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Modelling long-term fire occurrence factors in Spain by accounting for local variations with geographically weighted regression
J. Martínez-Fernández, E. Chuvieco,N. Koutsias
Natural Hazards and Earth System Sciences (NHESS) & Discussions (NHESSD) , 2013,
Abstract: Humans are responsible for most forest fires in Europe, but anthropogenic factors behind these events are still poorly understood. We tried to identify the driving factors of human-caused fire occurrence in Spain by applying two different statistical approaches. Firstly, assuming stationary processes for the whole country, we created models based on multiple linear regression and binary logistic regression to find factors associated with fire density and fire presence, respectively. Secondly, we used geographically weighted regression (GWR) to better understand and explore the local and regional variations of those factors behind human-caused fire occurrence. The number of human-caused fires occurring within a 25-yr period (1983–2007) was computed for each of the 7638 Spanish mainland municipalities, creating a binary variable (fire/no fire) to develop logistic models, and a continuous variable (fire density) to build standard linear regression models. A total of 383 657 fires were registered in the study dataset. The binary logistic model, which estimates the probability of having/not having a fire, successfully classified 76.4% of the total observations, while the ordinary least squares (OLS) regression model explained 53% of the variation of the fire density patterns (adjusted R2 = 0.53). Both approaches confirmed, in addition to forest and climatic variables, the importance of variables related with agrarian activities, land abandonment, rural population exodus and developmental processes as underlying factors of fire occurrence. For the GWR approach, the explanatory power of the GW linear model for fire density using an adaptive bandwidth increased from 53% to 67%, while for the GW logistic model the correctly classified observations improved only slightly, from 76.4% to 78.4%, but significantly according to the corrected Akaike Information Criterion (AICc), from 3451.19 to 3321.19. The results from GWR indicated a significant spatial variation in the local parameter estimates for all the variables and an important reduction of the autocorrelation in the residuals of the GW linear model. Despite the fitting improvement of local models, GW regression, more than an alternative to "global" or traditional regression modelling, seems to be a valuable complement to explore the non-stationary relationships between the response variable and the explanatory variables. The synergy of global and local modelling provides insights into fire management and policy and helps further our understanding of the fire problem over large areas while at the same time recognizing its local character.
Combating the effects of climatic change on forests by mitigation strategies
Michael K?hl, Rüdiger Hildebrandt, Konstantin Olschofksy, Raul K?hler, Thomas R?tzer, Tobias Mette, Hans Pretzsch, Margret K?thke, Matthias Dieter, Mengistu Abiy, Franz Makeschin, Bernhard Kenter
Carbon Balance and Management , 2010, DOI: 10.1186/1750-0680-5-8
Abstract: We simulated the development of managed forest ecosystems in Germany for the time period between 2000 and 2100 under different forest management regimes and climate change scenarios. The management regimes reflect different rotation periods, harvesting intensities and species selection for reforestations. The climate change scenarios were taken from the IPCC's Special Report on Emission Scenarios (SRES). We used the scenarios A1B (rapid and successful economic development) and B1 (high level of environmental and social consciousness combined with a globally coherent approach to a more sustainable development). Our results indicate that the effects of different climate change scenarios on the future productivity and species composition of German forests are minor compared to the effects of forest management.The inherent natural adaptive capacity of forest ecosystems to changing environmental conditions is limited by the long life time of trees. Planting of adapted species and forest management will reduce the impact of predicted future climate change on forests.31.5 percent of the land area in Europe (excluding the Russian Federation) is covered by forests, which provide multiple ecosystem services and functions. The carbon stored in their biomass amounts to an estimated 53 billion t C [1]. They are the single largest natural ecosystem supporting biodiversity in Europe [2] and a source of renewable energy and materials. Forest activities, wood industries and the pulp and paper industries combined contribute 1 percent of the Gross Domestic Product (GDP) in European countries [1].Temperature and the availability of soil moisture are governing the natural range of European tree species. The structure and composition of many forests are further influenced by natural disturbance regimes, such as storm, fire, or insects. Forests have adapted to changing climatic conditions in past millennia. However, the recent, human-induced changes of climatic conditions are occurring at
