Summer Fires Research Articles

Recent Tendency of Mongolian Wildland Fire Incidence: Analysis Using MODIS Hotspot and Weather Data

Mongolian wildland fires are a human-made disaster like some floods as shown by these fire disasters becoming prominent around the 1990s due to opening up of the country. The worst fire losses were in 1996, costing 192% of the GDP. This study reports recent wildland fire incidence and climate relationships analyzed using NASA-MODIS hotspots (fires) and NOAA weather data. Fires are categorized into spring fires from April to June in pasture areas, summer fires in July and August in forested areas, and autumn fires in September and October in forested areas. Fires frequently occur after 10 rainless days, while several millimeters of daily precipitation reduces the extent of fire. A weeklong effective humidity of below 35% coincided with large fires. In the seven most recent years, average temperatures increased by 3.4°C in July and summer precipitation decreased by about 50%, while the fire disaster intensity increased. The fires were mainly human caused, began at relatively low altitudes after the snow melt in April, and moved to higher-altitude areas in May. From 2001 to 2007, around 30% of forest areas were affected; the Selenge, Khentii, and Dornod provinces were the most fire prone. The severest spring and autumn fires occurred on May 5, 2007 and September 22, 2002.

The 2007 Southern California Wildfires: Lessons in Complexity

Abstract The 2007 wildfire season in southern California burned over 1,000,000 ac (∼400,000 ha) and included several megafires. We use the 2007 fires as a case study to draw three major lessons about wildfires and wildfire complexity in southern California. First, the great majority of large fires in southern California occur in the autumn under the influence of Santa Ana windstorms. These fires also cost the most to contain and cause the most damage to life and property, and the October 2007 fires were no exception because thousands of homes were lost and seven people were killed. Being pushed by wind gusts over 100 kph, young fuels presented little barrier to their spread as the 2007 fires reburned considerable portions of the area burned in the historic 2003 fire season. Adding to the size of these fires was the historic 2006-2007 drought that contributed to high dead fuel loads and long distance spotting. As in 2003, young chaparral stands and fuel treatments were not reliable barriers to fire in October 2007. Second, the Zaca Fire in July and August 2007 showed that other factors besides high winds can sometimes combine to create conditions for large fires in southern California. Spring and summer fires in southern California chaparral are usually easily contained because of higher fuel moisture and the general lack of high winds. However, the Zaca Fire burned in a remote wilderness area of rugged terrain that made access difficult. In addition, because of its remoteness, anthropogenic ignitions have been low and stand age and fuel loads were high. Coupled with this was severe drought that year that generated fuel moisture levels considerably below normal for early summer. A third lesson comes from 2007 conifer forest fires in the southern California mountains. In contrast to lower elevation chaparral, fire suppression has led to major increases in conifer forest fuels that can lead to unnaturally severe fires when ignitions escape control. The Slide and Grass Valley Fires of October 2007 occurred in forests that had been subject to extensive fuel treatment, but fire control was complicated by a patchwork of untreated private properties and mountain homes built of highly flammable materials. In a fashion reminiscent of other recent destructive conifer fires in California, burning homes themselves were a major source of fire spread. These lessons suggest that the most important advances in fire safety in this region are to come from advances in fire prevention, fire preparedness, and land-use planning that includes fire hazard patterns.

Degradacion de ecosistemas de la palma más austral del mundo (Jubaea Chilensis) acelerada por los fuegos estivales en los cordones litorales de Valparaíso y Viña del Mar (32°50'-33° 02'S). Un caso sostenido de perturbación del paisaje

Jubaea chilensis (Mol) Baillon es la palma más austral del mundo y se desarrolla como especie endémica de Chile en bosques esporádicos, entre los 30° - 37° sur, principalmente en enclaves de las montañas costeras de la zona mediterránea del país. La colinas periféricas de las ciudades de Valparaíso y Viña del Mar han soportado la presión y el avance de la población, lo cual ha causado fuertes impactos a los bosques esclerófilos húmedos remanentes de las agrupaciones vegetales de hace un siglo atrás. En este hábitat se hallaban varios centenares de palmeras que han ido desapareciendo por múltiples efectos. Se presentan resultados de una investigación iniciada 10 años atrás, para estudiar el proceso de retroceso de estos bosques y de la palma chilena. La tala, la ganadería, la búsqueda de leña y elaboración de carbón, el avance de las viviendas hacia las colinas por el crecimiento de las ciudades costeras, la construcción de caminos y carreteras, y la recurrencia de incendios vegetales desde 1960; han sido los impactos más recurrentes del estado actual de estos ecosistemas. Por otra parte, la explotación constante de la palma por sus frutos y uso de sus largas hojas, la han afectado en gran parte. Soportó un enorme impacto cuando en 1996 hubo grandes movimientos de tierras en estas laderas para construir una autopista, habiéndose eliminado y/o trasladado alrededor de 500 palmas. En 1999 se abrió espacio también en estos lugares para llevar el trazado de un ducto de gas para Viña del Mar. Nuevamente con ello, se perdieron decenas de palmeras y hasta hoy en día, los fuegos vegetales de verano siguen afectando a estos palmares.

