灌木林火灾研究综述

灌木林是森林与灌丛之间的中间类型,灌木林火后再生恢复能力强、繁殖快,且具有一定的抗火灾能力,灌木林火灾具有火势较均匀、发展较稳定、热释放较平稳等特性。综述了灌木林火灾研究方法,包括遥感监测法、损失评估法和实验室分析测定法;灌木林主要着火特性与可燃物含水率、可燃物载量、火强度、灰分含量相关。运用新仪器新装备新方法研究灌木林火灾特性,将为灌木林防火提供更为科学的理论依据。     

持续干旱对森林火灾的影响研究综述

文章通过对干旱定义和对干旱等级的划分,从持续干旱对森林可燃物、火源和林火行为等方面,综合分析了持续干旱对森林火灾的影响。结果表明,持续干旱会降低可燃物的含水率,使可燃物载量和分布发生变化,对森林可燃物有较大影响;持续干旱还会影响火源,使林火强度增大,林火蔓延速度加快,火烈度增大,提高森林火灾发生的几率和森林火灾的强度。     

Wildland fires and moist deciduous forests of Chhattisgarh,India: divergent component assessment

We studied moist deciduous forests of Chhattisgarh, India （1） to assess the effect of four levels of historic wildland fire frequency （high, medium, low, and no-fire） on regeneration of seedlings in fire affected areas during pre and post-fire seasons, （2） to evaluate vegetation struc- ture and diversity by layer in the four fire frequency zones, （3） to evalu- ate the impact of fire frequency on the structure of economically impor- tant tree species of the region, and （4） to quantify fuel loads by fire fre- quency level. We classified fire-affected areas into high, medium, low, and no-fire frequency classes based on government records. Tree species were unevenly distributed across fire frequency categories. Shrub density was maximum in zones of high fire frequency and minimum in low- frequency and no-fire zones. Lower tree density after fires indicated that regeneration of seedlings was reduced by fire. The population structure in the high-frequency zone was comprised of seedlings of size class （A） and saplings of size class （B）, represented by Diospyros melanoxylon, Dalbergia sissoo, Shorea robusta and Tectona grandis. Younger and older trees were more abundant for Tectona grandis and Dalbargia sis- soo after fire, whereas intermediate-aged trees were more abundant pre- fire, indicating that the latter age-class was thinned by the catastrophic effect of fire. The major contributing components of fuel load included duff litter and small woody branches and twigs on the forest floor. Total fuel load on the forest floor ranged from 2.2 to 3.38 Mg/ha. The netchange in fuel load was positive in high- and medium-frequency fire zones and negative under low- and no-fire zones. Repeated fires, how- ever, slowly reduced stand stability. An ecological approach is needed for fire management to restore the no-fire spatial and temporal structure of moist deciduous forests, their species composition and fuel loads. The management approach should incorporate participatory forest manage- ment. Use of c     

滇中安宁“3.29”重大森林火灾火烧迹地的可燃物特征初步分析

在滇中安宁“3·29”重大森林火灾火烧迹地选择无人为干扰的灌木林设置样地,并与未过火的灌木林进行比较,通过外业调查和实验室测定,研究了可燃物的种类、高度、绝对含水量、载量等特征。结果表明,火烧迹地死可燃物的高度为5．7m,与未过火的活灌木高度5．4m差不多,活灌木平均高度达1．5m;火烧迹地活灌木、死可燃物、CWD的热值及点着温度与未过火样地的差异均不明显;火烧迹地CWD的灰分含量仅为未过火的25．87％;火烧迹地总的可燃物载量为9．07kg/m^2,明显超过了未过火样地7．82kg／m^2。     

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）。     

林火动态研究与林火管理

林火动态是一个生态系统可持续性的稳定指标, 准确掌握林火动态和可燃物特性是制定合理林火管理策略或规划的基础。林火动态与可燃物积累过程密切相关, 了解森林可燃物积累过程是开展林火管理的基础。文中综述了林火动态及可燃物变化的研究进展。林火动态受地形、植被和气候等因素的影响, 随着气候、植被和人为活动的变化, 许多区域林火动态发生了显著变化, 并影响可燃物积累过程及其空间分布。森林结构和可燃物组成的变化会导致火频度、火灾类型和火强度发生变化, 林火管理对策也需要相应调整。我国重点林区的林火管理策略也应根据林火动态变化和可燃物情况进行调整, 以适应变化的气候和植被条件。     

