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1.
Restoring altered forest landscapes toward their ranges of natural variability (RNV) may enhance ecosystem sustainability and resiliency, but such efforts can be hampered by complex land ownership and management patterns. We evaluated restoration potential for southern-boreal forests in the ∼2.1 million ha Border Lakes Region of northern Minnesota (U.S.A.) and Ontario (Canada), where spatially distinct timber harvest and fire suppression histories have differentially altered forest conditions (composition, age–class distribution, and landscape structure) among major management areas, effectively resulting in forest landscape “bifurcation.” We used a forest landscape simulation model to evaluate potential for four hypothetical management and two natural disturbance scenarios to restore forest conditions and reduce bifurcation, including: (1) a current management scenario that simulated timber harvest and fire suppression practices among major landowners; (2) three restoration scenarios that simulated combinations of wildland fire use and cross-boundary timber harvest designed to emulate natural disturbance patterns; (3) a historical natural disturbance scenario that simulated pre-EuroAmerican settlement fire regimes and windthrow; and (4) a contemporary fire regime that simulated fire suppression, but no timber harvest. Forest composition and landscape structure for a 200-year model period were compared among scenarios, among major land management regions within scenarios, and to six RNV benchmarks. The current management scenario met only one RNV benchmark and did not move forest composition, age–class distribution, or landscape structures toward the RNV, and it increased forest landscape bifurcation between primarily timber-managed and wilderness areas. The historical natural disturbance scenario met five RNV benchmarks and the restoration scenarios as many as five, by generally restoring forest composition, age–class distributions, and landscape structures, and reducing bifurcation of forest conditions. The contemporary natural disturbance scenario met only one benchmark and generally created a forest landscape dominated by large patches of late-successional, fire-prone forests. Some forest types (e.g., white and red pine) declined in all scenarios, despite simulated restoration strategies. It may not be possible to achieve all objectives under a single management scenario, and complications, such as fire-risk, may limit strategies. However, our model suggests that timber harvest and fire regimes that emulate natural disturbance patterns can move forest landscapes toward the RNV. 相似文献
2.
Emulating natural forest disturbance is an increasingly popular forest management paradigm that is considered a means of achieving forest sustainability. Adopting this goal requires a sound understanding of natural disturbances at scales that correspond to management policies and strategies. In boreal forest landscapes driven by periodic stand-replacing fires this requires knowledge of fire regime characteristics, especially their spatial and temporal variability as well as stochasticity. The major goal of this study was to demonstrate the utility of fire regime simulation modeling to explore the variability of fire regime characteristics, with respect to formulating and assessing forest management strategies. We conducted a modeling experiment in a boreal forest landscape of northwestern Ontario, Canada, to examine its long-term fire regime in relation to forest policies on harvest size distribution. We used BFOLDS, a spatially explicit fire regime model that simulates individual fire events mechanistically in response to fire weather, fuel patterns, and terrain. The fire regimes in four large eco-regions were modeled for a 200-year period under three fire-weather (cold, normal, and warm) scenarios, with replications. We found that fire size distribution in all eco-regions followed power law under all weather scenarios, but their slopes and intercepts varied among eco-regions and fire weather scenarios. Warming fire weather increased burn rates and fire numbers in all eco-regions, albeit to different degrees. Overall, the variability among eco-regions was higher than the variability among fire weather scenarios, and among replicates. Comparisons of simulated fire size classes with those from an 86-year long fire history showed that empirical data cannot capture the variability that could be revealed by simulation modeling. We also show that fire size distribution is spatially heterogeneous within eco-regions, and provide several suggestions for forest policy directions with respect to forest harvest size distributions and harvest rates, based on the variability of fire regime characteristics. An assessment of present forest policies of emulating natural disturbances that guide forest harvest sizes showed that these are incongruent with simulated fire size distributions under all scenarios with one exception. Overall, this study illustrates the value of scenario simulation modeling to explore and quantify the variability of forest fire regime, for use in forest policies and strategies that attempt to emulate natural disturbance. 相似文献
3.