Post-fire forest management in southern Europe: a COST action for gathering and disseminating scientific knowledge
Barbati A,Arianoutsou M,Corona P,De Las Heras J
iForest : Biogeosciences and Forestry , 2010, DOI: 10.3832/ifor0523-003
Abstract: Every year about 45 000 forest fires occur in Europe, burning half a million hectares of forests and rural lands; between 1995 and 2004, more than 4 million hectares burned in the Mediterranean Region alone. Post-fire management of burned areas has been given much lesser attention than combating or preventing fires. However, important questions raise public concern and call for sound scientific knowledge to undertake appropriate post-fire actions: e.g., how to evaluate fire damages in economical terms? How to manage burned areas? Is it possible to establish, in the long-term, less flammable and more fire resilient forests and landscapes? To address these questions, a network of researchers and practitioners working in the field of fire ecology and forest management from all around Europe has been established in the frame of “COST Action FP0701-Post-Fire Forest Management in Southern Europe”, supported by the European Union Research and Technology Development Framework Program. The Action aims to: i) develop and disseminate scientifically based decision criteria for planning post-fire forest management, from the stand to the landscape level; ii) translate this scientific knowledge into management practices; iii) connect scientists and stakeholders for exchanging experiences, evaluating these practices, and putting them into practice. To achieve these objectives the scientific groups involved will a) review and summarize the current scientific knowledge on post-fire management in Europe, by gathering and evaluating the results of previous and ongoing research; b) translate this knowledge into technical recommendations, by producing thematic reports, a book on the state-of-the-art of scientific knowledge on post fire assessment, and an electronic handbook on post-fire restoration; c) disseminate this knowledge to stakeholders, practitioners and decision makers. Besides publications and a project website already active (http://uaeco.biol.uoa.gr/cost/), training schools and one major conference will be organized. Although focused on Southern Europe, the outcomes of this Action will be crucial for central and northern European countries as well, as climate change and land use changes often leading to more homogeneous and expanding forest areas are already increasing fire hazard in those regions.
Fire regimes in eastern coastal fynbos: Imperatives and thresholds in managing for diversity
Tineke Kraaij,Richard M. Cowling,Brian W. van Wilgen
Koedoe : African Protected Area Conservation and Science , 2013,
Abstract: Until recently, fire ecology was poorly understood in the eastern coastal region of the Cape Floral Kingdom (CFK), South Africa. Rainfall in the area is aseasonal and temperatures are milder than in the winter-rainfall and drier inland parts of the CFK, with implications for the management of fire regimes. We synthesised the findings of a research programme focused on informing ecologically sound management of fire in eastern coastal fynbos shrublands and explored potential east–west trends at the scales of study area and CFK in terms of fire return interval (FRI) and fire season. FRIs (8–26 years; 1980–2010) were comparable to those elsewhere in the CFK and appeared to be shorter in the eastern Tsitsikamma than in the western Outeniqua halves of the study area. Proteaceae juvenile periods (4–9 years) and post-fire recruitment success suggested that for biodiversity conservation purposes, FRIs should be ≥ 9 years in eastern coastal fynbos. Collectively, findings on the seasonality of actual fires and the seasonality of fire danger weather, lightning and post-fire proteoid recruitment suggested that fires in eastern coastal fynbos are not limited to any particular season. We articulated these findings into ecological thresholds pertaining to the different elements of the fire regime in eastern coastal fynbos, to guide adaptive management of fire in the Garden Route National Park and elsewhere in the region. Conservation implications: Wildfires are likely to remain dominant in eastern coastal fynbos, whilst large-scale implementation of prescribed burning is unattainable. Fires occurring in any season are not a reason for concern, although other constraints remain: the need for sufficient fire intensity, safety requirements, and integration of fire and invasive alien plant management.
