Fire regime of a Elionorus muticus Spreng. savanna, western Chaco region, Argentina

2001 ◽  
Vol 10 (1) ◽  
pp. 65 ◽  
Author(s):  
Sandra Bravo ◽  
Carlos Kunst ◽  
Ana Gimenez ◽  
Graciela Moglia
Keyword(s):  
Cross Sections ◽  
Native Species ◽  
Fire History ◽  
Fire Regime ◽  
Woody Species ◽  
Fire Frequency ◽  
Grass Species ◽  
Fire Scars ◽  
Chaco Region ◽  
Native Woody Species

Our objective was to assess the current fire regime of a 600 ha savanna dominated by the grass species Elionorus muticus Spreng., located in Santiago del Estero Province, north-western Chaco region, Argentina. The degree of tolerance of some native woody species to fire, the fire mean fire frequency (FF), and Weibull median probability (WMPI) were evaluated. Sampling sites were located in the ecotone between the savanna and the surrounding forests. A database was developed from fire scars found in cross sections of native tree and shrub species, cut at different heights above ground; that covered the recent 70 years of fire history (1925–1996). Results indicate that the savanna has a mean FF of 0.179 fires year–1 and an FI = 3 years. The mean height of fire scars found in trees and shrubs which indicate medium to high fireline intensities with flame lengths larger than 1 m are frequent in the savanna. Native species have different degrees of tolerance: Aspidosperma quebracho blanco (tree) and Schinopsis quebracho colorado (tree) are more tolerant to fire than Acacia furcatispina (shrub) and A. aroma (shrub). Bark thickness of the tree species (1–1.5 cm in mature individuals) allows them to withstand the frequent, high intensity fires of the savanna.

Comparing methods of reconstructing fire history using fire scars in a southwestern United States ponderosa pine forest

2006 ◽  
Vol 36 (4) ◽  
pp. 855-867 ◽  
Author(s):  
Megan L Van Horne ◽  
Peter Z Fulé
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Fire History ◽  
Sampling Methods ◽  
Fire Regime ◽  
Fire Frequency ◽  
Fire Scars ◽  
Fire Scar ◽  
Targeted Sampling ◽  
Fire Intervals

Fire scars have been used to understand the historical role of fire in ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) ecosystems, but sampling methods and interpretation of results have been criticized for being statistically invalid and biased and for leading to exaggerated estimates of fire frequency. We compared "targeted" sampling, random sampling, and grid-based sampling to a census of all 1479 fire-scarred trees in a 1 km2 study site in northern Arizona. Of these trees, 1246 were sufficiently intact to collect cross-sections; of these, 648 had fire scars that could be cross-dated to the year of occurrence in the 200-year analysis period. Given a sufficient sample size (approximately n ≥ 50), we concluded that all tested sampling methods resulted in accurate estimates of the census fire frequency, with mean fire intervals within 1 year of the census mean. We also assessed three analytical techniques: (1) fire intervals from individual trees, (2) the interval between the tree origin and the first scar, and (3) proportional filtering. "Bracketing" fire regime statistics to account for purported uncertainty associated with targeted sampling was not useful. Quantifying differences in sampling approaches cannot resolve all the limitations of fire-scar methods, but does strengthen interpretation of these data.

A cross-dated fire history from coast redwood near Redwood National Park, California

1994 ◽  
Vol 24 (1) ◽  
pp. 21-31 ◽  
Author(s):  
Peter M. Brown ◽  
Thomas W. Swetnam
Keyword(s):  
Cross Sections ◽  
National Park ◽  
Fire History ◽  
Fire Frequency ◽  
Fire Scars ◽  
Coast Redwood ◽  
Complete Representation ◽  
Fire Scar ◽  
Redwood National Park ◽  
The Mean

Cross sections from coast redwood trees (Sequoiasempervirens (D.Don.)Endl.) in and near Redwood National Park were dendrochronologically cross-dated and used to develop a fire history from 1714 to 1985. A master chronology for the study area was first developed from old-growth trees and provided dating control for fire-scarred samples. Redwood offers a challenge for dendrochronology owing to partially absent rings (ring wedging) and uniform ring widths (complacency). Cross dating was successful in portions of 12 of 24 fire-scarred trees. Fire events were dated by noting the position of fire scars and other fire-associated ring structures (resin ducts, double latewood, growth releases, and ring separations) in the cross-dated ring series. Using only dates of fire scars, the mean fire interval (MFI) was 9.9 years from the first recorded fire in 1714 to the last in 1962. The MFI was 8.0 years for the best represented (greatest sample depth) presettlement period from 1714 to 1881. Using dates for all fire-associated ring features, the MFI from 1714 to 1962 was 7.0 years and from 1714 to 1881 was 6.0 years. Use of all fire-associated ring characteristics is argued to be a more complete representation of past fire frequency due to possible under-representation of fire-scar records from stump-top samples. Based upon scar positions within annual rings, fires occurred predominately late in the growing season or after growth ceased for the year. The mean fire intervals determined are shorter than those reported in all except one other fire history study from coast redwood and suggest that fire frequency in redwood may have been underestimated in many past studies.

