arid-adapted taxa, and favours highly
generalized, more shade-tolerant taxa. In contrast, many small mammal species of high conservation value are
highly sensitive to frequent fire, and there are widespread concerns that their populations are threatened by current
fire management. Many of the species have shown dramatic population declines over recent decades, and, although
the causes are poorly understood, there is little doubt that fire is an important contributing factor. It is likely that
fire is acting synergistically with other underlying causes of decline, particularly predation by feral cats.The overall
resilience of most savanna animal species in relation to frequent fire suggests that they are secure under all but the
most extreme fire regimes. However, it is clear that more fire-sensitive groups such as small mammals need special
fire management attention.This needs to involve less frequent and finer-scale burning, along with the protection of
some large, infrequently burnt source areas.
Key words: ant, fire regime, fire resilience, frequent fire, small mammal.

Ano de Publicação: 2012

Growth of juvenile and sapling trees differs with both fire season and understorey type:Trade-offs and transitions out of the fire trap in an Australian savanna

Abstract

Canopy tree populations in mesic savannas are often bimodal with few saplings but many smaller individuals of indeterminate age that repeatedly suffer topkill and regenerate from underground tissues. Little is known about growth rates or mechanisms that allow subadult trees to reach the canopy. The wooded savannas of northern Australia have high frequencies of dry-season fires. In a 32 400-m2 field experiment, 2405 juveniles (<150-cm height) and saplings (150–499 cm) of the eucalypt canopy species were individually marked and measured the year prior to fires set in three different seasons and again at the end of the growing season (without fires) a year later.Trees in unburnt plots served as controls. All fire treatments were repeated in plots dominated by the most common understorey, a native annual grass (sorghum) and in plots dominated by perennial native species; these produce different fuels for fires and competitive regimes for young trees. After early dry-season fires, height growth of larger juveniles and all saplings was significantly enhanced, especially in sorghum. After late dry- or wet-season fires, juvenile trees grew well, but all of the small saplings (150- to 299-cm height) were reduced to ‘juveniles’ and did not recover pre-fire heights but, instead, produced many new basal (coppice) stems. Late, dry-season fires reduced more than 80% of large saplings (300–499 cm) to juvenile size in sorghum, whereas in non-sorghum, 60% of the trees grew to poles (500–999 cm). The results demonstrate that juvenile and sapling growth responses to fire and the probability of subadult trees reaching the canopy are related to fire–understorey interactions, and suggest that the mechanisms include morphological and carbohydrate storage dynamics which vary with tree size and life history stage. The key to successful management of a sustainable woody canopy lies in the understorey.
Key words: Eucalyptus population dynamics, fire: effect of fire season, fire–understorey interaction, savanna
woodland: tree: height growth, tree: canopy replacement.

Ano de Publicação: 2012

Evolution of human-driven fire regimes in Africa

Human ability to manipulate fire and the landscape has increased over evolutionary time, but the impact of this on fire regimes and consequences for biodiversity and biogeochemistry are hotly debated. Reconstructing historical changes in human-derived fire regimes empirically is challenging, but information is available on the timing of key human innovations and on current human impacts on fire; here we incorporate this knowledge into a spatially explicit fire propagation model. We explore how changes in population density, the ability to create fire, and the expansion of agropastoralism altered the extent and seasonal distribution of fire as modern humans arose and spread through Africa. Much emphasis has been placed on the positive effect of population density on ignition frequency, but our model suggests this is less important than changes in fire spread and connectivity that would have occurred as humans learned to light fires in the dry season and to transform the landscape through grazing and cultivation. Different landscapes show different limitations; we show that substantial human impacts on burned area would only have started ∼4,000 B.P. in open landscapes, whereas they could have altered fire regimes in closed/dissected landscapes by ∼40,000 B.P. Dry season fires have been the norm for the past 200–300 ky across all landscapes. The annual area burned in Africa probably peaked between 4 and 40 kya. These results agree with recent
paleocarbon studies that suggest that the biomass burned today is less than in the recent past in subtropical countries.