Michael S. Mitchell Melissa J. Reynolds-Hogland Michelle L. Smith Petra Bohall Wood John A. Beebe Patrick D. Keyser Craig Loehle Christopher J. Reynolds Paul Van Deusen Don White Jr. 《Forest Ecology and Management》2008
Numerous studies have explored the influence of forest management on avian communities empirically, but uncertainty about causal relationships between landscape patterns and temporal dynamics of bird communities calls into question how observed historical patterns can be projected into the future, particularly to assess consequences of differing management alternatives. We used the Habplan harvest scheduler to project forest conditions under several management scenarios mapped at 5-year time steps over a 40-year time span. We used empirical models of overall avian richness, richness of selected guilds, and probability of presence for selected species to predict avian community characteristics for each of the mapped landscapes generated for each 5-year time step for each management scenario. We then used time series analyses to quantify relationships between changes in avian community characteristics and management-induced changes to forest landscapes over time. Our models of avian community and species characteristics indicated habitat associations at multiple spatial scales, although landscape-level measures of habitat were generally more important than stand-level measures. Our projections showed overall avian richness, richness of Neotropical migrants, and the presence of Blue-gray Gnatcatchers and Eastern Wood-pewees varied little among management scenarios, corresponding closely to broad, overall landscape changes over time. By contrast, richness of canopy nesters, richness of cavity nesters, richness of scrub-successional associates, and the presence of Common Yellowthroats showed high temporal variability among management scenarios, likely corresponding to short-term, fine-scale changes in the landscape. Predicted temporal variability of both interior-forest and early successional birds was low in the unharvested landscape relative to that in the harvested landscape. Our results also suggested that early successional species can be sensitive to both availability and connectivity of habitat on the landscape. To increase or maintain the avian diversity, our projections indicate that forest managers need to consider landscape-scale configuration of stands, maintaining a spatially heterogeneous distribution of age classes. Our findings suggest which measures of richness or species presence may be appropriate indicators for monitoring effects of forest management on avian communities, depending on management objectives. 相似文献
4.
Douglas J. McRae 《林业研究》2011,22(3):437-446
Climate warming has a rapid and far-reaching impact on forest fire management in the boreal forests of China. Regional climate model outputs and the Canadian Forest Fire Weather Index (FWI) Sys- tem were used to analyze changes to fire danger and the fire season for future periods under IPCC Special Report on Emission Scenarios (SRES) A2 and B2, and the data will guide future fire management planning. We used regional climate in China (1961 1990) as our validation data, and the period (1991-2100) was modeled under SRES A2 and B2 through the weather simulated by the regional climate model system (PRECIS). Meteorological data and fire danger were interpolated to 1 km 2 by using ANUSPLIN software. The average FWI value for future spring fire sea- sons under Scenarios A2 and B2 shows an increase over most of the region. Compared with the baseline, FWI averages of spring fire season will increase by 0.40, 0.26 and 1.32 under Scenario A2, and increase by 0.60, 1.54 and 2.56 under Scenario B2 in 2020s, 2050s and 2080s, respectively. FWI averages of autumn fire season also show an increase over most of the region. FWI values increase more for Scenario B2 than for Scenario A2 in the same periods, particularly during the 2050s and 2080s. Average future FWI values will increase under both scenarios for autumn fire season. The potential burned areas are expected to increase by 10% and 18% in spring for 2080s under Scenario A2 and B2, respectively. Fire season will be prolonged by 21 and 26 days under ScenariosA2 and B2 in 2080s respectively. 相似文献
5.
