Spatial distribution of mean fire size and occurrence in eastern Canada: influence of climate, physical environment and lightning strike density

2019 ◽  
Vol 28 (12) ◽  
pp. 927 ◽  
Author(s):  
Jeanne Portier ◽  
Sylvie Gauthier ◽  
Yves Bergeron
Keyword(s):  
Environmental Factors ◽  
Moisture Content ◽  
Boreal Forests ◽  
Fire Regime ◽  
Fire Regimes ◽  
Lightning Strike ◽  
Annual Number ◽  
Fire Size ◽  
Eastern Canada ◽  
Deep Layers

In Canada, recent catastrophic wildfire events raised concern from governments and communities. As climate change is expected to increase fire activity in boreal forests, the need for a better understanding of fire regimes is becoming urgent. This study addresses the 1972–2015 spatial distributions of fire cycles, mean fire size (FireSz) and mean fire occurrence (mean annual number of fires per 100000ha, FireOcc) in eastern Canada. The objectives were to determine (1) the spatial variability of fire-regime attributes, (2) the capacity of FireSz and FireOcc to distinguish homogeneous fire zones and (3) the environmental factors driving FireSz and FireOcc, with some emphasis on lightning strikes. Fire cycles, FireSz and FireOcc greatly varied throughout the study area. Even within homogeneous fire zones, FireSz and FireOcc were highly variable. FireSz was controlled by moisture content in deep layers of the soil and by surficial deposits, whereas FireOcc was controlled by moisture content in top layers of the soil and by relief. The lack of a relationship between FireOcc and lightning-strike density suggested that the limiting effect of lightning-strike density on FireOcc could be operating only under certain circumstances, when interacting with other environmental factors.

scholarly journals A century of transformation: Fire regime transitions from 1919 to 2019 in southeastern British Columbia, Canada

2021 ◽  
Author(s):  
Jennifer N Baron ◽  
Sarah E. Gergel ◽  
Paul F. Hessburg ◽  
Lori D. Daniels
Keyword(s):  
British Columbia ◽  
Fire Regime ◽  
Fire Suppression ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Burned Area ◽  
Annual Number ◽  
Fire Size ◽  
Climatic Period ◽  
Fire Exclusion

The past 100 years marks a transition between pre-colonial and modern era fire regimes, which provides crucial context for understanding future wildfire behavior. Using the greatest depth of digitized fire events in Canada, we identify distinct phases of wildfire regimes from 1919 to 2019 by evaluating changes in mapped fire perimeters (>20-ha) across the East Kootenay forest region (including the southern Rocky Mountain Trench), British Columbia (BC). We detect transitions in annual number of fires, burned area, and fire size; explore the roles of lightning- and human-caused fires in driving these transitions; and quantify departures from historical fire frequency at the regional level. We found that, relative to historical fire frequency, fire exclusion created a significant fire deficit across 89% of the flammable landscape. Fire was active from 1919 to 1940 with frequent and large fire events, but the regime was already altered by a century of colonization. Fire activity decreased after 1940, coinciding with effective fire suppression influenced by a mild climatic period. After 2003, the combined effects of fire exclusion and accelerated climate change fueled a shift in fire regimes of various forest types, with increases in area burned and mean fire size driven by lightning.

Recent fire activity in the boreal forests of central western Siberia is unprecedented in the past 5000 years: palaeoenvironmental evidence contextualises a burning issue

2020 ◽  
Author(s):  
Angelica Feurdean ◽  
Andrei Cosmin Diaconu ◽  
Gabriela Florescu ◽  
Mariusz Galka ◽  
Simon M. Hutchinson ◽  
...  
Keyword(s):  
Plant Communities ◽  
Tree Species ◽  
Boreal Forests ◽  
Western Siberia ◽  
Fire Regime ◽  
Fire Regimes ◽  
Vegetation Composition ◽  
The Past ◽  
Invader Species

