bluuebunny/crossref_metadata_2025 huggingface dataset:
Soil characteristics at a long-term ecological research site in Taylor Valley, Antarctica
Authors: Campbell I. B.
Published: August 2003

Soils at a Long Term Ecological Research site near Lake Hoare in Taylor Valley, Antarctica, were investigated during November/December 1999. The soils alongside 6 experimental plots at the research site were described, repeatedly sampled over a 17-day period, and the gravimetric water content, particle size, and conductivity determined daily. At one nearby location, the soil water content was repeatedly measured after a plot irrigation, while at another, the water content of soil adjacent to a snow patch was repeatedly measured to determine the rate of water loss during thawing of snow. Soils at 2 sites at higher elevations outside the research area were also examined for comparison.The soils at the experimental plots were generally similar but differed in stoniness, the presence of occasional silty layers, and the depth to ice-cemented ground. Water contents (gravimetric) of surface horizons were <0.5% and increased with depth through the active layer to 12% or greater in the ice-cemented permafrost. There were small variations in the water content of surface horizons over the 17-day sampling period with larger variations at depth. A few siltier horizons had higher water contents. The water content profiles and <2 mm% particle size trends were broadly similar for all the sites. Conductivities were low, except in silty horizons where values were markedly higher. At the irrigated site, water was progressively lost over the first 9 days, after which values were close to those at unirrigated sites. There was a less marked loss of water from the soil alongside the thawing snow patch but an increased loss after all snow had thawed. The higher elevation soils outside the experimental area were more weathered and had higher salinities indicating a significantly greater soil age.Small changes in water content in the surface horizons appeared to be related to changing weather conditions, whereas at greater soil depth, changes in the water content corresponded with the increasing thawing depth. The results illustrate the dynamic nature of soil moisture over short periods of time in Antarctic Cold Desert soils.
Soil nematode responses to year-to-year variation of low levels of heavy metals
Authors: Yeates G. W. , Percival H. J. , Parshotam A.
Published: August 2003

The composition of the nematode assemblage in pasture plots that received sewage sludge amended with 4 rates of Cu, Ni, or Zn was assessed in 5 years; the highest rate of application of each metal was near the New Zealand regulatory limit. The activity of heavy metals in soil solution was determined at each sampling. In terms of management, pasture conditions in 1999 and 2000 were most settled, and while the activities of Cu, Ni, and Zn explained some 44% of variance in total nematodes, there were few significant correlations between nematode genera and individual heavy metals. Both Cu and Zn depressed nematode diversity (H′) and the decomposition index. There were, however, no consistent effects on any nematode functional group. Over the 5 years sampled there were few consistent correlations between soil nematodes and heavy metal activity, the greatest being significant depression of H′ by Zn in 3 years. There was no effect on the total maturity index. Although the few significant effects may reflect the relatively low heavy metal activities, a detailed analysis of heavy metal impact on the nematode assemblage, and thus its contribution to soil processes, would require relating the 6 functional groups to their food resources in the various plots.
Role of inorganic and organic soil amendments on immobilisation and phytoavailability of heavy metals: a review involving specific case studies
Authors: Bolan N. S. , Duraisamy V. P.
Published: August 2003

Soil is not only considered as a 'source' of nutrients for plant growth, but also as a 'sink' for the removal of contaminants from industrial and agricultural waste materials. The origin of heavy metal contamination of soils may be anthropogenic as well as geogenic. With greater public awareness of the implications of contaminated soils on human and animal health, there has been increasing interest amongst the scientific community in developing cost-effective and community-acceptable remediation technologies for contaminated sites. Unlike organic contaminants, most metals do not undergo microbial or chemical degradation, thereby resulting in their accumulation in soils. The mobilisation of metals in soils for plant uptake and leaching to groundwater can, however, be minimised through chemical and biological immobilisation. Recently there has been increasing interest in the immobilisation of metals using a range of inorganic compounds, such as lime and phosphate (P) compounds, and organic compounds, such as 'exceptional quality' biosolids. In this review paper, the results from selected New Zealand studies on the potential value of a range of soil amendments (phosphate compounds, liming materials, and biosolids) in the immobilisation of cadmium (Cd), chromium (Cr), and copper (Cu) is discussed in relation to remediation of contaminated soils. These case studies have indicated that lime is effective in reducing the phytoavailability of Cd and Cr(III), phosphate compounds are effective for Cd, and organic amendments are effective for Cu and Cr(VI). The mechanisms proposed for the immobilisation and consequent reduction in the phytoavailability of metals by the soil amendments include: enhanced metal adsorption through increased surface charge (e.g. phosphate-induced metal adsorption), increased formation of organic and inorganic metal complexes (e.g. cadmium-phosphate complex and copper-organic matter complex), precipitation of metals (e.g. chromic hydroxide), and reduction of metals from higher valency mobile form to lower valency immobile form [e.g. Cr(VI) to Cr(III)]. These case studies indicated that since bioavailability is the key factor for remediation technologies, chemical or biological immobilisation of metals may be a preferred option.
Fertiliser contaminants in New Zealand grazed pasture with special reference to cadmium and fluorine — a review
Authors: Loganathan P. , Hedley M. J. , Grace N. D. , Lee J. , Cronin S. J. , Bolan N. S. , Zanders J. M.
Published: August 2003