Ano de Publicação: 2012

Evidence for Adaptation to Fire Regimes in the Tropical Savannas of the Brazilian Cerrado

A recent controversy concerns whether plant traits that are assumed to be adaptations to fire originally
evolved in response to selective factors other than fire. We contribute to this debate by investigating the
evolution of the endemic woody flora of the fire-prone Cerrado of central Brazil, the most species-rich savanna
in the world. We review evidence from dated phylogenies and show that Cerrado lineages started to diversify
less than 10 million years ago. These Cerrado lineages are characterized by fire-resistant traits such as thick,
corky bark and root sprouting, which have been considered to have evolved as adaptations to drought or
nutrient-deficient soils. However, the fact that the lineages carrying these features arose coincident with the rise
to dominance of flammable C4 grasses and expansion of the savanna biome worldwide, and postdating the
earlier origin of seasonal climates and the nutrient-poor, acid Cerrado soils suggests that such traits should be
considered as adaptations to fire regimes. The nature of these features as adaptations to fire is further suggested
by their absence or poor development in related lineages found in fire-free environments with similar edaphic
conditions to the Cerrado and by their repeated independent origin in diverse lineages. We present evidence to
demonstrate that the evolutionary barrier to entry to the Cerrado is a weak one, presumably because of the
ease of evolution of the necessary adaptations to fire regimes for lineages inhabiting neighboring fire-free
biomes.
Keywords: adaptive radiation, exaptation, Neotropics, phylogenetic niche conservatism, plant evolution

Ano de Publicação: 2012

Does long-term fire exclusion in an Australian tropical savanna result in a biome shift? A test using the reintroduction of fire

Abstract

The structure of tropical savanna ecosystems is influenced by fire frequency and intensity. There is particular interest in the extent to which long-term fire exclusion can result in a shift from savanna to forest vegetation that is not easily reversed by the reintroduction of fire.This study examined changes in the structure and composition of a long-unburnt site within the northern Australian savannas following an extended period of active fire exclusion (>20 years), and the effect of the reintroducing fire through experimental fire regimes, including fires in the early and late dry season at a range of frequencies. After the long period of fire exclusion, the vegetation community was characterized by a well-developed midstorey and canopy layer, low grass cover, substantially higher densities of woody sprouts and saplings than frequently burnt savanna. The community composition included a high proportion of rainforest-affiliated species. Three years of experimental fires had no detectable effect on the overall composition of grass layer and woody plants but had an effect on woody vegetation structure. Continued fire exclusion further increased the density of woody stems, particularly in the midstorey (2.0–4.99 m), whereas
moderate-intensity fires (>800 kW m-1) significantly reduced the density of midstorey stems.The reintroduction of
higher moderate intensity fire events resulted in the vegetation in some compartments reverting to the open savanna
structure typical of frequently burnt sites. Such rapid reversibility suggests that in general, the woody thickening
resulting from long-term fire exclusion did not represent a biome shift to a non-savanna state. However, there was
a small proportion of the site that could not sustain the fires applied to them because grass cover was very low and
patchy and therefore appeared to have crossed an ecological threshold towards closed forest. Key words: biome shift, fire, fire behaviour, resprout, savanna, tropical woodland, woody thickening.

INTRODUCTION
State-and-transition models are useful for describing the range of complex ecosystem processes and multiple vegetation states observed in tree-grass ecosystems (Westoby et al. 1989; Angassa & Oba 2008). According to state-and-transition theory, vegetation can shift from one stable state to another, and this shift can be irreversible without dramatic intervention. Substantial changes in composition and structure may occur within

Ano de Publicação: 2012

ATUAÇÃO DA COORDENAÇÃO GERAL DE PROTEÇÃO AMBIENTAL – CGPRO NA PREVENÇÃO E COMBATE A INCÊNDIOS FLORESTAIS EM UNIDADES DE CONSERVAÇÃO FEDERAIS