Holocene vegetation–fire–climate linkages in northern Yellowstone National Park, USA

Yellowstone National Park has been an important location for paleoecologic studies that focus on the use of charcoal data to reconstruct past fire activity and on the role of climate variations in shaping past vegetation and fire regimes. One hypothesis, which has been explored in other parts of the western U.S., is the idea that present-day summer-dry and summer-wet precipitation regimes were intensified during the early Holocene as a result of greater-than-present summer insolation and its effect on atmospheric circulation patterns. In Yellowstone, this hypothesis was previously examined at two sites, one in summer-wet and one in summer-dry precipitation regions. The records showed variation in both fire and vegetation history that supported the hypothesis. We present a fire and vegetation history from Blacktail Pond, located in Pseudotsuga parkland in the transitional region. The Blacktail Pond data indicate the following ecological history: prior to 12,000 cal yr BP, the site supported tundra vegetation and fire episodes were infrequent. Between 12,000 and 11,000 cal yr BP, Picea– Pinus parkland was established and fire activity increased; these changes are consistent with increasing temperature, as a result of rising summer insolation. From 11,000 to 7600 cal yr BP, the presence of a closed forest of Pinus and some Picea is attributed to high levels of winter moisture, but high fire activity indicates that summers were drier than at present. After 7600 cal yr BP, the presence of forest and steppe vegetation in combination with high fire activity suggest that middle-Holocene conditions were warm and dry. The decrease in Picea and Betula in the last 4000 cal yr indicates continued drying in the late Holocene, although fire-episode frequency was relatively high until 2000 cal yr BP. The pollen data at Blacktail Pond and other low-elevation sites in the northern Rocky Mountains suggest a widespread vegetation response in summer-wet regions to effectively wetter conditions in the early Holocene and decreased moisture in the middle and late Holocene. In contrast, the more-variable fire history among the three sites implies either that (1) summer moisture stress and fire conditions are related to year-round moisture balance and not well predicted by the hypothesis, (2) the transitional area between summer-wet and summer-dry precipitation regimes experienced complicated shifts in effective moisture through time, and/or (3) fire-episode data have a limited source area that makes it difficult to separate local influences from regional climate changes in understanding long-term variations in fire-episode frequency.

Mesquite, Tobosagrass, and Common Broomweed Responses to Fire Season and Intensity

There has been increasing interest in the use of summer fires to limit woody plant encroachment on grasslands, but information regarding effects of such fires on perennial grass recovery and annual forb production is also needed. Our objective was to examine effects of fire seasonality and intensity on the woody legume honey mesquite (Prosopis glandulosa Torr.), the C4 midgrass tobosagrass (Pleuraphis mutica Buckl.), and the annual forb common broomweed (Amphiachyris dracunculoides [DC.] Nutt.). Treatments included summer fires, high-intensity winter fires, low-intensity winter fires, and no burn in replicated plots. None of the fire treatments caused whole-plant mortality (root kill) in mesquite. Mesquite aboveground mortality (top kill) was much greater after summer and high-intensity winter fires than low-intensity winter fires. Tobosagrass total yield (live + dead) was lower following summer fires and was not enhanced by any of the fire treatments for two growing seasons postfire when compared to the no-burn condition. However, tobosagrass live yield was 40% greater in the high-intensity winter fire treatment than the no-burn condition the first summer postfire and recovered in the other fire treatments by the end of the first growing season postfire. Tobosagrass percentage of live tissue was greatest in the summer fire treatment at the end of each of the two growing seasons postfire. Common broomweed cover increased in the summer fire treatment and decreased in both winter fire treatments relative to the no-burn condition by the end of the first growing season postfire. Summer fire offered no clear advantage over high-intensity winter fire with respect to mesquite suppression. However, the increase in late-season tobosagrass percentage live tissue caused by summer fire may be advantageous for forage quality. In addition, patch burning summer fires to increase broomweed cover in selected areas may be useful for wildlife habitat. Ha habido un creciente interés en el uso de fuego de verano para limitar el incremento de plantas leñosas en áreas de pastizal, pero se necesita información sobre el efecto de las quemas de verano en la recuperación de las gramíneas perennes y la producción de herbáceas anuales. Nuestro objetivo fue, evaluar el efecto de la estación y la intensidad del fuego sobre el mezquite (Prosopis glandulosa Torr.), el pasto tobosa C4 (Pleuraphis mutica Buckl.), y la herbácea anual escobilla común (Amphiachyris dracunculoides [DC.] Nutt.). Los tratamientos contemplados fueron: quema de verano, quema de invierno de alta y baja intensidad, y el control sin quema en parcelas repetidas. Ninguno de los tratamientos de quema causó la muerte total de plantas de mezquite (muerte de la raíz). La mortalidad de la parte aérea del mezquite fue superior después de las quemas de verano e invierno con alta-intensidad comparadas con las quemas de invierno baja-intensidad. El forraje disponible total del pasto tobosa (forraje vivo y muerto) fue menor después de la quema de verano, sin incrementarse por el efecto de los tratamientos de quema después de dos estaciones de crecimiento, comparado con el control sin quema. Sin embargo, el rendimiento de forraje vivo fue 40% mayor en los tratamientos de quema invernal de alta intensidad comparada con el control sin quema, el primer verano. El porcentaje de forraje vivo del pasto tobosa fue mayor en los tratamientos de quema de verano al final de de la época de crecimiento. La cobertura de la escobilla común se incrementó en los tratamientos de quema de verano y disminuyó en los tratamientos de quema invernal de alta y baja intensidad, en relación al control sin quema para el final de la primera época de crecimiento después de la quema. La quema de verano no ofreció una ventaja clara sobre la quema invernal de alta intensidad en relación a la eliminación del mezquite. Sin embargo, el incremento en el porcentaje de forraje verde del pasto tobosa, debido a la quema de verano puede ser benéfico para la calidad del forraje, adicionalmente, la quema de verano en partes para incrementar la cobertura de la escobilla común en áreas seleccionadas puede ser útil para el hábitat de la fauna silvestre.