Fire regime shift linked to increased forest density in a piñon–juniper savanna landscape

2014 ◽  
Vol 23 (2) ◽  
pp. 234 ◽  
Author(s):  
Ellis Q. Margolis
Keyword(s):  
Regime Shift ◽  
Fire History ◽  
Fire Regime ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Climatic Conditions ◽  
Tree Density ◽  
High Severity ◽  
Wide Range ◽  
In Fire

Piñon–juniper (PJ) fire regimes are generally characterised as infrequent high-severity. However, PJ ecosystems vary across a large geographic and bio-climatic range and little is known about one of the principal PJ functional types, PJ savannas. It is logical that (1) grass in PJ savannas could support frequent, low-severity fire and (2) exclusion of frequent fire could explain increased tree density in PJ savannas. To assess these hypotheses I used dendroecological methods to reconstruct fire history and forest structure in a PJ-dominated savanna. Evidence of high-severity fire was not observed. From 112 fire-scarred trees I reconstructed 87 fire years (1547–1899). Mean fire interval was 7.8 years for fires recorded at ≥2 sites. Tree establishment was negatively correlated with fire frequency (r=–0.74) and peak PJ establishment was synchronous with dry (unfavourable) conditions and a regime shift (decline) in fire frequency in the late 1800s. The collapse of the grass-fuelled, frequent, surface fire regime in this PJ savanna was likely the primary driver of current high tree density (mean=881treesha–1) that is >600% of the historical estimate. Variability in bio-climatic conditions likely drive variability in fire regimes across the wide range of PJ ecosystems.

Using simulation to map fire regimes: an evaluation of approaches, strategies, and limitations

2003 ◽  
Vol 12 (4) ◽  
pp. 309 ◽  
Author(s):  
Robert E. Keane ◽  
Geoffrey J. Cary ◽  
Russell Parsons
Keyword(s):  
Geographical Information Systems ◽  
Fire History ◽  
Fire Regime ◽  
Wildland Fire ◽  
Fire Regimes ◽  
Simulation Modelling ◽  
Fire Frequency ◽  
Geographical Information ◽  
Spatially Explicit ◽  
Eastern Australia

Spatial depictions of fire regimes are indispensable to fire management because they portray important characteristics of wildland fire, such as severity, intensity, and pattern, across a landscape that serves as important reference for future treatment activities. However, spatially explicit fire regime maps are difficult and costly to create requiring extensive expertise in fire history sampling, multivariate statistics, remotely sensed image classification, fire behaviour and effects, fuel dynamics, landscape ecology, simulation modelling, and geographical information systems (GIS). This paper first compares three common strategies for predicting fire regimes (classification, empirical, and simulation) using a 51�000�ha landscape in the Selway-Bitterroot Wilderness Area of Montana, USA. Simulation modelling is identified as the best overall strategy with respect to developing temporally deep spatial fire patterns, but it has limitations. To illustrate these problems, we performed three simulation experiments using the LANDSUM spatial model to determine the relative importance of (1) simulation time span; (2) fire frequency parameters; and (3) fire size parameters on the simulation of landscape fire return interval. The model used to simulate fire regimes is also very important, so we compared two spatially explicit landscape fire succession models (LANDSUM and FIRESCAPE) to demonstrate differences between model predictions and limitations of each on a neutral landscape. FIRESCAPE was developed for simulating fire regimes in eucalypt forests of south-eastern Australia. Finally, challenges for future simulation and fire regime research are presented including field data, scale, fire regime variability, map obsolescence, and classification resolution.

