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The phenomenon of a fire occurring in nature comes with a very high level of complexity. One central obstacle is the range of scales in such fires. In order to understand wildfires, research has to be conducted across these scales in order to study the mechanisms which drive wildfire behavior. The hazard related to such fires is ever more increasing as the living space of communities continues to increase and infringe with the wildland at the wildland-urban interface. In order to do so, a strong understanding on the possible wildfire behavior that may occur is critical. An array of factors impact wildfire behavior, which are generally categorized into three groups: (1) fuel (type, moisture content, loading, structure, continuity); (2) environmental (wind, temperature, relative humidity, precipitation); and (3) topography (slope, aspect). The complexity and coupling of factors impacting various scales of wildfire behavior has been the focus of much experimental and numerical work over the past decades. More recently, the need to quantify wildland fuel flammability and use the knowledge in mitigating risks, for example by categorizing vegetation according to their flammability has been recognized. Fuel flammability is an integral part of understanding wildfire behavior, since it can provide a quantification of the ignition and burning behavior of wildland fuel beds. Determining flammability parameters for vegetative fuels is however not a straight forward task and a rigorous standardized methodology has yet to be established. It is the intent of this work to aid in the path of finding a most suitable methodology to test vegetative fuel flammability. This is achieved by elucidating the fundamental heat and mass transfer mechanisms that drive ignition and burning behavior of porous wildland fuel beds. The work presented herein is a continuation of vegetative fuel flammability research using bench-scale calorimetry (the FM Global Fire Propagation Apparatus). This apparatus allows a high level of control of critical parameters. Experimental studies investigate how varying external heat flux (radiative), ventilation conditions (forced airflow rate, oxygen concentration, and temperature), and moisture content affect the ignition and burning behavior of wildland fuel. Two distinct ignition regimes were observed for radiative heating with forced convection cooling: (1) convection/radiation for low heating rates; and (2) radiation only for high heating rates. The threshold for the given convection conditions was near 45 kW.m-2. For forced convection, ignition behavior is dominated by convection cooling in comparison to dilution; ignition times were constant when the oxygen flow rate was varied (constant flow magnitude). Analysis of a radiative Biot number including heat losses (convection and radiation) indicated that the pine needles tested behaved thermally thin for the given heating rates (up to 60 kW.m-2). A simplified onedimensional, multi-phase heat transfer model for porous media is validated with experimental results (in-depth temperature measurements, critical heat flux and ignition time). The model performance was adequate for two species only, when the convective Froude number is less than 1.0 (only one packing ratio was tested). Increasing air flow rates resulted in higher heat of combustion due to increased pyrolysis rates. In the given experiments (ventilation controlled environment) combustion efficiency decreased with increasing O2 flow rates. Flaming combustion of pine needles in such environments resulted in four times greater CO generation rates compared to post flaming smoldering combustion. A link was made to live fuel flammability that is important for understanding the occurrence of extreme fire conditions such as crowning and to test if live fuel flammability contributes to the occurrence of a typical fire season. Significant seasonal variations were observed for the ignition and burning behavior of conditioned live pine needles. Variation and peak flammability due to ignition time and heat release rate can be associated to the growing season (physical properties and chemical composition of the needles). Seasonal trends were masked when unconditioned needles were tested as the release of water dominated effects. For wet fuel, ignition time increases linearly with fuel moisture content (FMC, R2 = 0.93). The peak heat release rate decreased non-linearly with FMC (R2 = 0.77). It was determined that above a threshold of 60% FMC (d.w.), seasonal variation in the heat release rate can be neglected. A novel live fuel flammability assessment to evaluate the seasonality of ignition and burning behavior is proposed. For the given case (NJ Pine Barrens, USA), the flammability assessment indicated that the live fuel is most flammable in August. Such assessment can provide a framework for a live fuel flammability classification system that is based on rigorous experimentation in well controlled fire environments.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2003. / Thesis documentation sheet inserted. Appendix reproduces four papers and manuscripts co-authored with others. Includes bibliographical references. Also issued electronically via World Wide Web in PDF format; online version lacks appendix.

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5 pp. / Eight different landscape mulches were tested for their flammability using a propane torch, charcoal briquette, and a cigarette at two different times of the year. Three randomized compete blocks with eight one square meter plots were tested at three locations; Tucson, Prescott, and Flagstaff, Arizona. Each of the mulches was subjected to the heat of a handheld propane torch (15 seconds), a glowing charcoal briquette (five minutes), and a lit cigarette (until burned out). We found that the least dense mulches (pine needles and straw) burned rapidly when subjected to the torch and ignited after the briquette was removed. The medium density mulches (pine bark nuggets and wood chips) had low flame lengths and smoldered. Heavy density mulches (garden compost and shredded bark) only smoldered. The decomposed granite and sod did not ignite or smolder.

