Burnt Trees Research Articles

Post-fire salvage logging increases restoration costs in a Mediterranean mountain ecosystem

Post-fire salvage logging (i.e. felling and removing burnt trees, often eliminating the remaining woody debris) is a practice routinely performed by forest managers worldwide. In Mediterranean-type ecosystems, salvage logging is considered a measure to reduce future reforestation costs, but this assumption remains largely untested. We made a cost analysis of different management schemes, addressing the immediate post-fire burnt-wood management as well as the costs and success of subsequent reforestation efforts. Two experimental 25-ha plots were established in a burnt pine reforestation of SE Spain, in which three replicates of three post-fire treatments were applied: non-intervention (NI), partial cut plus lopping (PCL; felling and lopping off the branches from most of the trees, leaving all biomass in situ), and salvage logging (SL). After 4 years, a mechanised reforestation was undertaken, and seedling mortality was monitored for 2 years. The cost of all management operations was recorded in situ, and the cost of re-planting the dead seedlings was estimated according to the expenses of previous reforestation. Initial cost of wood management was greatest in SL and zero in NI. Reforestation cost was highest in NI and lowest in SL, and seedling-mortality rates proved lowest in PCL (43 % vs. 51 % and 52 % in SL and NI, respectively). Considering all the post-fire management operations, salvage logging did not provide particular economic advantages for forest restoration, and had an overall cost of 3,436 ± 340 €/ha. By contrast, NI and PCL reduced total restoration costs by 50 and 35 %, respectively, and PCL indeed promoted restoration success. We suggest that the full cost of management operations needs to be considered when evaluating the economic implications of post-fire salvage logging.

Wildfire and post-fire management effects on early fungal succession in Pinus mugo plantations, located in Curonian Spit (Lithuania)

The objective of this study was to evaluate the effects of wildfire and subsequent forest management on the diversity and functional community structure of fungi during early stage of succession in the coastal sand dunes of the Curonian Spit in Lithuania. 12 permanent study plots were established in multiple forest areas: burnt, not managed (B); burnt, clear-cut (C); burnt, clear-cut and reforested (R) and unburnt (U). During three years of the study, a total of 390 different fungal species were determined. The overall number of recorded species in studied post-fire variants comprised 52% (B), 41% (C) and 48% (R) of unburnt sites (U, 261 species). Significantly different species compositions were registered between C and B plots, while no difference was observed between C and R plots. Fungal communities of all burnt sites showed more significant differences stemming from annual changes rather than from types of forest management. Early succession of the post-fire fungal communities maintained the fungi from all defined taxonomical and functional groups. However, a certain alteration within some fungal life styles was observed. The wildfire has negatively impacted the lichens and the mycorrhizal species, as the percentages of these groups decreased from 15% and 12% in U plots to 10% and 3% in B plots. Wood saprobic fungi and soil saprobes were affected negatively by harvesting of the burnt trees that reduced their percentage from 38% and 8% in B plots to 27% and 4% in C plots. Soil-associated fungi were less affected both by fire and post-fire management than the fungi inhabiting above-ground substrates. The percentage of soil-associated fungi initially increased in the burnt sites, but two years after the fire it returned to the pre-fire level. No significant effect on soil-inhabiting fungi was noted for the differently managed post-fire sites.

The bark of eucalypt trees: habitat quality for arthropods and impact of fire.

The bark of eucalypt trees is a significant habitat attribute of forests and woodlands, with different bark types supporting varying populations of invertebrate and vertebrate fauna. Bark also contributes to fuel load in wildfires and hazard reduction burning, with a concomitant loss of habitat and modification of habitat resources. We compared the composition and abundance of tree trunk invertebrates inhabiting four eucalypt bark types and determined the impact of burning the bark on population abundance and community composition. Trees of four bark types (gum, box, stringybark, ironbark) were selected at three sites and arthropod traps placed on burnt and unburnt trees of each type. Traps were left in place for 12 days and arthropod preferences for the four bark types (burnt and unburnt) were analysed. The total number of arthropods differed between bark types, with stringybark and ironbark supporting the largest numbers of invertebrates and the most diverse communities. Burnt stringybark and gum bark had reduced arthropod abundance compared to unburnt bark. The study highlights an ecological consequence of fire on an aspect of invertebrate habitat, with flow-on effects for vertebrates, that should be considered in fire management, as greater areas of land are subject to frequent hazard reduction burning in eastern Australia.