Seasonal variation in seed bank composition and its interaction with nutrient enrichment in the Everglades wetlands

In the Florida Everglades, nutrient enrichment from agricultural outflow and the change in hydrology have collectively contributed to the expansion of cattails ( Typha spp.). To assess the effectiveness of prescribed fire in controlling cattails and to predict vegetation dynamics after the fire, it is important to understand the seasonal variation of the soil seed bank and how the seed bank is affected by nutrient enrichment and fire. This paper investigates the effects of season, nutrient enrichment, and fire on soil seed bank species composition, richness, and density along a nutrient gradient in Water Conservation Area 2A (WCA 2A) of the Florida Everglades. Species richness was significantly affected by nutrient enrichment and season but not their interaction. Total seed density, however, was significantly affected by the interaction between nutrient enrichment and season. Yet, at species level, the relationship between seed density, nutrient enrichment and season varied. The highest seed density of cattail occurred in summer at highly enriched sites, but that of sawgrass occurred in fall regardless of enrichment; the seed density of water lily was very low regardless of season and nutrient enrichment, and the highest Amarathus seed density occurred at highly enriched sites year round. Moreover, germination timing differed greatly among species. While cattail seeds had a short incubation period and started to germinate 2–3 days after initiation of the germination assay, sawgrass seeds generally started to germinate 4 weeks later. Further, both the prescribed summer fire at the highly enriched site and the natural winter fire at the moderately enriched site reduced the seed density of cattail but not of sawgrass. Our results suggest that fire application for vegetation recovery in WCA 2A would benefit from explicitly considering seasonal dynamics of the seed bank.

