Predicting spatial patterns of fire on a southern California landscape

2008 ◽  
Vol 17 (5) ◽  
pp. 602 ◽  
Author(s):  
Alexandra D. Syphard ◽  
Volker C. Radeloff ◽  
Nicholas S. Keuler ◽  
Robert S. Taylor ◽  
Todd J. Hawbaker ◽  
...  
Keyword(s):  
Spatial Patterns ◽  
Southern California ◽  
Vegetation Type ◽  
Fire Hazard ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Fuel Loading ◽  
Landscape Characteristics ◽  
Management Actions ◽  
Fire Ignitions

Humans influence the frequency and spatial pattern of fire and contribute to altered fire regimes, but fuel loading is often the only factor considered when planning management activities to reduce fire hazard. Understanding both the human and biophysical landscape characteristics that explain how fire patterns vary should help to identify where fire is most likely to threaten values at risk. We used human and biophysical explanatory variables to model and map the spatial patterns of both fire ignitions and fire frequency in the Santa Monica Mountains, a human-dominated southern California landscape. Most fires in the study area are caused by humans, and our results showed that fire ignition patterns were strongly influenced by human variables. In particular, ignitions were most likely to occur close to roads, trails, and housing development but were also related to vegetation type. In contrast, biophysical variables related to climate and terrain (January temperature, transformed aspect, elevation, and slope) explained most of the variation in fire frequency. Although most ignitions occur close to human infrastructure, fires were more likely to spread when located farther from urban development. How far fires spread was ultimately related to biophysical variables, and the largest fires in southern California occurred as a function of wind speed, topography, and vegetation type. Overlaying predictive maps of fire ignitions and fire frequency may be useful for identifying high-risk areas that can be targeted for fire management actions.

scholarly journals Contribution of human and biophysical factors to the spatial distribution of forest fire ignitions and large wildfires in a French Mediterranean region

2017 ◽  
Vol 26 (6) ◽  
pp. 498 ◽  
Author(s):  
Julien Ruffault ◽  
Florent Mouillot
Keyword(s):  
Spatial Distribution ◽  
Spatial Patterns ◽  
Mediterranean Region ◽  
Fire Hazard ◽  
Regional Distribution ◽  
Boosted Regression Trees ◽  
Fire Weather ◽  
Explanatory Variables ◽  
Management Actions ◽  
Fire Ignitions

Identifying the factors that drive the spatial distribution of fires is one of the most challenging issues facing fire science in a changing world. We investigated the relative influence of humans, land cover and weather on the regional distribution of fires in a Mediterranean region using boosted regression trees and a set of seven explanatory variables. The spatial pattern of fire weather, which is seldom accounted for in regional models, was estimated using a semi-mechanistic approach and expressed as the length of the fire weather season. We found that the drivers of the spatial distribution of fires followed a fire size-dependent pattern in which human activities and settlements mainly determined the distribution of all fires whereas the continuity and type of fuels mainly controlled the location of the largest fires. The spatial structure of fire weather was estimated to be responsible for an average of 25% of the spatial patterns of fires, suggesting that climate change may directly affect the spatial patterns of fire hazard in the near future. These results enhance our understanding of long-term controls of the spatial distribution of wildfires and predictive maps of fire hazard provide useful information for fire management actions.

Aboveground and belowground carbon dynamics in response to fire regimes in the grazed rangelands of northern Australia: initial results from field studies and modelling

2014 ◽  
Vol 36 (4) ◽  
pp. 347 ◽  
Author(s):  
L. P. Hunt
Keyword(s):  
Field Study ◽  
Fire Regime ◽  
Vegetation Type ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Livestock Production ◽  
Grazing Pressure ◽  
Pasture Production ◽  
Soil C ◽  
C Stocks