A mechanistic, biogeochemical succession model, FIRE-BGC, was used to investigate the role of fire on long-term landscape dynamics in northern Rocky Mountain coniferous forests of Glacier National Park, Montana, USA. FIRE-BGC is an individual-tree model-created by merging the gap-phase process-based model FIRESUM with the mechanistic ecosystem biogeochemical model FOREST-BGC-that has mixed spatial and temporal resolution in its simulation architecture. Ecological processes that act at a landscape level, such as fire and seed dispersal, are simulated annually from stand and topographic information. Stand-level processes, such as tree establishment, growth and mortality, organic matter accumulation and decomposition, and undergrowth plant dynamics are simulated both daily and annually. Tree growth is mechanistically modeled based on the ecosystem process approach of FOREST-BGC where carbon is fixed daily by forest canopy photosynthesis at the stand level. Carbon allocated to the tree stem at the end of the year generates the corresponding diameter and height growth. The model also explicitly simulates fire behavior and effects on landscape characteristics. We simulated the effects of fire on ecosystem characteristics of net primary productivity, evapotranspiration, standing crop biomass, nitrogen cycling and leaf area index over 200 years for the 50,000-ha McDonald Drainage in Glacier National Park. Results show increases in net primary productivity and available nitrogen when fires are included in the simulation. Standing crop biomass and evapotranspiration decrease under a fire regime. Shade-intolerant species dominate the landscape when fires are excluded. Model tree increment predictions compared well with field data. 相似文献
6.
《Forest Ecology and Management》2002,155(1-3):257-270
We examined tree species responses under forest harvesting and an increased fire disturbance scenario due to climate warming in northern Wisconsin where northern hardwood and boreal forests are currently predominant. Individual species response at the ecosystem scale was simulated with a gap model, which integrates soil, climate and species data, stratified by ecoregions. Such responses were quantified as species establishment coefficients. These coefficients were used to parameterize a spatially explicit landscape model, LANDIS. Species response to climate warming at the landscape scale was simulated with LANDIS, which integrates ecosystem dynamics with spatial processes including seed dispersal, fire disturbance, and forest harvesting. Under a 5 °C annual temperature increase predicted by global climate models (GCM), our simulation results suggest that significant change in species composition and abundance could occur in the two ecoregions in the study area. In the glacial lake plain (lakeshore) ecoregion under warming conditions, boreal and northern hardwood species such as red oak, sugar maple, white pine, balsam fir, paper birch, yellow birch, and aspen decline gradually during and after climate warming. Southern species such as white ash, hickory, bur oak, black oak, and white oak, which are present in minor amounts before the warming, increase in abundance on the landscape. The transition of the northern hardwood and boreal forest to one dominated by southern species occurs around year 200. In the sand barrens ecoregion under warming conditions, red pine initially benefits from the decline of other northern hardwood species, and its abundance quickly increases. However, red pine and jack pine as well as new southern species are unable to reproduce, and the ecoregion could transform into a region with only grass and shrub species around 250 years under warming climate. Increased fire frequency can accelerate the decline of shade-tolerant species such as balsam fir and sugar maple and accelerate the northward migration of southern species. Forest harvesting accelerated the decline of northern hardwood and boreal tree species. This is especially obvious on the barrens ecoregion, where the intensive cutting regime contributed to the decline of red pine and jack pine already under stressed environments. Forest managers may instead consider a conservative cutting plan or protective management scenarios with limited forest harvesting. This could prolong the transformation of the barrens into prairie from one-half to one tree life cycle. 相似文献
7.
《Forest Ecology and Management》1997,95(1):63-77
Fires occur frequently in dry forests of the Inland West. Fire effects vary across the landscape, reflecting topography, elevation, aspect, slope, soils, and vegetation attributes. Patches minimally affected by successive fires may be thought of as ‘refugia’, islands of older forest in a younger forest matrix. Refugia support species absent within the landscape matrix. Our goal was to predict the occurrence of pre-settlement refugia using physiographic and topographic variables.We evaluated 487 plots across a 47000 ha landscape using three criteria to identify historical fire refugia: different structure from surrounding matrix; different fire regime from surrounding matrix; presence of old individuals of fire-intolerant tree species. Several combinations of aspect, elevation, and topography best predicted refugial presence.Less than 20% of the pre-settlement landscape was identified as historical fire refugia. Refugia were not connected except by younger stands within the matrix. Current management goals of increasing amounts and connectivity of old, refugia-like forests for the benefit of species associated with late-successional habitat increase the risk of insect and pathogen outbreaks and catastrophic wildfires. 相似文献
8.
