大理州森林火险天气预报方法

选用2001～2010年大理州的森林火灾次数与对应的气象数据进行统计分析,分析结果表明日最高气温、平均相对湿度、最大风速和前15日累计降水量对大理州森林火灾有较好的指示性,其中日平均相对湿度对大理州森林火险天气等级指示性最强。根据实际应用需要选用日最高气温、平均相对湿度、最大风速和前9日的降水数据建立模型计算森林火险天气等级。利用2011年大理州森林火灾数据对模型的模拟效果进行检验,检验效果很好,说明运用此模型进行大理州森林火险天气预报是可行的。     

Forest fire danger ratings in the 2040s for northeastern China

The average temperature of northeastern China is expected to increase 2.22 and 2.55°C under two scenarios selected from the Intergovernmental Panel on Climate Change (IPCC), i.e., A2 and B2, during the 2040s (2041 2050), which will have an impact on fire activities in those areas. We calculated the output of regional climate models, using the Canadian Forest Fire Weather Index (FWI) on a scale of 50 km × 50 km. Meteorological data and fire weather index were interpolated to a scale of 1 km × 1 km by using ANUSPLIN software. The results show that the model of Providing Regional Climate for Impacts Studies (PRECIS) had the ability to provide good temperature and precipitation estimates of the study area in the baseline period, by simulation. In the 2040s the mean FWI values of the study area will increase during most of the fire seasons under both selected scenarios, compared with the baseline period. Under scenario B2 the peak fire season will appear in advance. The changes of FWI ratio (2×CO 2 /1×CO 2 ) show that the potential burned areas will increase 20% under scenario B2 and lightly increase under scenario A2 in 2040s. The days of high, very high and extreme fire danger classes will add 5 and 18 d under scenarios A2 and B2, respectively. It suggests adapting the climate change through improving fuel management and enhancing the fighting abilities.     

云南松林区的林火与火险等级分区初探

云南松林区发生的森林火灾是多种自然因素和人为活动综合作用的结果。通过对四川省云南松分布区不同区域与林火有关的主要气候因子分析及综合值的比较,结合地形地貌、植被状况和人为活动等多种因素,将我省云南松分布区划分成5个不同等级的火险区,并提出了相应的护林防火对策。     

Future impacts of climate change on forest fire danger in northeastern China

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.     

基于RS和GIS的云南省森林火险预报研究

基于遥感、GIS技术,选取不同植被易燃等级、植被干燥度、森林气象火险预报等级作为森林火险预报因子,采用因子加权叠置法,计算得到云南省森林火险预报指数,划分为没有危险、低度危险、中度危险、高度危险和极度危险5个等级。研究结果表明,较之传统的森林火险气象预报,该预报模型能够更为准确地预测林火发生的可能性,更好地满足森林防火业务的需求。     

Spatio-temporal analysis of forest fire events in the Margalla Hills,Islamabad,Pakistan using socio-economic and environmental variable data with machine learning methods

Most forest fires in the Margalla Hills are related to human activities and socioeconomic factors are essential to assess their likelihood of occurrence.This study consid-ers both environmental (altitude,precipitation,forest type,terrain and humidity index) and socioeconomic (popula-tion density,distance from roads and urban areas) factors to analyze how human behavior affects the risk of forest fires.Maximum entropy (Maxent) modelling and random forest (RF) machine learning methods were used to predict the probability and spatial diffusion patterns of forest fires in the Margalla Hills.The receiver operating characteristic(ROC) curve and the area under the ROC curve (AUC) were used to compare the models.We studied the fire history from 1990 to 2019 to establish the relationship between the prob-ability of forest fire and environmental and socioeconomic changes.Using Maxent,the AUC fire probability values for the 1999s,2009s,and 2019s were 0.532,0.569,and 0.518,respectively;using RF,they were 0.782,0.825,and 0.789,respectively.Fires were mainly distributed in urban areas and their probability of occurrence was related to acces-sibility and human behaviour/activity.AUC principles for validation were greater in the random forest models than in the Maxent models.Our results can be used to establish preventive measures to reduce risks of forest fires by consid-ering socio-economic and environmental conditions.     