Long-Term Response Patterns of Tallgrass Prairie to Frequent Summer Burning

Knowledge of how tallgrass prairie vegetation responds to fire in the late growing season is relatively sparse and is based upon studies that are either spatially or temporally limited. To gain a more robust perspective of vegetation response to summer burning and to determine if repeated summer fire can drive vegetational changes in native tallgrass prairie, we evaluated species cover and richness over a 14-yr period on different topographic positions from ungrazed watersheds that were burned biennially in the growing season. We found that annual forbs were the primary beneficiaries of summer burning, but their fluctuations varied inconsistently among years. Concomitantly, species richness and diversity increased significantly with summer burning but remained stable through time with annual spring burning. After 14 yr, species richness was 28% higher in prairie that was burned in the summer than in prairie burned in the spring. Canopy cover of big bluestem ( Andropogon gerardii Vitman) and Indiangrass ( Sorghastrum nutans [L.] Nash) increased significantly over time with both summer and spring burning, whereas heath aster ( Symphyotrichum ericoides [L.] Nesom), aromatic aster ( Symphyotrichum oblongifolium [Nutt.] Nesom), and sedges ( Carex spp.) increased in response to only summer burning. Kentucky bluegrass ( Poa pratensis L.) cover declined in both spring-burned and summer-burned watersheds. Repeated burning in either spring or summer did not reduce the cover or frequency of any woody species. Most perennial species were neutral in their reaction to summer fire, but a few species responded with large and inconsistent temporal fluctuations that overwhelmed any clear patterns of change. Although summer burning did not preferentially encourage spring-flowering forbs or suppress dominance of the warm-season grasses, it is a potentially useful tool to increase community heterogeneity in ungrazed prairie. El conocimiento de cómo la vegetación de pasto alto responde al fuego en la temporada de crecimiento tardía es relativamente escaso y se basa en estudios que son espacialmente o temporalmente limitados. Para obtener una perspectiva más robusta de la respuesta vegetativa a la quema de verano, y para determinar si el fuego repetido de verano conduce a cambios vegetacionales en la pradera de pasto alto nativo, nosotros evaluamos la riqueza y la cobertura de especies por un periodo de 14 años en diferentes posiciones topográficas de las cuencas hidrográficas sin pastar que fueron quemadas cada dos años en la temporada de crecimiento. Nosotros encontramos que los arbustos anuales fueron los principales beneficiarios de la quema de verano, pero sus fluctuaciones variaron inconsistentemente entre los años. Al mismo tiempo, la diversidad y la riqueza de especies se incrementaron significativamente con la quema de verano, pero permanecieron estables a través del tiempo con la quema anual de primavera. Después de 14 años, la riqueza de especie fue 28% más alta en la pradera que fue quemada en el verano que la pradera quemada en la primavera. La cobertura de dosel de la pitilla grande [ Andropogon gerardii Vitman] y el zacate indio [ Sorghastrum nutans {L.} Nash] se incrementó significativamente a través del tiempo con ambas quemas de primavera y de verano, mientras que la “heath aster” ( Symphyotrichum ericoides [L.] Nesom), “aromatic aster” ( S. oblongifolium [Nutt.] Nesom), y las cortaderas ( Carex spp.) aumentaron en respuesta solo a la quema de verano. La cobertura de la hierba azul de Kentucky (Poa paratensis) declinó en ambas quemas de primavera y verano en las cuencas hidrográficas. Las quemas repetidas en cada primavera ó verano no redujeron la cobertura ó frecuencia de cualquier especie leñosa. Muchas especies perennes fueron neutrales en su reacción al fuego de verano, pero unas pocas especies respondieron con fluctuaciones temporales grandes e inconsistente que abruman algunos patrones claros de cambio. Aunque la quema de verano no fomenta preferentemente a los arbustos que florecen en primavera ó suprimen la dominancia de las hierbas de la temporada cálida, es una herramienta potencialmente útil para incrementar la heterogeneidad de la comunidad.

Rangeland Vegetation and Soil Response to Summer Patch Fires Under Continuous Grazing

Prescribed fire is used to reduce woody plant and cactus cover and restore degraded rangelands in the southern Great Plains, but little is known regarding the impact of summer fires. We evaluated the effects of summer fires applied as patch burns in continuously grazed rangeland in north Texas. Vegetation and soil responses were measured on patches burned within grazing units in the summers of 1998, 1999, and 2000 relative to that on adjacent unburned control areas in the same grazing units. Annual rainfall during the study was below average for six burns (1998 and 1999) and average or above for three burns (2000). If average rainfall preceded and followed summer burning, degradation was limited to a modest increase in bare ground which recovered to exceed unburned control levels within 2 years. However, when drought conditions preceded and followed burning, there was an increase in bare ground and the proportion of annual forbs and annual grasses at the expense of perennial grasses. These areas took 3–5 years to recover. Areas burned in any year did not recover until after a season of favorable precipitation. The degree of degradation was proportional to the severity of drought conditions. The fires reduced the cover of honey mesquite (Prosopis glandulosa Torr.), other shrubs and cactus (Opuntia spp.), which facilitated herbaceous recovery, mitigating the negative impacts of burning in summer and the increased herbivory on the burned patches. Increases in herbaceous species composition were positively related to woody plant and cactus reduction following fire treatment. Results suggest that summer burning may be an effective and low-cost means of controlling problem plants, increasing pasture heterogeneity, and reducing herbivore impact on intensively grazed patches. However, before the practice of summer burning can be advocated, research needs to determine if post-burn deferment will facilitate more rapid recovery through regulating herbivory after burning to increase the recovery of litter and herbaceous cover and restore desired herbaceous species composition and production.

Impact of the open biomass fires in spring and summer of 2006 on the chemical composition of background air in south-eastern Finland

In the spring and summer of 2006 the air quality in southern Finland was affected by two major biomass fire smoke episodes. At the Virolahti background station, closest to the eastern fire areas, the episodes lasted altogether several weeks. The high point in spring was 25 April and in summer 13 August. In spring the aerosol detected at Virolahti originated at distances of even hundreds of kilometres to the south and south-east, and consequently was a mixture of material from biomass burning and from other sources (both LRT and local), all of which contributed to the detected elevation of PM 10 concentrations. The elevated concentrations of trace elements (Cd, Pb, Zn) during the most intense biomass fire episode were associated with other anthropogenic emissions. In contrast, during August 2006, the PM 10 at Virolahti was quite exclusively impacted by close (ca. 50–100 km) biomass fire sources. The presumably organic component comprised, at its highest, as much as 90% of the total PM 10. In addition to record high PM 10 and PM 2.5 concentrations, the concentrations of polycyclic aromatic hydrocarbons were considerably elevated, even reaching values more typical of wintertime urban environments. During the peaks of the episodes in August, the total gaseous mercury concentration in the air was more than double its background value. In general, the trace elements did not exceed their background values.