The influences of conifer succession, physiographic conditions and herbivory on quaking aspen regeneration after fire

Fire suppression over the last century has increased conifer expansion and dominance in aspen-conifer forests, which appears to be a driving force behind aspen decline in some areas. The primary objective of this study was to examine how increasing conifer dominance affects aspen regeneration vigor following the return of fire. The influence of physiographic features and herbivory on aspen regeneration vigor were also examined. The study was conducted in the Sanford fire complex located in the Dixie National Forest in southern Utah, USA, where more than 31,000 hectares burned in the summer of 2002. Seven years after the burn (at 66 locations) we measured aspen regeneration density and height as response variables and former stand composition and density (the burned trees were still standing), soil characteristics, slope, aspect and presence or absence of herbivory as independent variables. Aspen regeneration (root suckering) densities ranged from <500 to 228,000 stems/hectare with an average of 37,000 stems/hectare. Post-fire aspen regeneration density was most strongly correlated with pre-fire stand successional status (as measured by stand composition and species abundance), with percent conifer abundance ( R 2 = −0.55) and overstory aspen density ( R 2 = + 0.50) being the most important. Average aspen suckering densities ranged from approximately 60,000 stems/hectare in what were relatively pure aspen stands (>90% aspen) to less than 5000 stems/hectare in stands where conifer abundance was greater than 90%. Soil C, N, and P showed positive correlations ( R 2 = 0.07 to 0.17) with aspen regeneration vigor, while soil texture had a relatively weak influence on sucker regeneration. Aspen regeneration densities were 15% lower on north facing aspects compared to east, west and south facing aspects with slope steepness showing no correlation with regeneration vigor. Regeneration density was significantly lower (8%) at sites with evidence of herbivory versus sites where herbivory was absent. Overall, the aspen regeneration response in the Sanford fire complex was strong despite high wildlife densities, which may be related to disturbance size. Where the maintenance of aspen is desired in the landscape we recommend promoting fire when the percentage of overstory conifer stems is greater than 80% or overstory aspen density is less than 200 overstory stems/hectare.

Wood-boring insect abundance in fire-injured ponderosa pine

1 Wood-boring larvae in the families Cerambycidae and Buprestidae are often found in high densities in burned trees after wildland fires. They play an important role in tree decomposition, often reducing the value of salvageable timber, and represent an important avian food source. 2 Three forest areas that experienced wildfires 1–3 years previously were surveyed during the summer of 2004. Ponderosa pine trees with green, scorched and consumed needles were examined for wood borer occurrence. Within each of the three needle damage categories, the mean wood borer incidence was similar between different age fires. Trees with scorched or consumed needles had significantly more wood borers than trees with green needles. 3 Larvae collected from under tree bark were identified to family; when possible, cerambycids were identified further to Acanthocinus spp., Monochamus sp., Rhagium inquisitor (L.) and Stictoleptura canadensis (LeConte), and buprestids were identified to Chalcophora spp. and Chrysobothris sp. 4 Classification tree models showed that the estimated probability of tree infestation by wood borers varied among needle damage categories. For trees with green needles, tree injury variables of high bole char height and phloem discolouration were important predictive variables. In trees where needles were consumed, tree size variables of diameter at breast height and tree height were important predictive variables. 5 More than half the dead trees examined were infested with wood borers, indicating that infestation of fire-killed ponderosa pine may represent an important food source for species such as woodpeckers and a potential problem for the utilization of infested trees.

Post-fire soil respiration in relation to burnt wood management in a Mediterranean mountain ecosystem