Phosphorus (P) fertilisers are an essential input for the economic production of legume-based pastures in New Zealand (NZ) and Australia, but they often contain some unwanted elements that can contaminate the soil, thereby creating potential risks to the health of grazing animal, food quality, and soil quality. Fluorine (F) and cadmium (Cd) are considered to be the elements of most concern. Incidences of F toxicity (from direct ingestion of fertiliser), and accumulation of Cd in offal products above the maximum permissible concentration (MPC) set by the food authorities, have been reported in NZ. Similarly, Cd concentrations in some food grains may exceed the newly proposed MPCs by the Australian and New Zealand Food Authority. Cadmium and F continue to accumulate in the topsoils of NZ and Australian pastures as a result of P fertiliser use. The mobility of both these elements in soils is low and is similar to that of P. Risk of ground water contamination from F and Cd applied to most NZ pastures is low. The plant uptake of these elements, especially F, is also low in most pastoral soils. Cadmium accumulates mainly in liver and kidney of grazing animals mostly through herbage ingestion, whereas F accumulates mainly in the bones of these animals, mostly through soil ingestion. Soil ingestion is highest during the wetter winter months and at high stocking rates. Models have been developed to assess the impact of fertiliser use on the potential risks associated with F and Cd accumulation in soils. Measures to control F and Cd accumulation in soils, plants, and grazing animals are presented and future research needs are identified.
Estimating a nitrous oxide emission factor for animal urine from some New Zealand pastoral soils
Authors: Klein Cecile A. M. de , Barton Louise , Sherlock Robert R. , Li Zheng , Littlejohn Roger P.
Published: August 2003

The Intergovernmental Panel on Climate Change methodology estimates that over 50% of total nitrous oxide (N2O) emissions in New Zealand derive from animal excreta-N deposited during grazing. The emission factor for excreta-N as used by this methodology has an important impact on New Zealand's total N2O inventory. The objectives of this study were to refine the N2O emission factor for urine by simultaneously measuring N2O emissions from 5 pastoral soils of different drainage class, in 3 different regions in New Zealand following a single application of urine; plus test various aspects of the soil cover method for determining emission factors. Cow urine and synthetic urine was applied to pastoral soils in autumn 2000 and N2O emissions were measured using closed flux chambers at regular intervals for 4–18 months following application. The N2O emission factors for cow urine estimated for the first 4 months after urine application varied greatly depending on rainfall and soil drainage class, and ranged from 0.3 to 2.5% of the urine-N applied, suggesting that adopting a single emission factor for New Zealand may be inappropriate. The largest emission factor was found in a poorly drained soil, and the lowest emission factor was found in a well-drained stony soil. Ongoing measurements on one of the soils resulted in an increase in emission factors as the N2O emissions had not reached background levels 4 months after urine application. To characterise urine-induced N2O emissions, we recommend measurements continue until N2O emissions from urine-amended soil return to background levels. Furthermore, we recommend using real animal urine rather than synthetic urine in studies when determining the N2O emission factor for urine.
Modelling water uptake by a mature apple tree
Authors: Green S. R. , Vogeler I. , Clothier B. E. , Mills T. M. , Dijssel C. van den
Published: August 2003

We report the results from a field experiment in which we examined the spatial and temporal patterns of water uptake by a mature apple tree (Malus domestica Borkh., 'Splendour') in an orchard. Time domain reflectometry was used to measure changes in the soil's volumetric water content, and heat-pulse was used to monitor locally the rates of sap flow in the trunk and roots of the tree. The tree's distribution of root-length density and supporting data to characterise the soil's hydraulic properties were determined for the purpose of modelling soil water movement in the root-zone under an apple tree. Experimental data are compared against the output from a numerical model of the soil water balance that uses Richards' equation for water flow, and uses a distributed macroscopic sink term for root uptake. In general, there was a very good agreement between the measured and modelled results. The apple trees consumed some 70 L of water per day during the middle of summer. The daily water use declined to about 20 L per day with the onset of autumn, coinciding with a reduced evaporative demand and an increasing number of rain days. Water movement in the root-zone soil was dominated by the water uptake via surface roots. Large changes in soil water content were also associated with each irrigation event. Our experimental data support the contention that more frequent irrigation in smaller doses will result in less water percolating through the root-zone. Such an irrigation strategy should make more efficient use of water by minimising the leaching losses. It will also be helpful for environmental protection by reducing the percolation losses of water and solute beyond the grasp of the roots.
Progress in selected areas of rhizosphere research on P acquisition
Authors: Trolove S. N. , Hedley M. J. , Kirk G. J. D. , Bolan N. S. , Loganathan P.
Published: August 2003

