Climate change and fire in the Arctic

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Published: February 9, 2010, 2:34 pm
Updated: May 7, 2012, 12:29 pm
Author: International Arctic Science Committee
Topic Editor: Sidney Draggan
Topics:

This is Section 14.9 of the Arctic Climate Impact Assessment.

Lead Author: Glenn P. Juday; Contributing Authors: Valerie Barber, Paul Duffy, Hans Linderholm, Scott Rupp, Steve Sparrow, Eugene Vaganov, John Yarie; Consulting Authors: Edward Berg, Rosanne D’Arrigo, Olafur Eggertsson,V.V. Furyaev, Edward H. Hogg, Satu Huttunen, Gordon Jacoby, V.Ya. Kaplunov, Seppo Kellomaki, A.V. Kirdyanov, Carol E. Lewis, Sune Linder, M.M. Naurzbaev, F.I. Pleshikov, Ulf T. Runesson,Yu.V. Savva, O.V. Sidorova,V.D. Stakanov, N.M.Tchebakova, E.N.Valendik, E.F.Vedrova, Martin Wilmking.

Fire is a major climate-related disturbance in the boreal forest, with pervasive ecological effects[1]. Climate, disturbance, and vegetation interact and affect each other, and together they influence the rate and pattern of changes in vegetation[2], the rate of future disturbance[3], and the pattern of new forest development[4]. Understanding these interactions and feedbacks is critical in order to understand how scenarios of climate change will affect future fire regimes and the consequences these ecological changes will have for both boreal forests and forest management.

The total area burned in North America has been increasing concurrently with recent temperature increases and other climatic changes[5]. The annual area burned in western North America doubled in the last 20 years of the 20th century[6]. Based upon less precise statistics there appears to be a similar trend in the Russian Federation[7].

Three factors are important when examining the impacts of climate change on the fire regime. First, boreal forests become increasingly flammable during succession as the forest floor and understory builds up. Conifer-dominated stands are usually more flammable than broad-leaved and other vegetation types. Early post-fire vegetation is generally less flammable than vegetation that is older and more structurally complex. Vegetation also influences fire probability indirectly through its effects on regional climate[8], with early successional stands absorbing and transferring only half the incoming solar radiation compared to late successional spruce stands[9]. A second factor is the need to understand the direct effects of climate on the fire regime. Finally, humans and their land-use changes affect the fire regime, and these changes must be considered to understand future fire effects in a warmer climate.

The role of fire in subarctic and boreal forest (14.9.1)

Disturbance is the driving force behind vegetation dynamics in the boreal biome. Wildfires, alluvial processes (i.e., erosion and flood deposition), tree-fall events caused by wind, and tree-killing insect outbreaks all play major roles that can affect large portions of the landscape. However, fire is particularly significant because of its pervasive presence, its strong link to climate, and the direct feedbacks it has to permafrost dynamics, regional climate, and the storage and release of carbon. Fire often follows large-scale tree death caused by other factors.

In the mosaic of old burns that covers the boreal forest landscape, there are four tendencies related to ecosystem development, expressed over timescales of decades to millennia and over differing landscape areas. There is a tendency toward paludification, which is the waterlogging and cooling of soil caused by the buildup of organic soil layers[10]. Paludification can be a significant factor in treeline retreat in maritime climates[11]. A second tendency is for the longer-lived conifer species to usurp the canopy from shorter-lived hardwood species[12] with an accompanying decline in living biomass[13]. The third tendency is toward the formation of a shifting-mosaic steady state in which burned areas at different stages of secondary succession form the pieces of the mosaic[14]. Finally, there is a tendency toward increased risk of burning with age. Fire opposes paludification by oxidizing the organic matter buildup on the ground surface[15]. Fire also interrupts conifer take-over by restarting successional development with the earliest broadleaf-dominated stages. In addition, because the time since the last fire is an important determinant of vegetation composition and soil conditions, fire frequency has a large influence on carbon storage and release within the boreal forest[16].

Fire is strongly controlled by both temporal and spatial patterns of weather and climate[17]. Specific fire behavior responds to hourly, daily, and weekly weather conditions. Solar radiation, continentality, topography, and specific terrain features influence these fire-generating conditions. The general fire regime of an area responds to long-term, landscape-level climatic patterns. As climate varies, the controlling weather variables can vary in magnitude and direction[18].

Case studies from northern coniferous forests have documented weather variables prior to and during specific fire events[19] and have identified good predictors of conditions that promote the rapid spread of fire. These conditions include warm [[temperature]s], little or no precipitation, low relative humidity, and high [[wind]s]. Synoptic weather conditions that produce cold frontal systems, drought, and low relative humidity have been found to be good predictors of area-burned activity[20]. Upper-air circulation patterns have been related to area burned[21]. Catastrophic burning events are related to the breakdown of the 500 millibar (mb) long-wave ridge[22]. Breakdown of these ridges generally occur at the same time as documented increases in lightning strikes and strong surface winds.

