Fire is an important disturbance in terms of forest management.A comprehensive understanding of the relationships between the spatial distribution of fire occurrence and its driving factors are critical for effective ...Fire is an important disturbance in terms of forest management.A comprehensive understanding of the relationships between the spatial distribution of fire occurrence and its driving factors are critical for effective forest fire management.To reveal biogeoclimatic and anthropogenic influences,this study introduced a geographical detector model to quantitatively examine the effects of multiple individual factors and their combinations on spatial patterns of fire occurrence in the Greater Khingan Mountains between 1980 and 2009.The geographical detector computes the explanatory power(q value)to measure the connection between driving factors and spatial distributions of fire occurrence.Kernel density estimation revealed the spatial variability of fire occurrence which was impacted by bandwidth.30 km might be the optimal bandwidth in this study.The biogeoclimatic and anthropogenic effects were explored using topography,climate,vegetation,and human activity factors as proxies.Our results indicated that solar radiation had the most influence on the spatial pattern of fire occurrence in the study area.Meanwhile,Normalized Difference Vegetation Index,temperature,wind speed,and vegetation type were determined as the major driving factors.For various groups of driving factors,climate variables were the dominant factors for the density of fire occurrence,while vegetation exerted a strong influence.The interactions between the driving factors had a more significant impact than a single factor.Individually,the factors in the topography and human activity groups exhibited weaker influences.However,their effects were enhanced when combined with climate and vegetation factors.This study improves our understanding of various driving factors and their combined influences on fire occurrences of the study area in a spatial context.The findings of this study verify that the geographical detector is applicable in revealing the driving factors of fire occurrence.展开更多
Background: Cumulative impacts of wildfires and forest harvesting can cause shifts from closed-crown forest to open woodland in boreal ecosystems. To lower the probability of occurrence of such catastrophic regime shi...Background: Cumulative impacts of wildfires and forest harvesting can cause shifts from closed-crown forest to open woodland in boreal ecosystems. To lower the probability of occurrence of such catastrophic regime shifts,forest logging must decrease when fire frequency increases, so that the combined disturbance rate does not exceed the Holocene maximum. Knowing how climate warming will affect fire regimes is thus crucial to sustainably manage the forest. This study aimed to provide a guide to determine sustainable forest harvesting levels, by reconstructing the Holocene fire history at the northern limit of commercial forestry in Quebec using charcoal particles preserved in lake sediments.Methods: Sediment cores were sampled from four lakes located close to the northern limit of commercial forestry in Quebec. The cores were sliced into consecutive 0.5 cm thick subsamples from which 1 cm3 was extracted to count and measure charcoal particles larger than 150 microns. Age-depth models were obtained for each core based on accelerator mass spectroscopy(AMS) radiocarbon dates. Holocene fire histories were reconstructed by combining charcoal counts and age-depth models to obtain charcoal accumulation rates and, after statistical treatment,long-term trends in fire occurrence(expressed as number of fires per 1000 years).Results: Fire occurrence varied between the four studied sites, but fires generally occurred more often during warm and dry periods of the Holocene, especially during the Holocene Thermal Maximum(7000–3500 cal. BP), when fire occurrence was twice as high as at present.Conclusions: The current fire regime in the study area is still within the natural range of variability observed over the Holocene. However, climatic conditions comparable to the Holocene Thermal Maximum could be reached within the next few decades, thus substantially reducing the amount of wood available to the forest industry.展开更多
Fire is a fundamental ecological driver shaping natural vegetation patterns.In the semi-arid southern Espinal-Monte ecotone of Argentina,the spatiotemporal patterns of fire occurrence related to and modulated by clima...Fire is a fundamental ecological driver shaping natural vegetation patterns.In the semi-arid southern Espinal-Monte ecotone of Argentina,the spatiotemporal patterns of fire occurrence related to and modulated by climatic gradients and antecedent conditions are not well researched.This study examined fire occurrence in the semi-arid southern Espinal-Monte ecotone(southeastern La Pampa,northeastern Río Negro,and southwestern Buenos Aires with an area of 68×103 km2)of Argentina,a key environmental transition zone with pronounced climatic and vegetation gradients.The objective was to identify the spatiotemporal