<p>Although wildfire events in Siberia have increased in frequency and intensity over recent decades, in the absence of long-term records, it is not clear how far this trend deviates from baseline conditions. Short-term datasets categorise the forest fire regime in Siberia as one of surface, litter fires alternating withdevastating crown fires, although there is significant variability within this region likely reflecting vegetation composition. However, a comprehensive understanding of how vegetation composition and properties determine fire regimes remains lacking. To address this question we used two peat records spanning the last 2500 yr and a 5000 yr, respectively of charcoal morphologies-derived fire regime, pollen-based vegetation dynamics and stable isotope and testate amoebae-based climate reconstructions from boreal forests in central western Siberia, combined with fire-related functional traits of key boreal tree species. Compared to the trend over the 5000 yr period (mean fire return interval=FRI of 400 yr), our reconstructed mean FRI of 145 yr for the last five centuries is notably the shortest in the record. Most fires in this area tend to be surface, litter fires, although over the last centuries surface fires show an increased trend towards crowning. Frequent fires between 5000 and 4000 cal yr BP and 1500 cal yr BP to the present were concurrent with the dominance of invader species (primarily Betula) and fire endurer (mainly herbs) with prevalence of resisters (Pinus sylvestris, Pinus sibirica). Longer fire return intervals (up to 500 yr) between 4000 and 1500 cal yr BP were associated with the dominance of fire resisters with a considerable proportion of fire avoiders (Abies sibirica and Picea obovata). The rising number of fire episodes and the intensification of fire events over the past 1500 years have likely promoted fire-adapted plant communities (invaders and endurers) that can rapidly reach maturity, contributing to the reduction of avoider and resister species. This trend demonstrates that fire avoider species particularly fail to regenerate if the intervals between fire episodes are too short and thatan increasing number of fire episodes can drive land cover towards more fire-adapted plant communities. Our long-term perspective shows that the current fire regime lies significantly outside baseline conditions, which may drive future change in forest composition towards an increased prevalence of invader species. This study also contributes to an understanding of disturbance regimes in Pinus-Betula forests and considers the potential of tree species to adapt to new fire regimes.</p><p> </p>

scholarly journals Small mammals decline with increasing fire extent in northern Australia: evidence from long-term monitoring in Kakadu National Park

2015 ◽  
Vol 24 (5) ◽  
pp. 712 ◽  
Author(s):  
Michael J. Lawes ◽  
Brett P. Murphy ◽  
Alaric Fisher ◽  
John C. Z. Woinarski ◽  
Andrew C. Edwards ◽  
...  
Keyword(s):  
Small Mammals ◽  
National Park ◽  
Fire Regime ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Small Scale ◽  
Northern Australia ◽  
Fire Size ◽  
Burnt Area ◽  
Fire Extent

Small mammal (<2 kg) numbers have declined dramatically in northern Australia in recent decades. Fire regimes, characterised by frequent, extensive, late-season wildfires, are implicated in this decline. Here, we compare the effect of fire extent, in conjunction with fire frequency, season and spatial heterogeneity (patchiness) of the burnt area, on mammal declines in Kakadu National Park over a recent decadal period. Fire extent – an index incorporating fire size and fire frequency – was the best predictor of mammal declines, and was superior to the proportion of the surrounding area burnt and fire patchiness. Point-based fire frequency, a commonly used index for characterising fire effects, was a weak predictor of declines. Small-scale burns affected small mammals least of all. Crucially, the most important aspects of fire regimes that are associated with declines are spatial ones; extensive fires (at scales larger than the home ranges of small mammals) are the most detrimental, indicating that small mammals may not easily escape the effects of large and less patchy fires. Notwithstanding considerable management effort, the current fire regime in this large conservation reserve is detrimental to the native mammal fauna, and more targeted management is required to reduce fire size.

Using spatially explicit simulations to explore size distribution and spacing of regenerating areas produced by wildfires: recommendations for designing harvest agglomerations for the Canadian boreal forest

2007 ◽  
Vol 83 (1) ◽  
pp. 72-83 ◽  
Author(s):  
Annie Belleau ◽  
Yves Bergeron ◽  
Alain Leduc ◽  
Sylvie Gauthier ◽  
Andrew Fall
Keyword(s):  
Forest Management ◽  
Boreal Forest ◽  
Size Distribution ◽  
Temporal Variability ◽  
Fire Regime ◽  
Natural Disturbance ◽  
Fire Regimes ◽  
Spatially Explicit ◽  
Fire Size ◽  
Canadian Boreal Forest

