Post-fire regeneration strategies and flammability traits of California chaparral shrubs

2010 ◽  
Vol 19 (7) ◽  
pp. 984 ◽  
Author(s):  
Peter D. Cowan ◽  
David D. Ackerly
Keyword(s):  
Water Status ◽  
Fuel Load ◽  
Regeneration Strategy ◽  
Fire Behaviour ◽  
Timing Of Reproduction ◽  
Adenostoma Fasciculatum ◽  
Physiological Processes ◽  
Heteromeles Arbutifolia ◽  
Regeneration Strategies ◽  
Ceanothus Cuneatus

Fire behaviour is strongly influenced by fuel load and structure; however, efforts to describe fuel patterns have largely ignored differences among species or post‐fire regeneration strategies. In California chaparral, evergreen shrubs can be grouped into three post‐fire regeneration strategies that correlate with a wide variety of physiological and demographic characteristics including seasonal water status and the timing of reproduction in response to fire. To test if regeneration strategy is also associated with flammability, we compared the fuel loads and structure of two post‐fire seeders, Adenostoma fasciculatum and Ceanothus cuneatus, and two obligate resprouters, Heteromeles arbutifolia and Prunus ilicifolia. Species and post‐fire regeneration strategies did not differ in total fuel per area, or bulk density. The proportion of fuels smaller than 6 mm in diameter differed among species, but not consistently with regeneration strategy. However, species with a post‐fire seeding regeneration strategy had higher proportions of dead branches. We discuss how this difference could have arisen from evolutionary, demographic, or physiological processes.

Fuel and fire characteristics in savanna - woodland of West Africa in relation to grazing and dominant grass type

2007 ◽  
Vol 16 (5) ◽  
pp. 531 ◽  
Author(s):  
Patrice Savadogo ◽  
Didier Zida ◽  
Louis Sawadogo ◽  
Daniel Tiveau ◽  
Mulualem Tigabu ◽  
...  
Keyword(s):  
Prescribed Burning ◽  
Management Tool ◽  
Fuel Load ◽  
Maximum Temperature ◽  
Fire Intensity ◽  
Fire Behaviour ◽  
Savanna Woodland ◽  
Vegetation Height ◽  
Average Maximum ◽  
Dominant Grass

Fuel characteristics, fire behaviour and temperature were studied in relation to grazing, dominant grass type and wind direction in West African savanna–woodland by lighting 32 prescribed early fires. Grazing significantly reduced the vegetation height, total fuel load, and dead and live fuel fractions whereas plots dominated by perennial grasses had higher values for vegetation height, total fuel load and the quantity of live fuel load. Although fire intensity remained insensitive (P > 0.05) to any of these factors, fuel consumption was significantly (P = 0.021) reduced by grazing, rate of spread was faster in head fire (P = 0.012), and flame length was shorter in head fire than back fire (P = 0.044). The average maximum temperature was higher (P < 0.05) on non-grazed plots, on plots dominated by annual grasses, on plots subjected to head fire, and at the soil surface. Lethal temperature residence time showed a nearly similar trend to fire temperature. Wind speed and total fuel load were best predictors of fire behaviour parameters (R2 ranging from 0.557 to 0.862). It can be concluded that grazing could be used as a management tool to modify fire behaviour, back fire should be carried out during prescribed burning to lower fire severity, and the fire behaviour models can be employed to guide prescribed early fire in the study area.

Forest fuels and potential fire behaviour 12 years after variable-retention harvest in lodgepole pine

2016 ◽  
Vol 25 (6) ◽  
pp. 633 ◽  
Author(s):  
Justin S. Crotteau ◽  
Christopher R. Keyes ◽  
Elaine K. Sutherland ◽  
David K. Wright ◽  
Joel M. Egan
Keyword(s):  
Lodgepole Pine ◽  
Structural Complexity ◽  
Fuel Load ◽  
Fire Behaviour ◽  
Forest Fuels ◽  
Fuel Loads ◽  
Variable Retention ◽  
Harvesting Technique ◽  
Trade Offs ◽  
Variable Retention Harvesting

Variable-retention harvesting in lodgepole pine offers an alternative to conventional, even-aged management. This harvesting technique promotes structural complexity and age-class diversity in residual stands and promotes resilience to disturbance. We examined fuel loads and potential fire behaviour 12 years after two modes of variable-retention harvesting (dispersed and aggregated retention patterns) crossed by post-harvest prescribed fire (burned or unburned) in central Montana. Results characterise 12-year post-treatment fuel loads. We found greater fuel load reduction in treated than untreated stands, namely in the 10- and 100-h classes (P = 0.002 and 0.049 respectively). Reductions in 1-h (P < 0.001), 10-h (P = 0.008) and 1000-h (P = 0.014) classes were greater in magnitude for unburned than burned treatments. Fire behaviour modelling incorporated the regenerating seedling cohort into the surface fuel complex. Our analysis indicates greater surface fireline intensity in treated than untreated stands (P < 0.001), and in unburned over burned stands (P = 0.001) in dry, windy weather. Although potential fire behaviour in treated stands is predicted to be more erratic, within-stand structural variability reduces probability of crown fire spread. Overall, results illustrate trade-offs between potential fire attributes that should be acknowledged with variable-retention harvesting.