patterns of fire occurrence and their relationship with climatic variables.Thermal anomaly(TA)data from the MODIS(Moderate Resolution Imaging Spectrometer;MOD14)sensor(November 2000–March 2020)with confidence levels>65.0%were analyzed.Climatic variables(rainfall isohyets and aridity indices)were obtained from the WorldClim datasets,and annual meteorological conditions(rainfall and potential evapotranspiration)were calculated using the climatic research unit(CRU)database.Monthly data and moving averages of rainfall and aridity indices from distinct periods(two and three years preceding fire events)were integrated.Spatial analysis was conducted using kernel density estimation on a 10 km×10 km grid to correlate TA with climatic gradients,while linear regression examined relationships between summer TA and meteorological variables over different periods.Results showed that the highest fire occurrence was recorded in summer,with peaks in December and January.Spatially,55.0%of TA occurred in areas with annual rainfall of 300–400 mm,and 64.5%in areas with an aridity index of 0.3–0.4,forming an arc-like distribution in the center of the ecotone.The highest TA densities were observed in southeastern La Pampa and northeastern Río Negro,decreasing toward southwestern Buenos Aires.Significant correlations(R2>0.700)were found among TA accumulation,aridity index values,and cumulative rainfall from previous two and three years,at both vegetation unit and provincial levels.Summer was the critical season for fire occurrence,with spatial distribution primarily determined by the interaction between climatic conditions and woody biomass availability.The lower fire incidence in southwestern Buenos Aires was linked to sparse woody vegetation and agricultural expansion,which reduced fuel load.These findings reinforce that fuel availability,modulated by climatic conditions from previous years,is a key limiting factor for fire dynamics in this area,and that human activities such as agriculture and grazing alter fire regimes by affecting fuel structure and continuity.展开更多
China is not rich in natural forest sources. Owing to natural and historical factors, forest fires have long been frequenting China. Forest fire prevention is the most important of all. Forest fire prevention and cont...China is not rich in natural forest sources. Owing to natural and historical factors, forest fires have long been frequenting China. Forest fire prevention is the most important of all. Forest fire prevention and controlling have long been held as a very important factor in our ecological plans. Taking china 's special geographical location, topography, climate and the distribution of forest sources into consideration, we have every reason to believe that forest fires in China have their own special env...展开更多
In recent years,many serious forest fires occuned in precious Pinus pumila forestsin Daxing'anlingMountains of Heilongjiang Province and Inner Mongolia.But up to now,there is still a lack ofproperunderstanding of ...In recent years,many serious forest fires occuned in precious Pinus pumila forestsin Daxing'anlingMountains of Heilongjiang Province and Inner Mongolia.But up to now,there is still a lack ofproperunderstanding of fire occurrence environments in P.pumila forests.In present paper,we investigated andstudied the fire occurence environments.The results showed that fires in P.pumila forests ha d their ownspecial fire environments.Abundant fiiel,drought weather,dry thunder and high altitude terrain created thespecial fire occurence environments in P.pumila forests in Daxing'anling Mountains.展开更多
Background:Wildfires play a key role in shaping Mediterranean landscapes and ecosystems and in impacting species dynamics.Numerous studies have investigated the wildfire occurrences and the influence of their drivers ...Background:Wildfires play a key role in shaping Mediterranean landscapes and ecosystems and in impacting species dynamics.Numerous studies have investigated the wildfire occurrences and the influence of their drivers in many countries of the Mediterranean Basin.However,in this regard,no studies have attempted to compare different Mediterranean regions,which may appear similar under many aspects.In response to this gap,climatic,topographic,anthropic,and landscape drivers were analyzed and compared to assess the patterns of fire ignition points in terms of fire occurrence and frequency in Catalonia(Spain),Sardinia,and Apulia(Italy).Therefore,the objectives of the study were to(1)assess fire ignition occurrence in terms of probability and frequency,(2)compare the main drivers affecting fire occurrence,and(3)produce fire probability and frequency maps for each region.Results:In pursuit of the above,the probability of fire ignition occurrence and frequency was mapped using Negative Binomial Hurdle models,while the models’performances were evaluated using several metrics(AUC,prediction accuracy,RMSE,and the Pearson correlation coefficient).The results showed an inverse correlation between distance from infrastructures(i.e.,urban roads and areas)and the occurrence of fires in all three study regions.This relationship became