It is now recognized that in the Canadian boreal forest, timber harvesting activities have replaced wildfires as the main stand-replacing disturbance. Differences in landscape patterns derived from these two sources of disturbance have, however, raised concerns that the way forest harvesting has been dispersed is potentially shifting patterns away from the natural range. In the context of natural disturbance-based management, we used a spatially explicit model designed to capture general fire regimes in order to quantify temporal variability associated with regenerating areas (burnt areas of 25 years or younger), and to develop strategic objectives for harvest agglomeration sizes and dispersion. We first evaluated temporal variability in the proportion of stands younger than 100 years (assumed to be even-aged stands) for various fire regimes (seven fire cycles: 50 to 400 years, and three mean fires sizes: 3000, 15 000 and 60 000 ha). Secondly, we quantified the size distribution and dispersion of regenerating areas for each fire regime. As expected by theoretical fire frequencies and size distributions, the importance of even-aged stands at the forest management unit level was found to decrease with longer fire cycles. However, the temporal variability associated with these proportions is shown to increase with mean fire size. It was also observed that the size distribution and dispersion of regenerating areas was primarily influenced by mean fire size. Based on these observations, natural disturbance-based management objectives were formulated, providing guidelines on harvest agglomeration size and dispersion. Key words: temporal variability, boreal forest, fire regime, forest management, age distribution, fire size distribution, clearcut agglomeration size distribution

Strong anthropogenic signals in historic forest fire regime: a detailed spatiotemporal case study from south-central Norway

2013 ◽  
Vol 43 (9) ◽  
pp. 836-845 ◽  
Author(s):  
Ken Olaf Storaunet ◽  
Jørund Rolstad ◽  
Målfrid Toeneiet ◽  
Ylva-li Blanck
Keyword(s):  
Forest Fires ◽  
Boreal Forests ◽  
Fire Regime ◽  
Fire Severity ◽  
Fire Regimes ◽  
Fire Scars ◽  
Time Intervals ◽  
Slash And Burn ◽  
South Central

To better understand the historic range of variability in the fire regime of Fennoscandian boreal forests we cross-dated 736 fire scars of remnant Scots pine (Pinus sylvestris L.) wood samples in a 3.6 km2 section of the Trillemarka-Rollagsfjell Reserve of south-central Norway. Using a kernel range application in GIS we spatially delineated 57 individual forest fires between 1350 and the present. We found a strong anthropogenic signal in the fire regime from 1600 and onwards: (i) infrequent variably sized fires prior to 1600 shifted to frequent fires gradually decreasing in size during the 1600s and 1700s, with only a few small fires after 1800; (ii) time intervals between fires and the hazard of burning showed substantial differences pre- and post-1600; (iii) fire seasonality changed from late- to early-season fires from the 1626 fire and onwards; and (iv) fire severity decreased gradually over time. Written sources corroborated our results, narrating a history where anthropogenic forest fires and slash-and-burn cultivation expanded with the increasing population from the late 1500s. Concurrently, timber resources increased in value, gradually forcing slash-and-burn cultivators to abandon fires on forest land. Our results strengthen and expand previous Fennoscandian findings on the anthropogenic influence of historic fire regimes.

Fire regime from 1973 to 2011 in north-western Patagonian grasslands

2016 ◽  
Vol 25 (9) ◽  
pp. 922 ◽  
Author(s):  
Facundo José Oddi ◽  
Luciana Ghermandi
Keyword(s):  
Fire Regime ◽  
Terrestrial Ecosystems ◽  
Fire Regimes ◽  
Burned Area ◽  
General Knowledge ◽  
Fire Size ◽  
Socioeconomic Impacts ◽  
Mean Size ◽  
Fire Size Distribution ◽  
North Western

Fire is one of the most important disturbances in terrestrial ecosystems and has major ecological and socioeconomic impacts. Fire regime describes the variation of individual fire events in time and space. Few studies have characterised the fire regime in grasslands in spite of the importance of these ecosystems. The aim of this study was to describe the recent fire regime (from 1973 to 2011) of north-western Patagonian grasslands in terms of seasonality, frequency and burned area. Our study area covered 560 000 ha and we used a remote sensing approach combined with statistics obtained from operational databases. Fires occur during the summer in 2 of every 3 years with a frequency of 2.7 fires per year and a mean size of 823 ha. Fire size distribution is characterised by many small fires and few large ones which would respond to a distribution from the power law family. Eighty per cent of the total area affected by fire was burned in the span of a few years, which were also widespread fire years in forests and woodlands of north-western Patagonia. This work contributes to general knowledge about fire regimes in grasslands and we expect that our results will serve as a reference to further fire regime research.

scholarly journals Wildfire history of the boreal forest of southwestern Yakutia (Siberia) over the last two millennia documented by a lake-sedimentary charcoal record