The world’s rangelands are often seen as offering considerable potential as a carbon (C) sink, which could contribute to the management of atmospheric C levels, but there are often few data available to assess this potential or to inform the type of management regimes that would be necessary. This paper reports on a review of the literature, a field study and modelling of C stocks under a selection of experimental fire regimes in two plant communities in Australia’s northern rangelands. The field study on an open eucalypt savanna woodland and a savanna grassland-open shrubland suggested that fire regime had no effect or an inconsistent effect on aboveground C stocks. However, modelling using the Century model for the open woodland site showed that increasing fire frequency was associated with reduced aboveground and soil C stocks. Thus, while infrequent fires allowed C stocks to increase (10-yearly fire) or remain stable (6-yearly fire) over a modelled 58-year period, a regime of more frequent fires (4- and 2-yearly fires) reduced C stocks over time. Simulation of C dynamics over 93 years of pastoral settlement suggested that total C stocks had increased by 9.5 t ha–1, largely due to an increase in C in woody vegetation following a reduction in fire frequency associated with pastoral settlement. Frequent burning, as recommended to maintain low woody density and promote pasture production for grazing, will, therefore, reduce aboveground and to a lesser extent soil C stocks where there has been a history of infrequent fire. The opportunities for pastoralists to increase C stocks will depend on the frequency of fire and vegetation type, especially its woodiness or potential woodiness. Reducing fire frequency in woody rangelands will increase C stocks but may have adverse effects on pasture and livestock production. Reducing grazing pressure or destocking might also increase C stocks but may be relevant only when a property is overstocked or where relatively unproductive land could be taken out of livestock production. Any C gains from altering fire and grazing management are likely to be modest.

scholarly journals Spatial patterns and controls on burned area for two contrasting fire regimes in Southern California

Ecosphere ◽  
2016 ◽  
Vol 7 (5) ◽  
Author(s):  
N. R. Faivre ◽  
Y. Jin ◽  
M. L. Goulden ◽  
J. T. Randerson
Keyword(s):  
Spatial Patterns ◽  
Southern California ◽  
Fire Regimes ◽  
Burned Area

Shifting fire regimes from late to early dry-season fires to abate greenhouse emissions does not completely equate with terrestrial vertebrate biodiversity co-benefits on Cape York Peninsula, Australia

2016 ◽  
Vol 25 (7) ◽  
pp. 742 ◽  
Author(s):  
Justin J. Perry ◽  
Eric P. Vanderduys ◽  
Alex S. Kutt
Keyword(s):  
Vegetation Type ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Dry Season ◽  
Carbon Abatement ◽  
Terrestrial Vertebrate ◽  
Savanna Burning ◽  
Cape York ◽  
Species Specific ◽  
The Relationship

Carbon farming initiatives have rapidly developed in recent years, influencing broad scale changes to land management regimes. In the open carbon market a premium can be secured if additional benefits, such as biodiversity conservation or social advancement, can be quantified. In Australia, there is an accepted method for carbon abatement that requires shifting fire frequency from predominantly late, defined as fires occurring after August 1, to early dry-season fires or by reducing overall fire frequency. There is an assumption and some evidence that this might accrue co-benefits for biodiversity. We tested this assumption by comparing terrestrial vertebrate biodiversity patterns (richness and abundance of reptiles, birds and mammals) against increasing fire frequency in the early and late dry-season at the same spatial resolution as the fire management for emission abatement method. We systematically sampled 202 sites on Cape York Peninsula, and examined the relationship between vertebrate fauna, fire and environmental metrics. We found that within the approved vegetation type, open woodlands in tropical savanna woodland, early and late dry-season fire frequency had the same weak linear relationship with only some elements of the observed fauna. Additionally, the response of each taxa to fire frequency were different across broad vegetation structural categories, suggesting that a more nuanced species-specific monitoring approach is required to expose links between savanna burning for carbon abatement and burning for biodiversity benefit.

scholarly journals Fire in Semi-Arid Shrublands and Woodlands: Spatial and Temporal Patterns in an Australian Landscape

2021 ◽  
Vol 9 ◽  
Author(s):  
Eddie J. B. van Etten ◽  
Robert A. Davis ◽  
Tim S. Doherty
Keyword(s):  
Large Scale ◽  
Arid Zone ◽  
Vegetation Type ◽  
Fire Hazard ◽  
Fire Regimes ◽  
Vegetation Types ◽  
Eucalypt Woodlands ◽  
Fire Extent ◽  
Semi Arid ◽  
Over Time