Large reserves of P have accumulated in soils of developed countries because additions of P fertiliser to sustain agricultural production have exceeded crop removal. By contrast, in many developing countries in the tropics and subtropics, soil P reserves are gravely low and large additions are required before maintenance requirements begin to decline. In addition, the cost of P fertiliser will increase as the currently accessible deposits of high-grade phosphate rock (PR) diminish. Developing plants that efficiently tap soil P reserves and low grade PR is therefore a priority for agricultural research. For the 50th anniversary of the New Zealand Soil Science Society, this paper reviews research on P efficiency in plants, conducted by staff, students, and research associates of Massey University, in the context of other research into plant mechanisms that enhance P uptake, including effects of root geometry, mycorrhizal associations, and root-induced changes in the soil. Techniques for fractionation of soil P are highlighted.
Phytoremediation: using plants as biopumps to improve degraded environments
Authors: Robinson Brett , Green Steve , Mills Tessa , Clothier Brent , Velde Marijn van der , Laplane Raphael , Fung Lindsay , Deurer Markus , Hurst Sarah , Thayalakumaran Thabo , Dijssel Carlo van den
Published: August 2003

Plants pump large amounts of water, solutes, and organic matter as part of their normal physiological processes. This pumping action can be exploited to improve degraded environments by stabilising, removing, or breaking-down contaminants in the substrates. In addition, soil amendments such as fertilisers and microbes may also be added to enhance the efficacy of the operation. Basic plant physiology sets limits on the capacity of phytoremediation. However, combining this technology with the production of saleable products may render the extra time needed for clean-up relatively unimportant. Phytoremediation is still poorly developed, particularly the phytoextraction of heavy metals. Continual innovation will greatly expand the scope and efficacy of phytoremediation. The greatest potential use for this technology may be in developing countries that have the highest levels of environmental degradation, and scant funds for remediation. Phytoremediation could provide a low-cost and sustainable way to improve local economies. Here a case study is reported on the phytoremediation of a 3.6 ha sawdust pile that was leaching unacceptable amounts of boron (B) into local waterways. High water-use poplars were used to control leaching and potentially remove B from the site via phytoextraction. Selected trees that are coppiced before leaf-fall could be mulched and used to provide 'organic' B on nearby orchards that are deficient in this element.
Application of municipal and industrial residuals in New Zealand forests: an overview
Authors: Magesan Gujja N. , Wang Hailong
Published: August 2003

Large quantities of wastewater are generated from municipal and industrial sources in New Zealand. More stringent discharge standards and recent improvements in wastewater treatment technology have contributed to the production of large quantities of solid residuals. Increasing public, cultural, and regulatory pressures to protect water quality have resulted in significant interest in applying residuals to plantation forests.In a well-managed land application site, the forest ecosystem can efficiently handle organic contaminants and recycle nutrients provided through the residuals, resulting in significant increase in plant growth. Due to large variations in characteristics of different residuals, land application system design must be tailored to match a particular residual with the assimilation capacities of a particular soil–plant system. In New Zealand, many wastewater irrigation systems are employed in forested land as an alternative treatment of liquid residuals. In recent years, large-scale forested land application of municipal and pulp and paper industrial solid residuals have also increased as a preferred alternative to landfilling. It has been suggested that natural abundance of 15N can be used to trace the fate of residual-derived N in the ecosystems. This technique can resolve one of the main environmental concerns associated with application of residuals in forested land, namely nitrate leaching. Intensive research indicates that significant economic and social benefits can be achieved with minimal adverse impact on the receiving environment. This paper provides an overview of the research issues associated with application of residuals on forested soils in New Zealand, such as sustainability, beneficial effects, and potential adverse impacts on soil and environmental quality. Performances of 4 case studies, representing application of 2 liquid residuals and 2 solid residuals to forested soils in New Zealand, are discussed.
Modeling potential erosion due to the Cerro Grande Fire with a GIS-based implementation of the Revised Universal Soil Loss Equation
Authors: Miller Jay D. , Nyhan John W. , R. Yool Stephen
Published: August 2003

Erosional processes directly influenced by wildland fire include reduction or elimination of above- ground biomass, reduction of soil organic matter, and hydrophobicity. High fuel loads promoted by decades of fire suppression in the U.S. increase the duration and intensity of burning, amplifying these effects. The Cerro Grande fire (6–31 May 2000) consumed approximately 15 000 hectares around and within the town of Los Alamos, New Mexico, USA. Private and public infrastructure including Los Alamos National Laboratory are at continuing risk due to increased threats of upstream erosion. We use a geographic information system (GIS) based implementation of the Revised Universal Soil Loss Equation (RUSLE) to model pre- and post-fire soil loss conditions and aid erosion risk analysis. Pre- and post-fire vegetation cover data layers were generated from Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM) data. Based upon annual average rainfall amounts we estimate that subwatershed average pre-fire erosion rates range from 0.45 to 9.22 tonnes ha–1 yr–1 while post-fire erosion rates before watershed treatments range from 1.72 to 113.26 tonnes ha–1 yr–1. Rates are approximately 3.7 times larger for 50 year return interval rainfall amounts. It is estimated that watershed treatments including reseeding will decrease soil loss between 0.34 and 25.98% in the first year on treated subwatersheds. Immediately after the fire an interagency Burned Area Emergency Rehabilitation (BAER) team produced initial estimates of soil erosion. Our estimates of average erosion rates by subwatershed were in general larger than those initial estimates.
Effects of fire season and intensity on Prosopis glandulosa Torr. var. glandulosa
Authors: Drewa Paul B.
Published: August 2003