After a wildfire, the management of burnt wood may determine microclimatic conditions and microbiological activity with the potential to affect soil respiration. To experimentally analyze the effect on soil respiration, we manipulated a recently burned pine forest in a Mediterranean mountain (Sierra Nevada National and Natural Park, SE Spain). Three representative treatments of post-fire burnt wood management were established at two elevations: (1) “salvage logging” (SL), where all trees were cut, trunks removed, and branches chipped; (2) “non-intervention” (NI), leaving all burnt trees standing; and (3) “cut plus lopping” (CL), a treatment where burnt trees were felled, with the main branches lopped off, but left in situ partially covering the ground surface. Seasonal measurements were carried out over the course of two years. In addition, we performed continuous diurnal campaigns and an irrigation experiment to ascertain the roles of soil temperature and moisture in determining CO 2 fluxes across treatments. Soil CO 2 fluxes were highest in CL (average of 3.34 ± 0.19 μmol m −2 s −1) and the lowest in SL (2.21 ± 0.11 μmol m −2 s −1). Across seasons, basal values were registered during summer (average of 1.46 ± 0.04 μmol m −2 s −1), but increased during the humid seasons (up to 10.07 ± 1.08 μmol m −2 s −1 in spring in CL). Seasonal and treatment patterns were consistent at the two elevations (1477 and 2317 m a.s.l.), although respiration was half as high at the higher altitude. Respiration was mainly controlled by soil moisture. Watering during the summer drought boosted CO 2 effluxes (up to 37 ± 6 μmol m −2 s −1 just after water addition), which then decreased to basal values as the soil dried. About 64% of CO 2 emissions during the first 24 h could be attributed to the degasification of soil pores, with the rest likely related to biological processes. The patterns of CO 2 effluxes under experimental watering were similar to the seasonal tendencies, with the highest pulse in CL. Temperature, however, had a weak effect on soil respiration, with Q 10 values of ca. 1 across seasons and soil moisture conditions. These results represent a first step towards illustrating the effects of post-fire burnt wood management on soil respiration, and eventually carbon sequestration.

Phase diagram and critical behavior of a forest-fire model in a gradient of immunity

The forest-fire model with immune trees (FFMIT) is a cellular automaton early proposed by Drossel and Schwabl [Physica A 199, 183 (1993)], in which each site of a lattice can be in three possible states: occupied by a tree, empty, or occupied by a burning tree (fire). The trees grow at empty sites with probability p, healthy trees catch fire from adjacent burning trees with probability (1-g), where g is the immunity, and a burning tree becomes an empty site spontaneously. In this paper we study the FFMIT by means of the recently proposed gradient method (GM), considering the immunity as a uniform gradient along the horizontal axis of the lattice. The GM allows the simultaneous treatment of both the active and the inactive phases of the model in the same simulation. In this way, the study of a single-valued interface gives the critical point of the active-absorbing transition, whereas the study of a multivalued interface brings the percolation threshold into the active phase. Therefore we present a complete phase diagram for the FFMIT, for all range of p, where, besides the usual active-absorbing transition of the model, we locate a transition between the active percolating and the active nonpercolating phases. The average location and the width of both interfaces, as well as the absorbing and percolating cluster densities, obey a scaling behavior that is governed by the exponent α=1/(1+ν), where ν is the suitable correlation length exponent (ν(⊥) for the directed percolation transition and ν for the standard percolation transition). We also show that the GM allows us to calculate the critical exponents associated with both the order parameter of the absorbing transition and the number of particles in the multivalued interface. Besides, we show that by using the gradient method, the collapse in a single curve of cluster densities obtained for samples of different side is a very sensitive method in order to obtain the critical points and the percolation thresholds.

The pulp and paper properties of Sirex noctilio infested and fire-damagedthermomechanically pulped, South African grown Pinus patula

Pinus patula is the softwood species most extensively planted in South Africa. However, large portions of these plantings are under threat from Sirex noctilio infestation and occasional forest fires. In this exploratory investigation, the effects of tree age, Sirex noctilio infestation and fire damage to wood from Pinus patula trees on their pulp and paper properties were evaluated. Pulp was produced using the thermomechanical pulping (TMP) process. The energy consumption required to pulp the different pulpwood materials was determined. Pulps were beaten for five different time periods to investigate the development of the fibre properties in response to increasing energy input. Paper properties such as burst, tear strength and breaking length were determined on handsheets manufactured from unbeaten and beaten pulps. Box and line plots and canonical variate analysis biplots were used to statistically analyse the data. It was found that the burst strength of paper produced from healthy trees was significantly higher than that from sirex-infested or fire damaged (burnt) trees. Similarly, the tear strength of paper from healthy and burnt trees was significantly better than from sirex-infested or young trees. No significant differences in breaking length were evident between the pulpwood materials and an increase in beating time did not lead to any improvements. From this study it can be concluded that wood from dead or dying, sirex-infested and young trees produced paper with consistently lower strength properties compared to wood obtained from healthy 12-year-old trees.