more significant when the frequency of fire ignition points was assessed.Moreover,a positive correlation was found between fire occurrence and landscape drivers according to region.The land cover classes more significantly affected were forest,agriculture,and grassland for Catalonia,Sardinia,and Apulia,respectively.Conclusions:Compared to the climatic,topographic,and landscape drivers,anthropic activity significantly influences fire ignition and frequency in all three regions.When the distance from urban roads and areas decreases,the probability of fire ignition occurrence and frequency increases.Consequently,it is essential to implement long-to medium-term intervention plans to reduce the proximity between potential ignition points and fuels.In this perspective,the present study provides an applicable decision-making tool to improve wildfire prevention strategies at the European level in an area like the Mediterranean Basin where a profuse number of wildfires take place.展开更多
基金funded by the National Natural Science Foundation of China(Grant No.41601438)Fundamental Research Funds for the Central Universities(Grant NO.2412019FZ002)。
文摘Fire is an important disturbance in terms of forest management.A comprehensive understanding of the relationships between the spatial distribution of fire occurrence and its driving factors are critical for effective forest fire management.To reveal biogeoclimatic and anthropogenic influences,this study introduced a geographical detector model to quantitatively examine the effects of multiple individual factors and their combinations on spatial patterns of fire occurrence in the Greater Khingan Mountains between 1980 and 2009.The geographical detector computes the explanatory power(q value)to measure the connection between driving factors and spatial distributions of fire occurrence.Kernel density estimation revealed the spatial variability of fire occurrence which was impacted by bandwidth.30 km might be the optimal bandwidth in this study.The biogeoclimatic and anthropogenic effects were explored using topography,climate,vegetation,and human activity factors as proxies.Our results indicated that solar radiation had the most influence on the spatial pattern of fire occurrence in the study area.Meanwhile,Normalized Difference Vegetation Index,temperature,wind speed,and vegetation type were determined as the major driving factors.For various groups of driving factors,climate variables were the dominant factors for the density of fire occurrence,while vegetation exerted a strong influence.The interactions between the driving factors had a more significant impact than a single factor.Individually,the factors in the topography and human activity groups exhibited weaker influences.However,their effects were enhanced when combined with climate and vegetation factors.This study improves our understanding of various driving factors and their combined influences on fire occurrences of the study area in a spatial context.The findings of this study verify that the geographical detector is applicable in revealing the driving factors of fire occurrence.
基金Financial support was provided by the Natural Sciences and Engineering Research Council of Canada and by the CNRS (Paleo2, INSU)
文摘Background: Cumulative impacts of wildfires and forest harvesting can cause shifts from closed-crown forest to open woodland in boreal ecosystems. To lower the probability of occurrence of such catastrophic regime shifts,forest logging must decrease when fire frequency increases, so that the combined disturbance rate does not exceed the Holocene maximum. Knowing how climate warming will affect fire regimes is thus crucial to sustainably manage the forest. This study aimed to provide a guide to determine sustainable forest harvesting levels, by reconstructing the Holocene fire history at the northern limit of commercial forestry in Quebec using charcoal particles preserved in lake sediments.Methods: Sediment cores were sampled from four lakes located close to the northern limit of commercial forestry in Quebec. The cores were sliced into consecutive 0.5 cm thick subsamples from which 1 cm3 was extracted to count and measure charcoal particles larger than 150 microns. Age-depth models were obtained for each core based on accelerator mass spectroscopy(AMS) radiocarbon dates. Holocene fire histories were reconstructed by combining charcoal counts and age-depth models to obtain charcoal accumulation rates and, after statistical treatment,long-term trends in fire occurrence(expressed as number of fires per 1000 years).Results: Fire occurrence varied between the four studied sites, but fires generally occurred more often during warm and dry periods of the Holocene, especially during the Holocene Thermal Maximum(7000–3500 cal. BP), when fire occurrence was twice as high as at present.Conclusions: The current fire regime in the study area is still within the natural range of variability observed over the Holocene. However, climatic conditions comparable to the Holocene Thermal Maximum could be reached within the next few decades, thus substantially reducing the amount of wood available to the forest industry.