A satellite‐based assessment of transpacific transport of pollution aerosol

It has been well documented that pollution and dust from east Asia can be transported across the North Pacific basin, reaching North America and beyond. In this study, we assess the transpacific transport of “pollution aerosol” (defined as a mixture of aerosols from urban/industrial pollution and biomass burning) by taking advantage of the much improved measurement accuracy and enhanced new capabilities of satellite sensors in recent years. A 4‐year (2002 to 2005) climatology of optical depth for pollution aerosol was generated from Moderate Resolution Imaging Spectroradiometer (MODIS) observations of fine‐ and coarse‐mode aerosol optical depths. The pollution aerosol mass loading and fluxes were then calculated using measurements of the dependence of aerosol mass extinction efficiency on relative humidity and of aerosol vertical distributions from field campaigns and available satellite observations in the region. We estimated that about 18 Tg/a pollution aerosol is exported from east Asia to the northwestern Pacific Ocean, of which about 25% reaches the west coast of North America. The imported flux of 4.4 Tg/a to North America is equivalent to about 15% of local emissions from the United States and Canada. The pollution fluxes are largest in spring and smallest in summer. For the period we have examined the strongest export and import of pollution particulates occurred in 2003, largely because of record intense Eurasia boreal forest fires in spring and summer. The overall uncertainty of pollution fluxes is estimated at a factor of 2. Simulations by the Goddard Chemistry Aerosol Radiation and Transport (GOCART) and Global Modeling Initiative (GMI) models agree quite well with the satellite‐based estimates of annual and latitude‐integrated fluxes, with larger model‐satellite differences in latitudinal and seasonal variations of fluxes.

The effectiveness of active restoration following alien clearance in fynbos riparian zones and resilience of treatments to fire

In 1998, a restoration field trial was initiated in a catchment near Wellington (Western Cape, South Africa) to determine whether fynbos riparian scrub vegetation cleared of woody invasive alien trees require post-clearance restoration actions to accelerate indigenous vegetation recovery. The aim was to assess the relative effectiveness of three sowing treatments for restoring indigenous vegetation cover after the widely used “Fell & Burn” method of clearing invasive alien trees. Sowing treatments included non-invasive alien grasses to determine whether they have a negative effect on recovering native vegetation. A summer fire, eight years after trial initiation, provided an opportunity to determine how resilient restoration treatments are to alien re-invasion and fire. Restoring the site after alien clearing by sowing indigenous seeds increased both diversity, by improving species presence and abundance. However, a census done 8 years later (in 2006) revealed that seedlings of woody invasive alien plants dominated all plots, and had also survived the burn by resprouting, indicating the importance of follow-up control to justify initial clearing and restoration costs. Indigenous grass density was significantly reduced in plots where alien grasses were sown, while in the control and fynbos sowing treatment, indigenous grass density increased. By 2006, alien grass density was negligible in all treatments, indicating that the two grass species sown are not persistent or invasive. Active restoration of riparian areas after alien plant clearing has potential to facilitate vegetation recovery, but must be coupled with a long-term plan for adequate follow-up removal of post-clearance and post-fire alien recruits.

Air Quality Impacts from Prescribed Forest Fires under Different Management Practices

Large amounts of air pollutants are emitted during prescribed forest fires. Such emissions and corresponding air quality impacts can be modulated by different forest management practices. The impacts of changing burning seasons and frequencies and of controlling emissions during smoldering on regional air quality in Georgia are quantified using source-oriented air quality modeling, with modified emissions from prescribed fires reflecting effects of each practice. Equivalent fires in the spring and winter are found to have a greater impact on PM2.5 than those in summer, though ozone impacts are larger from spring and summer fires. If prescribed fires are less frequent more biofuel is burnt in each fire, leading to larger emissions and air quality impacts per fire. For example, emissions from a fire with a 5-year fire return interval (FRI) are 72% larger than those from a fire of the same acreage with a 2-year FRI. However, corresponding long-term regional impacts are reduced with the longer FRI since the annual burned area is reduced. Total emissions for fires in Georgia with a 5-year FRI are 32% less than those with a 2-year FRI. Smoldering emissions can lead to approximately 1.0 or 1.9 microg/m3 of PM2.5 in the Atlanta PM2.5 nonattainment area during March 2002.