Influence of Post‐Clearing Treatment on the Recovery of Herbaceous Plant Communities in Amazonian Secondary Forests

Secondary forests are an increasingly common feature in tropical landscapes worldwide and understanding their regeneration is necessary to design effective restoration strategies. It has previously been shown that the woody species community in secondary forests can follow different successional pathways according to the nature of past human activities in the area, yet little is known about patterns of herbaceous species diversity in secondary forests with different histories of land use. We compared the diversity and abundance of herbaceous plant communities in two types of Central Amazonian secondary forests—those regenerating on pastures created by felling and burning trees and those where trees were felled only. We also tested if plant density and species richness in secondary forests are related to proximity to primary forest. In comparison with primary forest sites, forests regenerating on non‐burned habitats had lower herbaceous plant density and species richness than those on burned ones. However, species composition and abundance in non‐burned stands were more similar to those of primary forest, whereas several secondary forest specialist species were found in burned stands. In both non‐burned and burned forests, distance from the forest edge was not related to herbaceous density and species richness. Overall, our results suggest that the natural regeneration of herbaceous species in secondary tropical forests is dependent on a site's post‐clearing treatment. We recommend evaluating the land history of a site prior to developing and implementing a restoration strategy, as this will influence the biological template on which restoration efforts are overlaid.

Effect of wildfires and post-fire forest treatments on rabbit abundance

One of the main factors involved in the decline in the European wild rabbit in the Iberian Peninsula is the loss of suitable habitats caused by abandonment of agricultural and grazing activities. Nowadays, Mediterranean landscapes suffer from wildfires that affect extensive areas and produce considerable habitat changes. However, little is known about the influence of wildfires and post-fire treatments on rabbit abundance to address policies to recover their populations. To do so, we studied abundances of this species in four types of plots during three consecutive years after a wildfire in Catalonia (NE Spain): (A) unburnt forests, (B) burnt forests with removal of burnt trees but with branches left, (C) burnt forests with removal of burnt trees and branches, and (D) non-forested burnt plots. Rabbits progressively colonised burnt plots, where their abundance increased for at least 5 years after the fire, but decreased or even disappeared in unburnt ones, indicating that forest fires have a positive effect on rabbit populations. Although abundances did not differ between the three burnt plot types, plots with removal of burnt branches had the highest increase in abundance. In addition, soil covered by branches or by dense vegetation appeared negatively correlated with abundance, indicating that this could hinder rabbit movements, while some plant species could benefit rabbits by providing high quality food. Thus, post-fire treatments favourable to rabbit populations might therefore be a good way of increasing the conservation and economic value of areas affected by forest fires.

Fire, floods and woody debris: Interactions between biotic and geomorphic processes

Fire and floods interact in the riparian zone as processes that structure plant communities and landforms. Although much of the immediate impact of fire is on the vegetation, fire-related changes in runoff, sediment supply, riparian vegetation, and woody debris volume have ongoing geomorphic impacts on the valley floor. Consequent hydrogeomorphic changes, in turn, affect the composition and distribution of vegetation. This paper reviews these interactions, and provides an example of how fires and floods intersect to supply burnt trees as woody debris. Because the temporal and spatial distribution of woody debris is initially controlled by patterns of tree mortality, ecological disturbances, like fire, can be an important source for pulses of woody debris in riparian systems. To understand these interactions, we examine woody debris inputs 3 years after a wildfire in the riparian gallery forests of the western Transverse Ranges, California. Within our sample of 339 burned stems, snags fell in distinctive patterns: species were variable in susceptibility to falling, and fell at greater rates at sites with greater subsequent flooding. Discordance between the species composition of fallen snags and that of overall burned stems indicates that variability in forest composition must be considered in predicting post-disturbance inputs of woody debris. Variation in snagfall timing among species suggests that woody debris inputs are likely to occur in multiple, sequential pulses after wildfire. The role of flooding is superimposed on this ecological influence, as the timing and spatial variability of floods affect the recruitment of woody debris from the supply of snags created by fire.

Response of bark beetles and their natural enemies to fire and fire surrogate treatments in mixed-conifer forests in western Montana

