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

Journal of Forestry Research 2014年第4期25卷 857-866页

作者： B.H.Kittur S.L.Swamy S.S.Bargali Manoj Kumar Jhariya Department of Silviculture & Agroforestry College of Forestry Kerala Agriculture University Vellanikara Thrissure Kerala India Department of Forestry College of Agriculture Indira Gandhi Krishi Vishwavidyalaya Raipur (C.G.) 492006 India Department of Botany DSB Campus Kumaun University Nainital–263001 (Uttarakhand) India

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 ma

关键词： forest fire diversity fuel load vegetation structure

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Development of realistic design fire time-temperature curves for the testing of cold-formed steel wall systems

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Frontiers of Structural and Civil Engineering 2014年第4期8卷 427-447页

作者： Anthony Deloge ARIYANAYAGAM Mahen MAHENDRAN School of Civil Engineering and the Built Environment Science and Engineering FacultyQueensland University of Technology

Fire resistance rating of light gauge steel frame(LSF) wall systems is obtained from fire tests based on the standard fire time-temperature curve. However, fire severity has increased in modern buildings due to higher fuel loads as a result of modern furniture and light weight constructions that make use of thermoplastics materials, synthetic foams and fabrics. Some of these materials are high in calorific values and increase both the spread of fire growth and heat release rate, thus increasing the fire severity beyond that of the standard fire curve. Further, the standard fire curve does not include a decay phase that is present in natural fires. Despite the increasing usage of LSF walls, their behavior in real building fires is not fully understood. This paper presents the details of a research study aimed at developing realistic design fire curves for use in the fire tests of LSF walls. It includes a review of the characteristics of building fires,previously developed fire time-temperature curves, computer models and available parametric equations. The paper highlights that real building fire time-temperature curves depend on the fuel load representing the combustible building contents, ventilation openings and thermal properties of wall lining materials, and provides suitable values of many required parameters including fuel loads in residential buildings. Finally, realistic design fire time-temperature curves simulating the fire conditions in modern residential buildings are proposed for the testing of LSF walls.

关键词： fire safety standard fire curve realistic design fire time-temperature curves light gauge steel frame (LSF) walls fire resistance rating fuel load

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Short term effects of fire intensity and fire regime on vegetation dynamic in a tropical humid savanna(Lamto,central Cote d’Ivoire)

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Natural Science 2012年第12期4卷 1056-1064页

作者： A.B.N’Dri J.Gignoux A.Dembele S.Konate Unit of Training and Research in Natural Science Center for Research in EcologyLamto Station of EcologyNangui Abrogoua UniversityAbidjanCote d’Ivoire BIOEMCO(Laboratoire de BIOgeochimie et Ecologie des Milieux COntinentaux)Laboratory UMR-7618University Pierre et Marie CurieCNRSENSParisFrance

We tested the effects of different fire regimes (with different fire date and fuel load) on grass growth, tree debarking and topkill in a Guinea savanna of West Africa. Different fire intensities were simulated on two plots of 3.72 ha each, delimited in two shrubby savanna of the Lamto reserve (C?te d’Ivoire). Two fire regimes were applied, the mid-season fire (January) and the late fire (April). Two fuel levels (single: C1 and double: C2) have been used. For each fire regime, fire intensity was determined. It increases with the fuel quantity (1259 ± 356 kW·m–1 and 3380 ± 1472 kW·m–1 respectively for C1 and C2). The regrowth speed of grasses is also dependent on the fuel quantity (grasses). It increases with it and is higher after the mid-season fire than the late fire. The average intensity of the mid-season fire (2966 ± 2233 kW·m–1) is not significantly different from that of the late fire (1673 ± 1124 kW·m–1). Damages or debarking caused by fire on adult trees were recorded and are linked to fire intensity. Those damages appear to initiate the external cavity observed on trees, known to be detrimental to tree trunk mechanical resistance. They generally affect adult trees of Crossopteryx febrifuga species which is also the most commonly hollowed species. Mid-season fire remains the recommanded fire regime because it insures a faster regrowth of grasses which leads to the maintenance of equilibrium between grasses and trees.

关键词： Fire Intensity fuel load Fire Regime Savanna Vegetation

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