A spatially explicit forest succession and disturbance model is used to delineate the extent and dispersion of oak decline under two fire regimes over a 150-year period. The objectives of this study are to delineate potential current and future oak decline areas using species composition and age structure data in combination with ecological land types, and to investigate how relatively frequent simulated fires and fire suppression affect the dynamics of oak decline. We parameterized LANDIS, a spatially explicit forest succession and disturbance model, for areas in the Boston Mountains of Arkansas, USA. Land type distribution and initial species/age class were parameterized into LANDIS using existing forest data. Tree species were parameterized as five functional groups including white oak (Quercus alba L., Quercus stellata Wangenh., Quercus muehlenbergii Engelm.), red oak (Qurecus rubra L., Quercus marilandica Muenchh., Quercus falcata Michx., Quercus coccinea Muenchh.), black oak (Quercus velutina Lam.), shortleaf pine (Pinus echinata Mill), and maple (Acer rubrum L., Acer saccharum Marsh.) groups. Two fire regimes were also parameterized: current fire regime with a fire return interval of 300 years and a historic fire regime with an overall average fire return interval of 50 years. The 150-year simulation suggests that white oak and shortleaf pine abundance would increase under the historic fire regime and that the red oak group abundance increases under the current fire regime. The black oak group also shows a strong increasing trend under the current fire regime, and only the maple group remains relatively unchanged under both scenarios. At present, 45% of the sites in the study area are classified as potential oak decline sites (sites where red and black oak are >70 years old). After 150 simulation years, 30% of the sites are classified as potential oak decline sites under the current fire regime whereas 20% of the sites are potential oak decline sites under the historic fire regime. This analysis delineates potential oak decline sites and establishes risk ratings for these areas. This is a further step toward precision management and planning. 相似文献
9.
《Journal of Sustainable Forestry》2013,32(1-2):13-63
Euro-American settlement of the Inland West has altered forest and woodland landscapes, species composition, disturbance regimes, and resource conditions. Public concern over the loss of selected species and unique habitats (e.g., old-growth) has caused us to neglect the more pervasive problem of declining ecosystem health. Population explosions of trees, exotic weed species, insects, diseases, and humans are stressing natural systems. In particular, fire exclusion, grazing, and timber harvest have created anomalous ecosystem structures, landscape patterns, and disturbance regimes that are not consistent with the evolutionary history of the indigenous biota. Continuation of historical trends of climate change, modified atmospheric chemistry, tree density increases, and catastrophic disturbances seems certain. However, ecosystem management strategies including the initiation of management experiments can facilitate the adaptation of both social and ecological systems to these anticipated changes. A fairly narrow window of opportunity-perhaps 15-30 years-exists for land managers to implement ecological restoration treatments. 相似文献
10.