Using visual obstruction to estimate heathland fuel load and structure

2008 ◽  
Vol 17 (3) ◽  
pp. 380 ◽  
Author(s):  
G. M. Davies ◽  
A. Hamilton ◽  
A. Smith ◽  
C. J. Legg
Keyword(s):  
Vertical Distribution ◽  
Canopy Structure ◽  
Fuel Load ◽  
Vegetation Density ◽  
Fire Behaviour ◽  
Fuel Loading ◽  
Simple Method ◽  
Visual Obstruction ◽  
Non Destructive ◽  
The Vertical Distribution

We present a simple non-destructive technique for assessing fuel load and critical aspects of vegetation structure that play important roles in determining fire behaviour. The method is tested in a Scottish Calluna vulgaris (L.) Hull heathland but could be applied to any vegetation up to ~1 m high. Visual obstruction of a banded measurement stick (the FuelRule) placed vertically through a stand of vegetation is governed by a combination of the height of the vegetation and its density. The vertical distribution of visual obstruction is calibrated to give estimates of total fuel loading, the loading of separate size categories and the vertical distribution and horizontal heterogeneity of fuels. The present paper provides a quick and simple method for estimating total aboveground biomass and structure that may be useful not just in studies of fire behaviour but where non-destructive assessment of biomass, vegetation density or canopy structure is needed. Calibration equations can be rapidly created for use in other vegetation or fuel types.

scholarly journals Fire characteristics and environmental conditions shape plant communities via regeneration strategy

2021 ◽  
Author(s):  
Nicola Day ◽  
AL White ◽  
JF Johnstone ◽  
G Degré-Timmons ◽  
SG Cumming ◽  
...  
Keyword(s):  
Community Structure ◽  
Plant Regeneration ◽  
Plant Communities ◽  
Environmental Conditions ◽  
Fire Severity ◽  
Regeneration Strategy ◽  
Regeneration Strategies ◽  
Understory Plant ◽  
Fire Characteristics ◽  
Mature Stands

© 2020 The Authors. Ecography published by John Wiley & Sons Ltd on behalf of Nordic Society Oikos Climate change is altering disturbance regimes outside historical norms, which can impact biodiversity by selecting for plants with particular traits. The relative impact of disturbance characteristics on plant traits and community structure may be mediated by environmental gradients. We aimed to understand how wildfire impacted understory plant communities and plant regeneration strategies along gradients of environmental conditions and wildfire characteristics in boreal forests. We established 207 plots (60 m2) in recently burned stands and 133 plots in mature stands with no recent fire history in comparable gradients of stand type, site moisture (drainage) and soil organic layer (SOL) depth in two ecozones in Canada's Northwest Territories. At each plot, we recorded all vascular plant taxa in the understory and measured the regeneration strategy (seeder, resprouter, survivor) in burned plots, along with seedbed conditions (mineral soil and bryophyte cover). Dispersal, longevity and growth form traits were determined for each taxon. Fire characteristics measured included proportion of pre-fire SOL combusted (fire severity), date of burn (fire seasonality) and pre-fire stand age (time following fire). Results showed understory community composition was altered by fire. However, burned and mature stands had similar plant communities in wet sites with deep SOL. In the burned plots, regeneration strategies were determined by fire severity, drainage and pre- and post-fire SOL depth. Resprouters were more common in wet sites with deeper SOL and lower fire severity, while seeders were associated with drier sites with thinner SOL and greater fire severity. This led to drier burned stands being compositionally different from their mature counterparts and seedbed conditions were important. Our study highlights the importance of environment–wildfire interactions in shaping plant regeneration strategies and patterns of understory plant community structure across landscapes, and the overriding importance of SOL depth and site drainage in mediating fire severity, plant regeneration and community structure.