Long-Term Effects of a Summer Fire on Desert Grassland Plant Demographics in New Mexico

Plant demographic responses to an experimental summer fire were monitored for 12 yr on the Sevilleta National Wildlife Refuge, New Mexico, to determine recovery rates of burned plants and evaluate fire effectiveness in preventing shrub invasion of desert grasslands. Fourteen common species of grasses, shrubs, yucca, and cacti were measured for mortality, resprouting, regrowth, herbivory, and reproduction. After the first postfire growing season, black grama (Bouteloua eriopoda [Torr.] Torr.) declined 80% in size, whereas blue grama (Bouteloua gracilis [Willd. ex Kunth] Lag. ex Griffiths) exhibited no decline. Linear regression indicated that B. eriopoda needed 11 yr to recover. Spike dropseed (Sporobolus contractus A.S. Hitchc.) and purple three-awn (Aristida purpurea Nutt.) showed postfire declines in plant sizes, requiring 4- and > 5-yr recovery times, respectively. Sand muhly (Muhlenbergia arenicola Buckl.) exhibited no fire impact. Snakeweed (Gutierrezia sarothrae [Pursh] Britt. & Rusby) sustained 61% fire mortality and reduction in regrowth canopy size. Creosotebush (Larrea tridentata [Sesse & Moc. ex DC.] Coville) had 12% mortality, but survivors recovered over 12 yr. Fourwing saltbush (Atriplex canescens [Pursh] Nutt.) sustained 62% mortality, but recovered plant size in 5–6 yr. Winterfat (Krascheninnikovia lanata [Pursh] A. D. J. Meeuse & Smit) suffered 7% mortality, but required 9+ yr to recover. Pale desert-thorn (Lycium pallidum Miers) survived fire, recovering prefire canopy size in 3 yr. Torrey joint-fir (Ephedra torreyana Watson) exhibited < 1% mortality, and recovered in 2–3 yr. Soapweed yucca (Yucca glauca Nutt.) had < 2% mortality, recovered plant sizes in 2 yr, and increased numbers of rosettes 17%. Chollas (Opuntia imbricata [Haw.] DC. and Opuntia clavata Engelm.) suffered high mortality rates and required > 12 yr recovery times. Results demonstrated that summer fire may counter some shrub and cacti invasion in central New Mexico, but once shrubs mature, fire is less effective in removing woody plants to restore southwestern grasslands. Las respuestas demográficas de vegetación a un fuego experimental de verano fue monitoreado por 12 años en el Refugio Nacional de Fauna Silvestre Sevilleta, Nuevo México, para determinar las tasas de recuperación de plantas quemadas y evaluar la eficacia del fuego para la prevención de invasiones de arbustos en los pastizales de desierto. Catorce especies comunes de pastos, arbustos, yuca y cactus fueron medidas para determinar la mortalidad, el rebrote, el crecimiento, la herbívoria y la reproducción. Después de la primera temporada de crecimiento posterior a la quema, el tamaño de la navajita negra (Bouteloua eriopoda [Torr.] Torr.) disminuyó en un 80%, mientras que la navajita azul (B. gracilis [Willd. ex Kunth] Lag. ex Griffiths) no mostró ninguna disminución. El modelo de regresión linear indica que B. eriopoda necesitó 11 años para recuperarse. El zacate espigado (Sporobolus contractus A.S. Hitchc.) y el zacate tres barbas (Aristida purpurea Nutt.) también mostraron una reducción en el tamaño de las plantas después del fuego, y necesitaron 4 y >5 años de recuperacion respectivamente. El mal forrage (Muhlenbergia arenicola Buckl.) no mostró ningún efecto al fuego. El romerito (Gutierrezia sarothrae [Pursh] Britt. & Rusby) sufrió una mortalidad de 61% y una reducción el rebrote del tamaño del dosel por el incendio. La gobernadora (Larrea tridentata [Sesse & Moc. ex DC.] Coville) tuvo una mortalidad de 12%, pero las plantas sobrevivientes se recobraron en 12 años. El chamiso (Atriplex canescens [Pursh] Nutt.) sufrió 62% de mortalidad, pero el tamaño de planta se recuperó en 5–6 años. EL senecio (Krascheninnikovia lanata [Pursh] A. D. J. Meeuse & Smit) sufrió una mortalidad de 7%, pero tomo 9+ años para recuperarse. La mora de lobo (Lycium pallidum Miers) sobrevivió el fuego, recuperando tamaño del dosel en 3 años. La caniatilla (Ephedra torreyana Watson) mostró <1% mortalidad y se recuperó en 2–3 años. La yuca (Yucca glauca Nutt.) tuvo una mortalidad menor al 2%, recobró su tamaño en 2 años y aumentó el número de panículas en 17%. Las chollas (Opuntia imbricata [Haw.] DC. y O. clavata Engelm.) mostraron altas tasas de mortalidad y requirieron >12 años para su recuperación. Los resultados demuestran que un incendio en verano podria contrarrestar la invasión de arbustos y cactus en el centro de Nuevo Mexico, pero una vez que los arbustos están establecidos, el fuego es menos efectivo para remover plantas leñosas y restaurar los pastos del suroeste.