Global fire activity patterns (1996–2006) and climatic influence: an analysis using the World Fire Atlas  [PDF]
Y. Le Page,J. M. C. Pereira,R. Trigo,C. da Camara
Atmospheric Chemistry and Physics Discussions , 2007,
Abstract: Vegetation fires have been acknowledged as an environmental process of global scale, which affects the chemical composition of the troposphere, and has profound ecological and climatic impacts. However, considerable uncertainty remains, especially concerning intra and inter-annual variability of fire incidence. The main goals of our global-scale study were to characterise spatial-temporal patterns of fire activity, to identify broad geographical areas with similar vegetation fire dynamics, and to analyse the relationship between fire activity and the El Ni o-Southern Oscillation. This study relies on 10 years (mid 1996–mid 2006) of screened European Space Agency World Fire Atlas (WFA) data, obtained from Along Track Scanning Radiometer (ATSR) and Advanced ATSR (AATSR) imagery. Empirical Orthogonal Function analysis was used to reduce the dimensionality of the dataset. Regions of homogeneous fire dynamics were identified with cluster analysis, and interpreted based on their eco-climatic characteristics. The impact of 1997–1998 El Ni o is clearly dominant over the study period, causing increased fire activity in a variety of regions and ecosystems, with variable timing. Overall, this study provides the first global decadal assessment of spatio-temporal fire variability and confirms the usefulness of the screened WFA for global fire ecoclimatology research.
Global fire activity patterns (1996─2006) and climatic influence: an analysis using the World Fire Atlas  [PDF]
Y. Le Page,J. M. C. Pereira,R. Trigo,C. da Camara
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2008,
Abstract: Vegetation fires have been acknowledged as an environmental process of global scale, which affects the chemical composition of the troposphere, and has profound ecological and climatic impacts. However, considerable uncertainty remains, especially concerning intra and inter-annual variability of fire incidence. The main goals of our global-scale study were to characterise spatial-temporal patterns of fire activity, to identify broad geographical areas with similar vegetation fire dynamics, and to analyse the relationship between fire activity and the El Ni o-Southern Oscillation. This study relies on 10 years (mid 1996–mid 2006) of screened European Space Agency World Fire Atlas (WFA) data, obtained from Along Track Scanning Radiometer (ATSR) and Advanced ATSR (AATSR) imagery. Empirical Orthogonal Function analysis was used to reduce the dimensionality of the dataset. Regions of homogeneous fire dynamics were identified with cluster analysis, and interpreted based on their eco-climatic characteristics. The impact of 1997–1998 El Ni o is clearly dominant over the study period, causing increased fire activity in a variety of regions and ecosystems, with variable timing. Overall, this study provides the first global decadal assessment of spatial-temporal fire variability and confirms the usefulness of the screened WFA for global fire ecoclimatology research.
An Enhanced Contextual Fire Detection Algorithm Based on Remote Sensing Images
一种增强的基于上下文火点遥感影像识别方法

LI Ya-chun,ZHANG Xu-hui,WU Hong-yan,GAO Ping,XIA De-shen,
李亚春
,张旭晖,吴洪颜,高苹,夏德深

中国图象图形学报 , 2007,
Abstract: Most of the present satellite-based fire detection methods are based thresholds.The thresholds adopted in these methods are generally limited to a specific area,or certain seasonal weather conditions,therefore the actual effects are sometimes unsatisfactory especially in the detection of small-scale mountain forest fire.In response to these problems,an enhanced contextual algorithm for detection of forest fire(ECFDA) was introduced in this paper.Based on the relationships between the fire pixel and its background pixels,this algorithm made improvements on the confirmation of the neighbouring pixels of potential fire and established a criterion for the detection of fire.This method was adaptive to different areas and seasons and was sensitive to small-scale mountain forest fire.The results in our experiments have confirmed the potential of this method.
First passage times in integrate-and-fire neurons with stochastic thresholds  [PDF]
Wilhelm Braun,Paul C. Matthews,Rüdiger Thul
Quantitative Biology , 2015, DOI: 10.1103/PhysRevE.91.052701
Abstract: We consider a leaky integrate-and-fire neuron with deterministic subthreshold dynamics and a firing threshold that evolves as an Ornstein-Uhlenbeck process. The formulation of this minimal model is motivated by the experimentally observed widespread variation of neural firing thresholds. We show numerically that the mean first passage time can depend non-monotonically on the noise amplitude. For sufficiently large values of the correlation time of the stochastic threshold the mean first passage time is maximal for non-vanishing noise. We provide an explanation for this effect by analytically transforming the original model into a first passage time problem for Brownian motion. This transformation also allows for a perturbative calculation of the first passage time histograms. In turn this provides quantitative insights into the mechanisms that lead to the non-monotonic behaviour of the mean first passage time. The perturbation expansion is in excellent agreement with direct numerical simulations. The approach developed here can be applied to any deterministic subthreshold dynamics and any Gauss-Markov processes for the firing threshold. This opens up the possibility to incorporate biophysically detailed components into the subthreshold dynamics, rendering our approach a powerful framework that sits between traditional integrate-and-fire models and complex mechanistic descriptions of neural dynamics.