In pyrogenic ecosystems, responses of resprouting woody vegetation may depend more on fire season than on intensity. I explored this hypothesis by examining fire season and intensity effects on response of Prosopis glandulosa, a resprouting shrub in Chihuahuan desert grasslands of the south-western United States. Clipping as well as low and high intensity fires (natural and added fuels, respectively) were applied during the 1999 growing season and the 2000 dormant season. Both fire season and intensity affected shrub responses. Numbers of resprouts increased 16%, and heights increased 8% after dormant season versus growing season treatments of fire and clipping combined. Height and resprout number decreased with increased fire intensity. Fire season and intensity effects on canopy area and stem growth were generally not detected. My results do not support the above hypothesis. Instead, fire season and intensity influence shrub responses in different ways via different mechanisms. Prosopis glandulosa has the potential to respond more after dormant season than growing season fires, perhaps as determined by carbohydrate availability in underground organs at the time of fire. However, realization of this potential is contingent on fire intensity as influenced primarily by fuel amount. In turn, fire intensity will determine the amount and duration of heat penetration into soils and thus the amount of damage to growing points of under-ground organs.
Assessing canopy fuel stratum characteristics in crown fire prone fuel types of western North America
Authors: Cruz Miguel G. , Alexander Martin E. , Wakimoto Ronald H.
Published: August 2003

Application of crown fire behavior models in fire management decision-making have been limited by the difficulty of quantitatively describing fuel complexes, specifically characteristics of the canopy fuel stratum. To estimate canopy fuel stratum characteristics of four broad fuel types found in the western United States and adjacent areas of Canada, namely Douglas-fir, ponderosa pine, mixed conifer, and lodgepole pine forest stands, data from the USDA Forest Service's Forest Inventory and Analysis (FIA) database were analysed and linked with tree-level foliage dry weight equations. Models to predict canopy base height (CBH), canopy fuel load (CFL) and canopy bulk density (CBD) were developed through linear regression analysis and using common stand descriptors (e.g. stand density, basal area, stand height) as explanatory variables. The models developed were fuel type specific and coefficients of determination ranged from 0.90 to 0.95 for CFL, between 0.84 and 0.92 for CBD and from 0.64 to 0.88 for CBH. Although not formally evaluated, the models seem to give a reasonable characterization of the canopy fuel stratum for use in fire management applications.
Wildland firefighter load carriage: effects on transit time and physiological responses during simulated escape to safety zone
Authors: Ruby B. C. , III G. W. Leadbetter , Armstrong D. W. , Gaskill S. E.
Published: August 2003

The purpose of this investigation was to determine the effects of load carriage on transit time during simulated escape route evacuation. Subjects (8 males, 5 females) completed two maximal field hikes in random order on two successive days (16 kg [35 lb] line gear pack trial and no pack trial). Subjects carried a fire shelter and a Pulaski (the most commonly used fireline construction tool in the United States, consisting of a hoe/ax combination with an 80 cm handle) during each trial. Trials were completed on a dirt trail 660.5 m in length with a vertical rise of 137 m (average grade = 20.75%). Expired air samples were analysed continuously during each trial (Cosmed K4 or Aerosport VO2000). Blood samples were collected before and 2 min after exercise for lactate analysis. Transit time was significantly faster during the No pack trial, representing a 21.5 and 26.3% faster transit time for males and females, respectively. For the males, mean VO2 was higher during the No pack trial. The difference in blood lactate (peak–rest) was significantly higher during the Pack trial for the male subjects. High correlations between peak VO2 (L min–1) and transit rates were noted (r = 0.82 for the Pack trial and 0.87 for the No pack trial), indicating the contribution of aerobic fitness to transit time. These data suggest that escape routes should include a physical strain index related to load carriage, distance and slope and that line gear weight standards should be further evaluated.
Power of the fire—a thermodynamic analysis
Authors: Nelson, Jr. Ralph M.
Published: August 2003

G. M. Byram (1959) proposed a method for computing the ratio of the vertical flux of buoyancy generated by a wildfire (power of the fire Pf ) to the horizontal flux of kinetic energy due to the atmospheric winds (power of the wind Pw). Utilizing this power ratio in his case studies of wildfires, Byram concluded that when the ratio exceeds unity for at least 0.3 km above the fire, phenomena associated with blowup behavior such as firewhirls, spotting, and strong indrafts occur. Though Byram made this claim over 40 years ago, there has been little effort on the part of fire researchers to test it. Byram's calculation of Pf describes an ideal case—a fire that burns in a neutrally stable atmosphere and does not entrain atmospheric air into its convection column. In the present paper, these restrictions are relaxed and Byram's calculations are repeated for a fire whose column entrains air from a non-neutral atmosphere. The new model yields a Pf that is smaller than Byram's Pf by a factor of about 2, is weakly dependent on stability, and is independent of entrainment above a height of 0.5 km. Both models are moderately restricted in that column processes involving liquid water are not considered.
Assessing forest fire potential in Kalimantan Island, Indonesia, using satellite and surface weather data
Authors: Sudiana Dodi , Kuze Hiroaki , Takeuchi Nobuo , Burgan Robert E.
Published: August 2003