基于改进交叉影响法的木材加工产业园区火险因素研究

【目的】为正确把握木材加工产业园区的消防管控方向,运用改进的交叉影响分析法对木材加工产业园区火险影响因素进行研究,以深入剖析木材加工产业园区火险因素间的交互作用,为木材加工产业园区的科学防火提供模型支撑。【方法】首先从系统论和事故致因角度出发,建立包含人、物、环、管4方面共16个影响因素的木材加工产业园区火险因素体系,进而运用三元模糊法,基于各影响因素间的相互作用关系,构建火险因素的交叉影响关系矩阵,并将马尔科夫稳态预测模型引入交叉影响分析过程中,计算木材加工产业园区中火险因素火灾发生的校正概率,实现对木材加工产业园区火险因素交互作用下的发生概率变化趋势的预测。【结果】通过实例分析可知:消防安全意识、人员工作技能、木材贮存规范性、园区消防安全氛围、消防设施、消防救援力量、消防制度与机构、安全教育与培训、事故应急管理、消防巡查与监管的火灾发生概率呈上升趋势;人员基本素质、设备健康状态、木材贮存数量、园区规模、消防规划合理性的火险发生概率呈下降趋势。【结论】改进的交叉影响分析法可以应用到木材加工产业园区火险因素的预测中,且能够真实地反映因素交叉影响后的发展方向和程度,为木材加工产业园区的安全生产、科学管理及消防风险决策提供理论依据和新思路。     

Spatio-temporal perspectives of forest fires regimes in a maturing Mediterranean mixed pine landscape

It has been suggested that during the past several decades, the frequency and the intensity of wildfires have markedly increased in the Mediterranean basin. We came to assess this postulation in the forested region of Mount Carmel, Israel. This region is characterized by Quercus spp. and Pistacia spp. maquis and has been intensely afforested with Pinus spp. stands since the 1920s. We compiled a GIS-based database of the fires recorded in the region since 1983, in addition to archiving data beginning from the 1940s. The data were collected from land stewardship agencies’ archives, fire departments and aerial photographs. Prior to the early 1980s, no systematic documentation of the fires was available, rather just sporadic qualitative documentation of the large forest fires that occurred. Between 1944 and 1982, only 6 large fires were documented, while after that 11 large fires occurred. Analysis indicated that the spatial distribution of the fires does not occur at random, and their locations are significantly closer to roadsides compared to an expected random distribution. The annual number of fires and the areas burned during the last two decades were not correlated with annual precipitation in any manner. Accordingly, we suggest that the increased number of large forest fires during the last decades is associated with the maturation and senescence of the planted forest coupled with increased human activities.     

Relationships between long-term trends of air temperature,precipitation, nitrogen nutrition and growth of coniferous stands in Central Europe and Finland

Height growth of 19 Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) stands in Germany, Austria and Finland, for which long-term records of foliar nutrient levels were available, was assessed retrospectively by stem analyses and compared with data from regionally applied yield tables as references. Gridded historical time series of monthly temperature and precipitation were used to characterise the meteorologic conditions at the sampling sites. Climate parameters were tested against height growth in period 1950–2000, and needle N content was tested against height growth for the periods where N measurements were available by means of graphical comparison, as well as simple and multiple regression analyses with the aim to get evidence for causes of possible growth acceleration. Trends of referenced height increment of six out of nine Scots pine stands in Germany were positive during the observation period, and improved N nutrition appeared to be the most important driving factor for this growth acceleration. The variation of precipitation—exhibiting no consistent and uniform long-term temporal trend during the observation period—in contrast seems to be mainly responsible for the interannual fluctuation of height growth. We were not able to detect any general statistical influence of temperature parameters on height growth, although they generally increased. The referenced height growth of three Finnish pine stands slightly decreased during the observation period and there was no indication of a significant improvement of their N supply. Among four Norway spruce stands investigated in Germany and Austria, referenced height increment also increased in three cases; there was again some evidence that improved N nutrition was the stimulating factor. At three study sites in Finland, however, referenced height growth of this species decreased at least from 1985 onwards, whereas mostly no significant trends in N nutrition or precipitation were identified. These differences observed between species and regions are discussed in detail.     