Ryan D. Haugo Sonia A. Hall Elizabeth M. Gray Patrick Gonzalez Jonathan D. Bakker 《Forest Ecology and Management》2010
Across western North America, current ecosystem structure has been determined by historical interactions between climate, fire, livestock grazing, and logging. Climate change could substantially alter species abundance and composition, but the relative weight of the legacy of historical factors and projected future conditions in informing management objectives remains unresolved. We integrated land use histories with broad scale climatic factors to better understand how inland Pacific Northwest ecosystems may develop under projected climates. We measured vegetation structure and age distributions in five vegetation types (shrub steppe to subalpine forest) along an elevation gradient in the eastern Cascades of Washington. We quantitatively assessed compositional changes, and qualitatively summarized the environmental history (climate, fire and fire suppression, grazing, and logging) of each site. Little change was evident in woody species composition at the shrub steppe site. At the shrub steppe/forest ecotone, densities of drought-tolerant Artemisia tripartita and Pinus ponderosa increased. In the dry conifer, montane, and subalpine forest sites, increases in Pseudotsuga menziesii, Abies grandis, and Abies lasiocarpa, respectively, and decreases in Pinus ponderosa, Larix occidentalis, and Pinus contorta, respectively, have shifted species composition from fire and drought-tolerant species to shade-tolerant species. Fire suppression, grazing, and logging explain changes in species composition more clearly than climate variation does, although the relative influence of these factors varies with elevation. Furthermore, some of the observed changes in composition are opposite what we expect would be most suited to projected future climates. Natural resource managers need to recognize that the current state of an ecosystem reflects historical land uses, and that contemporary management actions can have long-term effects on ecosystem structure. Understanding the processes that generated an ecosystem's current structure will lead to more informed management decisions to effectively respond to projected climate changes. 相似文献
11.
We simulated how possible changes in wind and ground-frost climate and state of the forest due to changes in the future climate may affect the probability of exceeding critical wind speeds expected to cause wind damage within one northern and one southern study area in Sweden, respectively. The topography of the study areas was relatively gentle and the forests were dominated by Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.). Using estimated changes in the net primary production (NPP) due to climate change and assuming a relative change in the site productivity equal to a relative change in NPP, we simulated possible future states of the forest under gradual adjustment of the site index in response to climate change using the model The Forest Time Machine. Global climate change scenarios based on two emission scenarios and one general circulation model were downscaled to the regional level. The modified WINDA model was used to calculate the sensitivity of the forest to wind and the probability of wind damage for individual forest stands for the periods 2011–2041 and 2071–2100 and for a control period 1961–1990. This was done while taking into account effects on stability of the forest from expected changes in the occurrence of ground frost. Increasing sensitivity of the forest to wind was indicated for both study areas when adhering to recommended management rules of today. Adding also a changed wind climate further increased the probability of wind damage. Calculated probabilities of wind damage were generally higher in the southern study area than in the northern one and were explained by differences in wind climate and the state of the forests, for example with respect to tree species composition. The indicated increase in sensitivity of the forest to wind under the current management regime, and possibly increasing windiness, motivate further analysis of the effects of different management options on the probability of wind damage and what modifications of Swedish forest management are possibly warranted. 相似文献
12.
气候变化下森林火灾过火面积预测——以大兴安岭北方森林为例 总被引：1，自引：0，他引：1
利用Delta统计降尺度方法解集HadCM3 IPCC SRES A2a和B2a情景下气候基准时段(1961-1990年)与未来不同时段 (21世纪20年化,2010-2039年;21世纪50年代,2040-2069年;21世纪80年代,2070-2099年)的逐月的最高温度、相对湿度、降水和风速数据,结合历史火灾数据、气象资料以及加拿大火险天气指标系统中SSR指标数值的统计相关性,在假设林火动态对当前及未来气候变化具有相同响应方式的基础上,定量和定性相结合预估未来该区北方森林过火面积的变化趋势。结果表明:历史过火面积与SSR均值呈显著线性相关(r,0.16-0.61),SSR增值能作为过火面积增量指标。HadCM3 IPCC SRES A2a和B2a情景下,21世纪大兴安岭地区森林火灾过火面积相对于1961-1990年气候基准值呈显著增加趋势,其中21世纪80年代该区平均过火面积可能会增加1倍。21世纪该区过火面积呈现强烈的季节特征,夏季防火期和秋季防火期的过火面积增长较快,尤其是夏季防火期,A2a情景下21世纪80年代森林火灾过火面积将会增加1.5倍。图4表1参31。 相似文献
13.