Fire season effects on the recruitment of non‐sprouting serotinous Proteaceae in the eastern (bimodal rainfall) fynbos biome, South Africa

Abstract Research in Mediterranean‐climate shrublands in both South Africa and Australia shows that recruitment of proteoid shrubs (non‐sprouting, serotinous Proteaceae) is best after warm‐season (summer and autumn) fires and worst after cool‐season (winter and spring) ones. This pattern has been attributed to post‐dispersal seed attrition as well as size of pre‐dispersal seed reserves. Here we investigate patterns of post‐fire recruitment for four proteoid species in the eastern part of South Africa's fynbos biome, which has a bimodal (spring and autumn) rainfall regime. Despite the lack of significant differences in recruitment between cool‐ and warm‐season burns, we find some evidence for favourable recruitment periods following fires in spring and autumn, immediately before, and coinciding with, the bimodal rainfall peaks. This suggests that enhanced recruitment is associated with conditions of high soil moisture immediately after the fire, and that rapid germination may minimize post‐dispersal seed attrition. In two of the species, we also find a shift from peak flowering in winter and spring in the Mediterranean‐climate part of the fynbos biome, to summer and autumn flowering in the eastern part. Because these two species are only weakly serotinous, warm‐season flowering would result in maximal seed banks in spring, which could explain the spring recruitment peak, but not the autumn one. We conclude that eastern recruitment patterns differ significantly from those observed in the western and central parts of the biome, and that fire management protocols for the east, which are currently based on data and experience from the winter‐rainfall fynbos biome, need to be adjusted accordingly. Fire managers in the eastern fynbos biome should be less constrained by requirements to burn within a narrow seasonal range, and should therefore be in a better position to apply the required management burns.

Existing fire behaviour models under-predict the rate of spread of summer fires in open jarrah (Eucalyptus marginata) forest

SummaryFire behaviour data from Project Vesta experimental fires were used to evaluate the fire behaviour relationship on the Forest Fire Danger Meter (FFDM), the Forest Fire Behaviour Tables (FFBT) for Western Australia and the fire spread model of Burrows (1999) for predicting the rate of spread of fires in jarrah (Eucalyptus marginata) forest under dry summer conditions. Experimental fires were conducted at two sites in south-western Australia under conditions of moderate to high forest fire danger with fine fuel moisture contents of 6–9% oven dry weight and wind speeds up to 20 km h−1 (at 10 m in the open). Fuels ranged in age from 2 to 22 y since the last fire and had understorey shrub layers from 0.5 to 2.0 m tall. Mean rates of spread for experimental fires were 392 m h−1 and 405 m h−1 at the low and tall shrub sites respectively, with the fastest fires spreading at close to 1200 m h−1. Fires spread two to three times faster than predicted by the FFDM and FFBT fire spread models, and up to five times faster than predicted by the spread model of Burrows. Both the FFDM and FFBT models predicted fire spread better at the low shrub fuel site and when wind speeds were <12.5 km h−1. All models under-predicted fire spread at the tall shrub site and grossly under-predicted fire spread when wind speeds were >12.5 km h−1. We argue that existing fire behaviour models under-predict because they were developed using data from fires that had not achieved a quasi-steady rate of spread, whereas the line ignition technique used during Project Vesta experiments resulted in fires travelling at a speed closer to their potential rate of spread for the prevailing conditions. Existing guides remain valid for predicting spread during the early stages of fire growth when fires are developing from a point ignition and the headfire remains narrow.

Niveaux et vitesses de résilience des landes atlantiques après feux

If burning was a standard management tool for heathland, the loose of traditional management occurs more and more and might be the cause of severe humus fires. Through different diachronical techniques, we analyse plant and ecosystems responses linked with different fire intensities and their consequences. Four major dynamic trajectories occurred in relation with fuel accumulation, ash accumulation or erosion, and persistence or not of an active seed bank. Plant population dynamics and their responses to disturbance determine resilience levels and quickness of heathland communities after severe summer fires in 1976.

Comparison of Techniques for Visualising Fire Behaviour

AbstractDuring every Australian summer fires are common in the south‐eastern region of the continent. The combined forces of climate, topography and vegetation make Victoria in particular, one of the most fire prone regions on earth (DSE 2003). Throughout its history, Victoria has seen a number of devastating bushfires, including Black Friday 1939, Ash Wednesday 1983, and more recently in the northeast of the State in 2003. The loss of life combined with the damage caused to land and property results in a heavy cost to the community. In Victoria, two of the organizations involved in fire management are the Victorian Department of Sustainability and Environment (DSE) and the Country Fire Authority (CFA). Both use fire ‘meters’ to determine potential fire behaviour given certain conditions. Values for temperature, wind speed, fuel load and vegetation type are input and a numerical estimate of fire danger given. There are a number of different meters used for different locations and environmental types. The most common meter used in Victoria is the McArthur Meter (CSIR0 2001b). The output data from this meter is numerical, and provides no spatial representation of fire danger. This paper looks at a variety of techniques used to visualise the numerical output from the McArthur Forest Fire Danger Meter. The article outlines the different models used by fire managers to simulate a fire situation, to assess future scenarios and for decision making involving fire management. Particular emphasis is placed on the McArthur Forest Fire Danger Meter as this is commonly used by fire departments in Australia. The article then focuses on geographical visualisation and a number of techniques employed to convey spatial information are discussed. The article then goes on to describe the fire simulation prototypes created for a study, a visualisation proof‐of‐concept product for organizations involved in managing bushfires in Australia. Finally, results from the evaluation of the prototype are presented.