Introdução
A criação das Unidades de Conservação no Brasil iniciou-se em 1937, com o Parque Nacional do Itatiaia RJ, como uma estratégia para a conservação da biodiversidade. Atualmente, o país conta com um total de 884 Unidades de Conservação, com uma área de 755.204 km² em âmbito federal (BRASIL, 2012), representando todos os biomas do país, distribuídos entre as diferentes categorias dos grupos de proteção integral: Estação Ecológica (ESEC), Reserva Biológica (REBIO), Parque Nacional (PARNA), Monumento Natural (MN), Refúgio de Vida Silvestre (RVS); e de uso sustentável: Área de Proteção Ambiental (APA), Área de Relevante Interesse Ecológico (ARIE), Floresta Nacional (FLONA), Reserva Extrativista (RESEX), Reserva de Fauna (RF), Reserva de Desenvolvimento Sustentável (RDS) e Reserva Particular do Patrimônio Natural (RPPN). No geral, as Unidades de Conservação sofrem com diversos problemas diários, como falta de recursos financeiros, poucos profissionais, situação fundiária irregular, conflitos com as populações locais e tradicionais e incêndios florestais, prejudicando o manejo de suas áreas e de seu entorno. Os incêndios florestais, em especial, afetam principalmente as Unidades com fitofisionomias de cerrado, gerando muitas perdas e danos ambientais, confrontos, gastos públicos e individuais, além de grandes preocupações. Estudos apontam que, na maioria das ocorrências de incêndios florestais nas Unidades de Conservação, a principal causa não é de origem natural, ou seja, provocada por raios, mas sim pela ação antrópica, associada às práticas agrícolas e de pastagens. (MEDEIROS, 2002).
CLIMEP – Climatologia e Estudos da Paisagem
http://www.periodicos.rc.biblioteca.unesp.br/index.php/climatologia/index
Rio Claro (SP) – Vol.7 – n.1-2 – janeiro/dezembro/2012, p. 6
Para especialmente gerir as Unidades de Conservação, o Governo brasileiro fundou o Instituto Chico Mendes de Conservação da Biodiversidade (ICMBIO) em 2007, antes de responsabilidade do Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis (IBAMA), que se encarregava de tal tarefa e de várias outras funções relacionadas às questões ambientais. Dois anos após o estabelecimento do ICMBIO, criou-se a Coordenação Geral de Proteção Ambiental (CGPRO), que ficou encarregada, a partir de 2009, de cuidar das questões referentes aos incêndios florestais, dentro das Unidades de Conservação federais, responsabilizando-se, inclusive, por fazer os seus Boletins Informativos de Risco de Fogo. O trabalho da CGPRO com incêndios é ordenado pela Coordenação de Emergências Ambientais do ICMBIO, sendo uma continuação da antiga gestão do Centro Nacional de Prevenção e Combate aos Incêndios Florestais (PREVFOGO) ligada ao IBAMA, ambos atuando em parceria, quando necessário, nas áreas que são protegidas. Embora haja ocorrido essa mudança de gestão nas Unidades, de IBAMA para ICMBIO, as estratégias de combate e prevenção aos incêndios continuam parecidas, sofrendo com as mesmas carências e dificuldades, como a contratação de brigadistas, recursos financeiros e materiais insuficientes, pesquisas e conscientização da população do entorno das áreas protegidas.
O objetivo desta pesquisa é analisar como a CGPRO atua, assim como avaliar a eficiência de suas ações, nas Unidades de Conservação federais, em relação à prevenção e combate a incêndios florestais

Ano de Publicação: 2012

Análise Geoecológica dos Incêndios Florestais do Parque Nacional do Itatiaia - Boletim nº 15

