scholarly journals Relationships between annual plant productivity, nitrogen deposition and fire size in low-elevation California desert scrub

2015 ◽  
Vol 24 (1) ◽  
pp. 48 ◽  
Author(s):  
Leela E. Rao ◽  
John R. Matchett ◽  
Matthew L. Brooks ◽  
Robert F. Johnson ◽  
Richard A. Minnich ◽  
...  
Keyword(s):  
Predictive Ability ◽  
Fire Risk ◽  
N Deposition ◽  
Fuel Load ◽  
Fire Size ◽  
Fuel Production ◽  
Desert Ecosystems ◽  
Fire Size Distribution ◽  
Fire Spreading ◽  
Desert Scrub

Although precipitation is correlated with fire size in desert ecosystems and is typically used as an indirect surrogate for fine fuel load, a direct link between fine fuel biomass and fire size has not been established. In addition, nitrogen (N) deposition can affect fire risk through its fertilisation effect on fine fuel production. In this study, we examine the relationships between fire size and precipitation, N deposition and biomass with emphasis on identifying biomass and N deposition thresholds associated with fire spreading across the landscape. We used a 28-year fire record of 582 burns from low-elevation desert scrub to evaluate the relationship of precipitation, N deposition and biomass with the distribution of fire sizes using quantile regression. We found that models using annual biomass have similar predictive ability to those using precipitation and N deposition at the lower to intermediate portions of the fire size distribution. No distinct biomass threshold was found, although within the 99th percentile of the distribution fire size increased with greater than 125 g m–2 of winter fine fuel production. The study did not produce an N deposition threshold, but did validate the value of 125 g m–2 of fine fuel for spread of fires.

scholarly journals Correction: Land cover, more than monthly fire weather, drives fire-size distribution in Southern Québec forests: Implications for fire risk management

PLoS ONE ◽  
2017 ◽  
Vol 12 (9) ◽  
pp. e0185515 ◽  
Author(s):  
Jean Marchal ◽  
Steve G. Cumming ◽  
Eliot J. B. McIntire
Keyword(s):  
Risk Management ◽  
Land Cover ◽  
Size Distribution ◽  
Fire Risk ◽  
Fire Weather ◽  
Fire Size ◽  
Fire Size Distribution

scholarly journals Land cover, more than monthly fire weather, drives fire-size distribution in Southern Québec forests: Implications for fire risk management

PLoS ONE ◽  
2017 ◽  
Vol 12 (6) ◽  
pp. e0179294 ◽  
Author(s):  
Jean Marchal ◽  
Steve G. Cumming ◽  
Eliot J. B. McIntire
Keyword(s):  
Risk Management ◽  
Land Cover ◽  
Size Distribution ◽  
Fire Risk ◽  
Fire Weather ◽  
Fire Size ◽  
Fire Size Distribution

A parametric model of the fire-size distribution

2001 ◽  
Vol 31 (8) ◽  
pp. 1297-1303 ◽  
Author(s):  
S G Cumming
Keyword(s):  
Size Distribution ◽  
Sampling Interval ◽  
Parametric Modelling ◽  
Fire Size ◽  
Disturbance History ◽  
Threshold Size ◽  
Mixedwood Forests ◽  
Large Fires ◽  
Fire Size Distribution ◽  
Burnt Areas

This paper developes statistical models of the size distribution of lightning-caused wildfires in the boreal mixedwood forests of Alberta, Canada, for the intervals 1980––1998 and 1961––1998. Above any minimum threshold size [Formula: see text]3 ha, the logarithm of fire size is approximately exponentially distributed. However, computer simulations using the best-fit distribution would over predict the frequency of large fires, and thus the mean rate of disturbance. A truncated exponential distribution, which places an upper bound on fire size, is more suitable and, according to probability plots, provides an excellent fit to the data. I estimate the maximum fire size in the study area to be [Formula: see text] 650 000 ha. This estimate is insensitive to the choice of lower bound for fire sizes (between 3 and 1000 ha) and to the choice of sampling interval. Parametric modelling of fire sizes using covariates derived from forest inventory data shows that the expected size of a fire is positively related to the abundance of pine forest in the vicinity of the point of detection and negatively related to the abundance of recently logged or burnt areas. This implies that variation in forest structure and disturbance history impose marked spatial variability on the fire size distribution. Other covariates, such as periodic indices of fire weather, could readily be evaluated in this framework.