Responses of European forest ecosystems to 21st century climate: assessing changes in interannual variability and fire intensity
Dury M,Hambuckers A,Warnant P,Henrot A
iForest : Biogeosciences and Forestry , 2011, DOI: 10.3832/ifor0572-004
Abstract: Significant climatic changes are currently observed and, according to projections, will be strengthened over the 21st century throughout the world with the continuing increase of the atmospheric CO2 concentration. Climate will be generally warmer with notably changes in the seasonality and in the precipitation regime. These changes will have major impacts on the biodiversity and the functioning of natural ecosystems. The CARAIB dynamic vegetation model driven by the ARPEGE/Climate model under forcing from the A2 IPCC emission scenario is used to illustrate and analyse the potential impacts of climate change on forest productivity and distribution as well as fire intensity over Europe. The potential CO2 fertilizing effect is studied throughout transient runs of the vegetation model over the 1961-2100 period assuming constant and increasing atmospheric CO2 concentration. Without fertilisation effect, the net primary productivity (NPP) might increase in high latitudes and altitudes (by up to 40 % or even 60-100 %) while it might decrease in temperate (by up to 50 %) and in warmer regions, e.g., Mediterranean area (by up to 80 %). This strong decrease in NPP is associated with recurrent drought events occurring mostly in summer time. Under rising CO2 concentration, NPP increases all over Europe by as much as 25-75%, but it is not clear whether or not soils might sustain such an increase. The model indicates also that interannual NPP variability might strongly increase in the areas which will undergo recurrent water stress in the future. During the years exhibiting summer drought, the NPP might decrease to values much lower than present-day average NPP even when CO2 fertilization is included. Moreover, years with such events will happen much more frequently than today. Regions with more severe droughts might also be affected by an increase of wildfire frequency and intensity, which may have large impacts on vegetation density and distribution. For instance, in the Mediterranean basin, the area burned by wildfire can be expected to increase by a factor of 3-5 at the end of the 21st century compared to present.
Fire management and research in the Kruger National Park, with suggestions on the detection of thresholds of potential concern  [cached]
B.W. Van Wilgen,H.C. Biggs,A.L.F. Potgieter
Koedoe : African Protected Area Conservation and Science , 1998, DOI: 10.4102/koedoe.v41i1.248
Abstract: This paper reviews the options for management of the savanna ecosystems of the Kruger National Park using fire. The major goals of management have shifted from attempts to use fire to achieve a stable vegetation composition, to one of recognising that savanna ecosystems are in constant flux. Fire is a major form of disturbance that helps to maintain a state of flux, and thus to conserve biodiversity. Three candidate approaches for fire management have been put forward@the lightning fire approach, the patch mosaic burning approach, and an approach based on the assessment of ecological criteria. These approaches differ in their underlying philosophies, but not necessarily in their outcomes, although this cannot be predicted with confidence. We propose, therefore, that patterns of fire frequency, season, intensity and spatial distribution be recorded and monitored, and that these patterns should serve as surrogate measures of biodiversity. Guidelines for the definition of thresholds of potential concern with regard to these patterns are discussed. The monitoring of both fire patterns and trends in plant and animal populations can be used to identify interactions between fire and the components of the ecosystem, and these in turn can be used to define a relevant research agenda. The role of management in monitoring and assessing fire patterns (previously regarded as a research responsibility) is emphasised. Convergence in the patterns of fire that result from the different management approaches could also serve as a basis for merging some or all of these approaches in order to simplify management.
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