云南阳宗海流域过去13000年植被演替与森林火灾

以云南阳宗海1020 cm长的湖泊沉积物岩芯为研究对象,由7个木屑和树叶残体样的AMS14C测年建立岩芯年代框架,以18~19 cm间隔获取52个样品作花粉/炭屑分析,重建了阳宗海流域过去13000年的植被、气候以及森林火灾历史。研究结果表明,过去13000年植被演替、气候变化和森林火灾可分为5个阶段:1)13200~11000 cal.a B.P.,植被以常绿、落叶阔叶混交林为主,气候温凉湿润,森林火灾多发,后期(12300~11000 cal.a B.P.)随着温度和湿度的降低,森林火灾发生愈加频繁;2)11000~8000 cal.a B.P.,松林扩张,阔叶林缩小,气候较上阶段温暖偏干,森林火灾发生次数明显降低;3)8000~5000 cal.a B.P.,松林和常绿阔叶林占优势,且出现暖热性的枫香林,流域内气温升至13000 cal.a B.P.以来的最高值,湿度进一步降低,但森林火灾发生频率低;4)5000~800 cal.a B.P.,松林扩张至最盛,常绿阔叶林收缩,落叶阔叶林成分增加,气温和湿度均明显下降,森林火灾发生频率有所增加;5)800 cal.a B.P.至今,松林和常绿阔叶林收缩,落叶阔叶成分增加,草本植物中禾本科迅速上升,可能与人类活动有关,森林火灾发生频率低。阳宗海花粉/炭屑记录重建的植被、气候和森林火灾史表明,在滇中地区,落叶阔叶成分易引起森林火灾,冷气候导致多发的森林火灾,冷干气候是宜森林火灾发生的气候条件。     

关于风力发电机组加强火灾探测报警系统与消防系统设计的研究

本文通过分析风力发电机组发生火灾的原因,针对风力发电机组中火灾探测报警系统的特点,提出了适合的火灾探测器;并介绍了风力发电机组火灾探测报警系统设计中要注意的几个原则。     

大兴安岭林区火灾后冻土环境的变化——以古莲河煤矿地区为例

本文通过对我国大兴安岭古莲河煤矿地区火灾后第二年冻土环境的野外调查表明,火灾后气温、地温、蒸发量及风速有明显的增加;湿度、含冰量、含水量有显著的减小。所有这些因子的变化导致了季节融化深度的增加。这些结论说明了森林火灾后冻土环境确实有较大的变化。此外,结合室内试验,本文还对火灾后最大季节融化深度(ξ_(max))进行了预测、由于植被与冻土关系的复杂性,本文对今后的工作提出了自己的看法,以便更完善地研究火灾后冻土环境的变化及对森林生态系统的影响。     

国产高分系列卫星在森林火灾应急处置中的全流程应用——以四川九龙县三岩龙乡“4·08”森林火灾为例

四川西部高山峡谷地貌发育,山高林密且地质环境恶劣,区内林草资源丰富,森林火灾多发、易发、频发,灾害应急处置难度大,防控任务重。国产高分系列卫星影像具有时空分辨率高、载荷类型多、机动性强、幅宽范围大、成像迅速等优点,对川西地区森林防灭火、灾害应急处置及防灾减灾等有明显优势。以2021年四川九龙县三岩龙乡“4·08”森林火灾为例,利用国产高分系列卫星数据分别对森林火灾初期、中期及晚期开展应急处置,包括快速解译林火火灾救援要素(初期)、感知亮温异常态势(中期)、跟踪监测过火区动态(中期)、结合火场需求提供应急扑救部署建议(中期)、开展灾损解译评估(晚期)及火后泥石流易发性评价(火后)等,结果表明国产高分系列卫星对森林火灾应急处置的全流程应用具有实践指导意义。     

森林火灾对典型小流域径流影响模拟

以澳大利亚东南部Mcmahons Creek 流域1983年发生的森林火灾为例,运用AWRA-L和新安江模型模拟火灾后流域的基准径流过程,进而估算火灾对径流的影响。AWRA-L和新安江模型模拟结果表明,火灾发生后14年(1983—1997年)内流域产水量分别增加140 mm和123 mm,占火灾前(1974—1982年)年均径流量的33%和29%;火灾发生14年后的1998—2004年,增加量分别为43 mm和33 mm,占火灾前年均径流量的10%和8%。说明森林火灾引起短期内流域径流量的明显增加,随着植被的恢复流域产流增加量减少,森林砍伐是后期径流增加的重要原因。该研究对森林流域的水资源管理具有重要的参考价值。     