Fire regimes and their correlates in the Darwin region of northern Australia

2007 ◽  
Vol 13 (3) ◽  
pp. 177 ◽  
Author(s):  
Owen Price ◽  
Bryan Baker
Keyword(s):  
Fire History ◽  
Ad Hoc ◽  
Fire Regime ◽  
Negative Impact ◽  
Fire Suppression ◽  
Landsat Imagery ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Dry Season ◽  
Generalized Linear Modelling

A nine year fire history for the Darwin region was created from Landsat imagery, and examined to describe the fire regime across the region. 43% of the region burned each year, and approximately one quarter of the fires occur in the late dry season, which is lower than most other studied areas. Freehold land, which covers 35% of the greater Darwin region, has 20% long-unburnt land. In contrast, most publicly owned and Aboriginal owned land has very high fire frequency (60-70% per year), and only 5% long unburnt. It seems that much of the Freehold land is managed for fire suppression, while the common land is burnt either to protect the Freehold or by pyromaniacs. Generalized Linear Modelling among a random sample of points revealed that fire frequency is higher among large blocks of savannah vegetation, and at greater distances from mangrove vegetation and roads. This suggests that various kinds of fire break can be used to manage fire in the region. The overall fire frequency in the Darwin region is probably too high and is having a negative impact on wildlife. However, the relatively low proportion of late dry season fires means the regime is probably not as bad as in some other regions. The management of fire is ad-hoc and strongly influenced by tenure. There needs to be a clear statement of regional fire targets and a strategy to achieve these. Continuation of the fire mapping is an essential component of achieving the targets.

Relationship between fire frequency and nitrogen limitation on foliage production in a native grassland community in Victoria, Australia

2007 ◽  
Vol 29 (1) ◽  
pp. 101 ◽  
Author(s):  
J. W. Morgan
Keyword(s):  
Native Species ◽  
Fire History ◽  
Species Coexistence ◽  
Fire Frequency ◽  
N Availability ◽  
N Addition ◽  
Grassland Community ◽  
Native Grasslands ◽  
Native Grassland ◽  
Western Victoria

The relationship between fire frequency (annual v. infrequent) and nitrogen (N) limitation to foliage production in a temperate native grassland community in western Victoria, Australia, was assessed over one growing season using a simple ammonium nitrate addition experiment. Fire history affected the magnitude of the vegetation responses to N addition. At the community level, mean live biomass in infrequently-burned grasslands declined by 20 ± 8% in response to N addition. In contrast, mean biomass increased by 60 ± 15% in annually-burned grasslands in response to N addition. Both grasses and forbs responded positively to N addition in annually-burned grasslands, with forbs responding more substantially than grasses. Foliage production in annually-burned native grasslands therefore appears to be constrained by N availability. The results of this study may have important implications for understanding species coexistence and invasion by non-native species in temperate native grasslands.

The influences of drought and humans on the fire regimes of northern Pennsylvania, USA

2013 ◽  
Vol 43 (8) ◽  
pp. 757-767 ◽  
Author(s):  
Patrick H. Brose ◽  
Daniel C. Dey ◽  
Richard P. Guyette ◽  
Joseph M. Marschall ◽  
Michael C. Stambaugh
Keyword(s):  
American Indians ◽  
Cross Sections ◽  
Prescribed Fire ◽  
Fire History ◽  
Fire Regime ◽  
Fire Regimes ◽  
European Settlement ◽  
Pine Regeneration ◽  
Fire Exclusion ◽  
Dormant Season

Understanding past fire regimes is necessary to justify and implement restoration of disturbance-associated forests via prescribed fire programs. In eastern North America, the characteristics of many presettlement fire regimes are unclear because of the passage of time. To help clarify this situation, we developed a 435-year fire history for the former conifer forests of northern Pennsylvania. Ninety-three cross sections of fire-scarred red pines (Pinus resinosa Aiton) collected from three sites were analyzed to determine common fire regime characteristics. Prior to European settlement, fires occurred every 35–50 years and were often large dormant-season burns that sometimes initiated red pine regeneration. American Indians probably ignited these fires. Fire occurrence had a weak association with multiyear droughts. After European settlement started around 1800, fires occurred every 5–7 years due to widespread logging. Fire size and seasonality expanded to include small growing-season fires. The weak drought–fire association ceased. In the early 1900s, logging ended and wildfire control began. Since then, fires have been nearly absent from the sites despite several multiyear droughts in the 20th century. The human influences of cultural burning, logging, and fire exclusion are more important than the influence of drought to the fire regimes of northern Pennsylvania.

