林火管理与森林的可持续发展

森林火灾是在开放环境中的自由燃烧过程 ,由于受可燃物特征与分布、空气湿度、地形与风场分布等因素的影响 ,构成了森林火灾的复杂性与随机性。由于自燃、雷击和人为因素等火源不可能彻底排除 ,森林火灾不可避免。大面积高强度火可以烧毁森林 ,造成地面光秃和加速土壤侵蚀 ,但小面积低速度火却可以减少地面多余可燃物 ,有助于林木的火后更新和生物栖息。因此在预防森林火灾中 ,实现森林可燃物可持续管理是发展重点 ,用计划火烧减少可燃物 ,营造防火林带隔断可燃物的连续性 ,可以达到减少和控制森林火灾的目的。1　近年来林火管理面对的挑战…     

“五.六”大火前后大兴安岭北部林区可燃物调查分析

森林可燃物积累过多是酿成“五、六”特大森林火灾的基本物质条件,因此,对大火前后可燃物调查分析,是研究火行为的首要条件。在今后的林火管理中,定期调查可燃物积累情况,通过营林用火等科学方法减     

陕西针叶林下可燃物分布状况调查研究

森林中的一切物质都是可燃物。包括森林中的乔木、灌木、草本、苔藓、地衣、枯枝落叶、腐殖质等 ,他们都是森林火灾的载体 ,它的数量、类型、疏密度、分布和配置 ,对森林火灾的发展、控制和扑救以及安全用火 ,均有明显影响 ,特别是针叶林下可燃物 ,更易引起火灾 ,而且发生火灾后难以扑救 [1 ] 。随着陕西人工林面积迅速增加 ,针叶纯林面积越来越大 ,林下杂物越来越多 ,发生火灾的隐患也越来越大。为了摸清针叶林下可燃物的分布 ,绘制火险图、划分燃烧性等级和制作火灾发生预报等[1 ] ,我们对可燃物类型及其分布状况进行了调查研究 ,现总结以…     

森林可燃物负荷量测定方法研究

森林可燃物是引起森林火灾的重要条件,掌握可燃物负荷量的动态分布对于预防森林火灾和林火管理具有重要意义.本文介绍了森林可燃物负荷量的基本概念,总结了可燃物负荷量的研究现状,重点探讨了可燃物负荷量测定方法,指出了以往研究中存在的主要问题,并对今后的研究前景提出了展望,以期对快速且准确地掌握森林可燃物负荷量提供借鉴意见.     

森林可燃物阻隔带技术研究与应用

实现森林可燃物阻隔技术是减少和控制森林火灾的基础.基于可燃物阻隔技术的火烧阻隔带和生物阻隔带技术是预防和控制森林火灾重要组成部分,森林可燃物阻隔带技术易于形成不利于可燃物燃烧的环境,并使可燃物呈不连续分布.火烧阻隔带技术是充分利用火的作用,烧去燃烧的森林可燃物,降低森林火灾危险性.目前火烧阻隔带技术已成为森林经营和资源管理的一项重要措施.     

森林可燃物及其燃烧特性研究

较详细地分析了落叶松、红松、樟子松、柞树、大山杨及水曲柳这6个树种各自所在林分林下可燃物的特点及其燃烧特性,结果表明:落叶松与水曲柳不易发生火灾,红松和樟子松易发生火灾,大山杨和水曲柳是抗火性树种。提出在造林技术上采用营造混交林或营造防火林带,防止或减少森林火灾,为森林防火及营林用火提供可靠的理论依据。     

阿尔泰山林区森林可燃物类型分析

根据阿尔泰山林区林分状况,分析了该地区森林火灾发生的基本情况及特点。对阿尔泰山林区几种森林类型的燃烧性进行了分析,通过不同森林类型可燃物种类组成进行区划,这些林型为划分可燃物种类组成和火行为研究提供参考,有利于防止森林火灾的发生。     