An algorithm for assessing forest fire potential is tested for Kalimantan Island, Indonesia. It is based on a fuel model map modified from the US-National Fire Danger Rating System (US-NFDRS), Normalized Difference Vegetation Index (NDVI), and weather data. The Indonesian fuel model map was derived using the global 4-minute land cover data set consisting of 13 classes. The NDVI data were derived from the global 4-minute NOAA-AVHRR data. The output is presented as a monthly Fire Potential Index (FPI) from 1981 to 1993 and compared with trends in fire occurrences over the same time period. A case study illustrates correlation between the FPI and the hot-spot distribution derived from AVHRR data, as well as between the FPI and the Total Ozone Mapping Spectrometer (TOMS) Aerosol Index.
Fire ecology of Mexican pines and a fire management proposal
Authors: Rodríguez-Trejo Dante Arturo , Fulé Peter Z.
Published: August 2003

Many Mexican pine ecosystems are characterized by great biological diversity and are strongly influenced by fire. We summarize fire ecology information for 35 taxa (including infraspecific taxa) in terms of nine types of fire traits: serotiny, seed germination after fire, grass stage, fast initial growth, thick bark, protected buds, self-pruning capacity, resprouting, and canopy recovery from scorch. The majority of Mexican pine species appear to be adapted to a predictable, stand-thinning fire regime. Current fire regimes are often altered from long-term historical patterns due to a combination of natural fires plus anthropogenic fires. Human-caused fires are the most common and burning practices have deep historic and socioeconomic roots. As a consequence, there are three main categories of fire conditions: (1) pine forests endangered by excessive anthropogenic fire (eventually leading to deforestation); (2) pine forests maintained by an appropriate fire regime; and (3) pine forests with insufficient fire or fire exclusion due to fire protection. For managers, conservationists, and landowners concerned with maintaining the important benefits associated with fire, such as fuel hazard reduction and nutrient cycling, different approaches are needed. While recognizing the difficult social and economic factors that foster forest degradation, we recommend basing fire management in pine forests upon a site-specific and species-specific understanding of the historical and ecological role of fire, trying to reduce excessive anthropogenic burning, maintain appropriate burning, and restore fire into fire-excluded forests. The interaction of fire with other resource uses, such as timber harvesting and livestock grazing, should also be balanced in a holistic ecosystem management approach. These changes must be made in the context of seeking alternative economic options for rural residents and by thoughtful planning to obtain as many ecological and economic benefits from fire as possible while minimizing negative impacts.
Reaction times and burning rates for wind tunnel headfires
Authors: Nelson, Jr. Ralph M.
Published: August 2003

Catchpole et al. (1998) reported rates of spread for 357 heading and no-wind fires burned in the wind tunnel facility of the USDA Forest Service's Fire Sciences Laboratory in Missoula, Montana for the purpose of developing models of wildland fire behavior. The fires were burned in horizontal fuel beds with differing characteristics due to various combinations of fuel type, particle size, packing ratio, bed depth, moisture content, and wind speed. In the present paper, fuel particle and fuel bed data for 260 heading fires from that study (plus as-yet unreported combustion efficiency and reaction time data) are used to develop models for predicting fuel bed reaction time and mass loss rate. Reaction time is computed from the flameout time of a single particle and fuel bed structural properties. It is assumed that the beds burn in a combustion regime controlled by the rate at which air mixes with volatiles produced during pyrolysis, and that not all air entering the fuel bed reaction zone participates in combustion. Comparison of reaction time and burning rate predictions with experimental values is encouraging in view of the simplified modeling approach and uncertainties associated with the experimental measurements.
A review of prescribed burning effectiveness in fire hazard reduction
Authors: Fernandes Paulo M. , Botelho Hermínio S.
Published: August 2003

Wildfire hazard abatement is one of the major reasons to use prescribed burning. Computer simulation, case studies, and analysis of the fire regime in the presence of active prescribed burning programs in forest and shrubland generally indicate that this fuel management tool facilitates fire suppression efforts by reducing the intensity, size and damage of wildfires. However, the conclusions that can be drawn from the above approaches are limited, highlighting the need for more properly designed experiments addressing this question. Fuel accumulation rate frequently limits prescribed fire effectiveness to a short post-treatment period (2–4 years). Optimisation of the spatial pattern of fire application is critical but has been poorly addressed by research, and practical management guidelines are lacking to initiate this. Furthermore, adequate treatment efforts in terms of fire protection are constrained by operational, social and ecological issues. The best results of prescribed fire application are likely to be attained in heterogeneous landscapes and in climates where the likelihood of extreme weather conditions is low. Conclusive statements concerning the hazard-reduction potential of prescribed fire are not easily generalised, and will ultimately depend on the overall efficiency of the entire fire management process.
Feasibility of forest-fire smoke detection using lidar
Authors: Utkin Andrei B. , Fernandes Armando , Simões Fernando , Lavrov Alexander , Vilar Rui
Published: August 2003