EDITORIAL

O Boletim de Pesquisa do PNI Nº15-―Análise Geoecológica dos Incêndios Florestais no Parque Nacional do Itatiaia‖ é um trabalho do Analista Ambiental Gustavo W. Tomzhinski, do seu orientador Prof./Dr.Manoel do Couto Fernandes e de Kátia Torres Ribeiro. A pesquisa em tela foi apresentada em 2012 ao corpo docente do Programa de Pós-Graduação em Geografia da Universidade Federal do Rio de Janeiro, como parte dos requisitos necessários à obtenção do Grau de Mestre em Ciências: Geografia. O pesquisador dissecou uma área de estudo que definiu como o polígono abrangendo o PNI e seu entorno de 3 km. Essa área totaliza 57.924 ha. Gustavo relata o registro de 453 incêndios e ressalta os mais relevantes, nos anos: 1937, 1951, 1963, 1988, 1989, 2001, 2007, 2008, 2010 e 2011 e concluiu com os métodos utilizados para detecção de incêndios, regime de fogo, mapeamento geográfico da suscetibilidade e ocorrência de incêndios e outros questionamentos e conclusões.
As 143 referências bibliográficas utilizada pelo autor têm pontos de referências dos Boletins de Pesquisa do
PNI criado por Wanderbilt Duarte de Barros (1916-1997) em 1949. O Engenheiro Agrônomo Tomzhinski utilizou os Boletins Números 4, 5, 6 e 10, publicados respectivamente em 1955, 1956, 1957 e 2012. Levantando o passado do PARNA ITATIAIA, Gustavo consegue chegar ao presente através de mapas, gráficos e uma dissertação leve e prazerosa de um dos seus piores problemas que é o incêndio florestal e liga o futuro para que as novas gerações tenham perspectivas de usufruírem um modelo de integração sócio-ambiental livre de qualquer tipo de agressão a sua biótica e beleza natural.

LÉO NASCIMENTO. COORDENADOR DE PESQUISA DO PNI.


RESUMO
O fogo é importante elemento modificador da paisagem. Muitas vezes os incêndios florestais têm potencial devastador constituindo ameaça à biodiversidade. O Parque Nacional do Itatiaia (PNI) é uma unidade de conservação de significância histórica e ecológica, abrigando importantes remanescentes do Bioma Mata Atlântica. A Área de Estudo (AE) foi definida abrangendo o PNI e seu entorno em uma faixa de 3 km. Este trabalho tem o objetivo de ampliar o conhecimento da questão dos incêndios através de uma análise geoecológica na qual se busca estabelecer relacionamentos quantitativos e qualitativos entre os elementos da paisagem, incluindo a ação do homem sobre ela. A maior quantidade de incêndios na AE ocorre normalmente no mês de agosto, no entanto a maior concentração de área queimada é registrada para o mês de setembro, quando a precipitação acumulada atinge níveis mais baixos. O maior número de incêndios foi registrado fora dos limites do PNI, mas as maiores áreas atingidas ocorrem dentro, possivelmente devido às extensas áreas contínuas de formações campestres. Verificou-se que 58% das áreas atingidas pelos incêndios apresentam declividade alta, 51% forma convexa (alta), 73% alta incidência de radiação solar, 92% alta combustibilidade e 78% estão localizadas acima de 2.000 m de altitude. A análise da precipitação mostrou a relação inversa dos incêndios com a precipitação antecedente, especialmente nos anos dos maiores incêndios, quando essas condições foram muito abaixo da média. Foram avaliados indicadores de curto e médio prazo de precipitação acumulada, concluindo-se que estes devem ser utilizados em conjunto para o diagnóstico de condições críticas para a ocorrência de incêndios. Na análise espacial das principais variáveis ligadas ao risco à ignição, foi verificado que 73% dos incêndios estão a menos de 15 m de vias de transporte, edificações ou propriedades particulares dentro do PNI e que 93% das ocorrências dentro do Parque
estão total ou parcialmente inseridos nessas propriedades. Um mapa de suscetibilidade a ocorrência de incêndios florestais foi gerado para a área de estudo utilizando-se o método analítico-integrativo com as seguintes variáveis geoecológicas: combustibilidade, incidência de radiação solar, forma do relevo e declividade. O cruzamento das informações dos incêndios com esse mapa mostrou que 94% das áreas atingidas por eles foram classificadas como de alta suscetibilidade, o que aponta para a eficácia do método para a identificação de áreas com condições favoráveis à ocorrência desse fenômeno. A metodologia e os resultados encontrados constituem significativo subsídio para a modelagem do conhecimento relacionado à avaliação de cenários para a ocorrência de incêndios.