Four treatments (control, burn-only, thin-only, and thin-and-burn) were evaluated for their effects on bark beetle-caused mortality in both the short-term (one to four years) and the long-term (seven years) in mixed-conifer forests in western Montana, USA. In addition to assessing bark beetle responses to these treatments, we also measured natural enemy landing rates and resin flow of ponderosa pine (Pinus ponderosa) the season fire treatments were implemented. All bark beetles were present at low population levels (non-outbreak) for the duration of the study. Post-treatment mortality of trees due to bark beetles was lowest in the thin-only and control units and highest in the units receiving burns. Three tree-killing bark beetle species responded positively to fire treatments: Douglas-fir beetle (Dendroctonus pseudotsugae), pine engraver (Ips pini), and western pine beetle (Dendroctonus brevicomis). Red turpentine beetle (Dendroctonus valens) responded positively to fire treatments, but never caused mortality. Three fire damage variables tested (height of crown scorch, percent circumference of the tree bole scorched, or degree of ground char) were significant factors in predicting beetle attack on trees. Douglas-fir beetle and pine engraver responded rapidly to increased availability of resources (fire-damaged trees); however, successful attacks dropped rapidly once these resources were depleted. Movement to green trees by pine engraver was not observed in plots receiving fire treatments, or in thinned plots where slash supported substantial reproduction by this beetle. The fourth tree-killing beetle present at the site, the mountain pine beetle, did not exhibit responses to any treatment. Natural enemies generally arrived at trees the same time as host bark beetles. However, the landing rates of only one, Medetera spp., was affected by treatment. This predator responded positively to thinning treatments. This insect was present in very high numbers indicating a regulatory effect on beetles, at least in the short-term, in thinned stands. Resin flow decreased from June to August. However, resin flow was significantly higher in trees in August than in June in fire treatments. Increased flow in burned trees later in the season did not affect beetle attack success. Overall, responses by beetles to treatments were short-term and limited to fire-damaged trees. Expansions into green trees did not occur. This lack of spread was likely due to a combination of high tree vigor in residual stands and low background populations of bark beetles.

Classrooms in Conflict

© 2009 World Policy Institute 65 Uganda’s northern districts of Gulu, Kitgum, and Pader are just over 200 kilometers from the country’s bustling international capital of Kampala. The majority of the 800,000 inhabitants of these districts are ethnic Acholi, who make up 4 percent of Uganda’s total population. Traveling north out of Kampala is to experience the divide between rich and poor. The capital’s paved streets lined with air-conditioned shops turn into long stretches of deteriorating roads dotted with thatched huts and corrugated tin roofs. Traffic jams give way to streams of bicycles laden with harvested grass and sorghum. Women and girls sling baskets of fruit over their shoulders, balancing containers of water on their heads while infants cling to their backs. The landscape is a brilliant mix of burnt orange earth and vibrant green trees, of rich arable land and apparent tranquility. But the calm is a mirage. Since 1986, the region has been ravaged by a conflict between the rebel Lord’s Resistance Army (LRA) and the government of Uganda. The decades of war have seen some of the worst violence committed against children and adolescents in the world. The LRA professes to fight a spiritual war on behalf of the minority Acholi people, but has been responsible for countless atrocities committed against civilians in northern Uganda, southern Sudan, and the Democratic Republic of Congo (DRC), including the abduction of thousands of children and adolescents to serve as child soldiers, porters, cooks, and sex slaves. Neither is the Ugandan government innocent in this conflict. The Ugandan People’s Defense Forces (UPDF), which is responsible for providing security for all of the nation’s civilians, has failed spectacularly to do so—and has also committed human rights violations against millions it is sworn to protect, although to a far lesser extent than the LRA. In the course of this long war, schools, families, and communities have been torn apart. Children and youth in northern Uganda have known virtually nothing else but war—a war in which they are a prime target.