Daxing'anling is a key region for forest fire prevention in China.Assessing changes in fire risk in the future under multiple climatic scenarios will contribute to our understanding of the influences of climate change for the region and provide a reference for applying adaptive measures for fire management.This study analyzed the changes in fire weather indices and the fire season under four climate scenarios(RCP2.6,RCP4.5,RCP6.0,RCP8.5)for 2021–2050 using data from five global climate models together with observation data.The results showed that the analog data could project the average state of the climate for a given period but were not effective for simulating extreme weather conditions.Compared with the baseline period(1971–2000),the period 2021–2050 was predicted to have an increase in average temperature of 2.02–2.65 °C and in annual precipitation 25.4–40.3 mm,while the fire weather index(FWI) was predicted to increase by6.2–11.2% and seasonal severity rating(SSR) by5.5–17.2%.The DMC(Duff moisture code),ISI(initial spread index),BUI(build-up index),FWI and SSR were predicted to increase significantly under scenarios RCP4.5,RCP6.0,and RCP8.5.Furthermore,days with high or higher fire danger rating were predicted to be prolonged by 3–6 days,with the change in the southern region being greater under scenarios RCP4.5,RCP6.0,and RCP8.5. 相似文献
14.
Understanding both historic and current fire regimes is indispensable to sustainable forest landscape management. In this paper, we use a spatially explicit landscape simulation model, LANDIS, to simulate historic and current fire regimes in the Great Xing’an Mountains, in northeastern China. We analyzed fire frequency, fire size, fire intensity, and spatial pattern of burnt patches. Our simulated results show that fire frequency under the current fire scenario is lower than under the historic fire scenario; total area burnt is larger with lower fire intensity under the historic fire scenario, and smaller with higher fire intensity under the current fire scenario. We also found most areas were burned by high intensity fires under the current fire scenario, but by low to moderate fires under the historic fire scenario. Burnt patches exhibit a different pattern between the two simulation scenarios. Large patches burnt by high intensity class fires dominate the landscape under the current fire scenario, and under historic fire scenario, patches burnt by low to moderate fire intensity fires have relatively larger size than those burnt by high intensity fires. Based on these simulated results, we suggest that prescribed burning or coarse woody debris reduction should be incorporated into forest management plans in this region, especially on north-facing slopes. Tree planting may be a better management option on these severely burned areas whereas prescribed burning after small area selective cutting, retaining dispersed seed trees, may be a sound forest management alternative in areas except for the severely burned patches. 相似文献
15.
Fire histories contribute important information to contemporary fire planning, however, our knowledge is not comprehensive geographically. We evaluated the influence of topography on fire history patterns in two contrasting landscapes within the Santa Catalina Mountains of southeastern Arizona. Multiple fire-scarred trees from randomly selected 2-ha plots were used to develop plot composite mean fire intervals (PCMFIs) within the Butterfly Peak (BP) and Rose Canyon (RC) landscapes. BP is dominated by steep, northerly aspects and presence of potential fire spread barriers (exposed rock bluffs and scree slopes). RC is dominated by more gentle and southerly aspects with relatively few fire barriers. Within each landscape, PCMFIs did not differ significantly between aspect classes from A.D. 1748 to 1910 (BP: p = 0.73 and RC: p = 0.57). Pooled PCMFIs in the gentler RC landscape were, however, significantly shorter (p < 0.001) than in the steeper BP landscape. The frequency of relatively widespread fires (i.e., number of fire years when ≥2 plots scarred) was similar between landscapes, but fires in the gentler RC landscape were significantly larger (p = 0.033). The higher frequency of large fires (i.e., fires that burned >75% of the landscape) in RC resulted in more area burned over time and shorter fire intervals at individual plots. Conversely, smaller fires in the dissected BP landscape resulted in less area burned and longer periods between fires at individual plots. The different topographies in the two landscapes likely result in different wind intensities, fuel moistures, and fuel/vegetation types—and consequently, different historical fire spread patterns. Our conclusion is that fire history patterns are not influenced primarily by stand-scale topography, but rather by the topographic characteristics of the broader, surrounding landscape. 相似文献
16.