2020 ◽  
Author(s):  
Ramesh Glückler ◽  
Ulrike Herzschuh ◽  
Stefan Kruse ◽  
Andrei Andreev ◽  
Stuart Andrew Vyse ◽  
...  
Keyword(s):  
Boreal Forests ◽  
Environmental Changes ◽  
Fire Regime ◽  
Land Development ◽  
Fire Regimes ◽  
Tree Cover ◽  
Vegetation Composition ◽  
Climate Conditions ◽  
In Fire ◽  
The Last Two Millennia

Abstract. Wildfires, as a key disturbance in forest ecosystems, are shaping the world’s boreal landscapes. Changes in fire regimes are closely linked to a wide array of environmental factors, such as vegetation composition, climate change, and human activity. Arctic and boreal regions and, in particular, Siberian boreal forests are experiencing rising air and ground temperatures with the subsequent degradation of permafrost soils, leading to shifts in tree cover and species composition. Compared to the boreal zones of North America or Europe, little is known about how such environmental changes might influence long-term fire regimes in Russia. The larch-dominated eastern Siberian deciduous boreal forests differ markedly from the composition of other boreal forests, yet data about past fire regimes remain sparse. Here, we present a high-resolution macroscopic charcoal record from lacustrine sediments of Lake Khamra (SW Yakutia, Siberia) spanning the last c. 2200 years, including information about charcoal particle sizes and morphotypes. Our results reveal a phase of increased charcoal accumulation between 600–900 CE, indicative of relatively high amounts of burnt biomass and high fire frequencies. This is followed by an almost 900-year-long period of low charcoal accumulation without significant peaks, likely corresponding to cooler climate conditions. After 1750 CE fire frequencies and the relative amount of biomass burnt start to increase again, coinciding with a warming climate and increased anthropogenic land development after Russian colonisation. In the 20th century, total charcoal accumulation decreases again to very low levels, despite higher fire frequency, potentially reflecting a change in fire management strategies and/or a shift of the fire regime towards more frequent, but smaller fires. A similar pattern for different charcoal morphotypes and comparison to a pollen and non-pollen palynomorph record from the same sediment core indicate that broad-scale changes in vegetation composition were probably not a major driver of recorded fire regime changes. Instead, the fire regime of the last two millennia at Lake Khamra seems to be controlled mainly by a combination of short-term climate variability and anthropogenic fire ignition and suppression.

Interaction between peatland moisture and plant functional types drives fire dynamics in forested peatlands in central-western Siberia

2021 ◽  
Author(s):  
Angelica Feurdean ◽  
Andrei-Cosmin Diaconu ◽  
Geanina Butiseaca ◽  
Mariusz Galka ◽  
Simon M. Hutchinson ◽  
...  
Keyword(s):  
Boreal Forests ◽  
Western Siberia ◽  
Fire Regime ◽  
Fire Regimes ◽  
Forest Composition ◽  
Vegetation Composition ◽  
Picea Obovata ◽  
Peatland Hydrology ◽  
In Fire

&lt;p&gt;Boreal forests are among the ecosystems most significantly impacted by wildfires as a consequence of climate warming. A large proportion of the global boreal forest area is located in Siberia, however, its vast extent and restricted access limit datasets recording changes in wildfire activity, especially from a longer-term perspective. Such long-term records of wildfire activity are vital to understanding how fire regimes vary with changes in climate, vegetation composition and human-vegetation interaction, as well as the impacts of wildfires on boreal forests.&lt;/p&gt;&lt;p&gt;Here, we explore how patterns in fire regime (biomass burned, fire frequency, fire type) have changed over the Holocene. We focus on the relationship between fire regime, forest density and the fire-related traits of the main tree species, and peatland hydrology. We used charcoal-morphologies based reconstructions of fire regimes, along with pollen-based assessments of vegetation composition and testate amoebae-based hydro-climate reconstructions in Pinus-Betula dominated peatlands from central-western Siberia, Tomsk Oblast, Russia.&lt;/p&gt;&lt;p&gt;The occurrence of more severe fires (i.e., higher biomass burning per fire episode and abundant woody morphotypes) were recorded between 7500 and 5000 cal yr BP. Higher temperatures during that time, likely enhanced peatland dryness and fuel flammability creating conditions conducive to peat and forest fires. Drier peatland conditions also affected forest composition and density by favouring the expansion of a mix of light taiga and fire resisters (e.g., Pinus sylvestris, P. sibirica, Larix) with denser taiga and fire avoiders (Picea obovata and Abies sibirica) on the peatland. A shift to the lowest biomass burning and fire types affecting mostly litter and understorey vegetation, was registered between 4000 and 1500 cal yr BP. Temporally, it coincides with an increase in peatland surface moisture and a change in forest composition characterised by a decline in fire resisters, while fire avoiders remained abundant. An almost synchronous intensification in fires frequency and severity from ca. 2000 cal yr BP to the present at all sites, was concurrent with the rise to dominance of fire-invader species (Betula), as well as a more abundant biomass in the understory layer (shrubs, herbs, ferns, moss), while fire resisters and avoiders declined substantially. We found that Picea obovata to be highly vulnerable tree taxa to frequent, severe fires.&lt;/p&gt;&lt;p&gt;This long-term perspective demonstratesthat peatland hydrology is connected to, and feedbacks on peatland and forest composition and fuel dryness and ultimately fire regime. It also shows that more frequent fires of higher severity can lead to compositional or structural changes of forests, if trees cannot reach reproductive ages prior to the next burning events. Future predicted increases in temperatures are likely to enhance peatland drying, with cascading effects on forest and peat plant composition, subsequently exacerbating wildfire activity. This study thus contributes to an understanding of disturbance regimes in boreal forests and considers their potential to adapt to new climate conditions and fire regimes.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