大兴安岭南部春季火行为特征及可燃物消耗

利用标准地调查分析2007年春季大兴安岭2起森林火灾的火行为及可燃物变化.采用加拿大火险天气指数(FWI)系统分析火险变化,地表可燃物载量调查采用线状相交可燃物调查方法,并利用MODIS遥感数据对火烧程度进行分级.结果表明:FWI系统各指标可以很好地指示森林火险变化,2007年4-5月细小可燃物湿度码(FFMC)基本都在90以上,腐殖质湿度码(DMC)和干旱指数(DC)在4月份持续升高,2场大火也发生在火险高的时段.火烧类型以地表火为主,部分林分有冲冠火.火后阔叶林地表径级可燃物增加不明显,针阔混交林主要是5.0～6.99 cm径级可燃物增加,而落叶松纯林火烧后除0.50～0.99 cm径级可燃物减少外,其他径级可燃物都明显增加.不同火烧程度对地表可燃物载量的影响有差异.中度和重度火烧后草本盖度明显下降,有些林分下木层死亡率较高.罕诺河火场和松岭区壮志林场过火区重度火烧分别占33.2%和46.4%.     

Short- and long-term effects of thinning and prescribed fire on carbon stocks in ponderosa pine stands in northern Arizona

Euro-American logging practices, intensive grazing, and fire suppression have increased the amount of carbon that is stored in ponderosa pine (Pinus ponderosa Dougl. Ex Laws) forests in the southwestern United States. Current stand conditions leave these forests prone to high-intensity wildfire, which releases a pulse of carbon emissions and shifts carbon storage from live trees to standing dead trees and woody debris. Thinning and prescribed burning are commonly used to reduce the risk of intense wildfire, but also reduce on-site carbon stocks and release carbon to the atmosphere. This study quantified the impact of thinning on the carbon budgets of five ponderosa pine stands in northern Arizona, including the fossil fuels consumed during logging operations. We used the pre- and post-treatment data on carbon stocks and the Fire and Fuels Extension to the Forest Vegetation Simulator (FEE-FVS) to simulate the long-term effects of intense wildfire, thinning, and repeated prescribed burning on stand carbon storage.The mean total pre-treatment carbon stock, including above-ground live and dead trees, below-ground live and dead trees, and surface fuels across five sites was 74.58 Mg C ha⁻¹ and the post-treatment mean was 50.65 Mg C ha⁻¹ in the first post-treatment year. The mean total carbon release from slash burning, fossil fuels, and logs removed was 21.92 Mg C ha⁻¹. FEE-FVS simulations showed that thinning increased the mean canopy base height, decreased the mean crown bulk density, and increased the mean crowning index, and thus reduced the risk of high-intensity wildfire at all sites. Untreated stands that incurred wildfire once within the next 100 years or once within the next 50 years had greater mean net carbon storage after 100 years compared to treated stands that experienced prescribed fire every 10 years or every 20 years. Treated stands released greater amounts of carbon overall due to repeated prescribed fires, slash burning, and 100% of harvested logs being counted as carbon emissions because they were used for short-lived products. However, after 100 years treated stands stored more carbon in live trees and less carbon in dead trees and surface fuels than untreated stands burned by intense wildfire. The long-term net carbon storage of treated stands was similar or greater than untreated wildfire-burned stands only when a distinction was made between carbon stored in live and dead trees, carbon in logs was stored in long-lived products, and energy in logging slash substituted for fossil fuels.     

大兴安岭地区森林火险变化及FWI适用性评估

根据研究区内及附件气象站每日气温、相对湿度、24小时降水和风速计算1987—2006年大兴安岭每日的加拿大林火天气指数系统(FWI)各组分值。利用空间插值方法,获得1987—2006年所有森林火灾发生日的FWI系统各组分值。大兴安岭林区森林火灾主要发生在落叶针叶林(61.3%)、草地(23.9%)和落叶阔叶林(8.0%),主要火源是雷击火(占57.1%)。4—6月份森林火灾发生时的FWI、FFMC和ISI平均值高。根据1987—2006年FWI组分指数的分布和火发生情况,对森林火险指数进行了分级,低、中、高、很高和极高火险的FWI取值范围分别为0～2.5,2.6～10.0,10.1～18.0,18.1～31.0,≥31.1。FWI对大兴安岭地区森林火险有显著的指示意义,FFMC和ISI对预测火灾的发生与蔓延有较好的指示作用。1987—2001年每年明显有春季和秋季2个火险期,但2002—2006年火险期显著延长。春季火险严重度指数(SSR)波动幅度比较大,夏季SSR和春季SSR有相反的波动趋势,2000—2006年秋季火险严重度明显升高。     