The feasibility and fundamentals of forest fire detection by smoke sensing with single-wavelength lidar are discussed with reference to results of 532-nm lidar measurements of smoke plumes from experimental forest fires in Portugal within the scope of the Gestosa 2001 project. The investigations included tracing smoke-plume evolution, estimating forest-fire alarm promptness, and smoke-plume location by azimuth rastering of the lidar optical axis. The possibility of locating a smoke plume whose source is out of line of sight and detection under extremely unfavourable visibility conditions was also demonstrated. The eye hazard problem is addressed and three possibilities of providing eye-safety conditions without loss of lidar sensitivity (namely, using a low energy-per-pulse and high repetition-rate laser, an expanded laser beam, or eye-safe radiation) are discussed.
A review of radiant heat flux models used in bushfire applications
Authors: Sullivan A. L. , Ellis P. F. , Knight I. K.
Published: August 2003

The need to determine the radiant heat flux (RHF) from bushfires for fire behaviour prediction, firefighter safety, or building protection planning purposes has lead to the development and implementation of a number of RHF models, most of which are based on the Stefan-Boltzmann equation of radiative heat transfer. However, because of the complex nature of bushfire flames, a number of assumptions are made in order to make the implementation of the radiative heat transfer equation practical for wildland fire applications. The main assumptions are: bushfire flame characteristics (geometry, temperature), flame radiative qualities (emission type, emissivity), and the view of the flame at the receiving element. The common assumption of a uniform emissivity of unity and an isothermal rectangular emitting surface produces a generic RHF model described here as an 'opaque box'. Because of the broad assumptions inherent in the opaque box model, it predicts the RHF of bushfires poorly. A comparison is made between the generic opaque box RHF model and the measurements of radiant heat flux emitted by a stationary propane-fuelled artificial bushfire flame front. Knowledge about the geometry and an understanding of the flame characteristics of a bushfire front are needed before generic RHF models will adequately describe the RHF emitted from bushfire flames.
Detection of non-linearities in the dependence of burn area on fuel age and climatic variables
Authors: Schoenberg Frederic Paik , Peng Roger , Huang Zhijun , Rundel Philip
Published: August 2003

Evidence from Los Angeles County in California, USA suggests that the relationships between wildfire burn area and fuel age, temperature, precipitation, and fuel moisture are not linear. Instead, the relationships appear to have thresholds.The data seem to support the notion that fire risk is nearly constant provided various conditions are met: that fuel age and temperature exceed a given threshold, and that fuel moisture and precipitation are sufficiently low. There appears to be little distinction in terms of wildfire risk between conditions that are sufficient for wildfires and those that are extreme.
Ponderosa pine mortality following fire in northern Arizona
Authors: McHugh Charles W. , Kolb Thomas E.
Published: August 2003

Sampling of 1367 trees was conducted in the Side wildfire (4 May 1996), Bridger-Knoll wildfire (20 June 1996) and Dauber prescribed fire (9 September 1995) in northern Arizona ponderosa pine forests (Pinus ponderosa). Tree mortality was assessed for 3 years after each fire. Three-year post-fire mortality was 32.4% in the Side wildfire, 18.0% in the Dauber prescribed fire, and 13.9% in the Bridger-Knoll wildfire. In the Dauber and Side fires, 95% and 94% of 3-year post-fire mortality occurred by year 2, versus 76% in the Bridger-Knoll wildfire. Compared with trees that lived for 3 years after fire, dead trees in all fires had more crown scorch, crown consumption, bole scorch, ground char, and bark beetle attacks. Logistic regression models were used to provide insight on factors associated with tree mortality after fire. A model using total crown damage by fire (scorch + consumption) and bole char severity as independent variables was the best two-variable model for predicting individual tree mortality for all fires. The amount of total crown damage associated with the onset of tree mortality decreased as bole char severity increased. Models using diameter at breast height (dbh) and crown volume damage suggested that tree mortality decreased as dbh increased in the Dauber prescribed fire where trees were smallest, and tree mortality increased as dbh increased in the Side and Bridger-Knoll wildfires where trees were largest. Moreover, a U-shaped dbh–mortality distribution for all fires suggested higher mortality for the smallest and largest trees compared with intermediate-size trees. We concluded that tree mortality is strongly influenced by interaction between crown damage and bole char severity, and differences in resistance to fire among different-sized trees can vary among sites.
Corrigendum to: Ponderosa pine mortality following fire in northern Arizona
Authors: McHugh Charles W. , Kolb Thomas E.
Published: August 2003