scholarly journals People, El Niño southern oscillation and fire in Australia: fire regimes and climate controls in hummock grasslands

2016 ◽  
Vol 371 (1696) ◽  
pp. 20150343 ◽  
Author(s):  
Rebecca Bliege Bird ◽  
Douglas W. Bird ◽  
Brian F. Codding
Keyword(s):  
El Niño ◽  
Fire Regime ◽  
El Nino ◽  
Southern Oscillation ◽  
Fire Regimes ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
Fire Size ◽  
Antecedent Rainfall ◽  
Fire Incidence

While evidence mounts that indigenous burning has a significant role in shaping pyrodiversity, the processes explaining its variation across local and external biophysical systems remain limited. This is especially the case with studies of climate–fire interactions, which only recognize an effect of humans on the fire regime when they act independently of climate. In this paper, we test the hypothesis that an anthropogenic fire regime (fire incidence, size and extent) does not covary with climate. In the lightning regime, positive El Niño southern oscillation (ENSO) values increase lightning fire incidence, whereas La Niña (and associated increases in prior rainfall) increase fire size. ENSO has the opposite effect in the Martu regime, decreasing ignitions in El Niño conditions without affecting fire size. Anthropogenic ignition rates covary positively with high antecedent rainfall, whereas fire size varies only with high temperatures and unpredictable winds, which may reduce control over fire spread. However, total area burned is similarly predicted by antecedent rainfall in both regimes, but is driven by increases in fire size in the lightning regime, and fire number in the anthropogenic regime. We conclude that anthropogenic regimes covary with climatic variation, but detecting the human–climate–fire interaction requires multiple measures of both fire regime and climate. This article is part of the themed issue ‘The interaction of fire and mankind’.

Southern African fire regimes as revealed by remote sensing

2010 ◽  
Vol 19 (7) ◽  
pp. 861 ◽  
Author(s):  
S. Archibald ◽  
R. J. Scholes ◽  
D. P. Roy ◽  
G. Roberts ◽  
L. Boschetti
Keyword(s):  
Southern Africa ◽  
Human Activities ◽  
Spatial Information ◽  
Fire Regime ◽  
Fire Regimes ◽  
Fire Intensity ◽  
Fire Size ◽  
Regional Patterns ◽  
Radiative Power ◽  
Fire Radiative Power

Here we integrate spatial information on annual burnt area, fire frequency, fire seasonality, fire radiative power and fire size distributions to produce an integrated picture of fire regimes in southern Africa. The regional patterns are related to gradients of environmental and human controls of fire, and compared with findings from other grass-fuelled fire systems on the globe. The fire regime differs across a gradient of human land use intensity, and can be explained by the differential effect of humans on ignition frequencies and fire spread. Contrary to findings in the savannas of Australia, there is no obvious increase in fire size or fire intensity from the early to the late fire season in southern Africa, presumably because patterns of fire ignition are very different. Similarly, the importance of very large fires in driving the total annual area burnt is not obvious in southern Africa. These results point to the substantial effect that human activities can have on fire in a system with high rural population densities and active fire management. Not all aspects of a fire regime are equally impacted by people: fire-return time and fire radiative power show less response to human activities than fire size and annual burned area.

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