林火动态变化对我国东北地区森林生态系统的影响

我国积极的森林防火政策导致了我国东北林区的森林火周期延长,并影响到森林结构和可燃物组成的变化。火周期的延长会引起森林可燃物载量增加,并导致火频度、火灾类型和火强度发生改变。森林火周期延长还会引起大兴安岭地区云杉林的分布范围增大。植被的变化又对林火动态有反作用。为适应林火动态和可燃物的变化,我国东北林区森林防火政策需要作相应调整,采用林火管理思想开展森林防火工作。     

Behind the flaming zone: Predicting woody fuel consumption in eucalypt forest fires in southern Australia

Pre-fire woody fuel (diameter > 0.6 cm) structure and its consumption by fire were measured at experimental/prescribed fires and high intensity wildfires in eucalypt forests in southern Australia in order to better understand and model the dynamics of woody fuel consumption. Two approaches were used in model development: (1) a fire or plot level analysis, based on a dataset which includes the proportion of the pre-fire woody fuel load consumed at each fire; and (2) a stage level analysis, based on a dataset where woody fuel consumption was measured at a woody fuel particle level (i.e. pre-fire and post-fire diameter). For the plot level analysis a generalised linear model (GLM) approach identified the Forest Fire Danger Index (FFDI) as the best predictor of the proportion of woody fuel consumed, with an R² of 0.58 and mean absolute error of 10%. The stage level analysis recognised the various combustion stages through which a burning woody particle would pass, but failed to develop an accurate model that predicted the ignition, partial and full consumption of woody fuels based on fuel, fire behaviour and environmental variables. Analysis showed that consumption of woody fuel particles is highly variable and that variation in fire behaviour potentially has a greater impact on woody fuel consumption, than does variation in fuel characteristics (e.g. state of decay, fuel suspension and interactions with other fuel particles). The FFDI GLM provides forest and fire managers with a tool to manage woody fuel consumption objectives and may assist fire managers with forecasting post-frontal fire behaviour. The FFDI GLM may also assist forest and fire managers to better meet land management goals and to comply with air quality and emission targets.     

林火研究综述(Ⅱ)——林火预测预报*

林火预测预报是综合气象要素、地形、可燃物的干湿程度、可燃物类型特点和火源等，对森林可燃物燃烧危险性进行分析预测，天气预报的准确性直接影响林火预报的准确性。林火预测预报分为火险天气预报、林火发生预报和林火行为预报。林火预测预报从20世纪20年代迄今，已有80余年的历史，在世界各国发展很快。林火预报研究中的关键问题是主要因子的选择和预报因子的测定。林火预测预报主要方法有：经验法、数学方法、物理方法、野外实验法和室内测定法等。     

Nomographs for predicting crown fire initiation in Aleppo pine (<Emphasis Type="Italic">Pinus halepensis</Emphasis> Mill.) forests

Nomographs that calculate the threshold values of surface fire parameters which lead to crown fire initiation were created by linking two separate fire behavior models: Van Wagner’s crown fire ignition criteria and Byram’s surface fire model. The nomographs were also based on the existing surface (fuel load, fuel heat content) and canopy (foliar moisture content, live crown base height) fuel models of Aleppo (Pinus halepensis Mill.) pine forests of Mediterranean Greece. The most important fire parameters for crown fire initiation that are calculated by the nomographs are the critical flame length and the forward spread rate of the surface fire. These parameters are readily observable in the field during fires. The nomographs provide a judicious way to assess whether a crown fire is likely to occur in a conifer forest stand. Although the fire behavior models used had limited testing and are based on certain assumptions, yet they are widely applied in forestry practice worldwide, as a basis for justified fire prevention and suppression planning.     

森林可燃物含水率及其预测模型研究进展

森林可燃物是森林火灾发生的物质基础,其含水率的变化直接影响森林可燃物着火的难易程度。高效准确地模拟森林可燃物含水率动态变化的规律,对预测预报林火发生或林火行为具有重要意义。文中从可燃物含水率的影响因子、理论算法、预测模型3个方面阐述了森林可燃物含水率及其预测模型研究进展;指出了研究存在的问题;提出了可燃物含水率研究展望:加强野外定位观测研究,优化测定方法并强化野外采样和室内试验标准化工作,加强可燃物含水率时空异质性研究,加强观测尺度外推问题研究并构建含水率遥感反演模型。     

森林火行为与特殊火行为研究进展

森林火灾主要包括地表火、地下火、树冠火3种蔓延形式。目前火蔓延模型主要关注于森林地表火的蔓延研究, 对一些特殊的火行为, 如树冠火、火旋风、飞火等研究极为薄弱, 而这些火行为在特大森林火灾的蔓延传播中起着重要作用, 往往加速火蔓延, 并对扑火人员造成生命危险。我国森林大多集中在山区, 火灾一旦发生, 由于复杂的地形、不均匀的可燃物分布、多变的局地风和林火的相互作用, 极易形成复杂的火行为。文中对森林火灾中的火行为和特殊火行为进行了论述, 讨论了当前的研究进展和未来发展趋势。     

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%.     