新疆SCZ17剖面黑碳记录的16~12 ka火灾历史及其驱动因素探究

基于新疆深390 cm的SCZ17黄土剖面的黑碳(BC)记录以及总有机碳含量(TOC)和磁化率结果,并与巴里坤湖孢粉记录的温度数据对比,重建了该区末次冰消期(16~12 ka,对应剖面深度202~274 cm)的火灾历史并探讨了其控制因素。结果表明:1)在末次冰消期期间黑碳通量与TOC变化具有较好的一致性,均呈上升趋势,说明随着植被量的增加,生物质燃烧活动增加;2)BC通量与湿度和温度数据的EEMD结果显示:①在13~16 ka期间,剖面的黑碳通量指示的区域生物质燃烧变化与温度变化存在着近乎同步的关系,而在12~13 ka期间可能由于湿度的影响二者的同步关系不太明确;②χfd%所指示的湿度变化和黑碳通量的对比结果显示,湿度峰值/谷值分别对应着黑碳通量的谷值/峰值,即当气候湿润时,火灾活动频率低;气候干旱时,火灾活动频率高。因此,认为研究区火灾活动倾向于发生在暖干的气候条件下,且可燃生物量可能控制着区域火灾变化的长期趋势,而由温度和湿度变化所造成的火灾活动的次一级波动叠加在这一长期趋势上。     

近1100年来小兴安岭火灾演化历史及其对环境变化的响应

为揭示小兴安岭地区火灾长期演化规律,基于一个典型泥炭沉积柱芯的大（>125μm）、中（50～125μm）、小（<50μm）3种炭屑组分记录,分别重建了近1 100年来局地、局域和区域火灾演化历史,并结合区域已有气候、植被和人类活动资料,探讨了其对环境变化的响应机理。研究结果表明,相对暖干的气候条件易引发火灾,但火灾频率和强度分别受草本植物和木本植物相对比例的控制。受此环境条件影响,1 100～900 cal a BP采样泥炭地的局地、局域和区域火灾频率和强度较低,900～570 cal a BP达到最高,随后570～200 cal a BP显著降低。近200 cal a BP来,受人类活动和气温升高的共同驱动,采样地局域和区域火灾频率显著上升,而采样地局地火灾频率和强度相对较低,主要受湿度增加和乔木植物减少的制约。     

古火灾历史重建的研究进展

火是地球系统的重要组成部分,与气候、植被、生物地球化学循环和人类活动密切相关。火对全球气候和生态系统的影响已成为目前全球变化研究的一个热点。火灾发生后会在周围的环境中留下许多燃烧产物,如黑碳、木炭屑、多环芳烃、左旋葡萄糖等,它们广泛存在于海洋、湖泊、河流、土壤和陆地风成沉积物中;还会留下一些火灾痕迹,如树木火疤、土壤磁...     

森林火灾成因、预报监测和人工防止研究

森林火灾是一种频繁发生的自然灾害。除人为林火外,大多数森林火灾是由于高温干旱条件下雷闪电击引起的。而对于雷电闪击林火的预报监测和人工防止,均可采用近代大气科学的最新成果。     

末次间冰期以来兴凯湖黑碳的沉积记录及其环境意义

在我国东北地区,黑碳记录较少,尤其是长时间尺度记录,区域火灾如何响应于气候变化还存在争议。本研究通过对兴凯湖XK08-A2钻孔约336 cm岩芯,共136个沉积物样品的黑碳含量进行了分析,并结合石英光释光和加速器质谱14C测年结果,探讨了末次间冰期以来东北地区火灾历史与古环境的联系。兴凯湖沉积物黑碳含量的平均值在末次间冰期、末次冰期以及全新世分别为0.51±0.10‰、0.68±0.15‰和0.71±0.20‰。兴凯湖沉积物中黑碳含量从下向上呈增加趋势,表明末次间冰期区域火灾的发生频次较低、规模较小,末次冰期火灾的频次升高、规模越来越大,全新世阶段火灾的频次和规模与末次冰期相当。这些变化与轨道尺度东亚夏季风进退以及人类活动密切相关。从末次间冰期到末次冰期,东亚夏季风变化是东北地区火灾发生的主要控制因素。强盛的东亚夏季风带来充沛的降水,促进了低洼地区湿地沼泽的发育,缩短了火风险期,致使发生大规模火灾的概率较低。自然背景下季风降水主导我国东北地区火灾的发生,与黄土高原和西南地区一致,但与欧美地区受温度影响存在显著的空间差异。全新世在人类活动的影响下,虽然东亚夏季风增强,但是区域大规模火灾发生的概率已达到末次冰期的水平。     