德化县森林火灾发生规律及防控对策

对德化县森林火灾的发生规律、森林可燃物的分布特点及燃烧特性等进行统计分析,结果表明:无计划的农业生产用火是导致森林火灾发生的最主要因素,郁闭度小于0.8的针叶林分是德化县多年来森林火灾主要发生区和受灾区。根据德化的实际情况,森林火灾防控主要应从阻隔火源与可燃物的接触入手,强化林火阻隔体系建设,加强野外火源管理,配合其它防控措施,从而达到森林火灾防控的目的。     

可燃物处理对大兴安岭地区主要林型火行为的影响

【目的】模拟研究不同强度的可燃物处理对大兴安岭地区典型森林的火行为影响,为开展可燃物管理提供科学依据。【方法】在2019年火险期,分别对大兴安岭地区兴安落叶松林、白桦林、兴安落叶松白桦混交林等天然林和兴安落叶松与樟子松人工林进行可燃物调查和清理。每种林型分别设置3块样地(20 m×20 m),每块样地再分别设置4块小样地(10 m×10 m)。对每块样地进行林分结构调查,然后对4块小样地分别进行可燃物处理,包括割除枯死灌木和草本、清理枯枝和地表凋落物等。按可燃物处理程度分为未处理、低、中和高强度处理4个等级。低强度处理后林内无易燃及枯死灌草、地表无大型可燃物(10 h),可燃物梯最小高度为3 m,中强度处理后倒木、灌木及小乔木全部清除,高强度处理后地表存留可燃物不会支持火的持续燃烧和蔓延。调查可燃物处理后的可燃物空间分布。利用可燃物特征分类系统(FCCS)分别模拟各林分在火险期内一般天气情景和干旱情景下的火行为。一般天气情景下,模型输出的指数包括地表火蔓延速度、火焰高度和火强度指标;干旱情景下,模型输出指数为潜在地表火(火强度、火焰高度和蔓延速度)及潜在树冠火行为(树冠火发生指数、蔓延指数和蔓延速度指数)。【结果】模拟结果显示,低强度可燃物处理后,兴安落叶松天然林和人工林地表火蔓延速度分别降低51.6%和42.8%,火焰高度分别降低33.6%和39.4%,平均火强度分别降低22.8%和34%;而兴安落叶松白桦天然混交林、白桦林和樟子松人工林的火行为变化不明显。中强度可燃物处理后,兴安落叶松白桦混交林、白桦林、兴安落叶松天然林、兴安落叶松人工林和樟子松人工林的地表火蔓延速度分别降低29.4%、37.1%、79.1%、83.3%和19.7%,火焰高度分别降低33.3%、29.8%、67.2%、69.7%和38.1%。高强度可燃物处理后,兴安落叶松天然林、兴安落叶松人工林、兴安落叶松白桦天然混交林、白桦林和樟子松人工林平均蔓延速度分别降低95.3%、97.6%、85.7%、88.9%和77.6%,平均火焰高度分别降低93.1%、93.9%、92.6%、87.6%和87.3%。干旱情景下,5种林型地表火行为指标随着可燃物处理强度的增大而明显降低(P0.01),白桦林无树冠火发生,其他4种林型树冠火发生可能性及蔓延速度随可燃物处理强度的增大而明显降低(P0.01)。【结论】在一般天气情景和干旱情景下,中强度可燃物处理后,兴安落叶松白桦混交林、白桦林、兴安落叶松天然林和樟子松人工林的地表火蔓延速度均低于1 m·min~(-1),火焰高度低于1 m,兴安落叶松人工林的地表火蔓延速度和火焰高度分别低于人工0.1 m·min~(-1)和0.1m;各林型地表火焰高度低,蔓延速度慢,易于直接扑灭;兴安落叶松白桦混交林和樟子松人工的树冠火发生降幅超过20%,兴安落叶松天然林和人工林地表火蔓延速度减少40%以上,树冠火发生可能降低30%。而高强度可燃物处理后,会影响森林结构及其功能,因此,针对当前主要林型进行中强度的可燃物清理,清理地表未分解的枯落物和易燃灌木草本以及树冠下空间易燃可燃物,就可以有效降低地表火蔓延速度和避免树冠火发生。     

森林可燃物含水率预测及燃烧性等级划分

森林可燃物含水率预测及燃烧性等级划分黑龙江省人民政府森林防火指挥部办公室王瑞君黑龙江省第一林业调查规划设计院于建军吉林省吉林市林业局郑春艳林火预报就是通过测定和计算某些气象因子、人为因素和可燃物含水率等，预报火发生的火险天气、火灾发生以及火灾发生后火...     