Prickly Pear Cactus Responses to Summer and Winter Fires

Prescribed fire is used to reduce size and density of prickly pear cactus (Opuntia spp.) in many rangeland ecosystems. However, effects of dormant season fires (i.e., winter fires) are inconsistent. Thus, there is increasing interest in use of growing season (summer) fires. Our objective was to evaluate effects of fire season and fire intensity on mortality and individual plant (i.e., “motte”) structure (area per motte, cladodes per motte, motte height) of brownspine prickly pear (O. phaeacantha Engelm.). The study had 4 treatments: no fire, low-intensity winter fire, high-intensity winter fire, and summer fire. Three sizes of prickly pear mottes were evaluated: small (0–20 cladodes per motte), medium (21–100), and large (101–500). At 3 years postfire, prickly pear mortality in the summer fire treatment was 100% in small mottes, 90% in medium mottes, and 80% in large mottes. Motte mortality increased in this treatment over time, especially in large mottes. Mortality from high-intensity winter fires was 29% and 19% in small and medium mottes, respectively, but no large mottes were killed. Motte mortality was < 10% in low-intensity winter fire and no-fire treatments. Summer fires reduced all motte structural variables to 0 in small mottes and nearly 0 in other motte size classes. High-intensity winter fires reduced some structural variables of medium and large mottes, but had no long-term negative effects on area per motte or cladodes per motte in surviving small mottes. Low-intensity winter fires had no long-term negative effects on motte structure in any size class. Rapid growth of mottes, and especially small mottes, in the no-fire treatment suggested that resistance to winter fires can occur rapidly.

Re-evaluation of a riparian restoration experiment in the Western Cape Province: Status 8 years down the line

In 1998, a study was initiated to assess the relative effectiveness of three different sowing treatments for reducing soil erosion and restoring indigenous riparian vegetation cover after alien clearing in the Western Cape. The study concluded that introducing a mixture of seed to a riparian zone with a history of invasion can increase indigenous vegetation cover and species richness and has a stabilizing effect on eroded riverbanks. We report on a reassessment of the restoration plots after a period of 8 years (with no follow up control) and a summer fire in 2005. The re-assessment included a survey of all the burnt woody material within the different treatment plots to determine species presence (dead or resprouting) and abundance, as well as a survey of seedlings in a post-fire environment. Woody invasive plants (IAPs) dominated all plots, and had survived the burn with the majority re-sprouting, indicating the dire need for follow-up control to justify initial clearing and restoration cost. However the re-assessment revealed that indigenous vegetation cover was considerably higher in the plots that had received sowing treatments, while the control plots were dominated by Acacia mearnsii, the main invader of the tributary. Restoration of riparian areas after alien plant clearing has potential, but must be coupled with a long-term plan for follow up removal of post clearing IAP recruits.

Texas Wintergrass and Buffalograss Response to Seasonal Fires and Clipping

There is increased interest in the use of summer-season fires to limit woody plant encroachment into grasslands, but effects of these fires on grasses are poorly understood. We quantified effects of repeated winter fires, repeated summer fires, and clipping (to simulate grazing) on aboveground total yield, live yield, and percentage of live tissue of C3 Texas wintergrass (Nassella leucotricha (Trin. & Rupr.) Pohl.), and C4 buffalograss (Buchloedactyloides (Nutt.) Engelm.) in 2 experiments. Monospecific patches of each species were exposed to 1 of 3 fire treatments (no-fire, 2 winter fires in 3 years, or 2 summer fires in 3 years) and 1 of 2 clip treatments (no clip or clip once each spring). Experiment 1 evaluated effects of fire without grazing or clipping on late-growing season (late-season) yields. Late-season total yield of both species recovered from winter and summer fires within 1 or 2 growing seasons post-fire. By 3 years post-fire, Texas wintergrass late-season total yield was 2 times greater in the summer fire treatment than the winter fire or no-fire treatments, and buffalograss late-season total yield was 3 times greater in summer and winter fire treatments than in the no-fire treatment. Experiment 2 evaluated combined effects of fire and clipping the previous spring on spring-season yields. Clipping alone or with fire (summer or winter) reduced Texas wintergrass yields on more sample dates than occurred with buffalograss. By 3 years post-fire, buffalograss spring total yield was greater in all fire and fire þ clip treatments than in the clip only or untreated controls. Results suggest: 1) both species were tolerant of summer fire, 2) fire in either season with or without clipping stimulated buffalograss production, and 3) buffalograss was more tolerant than Texas wintergrass to the combined effects of clipping þ fire (either season).