Got to burn to learn: the effect of fuel load on grassland fire behaviour and its management implications

2018 ◽  
Vol 27 (11) ◽  
pp. 727 ◽  
Author(s):  
Miguel G. Cruz ◽  
Andrew L. Sullivan ◽  
James S. Gould ◽  
Richard J. Hurley ◽  
Matt P. Plucinski
Keyword(s):  
Fire Spread ◽  
Flame Height ◽  
Fuel Load ◽  
Limiting Factor ◽  
Fire Behaviour ◽  
Load Effect ◽  
Fire Propagation ◽  
Rate Of Spread ◽  
Eastern Australia ◽  
Modelling Assumptions

The effect of grass fuel load on fire behaviour and fire danger has been a contentious issue for some time in Australia. Existing operational models have placed different emphases on the effect of fuel load on model outputs, which has created uncertainty in the operational assessment of fire potential and has led to end-user and public distrust of model outcomes. A field-based experimental burning program was conducted to quantify the effect of fuel load on headfire rate of spread and other fire behaviour characteristics in grasslands. A total of 58 experimental fires conducted at six sites across eastern Australia were analysed. We found an inverse relationship between fuel load and the rate of spread in grasslands, which is contrary to current, untested, modelling assumptions. This result is valid for grasslands where fuel load is not a limiting factor for fire propagation. We discuss the reasons for this effect and model it to produce a fuel load effect function that can be applied to operational grassfire spread models used in Australia. We also analyse the effect of fuel load on flame characteristics and develop a model for flame height as a function of rate of fire spread and fuel load.

scholarly journals Photosynthetic parameters of Juglans nigra trees are linked to cumulative water stress

2019 ◽  
Vol 49 (7) ◽  
pp. 752-758
Author(s):  
Martin-Michel Gauthier ◽  
Douglass F. Jacobs
Keyword(s):  
Water Stress ◽  
Water Status ◽  
Net Photosynthesis ◽  
Juglans Nigra ◽  
Future Research ◽  
Photosynthetic Parameters ◽  
Water Deficits ◽  
Growth And Survival ◽  
Physiological Processes ◽  
Influence Of Water

The influence of water deficits and drought on tree physiological processes, growth, and survival has been the focus of substantial research efforts and debate over the past decades, but there is still a need to quantitatively link finer scale mechanistic explanations of the influence of water status with the physiological responses of trees, particularly for those past the sapling stage. Hence, the objective of this study was to link accumulated water stress during the growing season to leaf physiological response mechanisms of Juglans nigra L. trees. Results showed that trees subjected to higher cumulative water stress had lower maximum light-saturated photosynthesis (Amax), initiated net photosynthesis at higher light levels (Ic), and displayed reduced effectiveness of CO2 fixation per photons absorbed (Qe) at the bottom and upper positions along the vertical canopy gradient. Results suggest that water stress integral (Sψ), a variable that takes into account accumulated water deficits, would be useful to help future research efforts aimed at investigating responses to drought in trees past the sapling stage.

Slope and Fuel Load Effects on Fire Behavior: Laboratory Experiments in Pine Needles Fuel Beds

1995 ◽  
Vol 5 (3) ◽  
pp. 153 ◽  
Author(s):  
JL Dupuy
Keyword(s):  
Laboratory Experiments ◽  
Pinus Halepensis ◽  
Fire Behavior ◽  
Fuel Load ◽  
Fire Behaviour ◽  
Rate Of Spread ◽  
Load Effects ◽  
Heat Transfers ◽  
Different Levels ◽  
Fire Experiments

Laboratory fire experiments were conducted in both Pinus pinaster and Pinus halepensis litters in order to investigate the effect of slope on fire behaviour for different levels of fuel load. Simulated slopes ranged between -30 degrees and +30 degrees. The results are reported in terms of rate of spread and rate of mass loss when observed fire was quasi-steady. Upslope fires were observed, on the present devices, to be unsteady, and their flame to be three-dimensionnal, when slope and fuel load exceeded certain limits. The heat transfers involved in the explanation of the observed behaviours are discussed, especially on the base of the quite different results obtained in the two tested fuel. beds.

Relating fuel loads to overstorey structure and composition in a fire-excluded Sierra Nevada mixed conifer forest

2015 ◽  
Vol 24 (4) ◽  
pp. 484 ◽  
Author(s):  
Jamie M. Lydersen ◽  
Brandon M. Collins ◽  
Eric E. Knapp ◽  
Gary B. Roller ◽  
Scott Stephens
Keyword(s):  
Sierra Nevada ◽  
Predictive Models ◽  
Vegetation Type ◽  
Fuel Load ◽  
Small Scale ◽  
Conifer Forest ◽  
Fire Behaviour ◽  
Mixed Conifer ◽  
Fuel Loads ◽  
Mixed Conifer Forest