Sampling of 1367 trees was conducted in the Side wildfire (4 May 1996), Bridger-Knoll wildfire (20 June 1996) and Dauber prescribed fire (9 September 1995) in northern Arizona ponderosa pine forests (Pinus ponderosa). Tree mortality was assessed for 3 years after each fire. Three-year post-fire mortality was 32.4% in the Side wildfire, 18.0% in the Dauber prescribed fire, and 13.9% in the Bridger-Knoll wildfire. In the Dauber and Side fires, 95% and 94% of 3-year post-fire mortality occurred by year 2, versus 76% in the Bridger-Knoll wildfire. Compared with trees that lived for 3 years after fire, dead trees in all fires had more crown scorch, crown consumption, bole scorch, ground char, and bark beetle attacks. Logistic regression models were used to provide insight on factors associated with tree mortality after fire. A model using total crown damage by fire (scorch + consumption) and bole char severity as independent variables was the best two-variable model for predicting individual tree mortality for all fires. The amount of total crown damage associated with the onset of tree mortality decreased as bole char severity increased. Models using diameter at breast height (dbh) and crown volume damage suggested that tree mortality decreased as dbh increased in the Dauber prescribed fire where trees were smallest, and tree mortality increased as dbh increased in the Side and Bridger-Knoll wildfires where trees were largest. Moreover, a U-shaped dbh–mortality distribution for all fires suggested higher mortality for the smallest and largest trees compared with intermediate-size trees. We concluded that tree mortality is strongly influenced by interaction between crown damage and bole char severity, and differences in resistance to fire among different-sized trees can vary among sites.
Autonomous field-deployable wildland fire sensors
Authors: Kremens R. , Faulring J. , Gallagher A. , Seema A. , Vodacek A.
Published: August 2003

An Autonomous Fire Detector (AFD) is a miniature electronic package combining position location capability [using the Global Positioning System (GPS)], communications (packet or voice-synthesized radio), and fire detection capability (thermal, gas, smoke detector) into an inexpensive, deployable package. The AFD can report fire-related parameters, like temperature, carbon monoxide concentration, or smoke levels via a radio link to firefighters located on the ground. These systems are designed to be inserted into the fire by spotter planes at a fire site or positioned by firefighters already on the ground. AFDs can also be used as early warning devices near critical assets in the urban–wildland interface. AFDs can now be made with commercial off-the-shelf components. Using modern micro-electronics, an AFD can operate for the duration of even the longest fire (weeks) using a simple dry battery pack, and can be designed to have a transmitting range of up to several kilometers with current low power radio communication technology. A receiver to capture the data stream from the AFD can be made as light, inexpensive and portable as the AFD itself. Inexpensive portable repeaters can be used to extend the range of the AFD and to coordinate many probes into an autonomous fire monitoring network.
Evaluation of fire danger rating indexes using logistic regression and percentile analysis
Authors: Andrews Patricia L. , Loftsgaarden Don O. , Bradshaw Larry S.
Published: August 2003

Methods are presented for analysing the relationship between fire danger rating indexes and fire activity as a means of evaluating the performance of fire danger rating systems. Percentile analysis is used to examine the data itself; logistic regression provides a means for statistical analysis. Ranking of selected items indicates indexes that deserve further assessment using subjective considerations. Methods rely on generally available data: the fire danger index for every day in the fire season, fire discovery date, and final fire size. For logistic regression analysis, the independent variable is the index, and dependent variables are fire-day, large-fire-day, and multiple-fire-day. Data analysis methods have been incorporated into the FireFamily Plus computer program for easy application. Potential uses of the analysis include choosing the most appropriate fire danger index and fuel model for an area, evaluating proposed changes to a fire danger rating system, and assessing the performance of a system in a location other than that for which it was designed. As a demonstration, this technique was applied to evaluation of several indexes and fuel models of the U.S. National Fire Danger Rating System on the Tonto National Forest in Arizona, USA, using fire and weather data for 1974–2001.
Assessing fire regimes on Grand Canyon landscapes with fire-scar and fire-record data
Authors: Fulé Peter Z. , Heinlein Thomas A. , Covington W. Wallace , Moore Margaret M.
Published: August 2003