Forest Fires and Prevention Strategies in Northwestern Region of China

The paper described the natural conditions and forest types in Northwestern Region of China. Most forests in the region are distributed in subalpine areas. It is important to protect the existent forests in the region for maintaining ecological balance. According to the statistics results of 1991~2000, the paper analyzes the forest fires distribution and fire severity. Annually the numbers of forest fires range from 52 to 240. The incidence rate of forest fires in Northwestern Region is under 0.33 per ten thousand ha. There are 0.67-64.4 ha burned area per ten thousand ha forest. The main reasons for forest fires lie in the dry weather conditions, many firebrands, and high fuel loading. The strategies of fire management in the region are to stress the fire education in forest regions, strength the firebrands' management, emphasize the fuel management, and improve the fire monitoring and fire control ability.     

南方人工林森林火灾发生和危害之评估

根据全国25省区和南方4省区1999～2001年的森林火灾数据,分析评估了南方人工林发生森林火灾的原因、过程和危害的程度;探讨山火防范和控制,减少危害和投资风险的途径,并以肇庆市国有林场过去10年森林火灾发生情况作验证。人工林森林火灾受气候、地区森林覆盖率和特征、人工林特征、经营管理系统等的综合影响,每年10月至次年2月份为干旱季节,森林火灾发生最为频繁。肇庆国有林场过去10年森林火灾面积比率为0．023％0～4、840％0。通过设立健全的森林防火和控制系统,有效的营林管理,南方人工林发生火灾的面积机率可以最大限度地降低,应可以控制在1％以下。     

森林可燃物管理研究进展

立地条件、天气和可燃物决定了森林火灾的强度与烈度, 三大因素中, 只有对可燃物能进行有效的经营管理。研究表明:1)过去60~100年, 由于森林结构和组成的改变, 可燃物载量增加, 易发生高强度的森林火灾。2)林火模型、实践经验以及现场观察表明, 在特定的天气条件下, 林火行为受可燃物结构与组成的影响很大。3)减少重特大森林火灾的发生就必须降低地表可燃物的数量、密度、连续性, 移除过度可燃物, 或改造植被, 降低森林植被的燃烧性等。4)可燃物处理有效期评估涉及林火蔓延、林火强度、烈度、火场规模和扑火能力的研究, 景观尺度手段优于林分尺度。     

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     

Fire Environment Mechanism of Lightning Fire for Daxing''''an Mountains

Lightning fire is one of natural fires; its mechanism is very complex and difficult to control. Daxing'an Mountain is the main region that lightning fires occur in China. Research on lightning fires indicates that special fuel, dry-storm weather and high altitude form the lightning fire environment. Lightning fires have close relation with lights. When lightning occurs, especially dry-lightning which brings little precipitation with surface temperature growing and fuel dehydrating, these often lead to lightning fires. Lightning fires have characteristics of geography, time and topography. The higher altitude forest region in Daxing'an Mountain, the more lightning fires occur. Valley with altitude above 800 m in the north of 51.N and Larix gmelinii-Pinus pumila, Pinus sylvestris var. mongolica -Pinus pumila forests on the top of mountain are the most concentrating region where lightning fires occur. One serial dry-storming can ignites many lightning fires, the furthest between them is as long as 150 km.     