Global fire size distribution is driven by human impact and climate

2014 ◽  
Vol 24 (1) ◽  
pp. 77-86 ◽  
Author(s):  
Stijn Hantson ◽  
Salvador Pueyo ◽  
Emilio Chuvieco
Keyword(s):  
Size Distribution ◽  
Human Impact ◽  
Fire Size ◽  
Fire Size Distribution

Experimental Study on Feasibility of New Scaffold Construction Scheme in Preventing Fire Spread

2013 ◽  
Vol 357-360 ◽  
pp. 415-420
Author(s):  
Yun Yang ◽  
Jun Jie He ◽  
Jun Tao Yang
Keyword(s):  
Experimental Study ◽  
Fire Risk ◽  
Fire Spread ◽  
Construction Scheme ◽  
New Type ◽  
Fire Spreading ◽  
Layer Steel ◽  
Fire Experiments

Aiming at the problem of fire risk of the traditional scaffold construction scheme, a new type of scaffold construction scheme was proposed. In the vertical layout of scaffold board, this scheme alternately arranged to take the "two layers of bamboo fence one layer steel fence". In order to verify the feasibility of the prevention of the spread of fire about the new scaffold construction scheme, three groups of fire experiments were designed. By the analysis of experimental phenomena and data results, it is concluded that the steel fence boards used as isolation layers in the new scaffold construction scheme can effectively mitigate the risk of fire spreading upward or downward along the burning scaffold.

scholarly journals Impact of elevated precipitation, nitrogen deposition and warming on soil respiration in a temperate desert

2017 ◽  
Author(s):  
Ping Yue ◽  
Xiaoqing Cui ◽  
Yanming Gong ◽  
Kaihui Li ◽  
Keith Goulding ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Soil Temperature ◽  
Carbon Dioxide Emissions ◽  
Structural Equation ◽  
Environmental Changes ◽  
Northwest China ◽  
N Deposition ◽  
Single Factor ◽  
Desert Ecosystems ◽  
Temperate Desert

Abstract. Soil respiration (Rs) is the most important source of carbon dioxide emissions from soil to atmosphere. However, it is unclear what the interactive response of Rs would be to environmental changes such as elevated precipitation, nitrogen (N) deposition and warming, especially in unique temperate desert ecosystems. To investigate this an in situ field experiment was conducted in the Gurbantunggut Desert, northwest China, from September 2014 to October 2016. The results showed that precipitation and N deposition significantly increased Rs, but warming decreased Rs, which was mainly through its impact on the variation of soil moisture at 5 cm depth. In addition, the interactive response of Rs to combinations of the factors was much less than that of any single-factor, and the main interaction being a positive effect, except interaction from increased precipitation and high N deposition (60 kg N ha−1 yr−1). Although Rs was found to be a unimodal change pattern with the variation of soil mositure, soil temperature and soil NH4+-N content, and it was signicantly postively correlated to soil dissloved organic carbon (DOC) and pH, but from a structural equation model found that soil temperature was the most important controlling factor. Those results indicated that Rs was mainly interactively controlled by the soil multi-environmental factors and soil nutrients, and was very sensitive to elevated precipitation, N deposition and warming. But the interactions of multiple factors largely reduced between-year variation of Rs more than any single-factor, suggesting that the carbon cycle in temperate deserts could be profoundly influenced by positive carbon-climate feedbacks.

scholarly journals Statistical modelling of wildfire size and intensity: a step toward meteorological forecasting of summer extreme fire risk

2015 ◽  
Vol 33 (12) ◽  
pp. 1495-1506 ◽  
Author(s):  
C. Hernandez ◽  
C. Keribin ◽  
P. Drobinski ◽  
S. Turquety
Keyword(s):  
Statistical Approach ◽  
Fire Risk ◽  
Weather Conditions ◽  
Statistical Modelling ◽  
Conditional Density ◽  
Fire Size ◽  
Burnt Area ◽  
Rainfall Occurrence ◽  
Radiative Power ◽  
Fire Radiative Power