Semi-arid landscapes are of interest to fire ecologists because they are generally located in the climatic transition zone between arid lands (where fires tend to be rare due to lack of fuel, but are enhanced following large rainfall episodes) and more mesic regions (where fire activity tends to be enhanced following severe rainfall deficits). Here we report on the characteristics of the contemporary fire regimes operating in a semi-arid region of inland south-western Australia with rainfall averaging around 300 mm per annum. To characterize fire regimes, we analyzed a geodatabase of fire scars (1960–2018) to derive fire preferences for each major vegetation type and fire episode and used known fire intervals to model fire hazard over time and calculate typical fire frequencies. We also used super epoch analysis and correlations to explore relationships between annual fire extent and rainfall received before the fire. We found fires strongly favored sandplain shrublands, and these tended to experience hot crown fires once every 100 years (median fire interval), with fire hazard increasing linearly over time. In contrast, fires were rare in eucalypt woodland and other vegetation types, with a median interval of 870 years and broadly consistent fire hazard over time. Annual fire extent was most strongly linked with high rainfall in the year prior to fire, and this was particularly so for eucalypt woodlands. Large-scale fires in shrublands tended to favor areas burnt in previous large fires, whereas in woodlands they favored edges. In conclusion, we found divergent fire regimes across the major vegetation types of the region. Sandplain shrublands were similar to Mediterranean shrublands in that they experienced intense stand-replacing wildfires which recovered vigorously although slowly, meaning burnt shrublands did not experience fires again for at least 25 and 100 years on average. In contrast, eucalypt woodlands were fire sensitive (trees readily killed by fire) and experienced fires mostly around the edges, spreading into core areas only after large rainfall events elevated fuel levels. Overall, both vegetation types subscribed to typical arid-zone fire regimes where elevated rainfall, and not drought, promoted fires, although the role of fuel accumulation over time was more important in the shrublands.

scholarly journals New Biomass Estimates for Chaparral-Dominated Southern California Landscapes

2021 ◽  
Author(s):  
Charlie Schrader-Patton ◽  
Emma C. Underwood
Keyword(s):  
Southern California ◽  
Vegetation Type ◽  
Regional Scale ◽  
Remote Sensing Data ◽  
Management Actions ◽  
Biomass Estimate ◽  
Resource Managers ◽  
Dynamic Landscape ◽  
The Mean ◽  
Field Plots

Chaparral shrublands are the dominant wildland vegetation type in southern California and the most extensive ecosystem in the state. Disturbance by wildfire and climate change have created a dynamic landscape in which biomass mapping is key in tracking the ability of chaparral shrub-lands to sequester carbon. Despite this importance, most national and regional scale estimates do not account for shrubland biomass. Employing plot data from several sources, we built a random forest model to predict above ground live biomass in southern California using remote sensing data (Landsat NDVI) and a suite of geophysical variables. By substituting the NDVI and precipi-tation predictors for any given year we were able to apply the model to each year from 2000-2019. Using a total of 980 field plots, our model had a k-fold cross validation R2 of 0.51 and a RMSE of 3.9. Validation by vegetation type ranged from R2 = 0.17 (RMSE=9.7) for Sierran mixed conifer to R2 = 0.91 (RMSE = 2.3) for sagebrush. Our estimates showed an improvement in accuracy over a two other biomass estimates that included shrublands, with an R2 = 0.82 (RMSE = 4.7) compared to R2 = 0.068 (RMSE = 6.7) for a global biomass estimate and R2 = 0.29 (RMSE = 5.9) for a regional biomass estimate. Given the importance of accurate biomass estimates for resource managers we calculated the mean year 2010 shrubland biomass for the four national forests which ranged from 3.5 kg/m2 (Los Padres) to 2.3 kg/m2 (Angeles and Cleveland). Finally, we compared our estimates to field-measured biomass from the literature summarized by shrubland vegetation type and age class. Our model provides a transparent and repeatable method to generate biomass measure-ments in any year, thereby providing data to track biomass recovery after management actions or disturbances such as fire.

scholarly journals New Biomass Estimates for Chaparral-Dominated Southern California Landscapes

2021 ◽  
Vol 13 (8) ◽  
pp. 1581
Author(s):  
Charlie C. Schrader-Patton ◽  
Emma C. Underwood
Keyword(s):  
Southern California ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Vegetation Type ◽  
Regional Scale ◽  
Remote Sensing Data ◽  
Management Actions ◽  
Biomass Estimate ◽  
Resource Managers ◽  
Dynamic Landscape