基金funded by the National University of Río Negro Research Project (40-C-658)
文摘Fire is a fundamental ecological driver shaping natural vegetation patterns.In the semi-arid southern Espinal-Monte ecotone of Argentina,the spatiotemporal patterns of fire occurrence related to and modulated by climatic gradients and antecedent conditions are not well researched.This study examined fire occurrence in the semi-arid southern Espinal-Monte ecotone(southeastern La Pampa,northeastern Río Negro,and southwestern Buenos Aires with an area of 68×103 km2)of Argentina,a key environmental transition zone with pronounced climatic and vegetation gradients.The objective was to identify the spatiotemporal patterns of fire occurrence and their relationship with climatic variables.Thermal anomaly(TA)data from the MODIS(Moderate Resolution Imaging Spectrometer;MOD14)sensor(November 2000–March 2020)with confidence levels>65.0%were analyzed.Climatic variables(rainfall isohyets and aridity indices)were obtained from the WorldClim datasets,and annual meteorological conditions(rainfall and potential evapotranspiration)were calculated using the climatic research unit(CRU)database.Monthly data and moving averages of rainfall and aridity indices from distinct periods(two and three years preceding fire events)were integrated.Spatial analysis was conducted using kernel density estimation on a 10 km×10 km grid to correlate TA with climatic gradients,while linear regression examined relationships between summer TA and meteorological variables over different periods.Results showed that the highest fire occurrence was recorded in summer,with peaks in December and January.Spatially,55.0%of TA occurred in areas with annual rainfall of 300–400 mm,and 64.5%in areas with an aridity index of 0.3–0.4,forming an arc-like distribution in the center of the ecotone.The highest TA densities were observed in southeastern La Pampa and northeastern Río Negro,decreasing toward southwestern Buenos Aires.Significant correlations(R2>0.700)were found among TA accumulation,aridity index values,and cumulative rainfall from previous two and three years,at both vegetation unit and provincial levels.Summer was the critical season for fire occurrence,with spatial distribution primarily determined by the interaction between climatic conditions and woody biomass availability.The lower fire incidence in southwestern Buenos Aires was linked to sparse woody vegetation and agricultural expansion,which reduced fuel load.These findings reinforce that fuel availability,modulated by climatic conditions from previous years,is a key limiting factor for fire dynamics in this area,and that human activities such as agriculture and grazing alter fire regimes by affecting fuel structure and continuity.
基金the China NKBRSF project(No.2001CB409600)National Natural Science Foundation of China(No.59936140)
文摘China is not rich in natural forest sources. Owing to natural and historical factors, forest fires have long been frequenting China. Forest fire prevention is the most important of all. Forest fire prevention and controlling have long been held as a very important factor in our ecological plans. Taking china 's special geographical location, topography, climate and the distribution of forest sources into consideration, we have every reason to believe that forest fires in China have their own special env...
基金supported by the Central Public-interest Scientific Institution Basal Research Fund Supporting Program(CAFRIFEEP200809)the State Forestry Administration Key Project(2006-84)
文摘In recent years,many serious forest fires occuned in precious Pinus pumila forestsin Daxing'anlingMountains of Heilongjiang Province and Inner Mongolia.But up to now,there is still a lack ofproperunderstanding of fire occurrence environments in P.pumila forests.In present paper,we investigated andstudied the fire occurence environments.The results showed that fires in P.pumila forests ha d their ownspecial fire environments.Abundant fiiel,drought weather,dry thunder and high altitude terrain created thespecial fire occurence environments in P.pumila forests in Daxing'anling Mountains.
文摘Background:Wildfires play a key role in shaping Mediterranean landscapes and ecosystems and in impacting species dynamics.Numerous studies have investigated the wildfire occurrences and the influence of their drivers in many countries of the Mediterranean Basin.However,in this regard,no studies have attempted to compare different Mediterranean regions,which may appear similar under many aspects.In response to this gap,climatic,topographic,anthropic,and landscape drivers were analyzed and compared to assess the patterns of fire ignition points in terms of fire occurrence and frequency in Catalonia(Spain),Sardinia,and Apulia(Italy).Therefore,the objectives of the study were to(1)assess fire ignition occurrence in terms of probability and frequency,(2)compare the main drivers affecting fire occurrence,and(3)produce fire probability and frequency maps for each region.Results:In pursuit of the above,the probability of fire ignition occurrence and frequency was mapped using Negative Binomial Hurdle models,while the models’performances were evaluated using several metrics(AUC,prediction accuracy,RMSE,and the Pearson correlation coefficient).The results showed an inverse correlation between distance from infrastructures(i.e.,urban roads and areas)and the occurrence of fires in all three study regions.This relationship became more significant when the frequency of fire ignition points was assessed.Moreover,a positive correlation was found between fire occurrence and landscape drivers according to region.The land cover classes more significantly affected were forest,agriculture,and grassland for Catalonia,Sardinia,and Apulia,respectively.Conclusions:Compared to the climatic,topographic,and landscape drivers,anthropic activity significantly influences fire ignition and frequency in all three regions.When the distance from urban roads and areas decreases,the probability of fire ignition occurrence and frequency increases.Consequently,it is essential to implement long-to medium-term intervention plans to reduce the proximity between potential ignition points and fuels.In this perspective,the present study provides an applicable decision-making tool to improve wildfire prevention strategies at the European level in an area like the Mediterranean Basin where a profuse number of wildfires take place.