Abstract. In this article we investigate the use of statistical methods for wildfire risk assessment in the Mediterranean Basin using three meteorological covariates, the 2 m temperature anomaly, the 10 m wind speed and the January–June rainfall occurrence anomaly. We focus on two remotely sensed characteristic fire variables, the burnt area (BA) and the fire radiative power (FRP), which are good proxies for fire size and intensity respectively. Using the fire data we determine an adequate parametric distribution function which fits best the logarithm of BA and FRP. We reconstruct the conditional density function of both variables with respect to the chosen meteorological covariates. These conditional density functions for the size and intensity of a single event give information on fire risk and can be used for the estimation of conditional probabilities of exceeding certain thresholds. By analysing these probabilities we find two fire risk regimes different from each other at the 90 % confidence level: a "background" summer fire risk regime and an "extreme" additional fire risk regime, which corresponds to higher probability of occurrence of larger fire size or intensity associated with specific weather conditions. Such a statistical approach may be the ground for a future fire risk alert system.

scholarly journals Flammability Characteristics of Green Roofs

Buildings ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 126
Author(s):  
Nataliia Gerzhova ◽  
Pierre Blanchet ◽  
Christian Dagenais ◽  
Sylvain Ménard ◽  
Jean Côté
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Green Roof ◽  
Fire Risk ◽  
Green Roofs ◽  
Fuel Load ◽  
Growing Media ◽  
Maximum Heat ◽  
Flammability Characteristics

Assessing the fire risk of vegetated roofs includes the determination of their possible contribution to fire. Green roof components such as plants and growing media are organic materials and present a fuel that can catch and support the spread of fire. The flammability characteristics of these components were analyzed and compared to a typical roof covering. Growing media with 15% of organic matter were tested using cone calorimeter apparatus. The fuel load and heat release rate of the growing media were measured in both moist (30%) and dry conditions. It was observed that growing media in a moist condition do not present a fire risk, reaching a maximum heat release rate of 33 kW/m2. For dry substrates, a peak heat release rate of 95 kW/m2 was recorded in the first minute, which then rapidly decreased to 29 kW/m2 in the second minute. Compared to a typical bitumen roof membrane, the green roof showed a better fire performance. The literature data report more severe results for plant behavior, reaching peak heat release rates (HRRs) of 397 kW/m2 for dried and 176 kW/m2 for a green material. However, a rapid decrease in HRR to much lower values occurs in less than 2 min. The results also show that extensive and intensive types of green roofs present 22% and 95% of the additional fire load density when installed on a modified bitumen membrane, 19.7 and 85.8 MJ/m2, respectively.

Global fire size distribution: from power law to log-normal

2016 ◽  
Vol 25 (4) ◽  
pp. 403 ◽  
Author(s):  
Stijn Hantson ◽  
Salvador Pueyo ◽  
Emilio Chuvieco
Keyword(s):  
Size Distribution ◽  
Frequency Distribution ◽  
Power Law ◽  
Likelihood Estimation ◽  
Fire Size ◽  
Chi Square ◽  
Size Frequency Distribution ◽  
Size Frequency ◽  
Fire Size Distribution ◽  
Log Normal

Wildland fires are one of the main alleged examples of Self-Organised Criticality (SOC), with simple SOC models resulting in the expectation of a power-law fire size frequency distribution. Here, we test whether fire size distributions systematically follow a power law and analyse their spatial variation for eight distinct areas over the globe. For each of the areas, we examine the fire size frequency distribution using two types of plots, maximum likelihood estimation and chi-square tests. Log-normal emerges as a suitable option to fit the fire size distribution in this variety of environments. In only two of eight areas was the power law (which is a particular case of the log-normal) not rejected. Notably, the two parameters of log-normal are related to each other, displaying a general linear relation, which extends to the sites that can be described with a power law. These results do not necessarily refute the SOC hypothesis, but reveal the presence of other processes that are, at least, modulating the outcome of SOC in some areas.

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