贵州息烽林场森林火险的数量生态学分析及区划

对贵州息烽林场６７个森林火险调查样方进行ＰＣＡ、ＣＯＡ排序和模糊综合评判表明：海拔影响林场森林可燃物分布状况和土壤含水量;林场森林火险以危险和较危险两级为主,影响的主要因素是海拔、森林可燃物类型和火源状况;森林可燃物分为非林分型可燃物,林相整齐的中幼林型可燃物和近成过熟林型可燃物、林相不整齐林分型可燃物;林场森林型可燃物和近成熟林型可燃物、林相不整齐林分型可燃;林场森林火险区划为４级区域,即很危险区（Ⅰ）、危险区（Ⅱ）、较危险区（Ⅲ）和略危险区（Ⅳ）。     

Concept and feasibility study for the integrated evaluation of environmental monitoring data in forests

In the 1970s unexpected forest damages, called “new type of forest damage” or “forest decline”, were observed in Germany and other European countries. The Federal Republic of Germany and the German Federal States implemented a forest monitoring system in the early 1980s, in order to monitor and assess the forest condition. Due to the growing public awareness of possible adverse effects of air pollution on forests, in 1985 the ICP Forests was launched under the convention on long-range transboundary air pollution (CLRTAP) of the United Nations Economic Commission for Europe (UN-ECE). The German experience in forest monitoring was a base for the implementation of the European monitoring system. In 2001 the interdisciplinary case study “concept and feasibility study for the integrated evaluation of environmental monitoring data in forests”, funded by the German Federal Ministry of Education and Research, concentrated on in-depths evaluations of the German data of forest monitoring. The objectives of the study were: (a) a reliable assessment of the vitality and functioning of forest ecosystems, (b) the identification and quantification of factors influencing forest vitality, and (c) the clarification of cause-effect-relationships leading to leaf/needle loss. For these purposes additional data from external sources were acquired: climate and deposition, for selected level I plots tree growth data, as well as data on groundwater quality. The results show that in particular time series analysis (crown condition, tree growth, and tree ring analysis), in combination with climate and deposition are valuable and informative, as well as integrated evaluation of soil, tree nutrition and crown condition data. Methods to combine information from the extensive and the intensive monitoring, and to transfer process information to the large scale should be elaborated in future.

The ecology of mixed severity fire regimes in Washington, Oregon, and Northern California

Forests characterized by mixed-severity fires occupy a broad moisture gradient between lower elevation forests typified by low-severity fires and higher elevation forests in which high-severity, stand replacing fires are the norm. Mixed-severity forest types are poorly documented and little understood but likely occupy significant areas in the western United States. By definition, mixed-severity types have high beta diversity at meso-scales, encompassing patches of both high and low severity and gradients in between. Studies of mixed-severity types reveal complex landscapes in which patch sizes follow a power law distribution with many small and few large patches. Forest types characterized by mixed severity can be classified according to the modal proportion of high to low severity patches, which increases from relatively dry to relatively mesic site conditions. Mixed-severity regimes are produced by interactions between top-down forcing by climate and bottom-up shaping by topography and the flammability of vegetation, although specific effects may vary widely across the region, especially the relation between aspect and fire severity. History is important in shaping fire behavior in mixed-severity landscapes, as patterns laid down by previous fires can play a significant role in shaping future fires. Like low-severity forests in the western United States, many dry mixed-severity types experienced significant increases in stand density during the 20th century, threatening forest health and biodiversity, however not all understory development in mixed-severity forests increases the threat of severe wild fires. In general, current landscapes have been homogenized, reducing beta diversity and increasing the probability of large fires and insect outbreaks. Further loss of old, fire tolerant trees is of particular concern, but understory diversity has been reduced as well. High stand densities on relatively dry sites increase water use and therefore susceptibility to drought and insect outbreaks, exacerbating a trend of increasing regional drying. The need to restore beta diversity while protecting habitat for closed-forest specialists such as the northern spotted owl call for landscape-level approaches to ecological restoration.     