Taffeta, and: Hand Me Downs, and: Starlight, and: Blue Flowers

Taffeta, and: Hand Me Downs, and: Starlight, and: Blue Flowers Ellen Saunders (bio) Taffeta As a girl, she perfected the fox-trot in the hotels of St. Louis. A taffeta skirt circled her ankles, its swishing sound followed her as she moved across the high ceilinged room with crystal chandeliers, the sounds of Glen Miller. Raven hair fell down her shoulders, her eyes like sapphires. Too soon, she married, moved to suburbia, [End Page 94] had seven children, and ceased to dance. She wore cotton skirts until she discovered no-iron polyester. The Beatles blasted from her radio. But she never forgot the dance, the way she was wrapped in taffeta the color of peaches. Hand Me Downs My mother lived her life inside a mask; not the kind to hide from the world, but one to disguise what she couldn’t stand to see. A magical mask that made burning trees look alive with yellow blossoms; poisonous snakes like harmless lizards. As a child, I knew she was wearing it because she couldn’t see the things I saw: the fire that raged around us, our lives in cinder, powerful enough to make her think my father was a harmless lizard. There are times when I catch myself wearing a mask just like mother’s. I think she handed it down to me. [End Page 95] Starlight When I was twelve years old, my father died. It was the night he crept into my dark room where even starlight hid behind the curtains. He walked to my bed, no book in his hand, no glass of milk, and lay down next to me, red hair against my pillow. He stroked my cheek; fingers moved to my chest, the small mounds, which only months before did not exist. I pushed him away until he stopped. My innocence waited outside the window. He left, angry and disappointed not to have found his daughter a willing lover. Afterward, I let the starlight spill in. I knew he was gone forever. Blue Flowers It’s been three years since you died, three years of missed Decembers. Do you know, Mother, I haven’t bought a nightgown since? You gave me so many, Christmas after Christmas, wrapped with tissue in pretty pink boxes. They’re perfectly placed in my drawer; ones for winter, others for summer, some I’ve never worn. The one with lace and little blue flowers around the neck is beginning to go; a few small holes, the blue faded after so many washings. [End Page 96] But I can’t bring myself to toss it out; the pale blue flowers wilting in the trash, the stranger who comes to haul them away. Ellen Saunders Ellen Saunders’s work has appeared or is forthcoming in New Formalist, Lyric, Prism Quarterly, Pearl, Poetry East, Toronto Quarterly, and elsewhere. Copyright © 2009 University of Nebraska Press

Herbaceous Succession After Burning of Cut Western Juniper Trees

The expansion of western juniper (Juniperus occidentals spp. occidentalis Hook.) in the northern Great Basin has resulted in the wide-scale conversion of sagebrush-steppe communities to juniper woodlands. Prescribed fire and mechanical cutting are the 2 main methods used to remove juniper and restore sagebrush steppe. Mechanical treatments commonly leave cut juniper on site. Disadvantages of leaving cut juniper are the increased fuel hazard and the potential for increased establishment and growth of invasive species. This study evaluated the response of herbaceous plants to winter burning of cut western juniper. Vegetation response was compared among 2 burning treatments (burning trees the first winter after cutting and burning the second winter after cutting), a control (cut-unburned juniper), and the interspace between cut trees. To minimize fire impacts to herbaceous perennials, cut trees were burned in the winter when soils and ground litter were frozen and/or soils were at field capacity. Only felled trees were burned, as fire did not carry into interspaces or litter mats around western juniper stumps. We hypothesized that winter season burning would increase herbaceous perennials and would reduce cheatgrass establishment when compared to the cut-unburned control. After 10 years, total herbaceous and perennial grass cover was 1.5- to 2-fold greater, respectively, in burned treatments compared to cut-unburned controls. Perennial grass density was 60% greater in the burned treatments than in the cut-unburned treatment and the interspace. Cheatgrass cover was twice as great in the control than in the 2 burn treatments and the interspace. We concluded that burning cut western juniper when soils were wet and frozen in winter enhanced community recovery of native perennials compared to leaving cut juniper unburned.

Postfire forest management and Mediterranean birds: the importance of the logging remnants

Fire is a crucial element needed to understand the biodiversity patterns of forest landscapes in most Mediterranean countries. However, little is known about the quanti- tative responses of bird communities to postfire forest management in this region, in which the logging of burnt trees is a common practice. Several studies have already described the negative effects of felling burnt trees on birds but none has focussed on the remaining wood remnants. We investigated this question in a large burnt area located in north-east Iberian Peninsula. The amount of logging remnants left on the ground had positive linear and negative quadratic relationships with the indices of bird abundance and bird richness. The results obtained at a species level were similar, since 36% of the most abundant species revealed the same type of relations with logging remnants, whereas none showed an opposite pattern. Thus, birds in general seem to be positively influenced by the amount of wood remnants left on the ground to a certain point, from which the relation reverses. The results of this study indicate that a moderate amount of wood remnants left on the ground may be positive for the overall bird community. We suggest that management plays a role in the recovery of the bird community after fire and, therefore, biodiversity criteria should be incorporated in the guidelines driving postfire actions.