Although knowledge of surface fuel loads is critical for evaluating potential fire behaviour and effects, their inherent variability makes these difficult to quantify. Several studies relate fuel loads to vegetation type, topography and spectral imaging, but little work has been done examining relationships between forest overstorey variables and surface fuel characteristics on a small scale (<0.05 ha). Within-stand differences in structure and composition would be expected to influence fuel bed characteristics, and thus affect fire behaviour and effects. We used intensive tree and fuel measurements in a fire-excluded Sierra Nevada mixed conifer forest to assess relationships and build predictive models for loads of duff, litter and four size classes of downed woody fuels to overstorey structure and composition. Overstorey variables explained a significant but somewhat small percentage of variation in fuel load, with marginal R2 values for predictive models ranging from 0.16 to 0.29. Canopy cover was a relatively important predictor for all fuel components, although relationships varied with tree species. White fir abundance had a positive relationship with total fine woody fuel load. Greater pine abundance was associated with lower load of fine woody fuels and greater load of litter. Duff load was positively associated with total basal area and negatively associated with oak abundance. Knowledge of relationships contributing to within-stand variation in fuel loads can increase our understanding of fuel accumulation and improve our ability to anticipate fine-scale variability in fire behaviour and effects in heterogeneous mixed species stands.

scholarly journals Improving silvicultural practices for Mediterranean forests through fire behaviour modelling using LiDAR-derived canopy fuel characteristics

2019 ◽  
Vol 28 (11) ◽  
pp. 823 ◽  
Author(s):  
Brigite Botequim ◽  
Paulo M. Fernandes ◽  
José G. Borges ◽  
Eduardo González-Ferreiro ◽  
Juan Guerra-Hernández
Keyword(s):  
Bulk Density ◽  
Forest Type ◽  
Classification Tree ◽  
Airborne Lidar ◽  
Fuel Load ◽  
Mediterranean Forests ◽  
Fire Behaviour ◽  
Fuel Loading ◽  
Fuel Characteristics ◽  
Stand Height

Wildfires cause substantial environmental and socioeconomic impacts and threaten many Spanish forested landscapes. We describe how LiDAR-derived canopy fuel characteristics and spatial fire simulation can be integrated with stand metrics to derive models describing fire behaviour. We assessed the potential use of very-low-density airborne LiDAR (light detection and ranging) data to estimate canopy fuel characteristics in south-western Spain Mediterranean forests. Forest type-specific equations were used to estimate canopy fuel attributes, namely stand height, canopy base height, fuel load, bulk density and cover. Regressions explained 61–85, 70–85, 38–96 and 75–95% of the variability in field estimated stand height, canopy fuel load, crown bulk density and canopy base height, respectively. The weakest relationships were found for mixed forests, where fuel loading variability was highest. Potential fire behaviour for typical wildfire conditions was predicted with FlamMap using LiDAR-derived canopy fuel characteristics and custom fuel models. Classification tree analysis was used to identify stand structures in relation to crown fire likelihood and fire suppression difficulty levels. The results of the research are useful for integrating multi-objective fire management decisions and effective fire prevention strategies within forest ecosystem management planning.

Effects of fuel load and moisture content on fire behaviour and heating in masticated litter-dominated fuels

2013 ◽  
Vol 22 (4) ◽  
pp. 440 ◽  
Author(s):  
Jesse K. Kreye ◽  
Leda N. Kobziar ◽  
Wayne C. Zipperer
Keyword(s):  
Moisture Content ◽  
Fuel Load ◽  
Maximum Temperature ◽  
Fire Behaviour ◽  
Fuel Loading ◽  
Pine Flatwoods ◽  
Rate Of Spread ◽  
Soil Temperatures ◽  
Fuel Moisture Content ◽  
In Fire

Mechanical fuels treatments are being used in fire-prone ecosystems where fuel loading poses a hazard, yet little research elucidating subsequent fire behaviour exists, especially in litter-dominated fuelbeds. To address this deficiency, we burned constructed fuelbeds from masticated sites in pine flatwoods forests in northern Florida with palmetto-dominated understoreys and examined the effects of fuel load and fuel moisture content (FMC) on fire behaviour. Flame lengths (49–140 cm) and fireline intensity (183–773 kJ m–1 s–1) increased with loading (10–30 Mg ha–1) and were reduced by 40 and 47% with increasing FMC from 9 to 13%. Rate of spread was not influenced by fuel load, but doubled under drier FMC. Fuel consumption was >90% for all burns. Soil temperatures were influenced by both fuel load and FMC, but never reached lethal temperatures (60°C). However, temperatures of thermocouple probes placed at the fuelbed surface reached 274–503°C. Probe maximum temperature and duration at temperatures ≥60°C (9.5–20.0°C min) both increased with fuel load, but were unaffected by FMC. The fire behaviour observed in these unique litter-dominated fuelbeds provides additional insight into the burning characteristics of masticated fuels in general.

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