3 pp. / Mondell pine should not be planted within a mile of Comandra populations. Infection of pine occurs through needles by spores produced on Comandra, but spores produced on pine cannot re-infect pine. This article gives information about the disease cycle, the symptoms and prevention and control methods for blister rust.

Abstract The results of the comparison of various dissolution methods for sulphur showed, that HNO3 together with H2O2 gave more complete decomposition of organic components than HNO3 alone. The acid procedure with a mixture of HNO3+H2O2 slightly underestimated the S concentrations of plant material. The losses of sulphur were the highest in the dry ashing digestion procedure (HF(DAC)). The Leco combustion technique with infrared (IR) detection gave good precision and accuracy for sulphur. For the determination of heavy metals in plant materials, both the HNO3 and HNO3+H2O2 procedures were especially effective for determining Cr. However, the HNO3+HClO4 procedure gave lower results, and HF and HF(DAC) procedures greater values for Cr. Sulphur accumulation in pine needles around the pulp and paper mills was clearly higher than other points in the Kemi area. For example, within a radius of about 1-1.5 km around the mills of Oy Metsä-Botnia Ab Kemi Mills, the sulphur concentrations for (C) and (C+1) needles were 28 % and 26 % higher than those in the corresponding background samples collected in Kuivaniemi at a distance about 25 km from Kemi. Pine needles do not appeared to be appropriate a method for monitoring the accumulation of Fe, Zn, V and Pb emitted from pulp and paper mills. However, the Ca concentrations in (C+1) needles in the vicinity of the Oy Metsä-Botnia Ab Kemi Mills was 48 % higher than the average Ca concentration calculated from all (C+1) needles; thus it is likely that part of the Ca in the needles is derived from the mills. The regional distribution pattern of Cr and Ni in mosses in the Kemi-Tornio area in 2000 showed clearly that the most polluted area (Cr > 200 μg/g and Ni > 20 μg/g) appeared to lie within a few kilometres of the ferrochrome and stainless steel works of AvestaPolarit Stainless Oy. Within this area, the Cr concentrations in mosses were 4-13 times higher than those outside the urban area of Tornio. The area most polluted by the opencast chromium mining complex (Cr > 200 μg/g and Ni < 20 μg/g) appeared to be in the immediate vicinity of complex. All the 95th percentile values for TSP (total suspended particles) in the mine area of AvestaPolarit Chrome Oy Kemi Mine were below the current Finnish air quality limit value of 300 μg/m3. However, the 98th percentile value exceeded the Finnish air quality guideline value of 120 μg/m3 at one monitoring site. According to leaching studies, the sum of calculated annual airborne pollution impact of water-soluble fraction (H2O) and environmentally mobile (CH3COONH4) fraction from the AvestaPolarit Chrome Oy Kemi Mine was Cr 1.2 kg, Fe 29 kg, Cu 63 kg, Ni 2.5 kg and Cd < 100 mg. According to the homogeneity studies of heavy metal deposition on TSP filters, Cr, Ni, Cu and Fe were non-uniformly distributed over the glass fibre filters. The rsd values varied between 5.4-33.9 % for Cr, between 7.5-35.0 % for Ni, between 3.6-25.9 % for Cu, and between 6.6-19.9 % for Fe.

Aluminum (Al) is a potentially toxic element for humans, animals, and plants. Al emitted from smelter plants is one source of Al that may be responsible for increased exposure to humans and the environment. In this study I investigated whether the Kubikenborg aluminum smelter (Kubal AB) emitted Al to such extent that it can be detected above regional background concentrations in soils and plants. The study was conducted by analyzing O- horizon cores and Scots’ pine (Pinus sylvestris) needles along two transects using X-ray fluorescence spectrometry (XRF). In the O-horizon cores, Al concentrations along the two transects (mean conc. 5250 mg kg-1 in T1 and 3472 mg kg-1 in T2) did not decrease with distance from the smelter. In Scots’ pine needles, Al concentrations (mean conc. 491 mg kg-1 in T1 and 590 mg kg-1 in T2) decreased significantly with distance along transect T2. Aluminum showed high negative co-variance with soil organic matter content (R2 = 0.47) and positive with silicon (Si) and titanium (Ti) in the soil (R = 0.84 and R = 0.86 respectively), suggesting that mineral dust is the main source of Al. However, the Al/Si ratio of the soil decreased with increasing distance from the smelter along T1, indicating a possible additional source of Al besides that of soil dust that may originate from smelter emission. Nevertheless, I found no strong support for detectable Al emissions in humus and Scots’ pine needles near the Kubal AB smelter.