Nitrogen leaching from a forest soil exposed to fire retardant with and without fire: A laboratory study

The application of Long Term fire Retardants (LTRs) for forest fire prevention and/or suppression purposes can result in chemicals leaching, from soil to the drainage water, during the annual rain fall period. In leachates, large concentrations of nitrogen (N), one of the major components of LTRs, could affect the groundwater quality. N leaching due to the application of a nitrogen phosphate based LTR was studied in laboratory microcosms. The concentrations of nitrate (NO 3 − -N) and ammonium nitrogen (NH 4 + -N) were measured in the resulting leachates from pots with forest soil and pine seedlings (Pinus halepensis) alone and in combination with fire. Up to 30% of the total N in the retardant was lost to leaching, primarily as NO 3 − -N. The vegetation seems to decrease to some extent the N leaching. The N leaching from treated pots with a burnt tree is lower compared with that from treated pots with a living tree, due to the partial N volatilization during the fire. Although this is a laboratory study, these results may be considered as rough indications of LTR environmental implications, due to the leaching of a significant part of the retardant’s N into groundwater.

On the development and characterization of a firebrand generator

A unique experimental apparatus has been constructed in order to generate a controlled and repeatable size and mass distribution of glowing firebrands. The present study reports on a series of experiments conducted in order to characterize the performance of this firebrand generator. Firebrand generator characterization experiments were performed at the Fire Research Wind Tunnel Facility (FRWTF) at the Building Research Institute (BRI) in Tsukuba, Japan. The firebrand generator was fed with three different initial firebrand geometries, two different sized cylinders and one size of disks. Cylinders were used to simulate firebrand fluxes from vegetation, such as trees, while disks were used to simulate a firebrand flux from burning structures. Samples of these geometries were constructed from wood dowels, fed into the firebrand generator, ignited, and the glowing firebrands generated were collected using an array of water filled pans. The pans were filled with water in order to quench combustion. The collected firebrands were subsequently dried and the size and mass distribution was measured. These experiments were performed over a range of wind tunnel speeds, with no wind speed present to 9 m/s, to determine the lofting distance of the firebrands generated. Finally, the size and mass distribution produced from the firebrand generator are compared to those produced from burning trees. Results of the study are presented and discussed.

Modeling transport and combustion of firebrands from burning trees

Burning embers, commonly called firebrands, are lofted by a fire's buoyant plume and transported downwind to ignite new fires (spot fires) ahead of the main fire. In the present work, transport and combustion of firebrands from burning trees are numerically investigated. A three-dimensional physics-based model is used to precompute the steady-state gas flow and thermal fields induced by a crown fire into which firebrands will be injected. Another preliminary study of the thermal degradation and combustion of woody fuel particles is conducted to determine the burning characteristics of firebrands. Then the trajectories and burning rates of disk-shaped firebrands lofted by the crown fire plume and transported downwind are calculated for various values of the wind speed, U wind , and of the fire intensity, I. Firebrands of different sizes and densities are first launched from a specified location at the top of the canopy. Firebrands that fall on the ground are in a flaming or a glowing state depending on the product ρ f w 0 × τ ( ρ f w 0 : initial firebrand density, τ: firebrand thickness). Results show that for firebrands that remain longer in the thermal plume, the distance covered upon landing is independent of the initial particle diameter and correlates well with I 0.1 U wind 0.9 ( ρ f w 0 × τ ) −0.2 . The normalized brand mass fraction at landing also correlates with the flight time normalized by the product ρ f w 0 × τ for flaming firebrands or by the product ρ f w 0 × D 0 5 / 3 ( D 0 : initial firebrand diameter) for glowing firebrands. For firebrands released from random locations within the canopy, the above correlations remain unchanged, thereby demonstrating the generality of the developed approach.

Tree use by koalas (Phascolarctos cinereus) after fire in remnant coastal forest

The aim of this study was to examine the effects of fire on resource use by a population of koalas in remnant coastal forest. Fifty-five koalas were monitored regularly by radio-tracking for up to 35 months. The attributes of each tree in which the koala was sighted were recorded, giving a total of 8390 records. Analyses were undertaken on a range of ecological information. Regeneration of the forest began immediately following the fires and within three months koalas were seen among the epicormic growth. From a total 4631 trees used by koalas, 3247 (70%) were burnt. Observations of koalas feeding included 53% in burnt trees. Koalas changed trees frequently; individual trees were used once only on 3555 occasions (42% of all observations). Of all the trees used, 95% were used by only one collared koala; no trees were used by more than three koalas. Swamp mahogany (Eucalyptus robusta) was the tree species most frequently used by koalas, particularly at night and by breeding females. Koalas preferred trees of larger diameter (&gt;30 cm) and used significantly taller trees during summer. This study has shown that resource depletion from intense wildfire is short-term for koalas because they utilise burnt trees within months of the fire for both food and shelter.