Chaparral shrublands are the dominant wildland vegetation type in Southern California and the most extensive ecosystem in the state. Disturbance by wildfire and climate change have created a dynamic landscape in which biomass mapping is key in tracking the ability of chaparral shrublands to sequester carbon. Despite this importance, most national and regional scale estimates do not account for shrubland biomass. Employing plot data from several sources, we built a random forest model to predict aboveground live biomass in Southern California using remote sensing data (Landsat Normalized Difference Vegetation Index (NDVI)) and a suite of geophysical variables. By substituting the NDVI and precipitation predictors for any given year, we were able to apply the model to each year from 2000 to 2019. Using a total of 980 field plots, our model had a k-fold cross-validation R2 of 0.51 and an RMSE of 3.9. Validation by vegetation type ranged from R2 = 0.17 (RMSE = 9.7) for Sierran mixed-conifer to R2 = 0.91 (RMSE = 2.3) for sagebrush. Our estimates showed an improvement in accuracy over two other biomass estimates that included shrublands, with an R2 = 0.82 (RMSE = 4.7) compared to R2 = 0.068 (RMSE = 6.7) for a global biomass estimate and R2 = 0.29 (RMSE = 5.9) for a regional biomass estimate. Given the importance of accurate biomass estimates for resource managers, we calculated the mean year 2010 shrubland biomasses for the four national forests that ranged from 3.5 kg/m2 (Los Padres) to 2.3 kg/m2 (Angeles and Cleveland). Finally, we compared our estimates to field-measured biomasses from the literature summarized by shrubland vegetation type and age class. Our model provides a transparent and repeatable method to generate biomass measurements in any year, thereby providing data to track biomass recovery after management actions or disturbances such as fire.

scholarly journals A spatial and temporal assessment of fire regimes on different vegetation types using MODIS burnt area products

Bothalia ◽  
2016 ◽  
Vol 46 (2) ◽  
Author(s):  
Nokuphila L.S. Buthelezi ◽  
Onisimo Mutanga ◽  
Mathieu Rouget ◽  
Mbulisi Sibanda
Keyword(s):  
Vegetation Type ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Fire Season ◽  
Burned Area ◽  
Vegetation Types ◽  
Remotely Sensed Data ◽  
Burnt Area ◽  
Coastal Belt ◽  
Kwazulu Natal

Background: The role of fire in maintaining grassland diversity has been widely recognised; however, its effect in KwaZulu-Natal grasslands is still rudimentary. In that regard, understanding fire regimes of different vegetation types in KwaZulu-Natal is a critical step towards the development of effective management strategies that are specific to each vegetation type. Objective: To assess the effect of different vegetation types on fire regimes in KwaZulu-Natal using moderate resolution imaging spectroradiometer (MODIS) burnt fire products. Method: Ten years of fire data for four different vegetation types (Ngongoni Veld, KwaZuluNatal Sandstone Sourveld, Eastern Valley Bushveld and KwaZulu-Natal Coastal Belt) were extracted from the MODIS products and used as a basis to establish three parameters: annual burnt areas, fire season and fire frequency. The total burnt area within each vegetation type over the 10-year period was quantified. Results: The KZN Sandstone Sourveld had a high-burnt area of 80% in 2009 with KwaZuluNatal Coastal Belt having the least burnt area of less than 5%. Ngongoni Veld and the KwaZuluNatal Sandstone Sourveld had the highest fire frequency, while the coastal region had low fire frequencies. Results showed high fire prevalence during the late period of the dry season (which extends from June to August) across all the vegetation types. Conclusion: This study underscores the potential of remotely sensed data (MODIS burned area products) in providing a comprehensive view of fire patterns in different vegetation types

scholarly journals Decadal changes in fire frequencies shift tree communities and functional traits

2020 ◽  
Author(s):  
Adam F. A. Pellegrini ◽  
Tyler Refsland ◽  
Colin Averill ◽  
César Terrer ◽  
A. Carla Staver ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Fire History ◽  
Vegetation Type ◽  
Basal Area ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Tree Communities ◽  
In Fire ◽  
The Impact

Global change has resulted in chronic shifts in fire regimes, increasing fire frequency in some regions and decreasing it in others. Predicting the response of ecosystems to changing fire frequencies is challenging because of the multi-decadal timescales over which fire effects emerge and the variability in environmental conditions, fire types, and plant composition across biomes. Here, we address these challenges using surveys of tree communities across 29 sites that experienced multi-decadal alterations in fire frequencies spanning ecosystems and environmental conditions. Relative to unburned plots, more frequently burned plots had lower tree basal area and stem densities that compounded over multiple decades: average fire frequencies reduced basal area by only 4% after 16 years but 57% after 64 years, relative to unburned plots. Fire frequency had the largest effects on basal area in savanna ecosystems and in sites with strong wet seasons. Analyses of tree functional-trait data across North American sites revealed that frequently burned plots had tree communities dominated by species with low biomass nitrogen and phosphorus content and with more efficient nitrogen acquisition through ectomycorrhizal symbioses (rising from 85% to nearly 100%). Our data elucidate the impact of long-term fire regimes on tree community structure and composition, with the magnitude of change depending on climate, vegetation type, and fire history. The effects of widespread changes in fire regimes underway today will manifest in decades to come and have long-term consequences for carbon storage and nutrient cycling.

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.

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