Fire history recorded on pine trunks and stumps: Influence of land use and fires on forest structure in North Karelia

Dendrochronological dating of fire scars was used to determine the history of forest fires, and the effects of the fires and of slash‐and‐burn cultivation on forest structure were studied in eastern Finland. A total of 67 fire years were dated over an area of 26 km². Forest fires increased towards the end of the 17th century and again towards the end of the 18th century, but decreased markedly in the middle of the 19th century. The mean fire interval was shorter near the historically known slash‐and‐burn cultivation areas than elsewhere. A forest survey map from 1913 was used to reconstruct the forest structure after the cessation of slash‐and‐burn cultivation and forest fires. This map showed that most of the younger forests were situated near old slash‐and‐burn cultivation areas, while the older forests were situated farther away from these. The proportion of deciduous trees decreased with increasing distance from slash‐and‐burn cultivation areas.     

松阳县生物防火林带布设初探

通过对松阳县2000-2010年森林火灾发生情况的分析,将松阳县划分为Ⅰ、Ⅱ、Ⅲ级森林火险区,在行政区划和森林火险等级区划的基础上,结合区域林中空地、防火公路和山脊线分布等主要影响因子,采用分区控制的方法,确定生物防火林带的空间布局:在Ⅰ、Ⅱ级森林火险区内布设规划生物防火林带,将整个防火林带网络分割成2 691个网格,网眼平均面积为34 hm2,其中Ⅰ级火险区有1909个网格,平均网眼面积为28 hm2,Ⅱ级火险区有782个网格,平均网眼面积为48 hm2;生物防火林带总长度为4 587.1 km,防火网络所形成的网络密度为50.1 m/hm2,防火林带设计宽度应不小于15 m,防火网络总面积占区域面积的7.5%。主要造林树种为木荷(Schima superba)、杨桐(Adinandra millettii)、杜英(Elaeocarpus sylvestris)、浙江红花油茶(Camellia Chekiang-oleosa)、杨梅(Myrica rubra)等。     

Multi-source land cover classification for forest fire management based on imaging spectrometry and LiDAR data

Forest fire management practices are highly dependent on the proper monitoring of the spatial distribution of the natural and man-made fuel complexes at landscape level. Spatial patterns of fuel types as well as the three-dimensional structure and state of the vegetation are essential for the assessment and prediction of forest fire risk and fire behaviour. A combination of the two remote sensing systems, imaging spectrometry and light detection and ranging (LiDAR), is well suited to map fuel types and properties, especially within the complex wildland–urban interface. LiDAR observations sample the spatial information dimension providing explicit geometric information about the structure of the Earth's surface and super-imposed objects. Imaging spectrometry on the other hand samples the spectral dimension, which is sensitive for discrimination of surface types. As a non-parametric classifier support vector machines (SVM) are particularly well adapted to classify data of high dimensionality and from multiple sources as proposed in this work. The presented approach achieves an improved land cover mapping adapted to forest fire management needs. The map is based on a single SVM classifier combining the spectral and spatial information dimensions provided by imaging spectrometry and LiDAR.     

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.     

应用无人机森林防火的优势分析与操作规范

为切实加强森林防火防控,遏制重大森林火灾的发生,转变现有的森林防火应急处置机制。分析了应用无人机进行森林防火优缺点,提出了进一步的优化设计与处置思路,可从根本上解决森林防火处置难度大、应急响应慢等问题,为消除林区火灾易燃点排查盲区提供一定的参考。     

生物防火林带的功能与营造技术

指出了生物防火林带的营建缺乏直接经济效益,难以通过政府投资获得资金,从而导致民众积极性较低。因此,生物防火林带的物种选择尤为重要,既要具有耐火特性,又要具有一定的经济价值。重点分析了生物防火林带的功能,探讨了生物防火林带的营造技术,以期为生物防火林带的建设提供思路上的贡献。     

永安市森林火灾的火源分析

分析结果认为，烧荒、烧田边草是引发森林火灾的最主要因素．同时也分析了各种野外火源的发生规律及在不同月份中的分布状况．     

防火林带研究进展

综述了当前生物防火的研究成果,指出防火树种的研究现状及其选择和应用,讨论了防火林带的技术特点和混交造林在森林防火上的应用。防火林带在我国南方林区已发挥了良好的防火效益,并有着广阔的发展前景。对防火机理的研究应当由定性到定量地分析,改变目前树种单一、结构简单的防火林带状况,向多树种、复层结构发展,同时应当提倡多元化造林和林业多种经营。     

落叶栎林对森林火灾的影响分析

根据落叶栎林的特点,着重分析了落叶栎林与森林火灾的关系,结果表明,落叶栎林不仅存在着较强的潜在地表火,而且存在着潜在树冠火危险,是栎林火灾的最大隐患之一。同时还简要分析了栎类由于长期的自然适应而对森林火灾产生的抗火机制。     

林火视频监控中烟识别方法概述

介绍国内外林火监测技术的发展现状,火灾的物理特征,烟图像的火灾监测技术,火灾图像的获取与预处理,火灾图像烟的纹理特征、动态特征、形状特征．认为森林火灾的探测基础理论及技术仍然不够完善,将数字图像处理技术应用到火灾报警上是一种有效的火灾探测手段．