Palavras-chave: CARTOGRAFIA GEOECOLÓGICA, GEOPROCESSAMENTO, REGIME DE FOGO, UNIDADES DE CONSERVAÇÃO.

Ano de Publicação: 2012

The human dimension of fire regimes on Earth

ABSTRACT

Humans and their ancestors are unique in being a fire-making species, but ‘natural’ (i.e. independent of humans) fires have an ancient, geological history on Earth. Natural fires have influenced biological evolution and global biogeochemical cycles, making fire integral to the functioning of some biomes. Globally, debate rages about the impact on ecosystems of prehistoric human-set fires, with views ranging from catastrophic to negligible. Understanding of the diversity of human fire regimes on Earth in the past, present and future remains rudimentary. It remains uncertain how humans have caused a departure from ‘natural’ background levels that vary with climate change. Available evidence shows that modern humans can increase or decrease background levels of natural fire activity by clearing forests, promoting grazing, dispersing plants, altering ignition patterns and actively suppressing fires, thereby causing substantial ecosystem changes and loss of biodiversity. Some of these contemporary fire regimes cause substantial economic disruptions owing to the destruction of infrastructure, degradation of ecosystem services, loss of life, and smoke-related health effects. These episodic disasters help frame negative public attitudes towards landscape fires, despite the need for burning to sustain some ecosystems. Greenhouse gas-induced warming and changes in the hydrological cycle may increase the occurrence of large, severe fires, with potentially significant feedbacks to the Earth system. Improved understanding of human fire regimes demands: (1) better data on past and current human influences on fire regimes to enable global comparative analyses, (2) a greater understanding of different cultural traditions of landscape burning and their positive and negative social, economic and ecological effects, and (3) more realistic representations of anthropogenic fire in global vegetation and climate change models. We provide an historical framework to promote understanding of the development and diversification of fire regimes, covering the pre-human period, human domestication of fire, and the subsequent transition from subsistence agriculture to industrial economies. All of these phases still occur on Earth, providing opportunities for comparative research.

Keywords Fire and culture, fire management, fire regime, global environmental change, landscape fire, palaeoecology, prehistoric human impacts, pyrogeography.

Ano de Publicação: 2011

Role of Fire in the Germination Ecology of Fountain Grass (Pennisetum setaceum), an Invasive African Bunchgrass in Hawai'i

Abstract: 

Field and laboratory studies were carried out to test factors expected to be relevant for the germination of fountain grass: (1) light; (2) emergence of fountain grass seedlings from depths of 0, 2.5, and 5 cm; (3) fire passing over exposed and buried seeds; (4) laboratory heat treatment mimicking exposure to grass fire. Both fire in the field and heat applied in the laboratory killed fountain grass seeds. In the laboratory, some seeds were killed after  xposure to 75C for 3 min, and all seeds were killed at 100C. During the prescribed burns, temperatures at the soil surface reached at least 204C, but temperatures at depths of 2.5 and 5 cm showed no measurable change. Light is not essential for germination of fountain grass seeds, and seedlings can emerge from depths of at least 5 cm. Both of these traits contribute to the invasive capacity of the species. Because fountain grass seeds are killed at temperatures in excess of 100C, the species depends on its ability to resprout and quickly set seed after fire for population growth and spread. Seeds buried beneath the soil may escape exposure to fire, and substrate heterogeneity may provide refuge from temperature extremes experienced during fire. The morphology of fountain grass seeds likely inhibits burial in the soil for the most part, but there are several potential burial mechanisms. Prescribed burns could prove to be a useful tool for fountain grass control in large, degraded sites where fountain grass has invaded but only when coupled with additional control measures. 

Ano de Publicação: 2011