Oleg Chertov Jagtar S. Bhatti Alexander Komarov Alexey Mikhailov Sergey Bykhovets 《Forest Ecology and Management》2009
The results of EFIMOD simulations for black spruce (Picea mariana [Miller]) forests in Central Canada show that climate warming, fire, harvesting and insects significantly influence net primary productivity (NPP), soil respiration (Rs), net ecosystem production (NEP) and pools of tree biomass and soil organic matter (SOM). The effects of six climate change scenarios demonstrated similar increasing trends of NPP and stand productivity. The disturbances led to a strong decrease in NPP, stand productivity, soil organic matter (SOM) and nitrogen (N) pools with an increase in CO2 emission to the atmosphere. However the accumulated NEP for 150 years under harvest and fire fluctuated around zero. It becames negative only at a more frequent disturbance regime with four forest fires during the period of simulation. The results from this study show that changes in climate and disturbance regimes might substantially change the NPP as well as the C and N balance, resulting in major changes in the C pools of the vegetation and soil under black spruce forests. 相似文献
17.
Guang Yang Xue-ying Di Qing-xi Guo Zhan Shu Tao Zeng Hong-zhou Yu Chao Wang 《林业研究》2011,22(2):249-257
The Great Xing’an Mountains boreal forests were focused on in the northeastern China.The simulated future climate scenarios of IPCC SRES A2a and B2a for both the baseline period of 1961-1990 and the future scenario periods were downscaled by the Delta Method and the Weather Generator to produce daily weather data.After the verification with local weather and fire data,the Canadian Forest Fire Weather Index System was used to assess the forest fire weather situation under climate change in the study region.An increasing trend of fire weather severity was found over the 21st century in the study region under the both future climate change scenarios,compared to the 1961-1990 baseline period.The annual mean/maximum fire weather index was predicted to rise continuously during 2010-2099,and by the end of the 21st century it is predicted to rise by 22%-52% across much of China’s boreal forest.The significant increases were predicted in the spring from of April to June and in the summer from July to August.In the summer,the fire weather index was predicted to be higher than the current index by as much as 148% by the end of the 21st century.Under the scenarios of SRES A2a and B2a,both the chance of extremely high fire danger occurrence and the number of days of extremely high fire danger occurrence was predicted to increase in the study region.It is anticipated that the number of extremely high fire danger days would increase from 44 days in 1980s to 53-75 days by the end of the 21st century. 相似文献
18.
未来情景下西南地区森林火险变化 总被引：1，自引：0，他引：1
采用区域气候模式输出的日值和加拿大森林火险天气指数系统,在50 km×50 km尺度下,分析IPCCSRES A2和B2情景下中国西南地区未来不同时段区域森林火险和森林火险期变化,为科学制定未来林火管理规划提供参考.气候情景数据使用区域气候模式系统(PRECIS)对中国区域1961-2100年SRES A2,B2情景下的气候模拟结果,计算研究区各格点森林火险天气指数( FWI),并利用ANUSPLIN软件把研究结果插值到1 km×1 km水平.结果表明:PRECIS模式对研究区的平均气温和月均降水均有较好的模拟能力,气温和降水空间分布形态及中心区域与观测数值基本一致.A2和B2情景下西南地区火险期(11月至翌年5月)内森林火险天气指数平均分别增加1.66和1.40.A2和B2情景下2041-2050年火险期FWI平均变率分别为1.22倍和1.24倍,表明A2和B2情景下西南地区的森林火烧面积在2041-2050年可能比基准时段增加22％和24％,并且在火险高的月份潜在的森林火烧面积增加更为明显.与基准时段相比,2种情景下都表现出低火险日数明显减少和极高火险日数显著增加的趋势.A2和B2情景下,2041-2050年高、很高和极高火险等级总日数分别增加17和13天.建议根据未来森林火险和火险期变化特点,加强早期预警、火灾监测和可燃物管理等,提高该区域适应气候变化的能力. 相似文献
19.