Fire regimes were reconstructed from fire-scarred trees on five large forested study sites (135–810 ha) on the North and South Rims at Grand Canyon National Park. Adequacy of sampling was tested with cumulative sample curves, effectiveness of fire recording on individual trees, tree age data, and the occurrence of 20th Century fires which permitted comparison of fire-scar data with fire-record data, a form of modern calibration for the interpretation of fire-scar results. Fire scars identified all 13 recorded fires >8 ha on the study sites since 1924, when record keeping started. Records of fire season and size corresponded well with fire-scar data. We concluded that the sampling and analysis methods were appropriate and accurate for this area, in contrast to the suggestion that these methods are highly uncertain in ponderosa pine forests. Prior to 1880, fires were most frequent on low-elevation ‘islands’ of ponderosa pine forest formed by plateaus or points (Weibull Median Probability Intervals [WMPI] 3.0–3.9 years for all fires, 6.3–8.6 years for ‘large’ fires scarring 25% or more of the sampled trees). Fires were less frequent on a higher-elevation ‘mainland’ site located further to the interior of the North Rim (WMPI 5.1 years all fires, 8.7 years large fires), but fires tended to occur in relatively drier years and individual fires were more likely to burn larger portions of the study site. In contrast to the North Rim pattern of declining fire frequency with elevation, a low-elevation ‘mainland’ site on the South Rim had the longest fire-free intervals prior to European settlement (WMPI 6.5 years all fires, 8.9 years large fires). As in much of western North America, surface fire regimes were interrupted around European settlement, 1879 on the North Rim and 1887 on the South Rim. However, either two or three large surface fires have burned across each of the geographically remote point and plateau study sites of the western North Rim since settlement. To some extent, these sites may be rare representatives of nearly-natural conditions due to the relatively undisrupted fire regimes in a never-harvested forest setting.
Flame characteristics, temperature - time curves, and rate of spread in fires propagating in a bed of Pinus pinaster needles
Authors: Mendes-Lopes José M. C. , Ventura João M. P. , Amaral José M. P.
Published: August 2003

An extensive set of experiments was carried out in order to collect data to validate fire propagation models being developed in the context of an European research project. The experiments were performed in a dedicated burning tray (2.0 m × 0.70 m working section), where wind velocity, fuel moisture content and slope were varied to study fire propagation in beds of Pinus pinaster needles. All the runs were videotaped and, from the recordings, information on flame geometry (i.e. flame height, flame length and flame angle) and rate of spread was obtained. Temperature measurements were also carried out by a small tower of six thermocouples at different heights above the fuel bed. Results show that headfire rate of spread increases steeply with wind speed for wind-driven fires but does not depend on wind speed for backing fire spread rates. Rate of spread increases slightly with slope for up-hill propagation, and is not slope dependent for down-hill cases. Rate of spread decreases when fuel moisture content increases. Flame angle and flame height are also dependent on wind velocity, slope, and fuel moisture content. The importance of temperature for fire propagation is discussed, emphasizing the role of radiation heat transfer in the process. Correlations between temperature and other indicators of fire behaviour (namely the rate of spread) are presented. Results are discussed and compared. The results obtained provide a good database for the assessment of fire propagation models.
Calculation of fire spread rates across random landscapes
Authors: Finney Mark A.
Published: August 2003

An approach is presented for approximating the expected spread rate of fires that burn across 2-dimensional landscapes with random fuel patterns. The method calculates a harmonic mean spread rate across a small 2-dimensional grid that allows the fire to move forward and laterally. Within this sample grid, all possible spatial fuel arrangements are enumerated and the spread rate of an elliptical fire moving through the cells is found by searching for the minimum travel time. More columns in the sample grid are required for accurately calculating expected spread rates where very slow-burning fuels are present, because the fire must be allowed to move farther laterally around slow patches. This calculation can be used to estimate fire spread rates across spatial fuel mixtures provided that the fire shape was determined from wind and slope. Results suggest that fire spread rates on random landscapes should increase with fire size and that random locations of fuel treatments would be inefficient in changing overall fire growth rates.
Estimation of vegetative fuel loads using Landsat TM imagery in New South Wales, Australia
Authors: Brandis Kate , Jacobson Carol
Published: August 2003

Fuel loads in forest areas are dependent on vegetation type and the time since the last fire. This paper reports a study on the feasibility of using remotely sensed data to estimate vegetative fuel loads. It describes two methods for estimating fuel loads using Landsat TM data based on equations describing litter accumulation and decomposition. The first method uses classification techniques to predict vegetation types coupled with fire history data to derive current fuel loads. The second method applies a canopy turnover rate to estimate litterfall and subsequently accumulated litter from biomass, thus utilising the dominant influence of canopy on remotely sensed data. Both methods are compared with data collected from Popran National Park in coastal New South Wales. The amounts of litter calculated with the biomass method were similar to field results, but the classification method was found to overestimate fuel loads. A sensitivity analysis investigated the impact of varying the vegetation constants and rates used in the fuel estimates to simulate uncertainty or error in their values. The biomass method was less subject to uncertainties and has potential for estimating fuel quantities to provide useful spatial information for fire managers.
Fine-scale patchiness of different fire intensities in sandstone heath vegetation in northern Australia
Authors: Price Owen , Russell-Smith Jeremy , Edwards Andrew
Published: August 2003

We assessed the extent of burning and rockiness in 3712 5 × 5 m quadrats along 9.2 km of transects sampling five different fires in sandstone heaths where contemporary fire regimes are thought to be reducing the populations of many plants. All fires were patchy, with means of 64% burnt for early dry season and 84% for late dry season fires. Rockiness was strongly related to the presence of unburned patches, and some late dry season fires leave no patches in the absence of rocks. Half of the unburned patches were 10 m or less in length and of the 83 patches identified only three were still detectable when data were amalgamated into quadrats of 500 m2. Thus, very few patches could be recognised from satellite images. The results suggest that fires are much more patchy than satellite-derived fire maps indicate. This has important implications for understanding how populations of fire sensitive plants will respond to different fire regimes.