Fires in temperate peatlands (southern Quebec): past and recent trends

2007 ◽  
Vol 85 (3) ◽  
pp. 263-272 ◽  
Author(s):  
Claude Lavoie ◽  
Stéphanie Pellerin
Keyword(s):  
Fire History ◽  
Fire Regime ◽  
Fire Frequency ◽  
Time Interval ◽  
Temperate Region ◽  
Forest Expansion ◽  
Short Period ◽  
History Of ◽  
Recent Trends

In this study, we reconstructed the long-term fire history of a set of ombrotrophic peatlands (bogs) located in a temperate region of southern Quebec (Bas-Saint-Laurent). Past and recent fire-free intervals (time interval between two consecutive fires) were compared using macrofossil analyses. During most of the Holocene epoch, fires were relatively rare events in bogs of the Bas-Saint-Laurent region. The fire-free intervals were approximately ten times longer (all sites considered) before the beginning of agricultural activities in the region (1800 AD) than after. This strongly suggests an anthropogenic influence on the fire regime prevailing in the bogs over the last 200 years. However, the shortening of the fire-free intervals was mainly the result of the ignition of one or two fires in almost every site during a relatively short period (200 years), rather than a higher fire frequency in each of the bogs. In some cases, fires had an influence on the vegetation structure of bogs, but it is more likely that a combination of several disturbances (fire, drainage, and drier than average summers) favoured the establishment of dense stands of pine and spruce, a forest expansion phenomenon that is now widespread in temperate bogs.

The influence of a variable fire regime on woodland structure and composition

2015 ◽  
Vol 24 (1) ◽  
pp. 59 ◽  
Author(s):  
Emma E. Burgess ◽  
Patrick Moss ◽  
Murray Haseler ◽  
Martine Maron
Keyword(s):  
Fire History ◽  
Stand Structure ◽  
Fire Regime ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Fire Event ◽  
Time Since Fire ◽  
Eucalypt Woodlands ◽  
Vegetation Structures ◽  
The Relationship

The post-fire response of vegetation reflects not only a single fire event but is the result of cumulative effects of previous fires in the landscape. For effective ecological fire management there is a need to better understand the relationship between different fire regimes and vegetation structure. The study investigated how different fire regimes affect stand structure and composition in subtropical eucalypt woodlands of central Queensland. We found that fire history category (i.e. specific combinations of time since fire, fire frequency and season of last burn) strongly influenced richness and abundance of species categorised as mid-storey trees and those individuals currently in the mid-level strata. Time since fire and fire frequency appeared to have the strongest influence. A longer time since fire (>4 years since last burn), combined with infrequent fires (<2 fires in 12 year period) appeared to promote a dense mid-storey with the opposite conditions (<4 years since last burn; >2 fires in 12 year period) promoting more-open woodlands. Consideration of these combined fire regime attributes will allow fire managers to plan for a particular range of fire-mediated patches to maintain the desired diversity of vegetation structures.

Anatomical changes induced by fire-damaged cambium in two native tree species of the Chaco Region, Argentina

IAWA Journal ◽  
2010 ◽  
Vol 31 (3) ◽  
pp. 283-292 ◽  
Author(s):  
Sandra Bravo
Keyword(s):  
Cross Sections ◽  
Wood Quality ◽  
Cambial Activity ◽  
Wood Formation ◽  
Vessel Diameter ◽  
Fire Damage ◽  
Fire Scars ◽  
Fire Scar ◽  
Chaco Region ◽  
Altered Zone

This study examined anatomical responses to fire damage of the cambium in Schinopsis lorentzii and Aspidosperma quebracho-blanco. Bole cross sections were extracted from specimens with external signs of fire damage. Samples were taken from zones designated normal, discoloured and wound altered. The vessel, fibre, axial and ray parenchyma percentages, tangential vessel diameter, vessels per mm2, rays per mm, and ray width and height of these zones were compared. Fire scars and fire marks were identified on cross sections of S. lorentzii and A. quebracho-blanco. The fire marks reflect minor wounds that did not affect wood formation. The fire scars, on the other hand, are the result of wounds that interrupted cambial activity thus affecting the shape of the bole and causing discolouration of pre-existing wood adjacent to wounds. The wood formed after fire damage included callus, barrier zones at fire scar edges and the formation of ribs of wound wood. The wound altered zone was characterised by a decrease in the percentage of vessels and fibres, an increase in the percentage of axial parenchyma, the formation of grouped rays, a decrease in vessel tangential diameter, and occurrence of fibres with atypical structure. Disorientation in the axial xylem system was observed in the barrier zone. The anatomical responses to cambium damage and formation of discoloured wood and woundwood ribs suggest that wood quality and utilisable volume of bole in the studied species is affected by fire.

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