Establishment and growth of coniferous seedlings in an altered forest floor after long-term exclusion of deer

We evaluated differences between the forest floors and the establishment and growth of coniferous seedlings in fenced (13 years) and unfenced plots on Mt Ohdaigahara where the sika deer (Cervus nippon) population density is high. Large coniferous seedlings (height > 0.05 m) were less abundant in the unfenced plot, as a result of deer browsing. Small coniferous seedlings (height < 0.05 m), however, were more abundant in the unfenced plot, where most seedlings of Abies homolepis were found on bare ground and those of Picea jezoensis var. hondoensis were found on buttresses and fallen logs. The large area of bare ground in the unfenced plot was caused by deer browsing. Deer therefore have an indirect effect on the emergence and growth of small coniferous seedlings by modifying the forest floor.     

Gradient analysis of an eastern sand savanna's woody vegetation,and its long-term responses to restored fire processes

Little information is available comparing historic and modern sand savannas, and how remnants respond to restored fire. We compared short- and long-term effects of restored fire on the Tefft Savanna, a 197 ha eastern sand savanna in northwest Indiana that had undergone three decades of fire protection. U.S. Public Land Survey data from Tefft in 1833 indicate black and white oak barrens, and pin oak savanna, with trees averaging 50 stems/ha and 4 m²/ha basal area. We used ordination and a digital elevation model to assess topographic distribution of tree species in 1986. In 1986, we also compared initial effects of high- and low-intensity dormant season fire on woody vegetation among nine blocks containing black oak, white oak, and pin oak stands. Twenty years later, we compared the same blocks, all of which had been burned three times per decade with low-intensity fires. In 1986, black oak, white oak and pin oak occurred across a gradient of decreasing elevation and slope. At that time, unburned black oak and white oak stands averaged >400 stems/ha and about 10 m²/ha basal area, and their smaller size classes contained non-oak woody vegetation that apparently had invaded with fire exclusion. After initial burns, black oak and white oak stands receiving high-intensity fire averaged <200 stems/ha and had significantly lower oak canopy cover and basal area than unburned stands. Stands receiving low-intensity fire had intermediate oak canopy cover, with basal area similar to unburned stands. Pin oak stands were more fire-resistant, apparently because spring flooding often reduced fire effects. Density, cover and basal area of non-oak tree species were much lower than oaks, and were not reduced by initial burning. Repeated low-intensity burning over 20 years tended to maintain structure caused by initial fires. However, it reduced lower size class stem densities, promoted post-fire sprouting into the shrub layer, and allowed oak basal area to increase in larger size classes. Time since fire regulated shrub layer structure on a 4-year cycle. Density and cover of trees and shrubs returned to pre-burn conditions by the second and fourth growing seasons after fire, respectively, with non-oak tree species exceeding pre-burn cover and density by the fourth season. These results suggest that high-intensity fire is more important than repeated low-intensity burning in structuring and restoring eastern sand savanna, and that non-oak tree species, once established, may be resistant to low-intensity fire.     

Long-term impacts of prescribed burning on regional extent and incidence of wildfires—Evidence from 50 years of active fire management in SW Australian forests

Prescribed burning is advocated for the sustainable management of fire-prone ecosystems for its capacity to reduce fuel loads and mitigate large high-intensity wildfires. However, there is a lack of comprehensive field evidence on which to base predictions of the benefits of prescribed burning for meeting either wildfire hazard reduction or conservation goals. Australian eucalypt forests are among the very few forest types in the world where prescribed burning has been practised long enough and at a large enough spatial scale to quantify its effect on the incidence and extent of unplanned fires. Nevertheless even for Australian forests evidence of the effectiveness of prescribed burning remains fragmented and largely unpublished in the scientific literature.     

The environmental characteristics of forest land and the techniques of reforestation in fired land in Daxing’an mountains

Analysis of nature environmental condition and evaluation of selection and integration of techniques have been carried out in Daxing’an mountains from 1987. The character of soil generation in this area is influenced by the frigid, coniferous forest vegetation, weather, glacier and late soil formation process. Synthesis techniques for high yield plantation include high seedling quality, suitable site preparation and effective protection measures for young trees.