辽东地区森林可被燃物载量的调查研究

森林地被可燃物是引起森林火灾的重要原因，掌握森林地被可燃物的载量分布，对森林火灾的预防有着十分重要的意义。通过对辽东地区不同森林类型的调查，搞清楚了一些常见的主要林型地被可燃物平均载量情况，同时对油松人工砘林、落叶松人工纯林和天然阔叶杂木林3个具有代表性的林型，按不同林分密度、林龄、坡向和坡位等因素，进行地被可燃物载量分布状况调查，结果表明，辽东中、北部地区载量大于辽东南部地区；林分密度和林龄愈大，则载量愈高；南坡载量大于北坡，北坡最小；坡位愈高，则载量愈小。     

Summer Forest Fire Meteorological Environment in the North of Daxingan Mountains

In recent years, especially in the summer of 2002, the most serious forest fires occurred in the Daxingan Mountain of Heilongjiang province and Inner Mongolia. There has been long time serious forest fire environment in summer in Daxingan Mountain. The grass in the forest is scorched for long time drought and the moisture content of litter and turf layer decrease rapidly. The accumulation and dryness of fuel build the summer forest fire environment, which are major caused by Meteorological environment. Human are lack of the right recognition of summer fires, and can not achieve the goal of detecting and fighting in time. Also summer fires have the tendency to increase in some areas of the world and human have to pay much more attention to how to prevent and control summer fires.     

Comparing the role of fuel breaks across southern California national forests

Fuel treatment of wildland vegetation is the primary approach advocated for mitigating fire risk at the wildland-urban interface (WUI), but little systematic research has been conducted to understand what role fuel treatments play in controlling large fires, which factors influence this role, or how the role of fuel treatments may vary over space and time. We assembled a spatial database of fuel breaks and fires from the last 30 years in four southern California national forests to better understand which factors are consistently important for fuel breaks in the control of large fires. We also explored which landscape features influence where fires and fuel breaks are most likely to intersect. The relative importance of significant factors explaining fuel break outcome and number of fire and fuel break intersections varied among the forests, which reflects high levels of regional landscape diversity. Nevertheless, several factors were consistently important across all the forests. In general, fuel breaks played an important role in controlling large fires only when they facilitated fire management, primarily by providing access for firefighting activities. Fire weather and fuel break maintenance were also consistently important. Models and maps predicting where fuel breaks and fires are most likely to intersect performed well in the regions where the models were developed, but these models did not extend well to other regions, reflecting how the environmental controls of fire regimes vary even within a single ecoregion. Nevertheless, similar mapping methods could be adopted in different landscapes to help with strategic location of fuel breaks. Strategic location of fuel breaks should also account for access points near communities, where fire protection is most important.     

Fire Occurrence Environments in Pinus pumila Forests

In recent years, many serious forest fires occurred in precious Pinus pumila forests in Daxing'anling Mountains of Heilongjiang Province and Inner Mongolia. But up to now, there is still a lack of proper understanding of fire occurrence environments in P. pumila forests. In present paper, we investigated and studied the fire occurrence environments. The results showed that fires in P. pumila forests had their own special fire environments. Abundant fuel, drought weather, dry thunder and high altitude terrai...     

Chapter 12. A Wildfire and Emissions Policy Model for the Boise National Forest

Summary

We utilized the Boise National Forest's Hazard/Risk model, along with fire history records and fire behavior models, to estimate the current and anticipated levels of large wildfires and associated greenhouse gas and particulate emissions based on the forest condition and wildfire regime on the BNF. The model indicated that the forests at greatest risk of large, intense wildfires are the dense pondero-sa pine-Douglas-fir forests that make up over 1.1 million acres on the forest. We conclude that without an aggressive treatment program to reduce large areas of contiguous heavy fuel loadings the forest will be burned at an annual average rate of about 7.5% of the remaining at-risk forest. Using recent fire data to develop average patterns of intensity in wildfires within this forest type, we estimate that emissions will average around 1 million tons of carbon (C) per year over the next 20 years as the bulk of the ponderosa pine forests are burned. An aggressive treatment program featuring the removal of fuels where necessary, and prescribed fire as a means of re-introducing fire to these ecosystems, would result in a 30-50 percent reduction in the average annual wildfire experienced in the dense ponderosa pine forests, a 14-35% decrease in the average annual C emissions, and a 10-31% decrease in particulate emissions. We argue that the most effective way to curb emissions is with an aggressive treatment program linked to a landscape-based ecosystem management plan. This would have the effect of breaking up large contiguous landscape patterns so that fires become more patchy and diverse in their environmental impact, resulting in significantly reduced emissions as well as improved landscape diversity.