Modeling fire susceptibility in west central Alberta, Canada 总被引：1，自引：0，他引：1
Jennifer L. Beverly Emily P.K. Herd J.C. Ross Conner 《Forest Ecology and Management》2009,258(7):1465-1478
Strategic modification of forest vegetation has become increasingly popular as one of the few preemptive activities that land managers can undertake to reduce the likelihood that an area will be burned by a wildfire. Directed use of prescribed fire or harvest planning can lead to changes in the type and arrangement of forest vegetation across the landscape that, in turn, may reduce fire susceptibility across large areas. While among the few variables that fire managers can influence, fuel conditions are only one of many factors that determine fire susceptibility. Variations in weather and topography, in combination with fuels, determine which areas are more likely to burn under a given fire regime. An understanding of these combined factors is necessary to identify high fire susceptibility areas for prioritizing and evaluating strategic fuel management activities, as well as informing other fire management activities, such as community protection planning and strategic level allocation of fire suppression resources across a management area. We used repeated fire growth simulations, automated in the Burn-P3 landscape-fire simulation model, to assess spatial variations in fire susceptibility across a 2.4 million ha study area in the province of Alberta, Canada. The results were used to develop a Fire Susceptibility Index (FSI). Multivariate statistical analyses were used to identify the key factors that determine variation in FSI across the study area and to describe the spatial scale at which these variables influence fire susceptibility at a given location. A fuel management scenario was used to assess the impact of prescribed fire treatments on FSI. Results indicated that modeled fire susceptibility was strongly influenced by fuel composition, fuel arrangement, and topography. The likelihood of high or extreme FSI values at a given location was strongly associated with the percent of conifer forest within a 2-km radius, and with elevation and ignition patterns within a 5-km radius. Results indicated that prescribed fire treatments can be effective at reducing forest fire susceptibility in community protection zones and that simulation modeling is an effective means of evaluating spatial variation in landscape fire susceptibility. 相似文献
20.
Simulation models of disturbance and succession are being increasingly applied to characterize landscape composition and dynamics under natural fire regimes, and to evaluate alternative management strategies for ecological restoration and fire hazard reduction. However, we have a limited understanding of how landscapes respond to changes in fire frequency, and about the sensitivity of model predictions to assumptions about successional pathways and fire behavior. We updated an existing landscape dynamics model (LADS) to simulate the complex interactions between forest dynamics, fire spread, and fire effects in dry forests of the interior Pacific Northwest. Experimental model runs were conducted on a hypothetical landscape at fire rotations ranging from 5 to 50 years. Three sensitivity analyses were carried out to explore the responses of landscape composition to (1) parameters characterizing succession and fire effects on vegetation, (2) the probability of fire spread into different successional stages, and (3) the size and spatial pattern of static fire refugia. The area of old open-canopy forests was highest at the shortest fire rotations, and was particularly sensitive to the probability of stand-replacement fire in open-canopy forests and to the fire-free period required for ingrowth to occur in open-canopy forests. The area of old closed-canopy forests increased with lengthening fire rotation, but always comprised a relatively small portion of the landscape (<10%). The area of old closed-canopy forests increased when fire spread was more rapid in open-canopy forests than in closed-canopy forests, and when the physical landscape incorporated large “fire refugia” with low fire spread rates. Old closed-canopy forests appear to comprise a relatively minor landscape component in mixed-severity fire regimes with fire rotations of 50 years or less. However, these results are sensitive to assumptions about the spatial interactions between fire spread, landscape vegetation patterns, and the underlying physical landscape. 相似文献