林火研究综述(Ⅰ)——研究热点与进展*

在危害森林的诸因子中火灾是一种最具破坏性的灾害。各林业先进国家都非常重视林火研究工作。森林防火是一门综合性的科学，其研究热点包括基础研究和应用研究。近些年林火研究涉及国家森林火险等级预报、林火控制技术、雷击火自动定位系统、遥测自动林火天气站网、火发生与火行为规律、计划烧除、火生态、可燃物燃烧过程、灭火喷洒技术、烟尘特征和扩散等。     

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。     

基于防火的杉木幼林生物质能持续利用探讨

对杉木人工纯林,杉木-马尾松、杉木-木荷、杉木-马尾松-木荷人工混交林的可燃物负荷量和生物质能进行了调查测定。结果表明:4个林分的可燃物负荷量和生物质能由高至低的顺序依次为:杉木-马尾松混交林、杉木-马尾松-木荷混交林、杉木人工纯林和杉木-木荷混交林。     

林火碳排放研究进展

火是森林生态系统主要的干扰因子, 森林火灾的频繁发生不仅使森林生态系统遭到破坏, 同时也造成了含碳温室气体的大量释放。综述了火烧面积、森林可燃物以及燃烧效率等主要因子对森林火灾排放碳量估计的影响, 分析了这一领域未来研究发展趋势。大量研究表明:1)卫星遥感是估测大尺度上森林过火面积的主要手段, 随着高分辨率卫星的应用, 森林火灾面积的估计精度不断得到提高。目前的研究主要集中于大尺度上林火面积的估计和估算方法的改进。2)遥感数据是目前估计大尺度可燃物燃烧量的有效手段, 利用遥感数据的同时结合有效可燃物计算模型, 运用多元线性与非线性分析结合等方法提高对可燃物燃烧量的估计。3)燃烧效率是决定可燃物消耗量的主要因子, 也是估计森林火灾释放含碳气体量的关键。未来的研究是利用高分辨率的遥感数据, 结合复杂的可燃物计算模型, 更精确地估计林火碳排放。     

Effects of fuel treatments on carbon-disturbance relationships in forests of the northern Rocky Mountains

Fuel treatments alter conditions in forested stands at the time of the treatment and subsequently. Fuel treatments reduce on-site carbon and also change the fire potential and expected outcome of future wildfires, including their carbon emissions. We simulated effects of fuel treatments on 140 stands representing seven major habitat type groups of the northern Rocky Mountains using the Fire and Fuels Extension to the Forest Vegetation Simulator (FFE-FVS). Changes in forest carbon due to mechanical fuel treatment (thinning from below to reduce ladder fuels) and prescribed fire were explored, as well as changes in expected fire behavior and effects of subsequent wildfire. Results indicated that fuel treatments decreased fire severity and crown fire occurrence and reduced subsequent wildfire emissions, but did not increase post-wildfire carbon stored on-site. Conversely, untreated stands had greater wildfire emissions but stored more carbon.     

塔河林业局森林可燃物类型区划分的研究

以塔河林业局的林场为单位,根据森林资源特性的评定值来综合评定各林场的火险,而后依据各林场潜在的火险值（D）的大小,来划分各林场的森林可燃物的火险等级的高低。研究表明：森林可燃物类型区的划分也是林火预测预报的基础,只有在森林可燃物的基础上,才能使林火行为预报较为精确,为火险区域的划分提供了科学依据。     

Study on Effect of Schima superba Fuelbreak

Schima superba is a pioneer species for forestation inwildland in tropical and subtropical zones. It can growwell in arid and barren sites and has a strong power ofsprouting from stools. The species has been widelyused for fuelbreak in southern China. In China thefuelbreak is often created by planting broadleaf treesalong the ridge, which is different from the conceptdiscussed in some papers (Agee, et al, 2000; Green,1977; Omi, 1996). In these studies, the shaded fuelbreakwas created by alte…