Fire Weather in Israel — Synoptic Climatological Analysis

The study examines the synoptic situations and weather conditions under which occurred Israel's largest forest fires between the years 1987–1995. Annual rainfall and maximum temperature were found to have a positive correlation with both the size of the burnt area and the frequency of fires. A negative correlation was found for the relative humidity at 12 UTC for the same parameters. The fire season in Israel starts in May and ends in November, the peak months being May, June and July. No large fires were observed during the rainy season, December–February, despite the relatively low precipitation characterizing the region. Atmospheric disturbances as well as quasi-stationary systems were found to be favorable for the development of forest fires in Israel: the North African (‘Sharav’) cyclone and the Red Sea trough, which are common during spring and autumn. These systems carry hot, dry air from the deserts and are responsible for 55% of the burnt area from major forest fires in Israel and up to 33% of the major forest fires. Sixty-five percent of the forest fires occurred during the summer all of them under the quasi-stationary system of the Persian Gulf trough. These fires did not spread as widely as those that occurred under the North African cyclone and the Red Sea trough systems. The role of weather in the propagation of fire is exemplified in the case study of the ‘Sha'ar ha Gai’ fire of July 1995 — the biggest forest fire in the history of Israel (1300 ha). This revised version was published online in July 2006 with corrections to the Cover Date.     

Dynamics of forest fires and climate in Ilmen nature reserve, 1948–2013

This paper considers the impact of climatic factors on the forest fire rate in Ilmen State Reserve based on 66 years of direct observation data for 1948–2013. This period was marked by a gradual annual increase in the number of recorded fires in the reserve. The higher fire rate is generally related to lengthening of the fire season and more frequent fires in the spring and summer–early autumn periods. We did not obtain sufficient evidence to verify a relation of the higher fire rate to climate changes. The average monthly and seasonal weather conditions can be involved to explain only some causes of the interannual fire rate variability. The observed changes in some climatic characteristics could have contributed to an increase in the fire rate, while others could have reduced it.     

Evaluating the persistence of post‐fire residual patches in the eastern Canadian boreal mixedwood forest

In boreal forest ecosystems, wildfire severity (i.e. the extent of fire‐related tree mortality) is affected by environmental conditions and fire intensity. A burned area usually includes tree patches that partially or entirely escaped fire, called ‘residual patches’. Although the occurrence of residual patches has been extensively documented, their persistence through time, and thus their capacity to escape several consecutive fires, has not yet been investigated. Macroscopic charcoal particles embedded in organic soils were used to reconstruct the fire history of 13 residual patches of the eastern Canadian boreal mixedwood forest. Our results display the existence of two types of residual patches: (i) patches that only escaped fire by chance, maybe because of local site or meteorological conditions unsuitable for fire spread (random patches), and (ii) patches with lower fire susceptibility, also called ‘fire refuges’ that escaped at least two consecutive fires, probably because of particular site characteristics. Fire refuges can escape fire for more than 500 years, up to several thousand years, and probably burn only during exceptionally severe fire events. Special conservation efforts could target fire refuges owing to their old age, long ecological continuity and potential specific biological diversity associated to different microhabitats.     

Long-term Trends in Vegetation Dynamics and Forest Fires in Brandenburg (Germany) Under a Changing Climate

The human influence on environmental processes has been described for many types of land use. One of the oldest tools to modify people’s environment is fire, which has dominated fire regimes in many regions over long time scales. This paper focuses on a German case study region, where 80–90% of the fires are human-caused. The objectives of this study are the application of the Regional Fire Model (Reg-FIRM), a process-based fire model that is incorporated into the LPJ Dynamic Global Vegetation Model, to temperate forests under historic climate conditions and to explore ranges of potential impacts of future climate change on fire and vegetation dynamics. Simulation experiments are designed to simulate historic fire pattern and to explore influences of vegetation on fire. Simulated fire pattern reproduced the observed average fire conditions reasonably well although with a smaller amplitude. This leads to underestimation of extreme fire years as well as an overestimation of low fire years. Vegetation composition influenced fire spread conditions in the temperate forest and had little impact on fire ignition potentials, except when only broad-leaved deciduous forests were assumed. Fire is likely to change under climate change conditions. Simulated experiments were conducted to explore the effects of climate change and rising CO₂ concentration given the potential natural vegetation as the best-case for Brandenburg. Three GCM scenarios predicting different future climatic changes were applied, and resulted in quantitatively different future fire patterns. Depending on future precipitation pattern and the influence of the CO₂ effect on canopy conductance and thus litter moisture, fire was predicted to either decrease or slightly increase in Brandenburg forests, but the burnt area would not exceed current, extreme fire years. Generally, fire changes had no implication for vegetation composition in Brandenburg, but reduced vegetation carbon gain after 2050. In the HadCM3 application, simulated increase in grass cover due to a large burnt area after 2075 accelerated fire spread conditions, thus still increasing the burnt area, while climatic fire danger and number of fires already began to decline. These interactions underline the importance to consider the full range of fire processes and interactions with vegetation dynamics in a simulation model.     

