西藏森林火灾扑救窗口期的讨论与建议

森林火灾受多种因素影响,在不同条件下持续变化发展。当火行为强度较小且处于稳定阶段,是扑救森林火灾的灭火窗口期。西藏地区由于气候环境和地形植被的特殊性,火行为与全国其他地方有所不同,呈规律性变化。在组织扑救森林火灾的过程中,可以利用这种规律,提前预判火行为发展,把握火势小且稳定的有利窗口期,集中力量扑灭或控制火情。通过总结近年来扑救西藏地区森林火灾成功案例,介绍火行为变化发展的规律,提出科学判断并合理利用窗口期的思考建议,为安全高效组织灭火救援行动提供参考。

A mathematical model of the temperature in a coalfield fire area

The regular pattern of temperature change in a coalfield fire area while the fire is being extinguished was studied. To determine the extinguishing effect, a series of linear, logarithmic, polynomial or exponential mathematical regression models were constructed using the observed temperature data from the Xinjiang coalfield fire extinguishing project. The quadratic polynomial mathematical model had the best fit. A large coal fire oven was also used to simulate the coal fire extinguishing process. The same mathematical regression experiments were carried out on that observed data. The results verified that the quadratic polynomial mathematical model had the best fit. Therefore, a quadratic polynomial mathematical model is proposed to accurately model the temperature-time relationship in a coalfield fire area. An application to coalfield fire suppression shows that the deduced mathe-matical model can be used to predict the temperature conditions and to determine the effect of fire extinguishing, thereby helping to speed up the fire suppression process in the coalfield fire area.

Small-scale area survey and analysis of Xinjiang's coal field fire in China

In this paper, Xinjiang＇s coal field is selected as the investigation area. Through a series of field surveys in Xinjiang, we made the small-scale area analysis of coal field fire using the ground remote sensing technique, and presented the reasonable evaluation of thermal anomaly conditions of Xinjiang＇s coal field arising from coal self-ignition fires. The results show that the method of small-scale area analysis is available for examining the extinguished actuality of coal fires and detecting fire spots. Therefore, for the selected fire-extlngulshed coal field in Xinjiang, the fire extinguishing effect was effectively analyzed by the means, and the new hidden thermal dangers were sought and diagnosed. For the coal field where the fire has not been extinguished, the utilization of this means approximately identified the severity and range of the fire area, and provided the quantitative and ground references for extinguish engineering.

Tree Planting:How Fast Can It Accelerate Post-fire Forest Restoration?——A Case Study in Northern Da Hinggan Mountains,China

In 1987,a catastrophic fire burned over 1330000 ha in the densely forested area of the Da Hinggan Mountains in the northeastern China.After the fire,intensive management including burned trunk harvesting and coniferous tree planting had been conducted to accelerate forest restoration.To study the long term effect of these activities on forest recovery,we used a simulation modeling approach to study long-term(300 years) forest dynamics under current planting and natural regeneration scenarios.Results indicate that under tree planting scenario in the severely burned area,the dominant species Dahurian larch(Larix gmelinii) can reach pre-fire level(60% of the area) within 20 years and the maximum abundance can reach nearly 90% within 100 years.While under natural regeneration scenario,it needs about 250 years to reach its pre-fire level.From the perspective of timber production,tree planting can bring twice as much timber volume as that under natural regeneration within 300 years,which is the average longevity of L.gmelinii.It needs about 70 years to reach the timber volume of pre-fire level under the planting scenario,whereas it requires at least 250 years to reach the timber volume of pre-fire level under natural regeneration scenario.Another dominant species Asian White birch(Betula platyphylla) responded negatively to the planting of coniferous species.In general,tree planting of coniferous species after fire can greatly accelerate forest restoration in terms of species abundance and target timber volume,with desirable ecological and economic returns.

Exploring seven hundred years of transhumance, climate dynamic, fire and human activity through a historical mountain pass in central Spain

A high-altitude peat sequence from the heart of the Spanish Central System(Gredos range) was analysed through a multi-proxy approach to determine the sensitivity of high-mountain habitats to climate, fire and land use changes during the last seven hundred years, providing valuable insight into our understanding of the vegetation history and environmental changes in a mountain pass close to a traditional route of transhumance. The pollen data indicate that the vegetation was dominated by shrublands and grasslands with scattered pines in high-mountain areas, while in the valleys cereals, chestnut and olive trees were cultivated. Strong declines of high-mountain pines percentages are recorded at 1540, 1675, 1765, 1835 and 1925 cal AD, which may be related to increasing grazing activities and/or the occurrence of anthropogenic fires. The practice of mountain summer farming and transhumance deeply changed and redesigned the landscape of the high altitudes in central Spain(Gredos range) since the Middle Ages, although its dynamics was influenced in some way by climate variability of the past seven centuries.

Seasonal fires shape the germinable soil seed bank community in eastern Mediterranean woodlands

We explored if and how seasonal fires interact with microhabitat type(i.e.under Pistacia shrub,under Cistus shrub or a canopy gap)to influence the composition of the germinable soil seed bank(GSSB)community in a typical eastern Mediterranean woodland.We conducted a field experiment,involving prescribed spring and autumn burns,and thereafter quantified the seed germination patterns using soil samples collected from both burned and adjacent unburned control plots.Soil temperature was significantly higher during autumn burns,while being more variable during spring burns.Fire caused overall reductions in GSSB density,richness and diversity.The reductions in GSSB richness and diversity were significantly stronger under Pistacia and Cistus shrubs located within plots subjected to autumn burns,and these patterns were mainly evident among annuals.GSSB density of dwarf shrubs was higher in samples collected from burned plots,and this pattern was more pronounced in samples collected under Pistacia and Cistus shrubs.Together with the appearance of unique species,seasonal fires led to significant changes in the composition of the GSSB community.Our results illustrate that seasonal fires interact with spatial heterogeneity to influence the composition of the GSSB community mostly via differential effects on the germination densities of annuals and dwarf shrubs.These findings imply that the increase in the frequency of seasonal fires,which has occurred in the eastern Mediterranean basin during the last few decades,may translate into a shift in eco-evolutionary selection pressures,operating on plants inhabiting this unique ecosystem.

Study and Application of Fuel-breaks in Southwest China

All of the plants can be combusted. The mechanism of forest belts resistance is that the tree specieswerent liable to be burned compared with other plant species. In this paper new concepts on fire resistanttrees and fuel-breaks trees were presented. The fire resistance mechanism includes 3 aspects, fire-resistanttree species, rational construction forest belts and environment. Tree crowns can resist fire forwarding.Forest belts can form the environment, which is not easy to fire, and also make fuels distributed discontinuous.The network of forest belts has large area of conifer forest segregated. The ideal fire resistant tree species hadbetter to embrace some characteristics, such as high fire resistance, rational planting and biological characteristics.