Predictive analysis of fire frequency based on daily temperatures

Frequent fires can affect ecosystems and public safety. The occurrence of fires has varied with hot and cold months in China. To analyze how temperature influences fire frequency, a fire dataset including 20,622 fires and a historical weather dataset for Changsha in China were gathered and processed. Through data mining, it was found that the mean daily fire frequency tended to be the lowest in the temperature range of (20 °C, 25 °C] and should be related to the low utilization rate of electricity. Through polynomial fitting, it was found that the prediction performance using the daily minimum temperature was generally better than that using the daily maximum temperature, and a quadruplicate polynomial model based on the mean daily minimum temperature of 3 days (the day and the prior 2 days) had the best performance. Then, a temperature-based fire frequency prediction model was established using quadruplicate polynomial regression. Moreover, the results are contrary to the content stipulated in China’s national standard of urban fire-danger weather ratings GB/T 20487-2006. The findings of this study can be applied as technical guidance for fire risk prediction and the revision of GB/T 20487-2006.

     

Forest fire spread simulation algorithm based on cellular automata

Traditional models result in low efficiency and poor accuracy when simulating the spread of large-scale forest fires. We constructed an improved model that couples cellular automata with an existing forest fire model to ensure better time accuracy of forest fire spread. Our model considers the impact of time steps on simulation accuracy to provide an optimal time step value. The model was tested using a case study of forest fire spread at Daxing’an Mountain in May 2006. The results show that the optimal time step for the forest fire spread geographic cellular automata simulation algorithm is 1/8 of the time taken for cellular material to be completely combusted. When compared with real fire data from Landsat Thematic Mapper (TM) images, our model was found to have high temporal and spatial consistency, with a mean Kappa coefficient of 0.6352 and mean accuracy of 87.89%. This algorithm can be used to simulate and predict forest fire spread and is also reversible (i.e., it can identify fire source points).     

基于MapGIS的森林防火监测预警系统设计与实现

快速、准确的进行林火火源监测及定位可以有效缩短扑救时间,降低林业资源损失和自然环境污染.为了解决这一问题,采用地理信息系统(geographic information system, GIS)和遥感(remote sensing, RS)作为研究手段、运用实例研究的方法,以MapGIS开发平台为基础,设计并开发“森林防火监测预警系统”.“遥感影像定位”和“视频图像定位”作为两种常用的监测定位手段,可以从宏观和微观的不同角度互补;火险等级预报为监测重点提供参考依据;火势推演分析紧密结合气象信息和植被信息模拟火场扩散情况.结果表明,GIS在森林防火监测定位方面不仅有着良好的可视性,其强大的空间分析特性尤为突出,对促进森林防火管理的信息化、科学化起到十分重要的作用.      

Environmental change and fire history of southern Patagonia (Argentina) during the last five centuries

Geochemical, geophysical, charcoal and pollen analyses from the very poorly investigated southern Patagonian steppe area show that in the vicinity of Laguna Potrok Aike (Santa Cruz Province, Argentina) and north of the Strait of Magellan the detectable impact of Europeans as explorers, settlers and farmers on fire intensity, vegetation and lake ecosystems started with first regional signs during the 1840s. A massive anthropogenic impact on a supra-regional scale followed as the result of the introduction of sheep farming at the end of the 19th century. Furthermore, since the first European explorations, fires in the steppe areas of southernmost Patagonia as recorded at Laguna Potrok Aike occurred contemporaneously in the steppe-forest ecotone further west and probably also in the Andean forest itself. Environmental changes which are not caused by anthropogenic influence are also revealed and were most likely the result of temperature variations and enhanced and reduced wind speeds, respectively. A fire event around AD 1600, before the arrival of European settlers, occurred during a dry period in the forest and steppe-forest ecotone and followed a wet phase in the steppe that caused favorable ignition conditions in all environments.