Regional and global links (teleconnections) between meteorological variables and weather anomalies have been identified. The most documented sources of teleconnections are the El Niño–Southern Oscillation and the Pacific Decadal Oscillation (Section 2.2.2.2 (Climate change and fire in the Arctic)). Several North American studies have linked teleconnections to area-burned anomalies[23]. Teleconnections may offer long-range forecasting techniques for temperature and precipitation anomalies that fire managers could use in estimating fuel moisture and fire potential[24]. Winter sea surface temperatures in the Pacific are significantly correlated with warm-season temperature and seasonal area burned in Canada[25]. Significant correlations between these factors vary by provincial region and phase of the North Pacific Oscillation (1953–1976 versus 1977–1995). Interestingly, the sign of the correlation changed from strongly negative (1953–1976) to strongly positive (1977–1995) for four regions (Alberta, western Ontario, eastern Ontario, and Quebec) at the same time they changed from strongly positive to strongly negative for two regions (British Columbia and Saskatchewan). During the same period, two regions did not change sign (Yukon/Northwest Territories and Manitoba). These shifts occurred at previously identified changes in climate regimes (e.g., ACIA, Section 14.6.2, Fig. 14.15), and emphasize the control the overall atmospheric circulation has on fire at a regional scale in understandable, but varying ways.

There are two different scenarios of the relay floristics (rate of spread of vegetation[26]) pathway for secondary succession after fire that operate in the boreal forest. The first is the process in which deciduous shrubs and trees initially colonize burned sites, but are replaced in the overstory in approximately 150 to 200 years by coniferous trees that may be limited in movement by the time necessary for successive generations to reach reproductive maturity or the presence of individual surviving trees dispersed throughout the burn. The second process is self-replacement, which occurs after fires by root sprouting (i.e., aspen, birch, balsam poplar (Populus balsamifera), and numerous shrub species) or by fire-stimulated seed release (i.e., black spruce)[27]. Both of these successional processes occur in the boreal forest. However, the relative importance of each pathway in determining the structure of the boreal forest at a landscape scale is still unknown.

The fire regime describes the general characteristics of fire and its effects on [[ecosystem]s] over time. It can be defined by specific components such as frequency, intensity, severity, size, and timing. These characteristics have been used to develop classification systems that aim to describe the principal types of fire regimes associated with different ecosystems. These fire/ecosystem regime categories are general and broad due to the large spatial and temporal variability exhibited by specific ecosystems[28], but they do provide a conceptual model useful for understanding both fire behavior and fire effects in a particular system. Documentation of the components of fire regimes (i.e., ignition sources, frequency, extent, and severity) for specific ecosystems and geographic regions is also highly variable, and in many cases not well quantified.

Lightning strikes and humans are the two sources of ignitions in the boreal forest. Lightning is the most significant cause of fires (defined by total area burned), although this trend varies among regions. The number of lightning-caused fires generally declines as latitude increases because of decreased heating at the ground surface necessary to produce convective storms, and as climate becomes more maritime (cool layer at ground surface)[29]. Humans are responsible for high numbers of ignitions, but the fires started consume much less area because usually they are actively suppressed. Indigenous peoples ignited fires for specific purposes throughout history, but their impact on past overall fire regimes remains uncertain[30]. Specific regions of the boreal forest in North America experienced substantial anthropogenic fire impacts during the "gold rush" era of the late 19th and early 20th centuries.

Regional fire regimes (14.9.2)

Russia (14.9.2.1)

Fire statistics for the Russian Federation in general, and the Russian boreal region specifically, are incomplete at best[31]. Official fire statistics have been reported only for protected regions of Forest Fund land (Section 14.3.1 (Climate change and fire in the Arctic)). Furthermore, only 60% of the Forest Fund land is identified as protected[32]. Approximately 430 million hectares (ha) of forested tundra and middle taiga in Siberia and the Far East receive no fire protection. The paucity of reliable statistics is a result of numerous issues including remoteness, lack of detection and mapping technology, lack of fire-management funding, and deliberate falsification of past records for political reasons. Humans were identified as the major source of ignitions at 65%, followed by lightning (16%), prescribed agricultural burning (7%), and other/unknown activities (12%)[33]. Intensive prevention and education programs have had little success in decreasing anthropogenic fires. Many of these fires grow to large sizes due to overstretched suppression resources.

Keeping these limitations in mind, the statistics for the protected Forest Fund area provide some perspective on fire across the Russian Federation. Between 18,000 and 37,000 forest fires were detected annually from 1950 to 1999. The average annual area burned within the zone of detection for the decades 1950 to 1959, 1960 to 1969, 1970 to 1979, 1980 to 1989, and 1990 to 1999 was 1.54, 0.68, 0.48, 0.54, and 1.2 million ha, respectively[34]. Indirect estimates of annual area burned in both protected and unprotected Forest Fund areas have been developed through modeling techniques. Shvidenko and Goldammer[35] used a modified expert system model[36], available fire statistics, and forest inventory data on age and stand structure to calculate an estimated total of the annual average area burned in all of Russia over the past 30 years. The estimate applies to the Forest Fund and State Land Reserve area. An estimated 5.10 million ha burned annually, of which 3.94 million ha were in the boreal bioclimatic zones of forest tundra–northern taiga, middle taiga, and southern taiga (see Fig. 14.1).

Satellite remote-sensing techniques provide insight into the potential total extent of area burned across major regions of the Russian Federation. In 1987, an estimated 14.4 million ha burned in the Russian Far East and eastern Siberia[37], and in 1992, an estimated 1.5 million ha burned in all of the Russian territories[38]. In 1998, following a very strong El Niño, an estimated 9.4 million ha burned in the Asian regions of Russia[39].

Only a small fraction of total forested area falls under any organized fire-suppression management. Fire suppression is headed by the Ministry of Natural Resources of Russia, which manages suppression efforts through regional offices. Fire-suppression resources include both ground and aerial operations. Aerial operations provide detection and monitoring services, and direct suppression resources (i.e., water and retardant drops, transport of ground personnel and smokejumpers). The State Forest Guard (ground suppression) and the Avialesookhrana (aerial detection and suppression) coordinate fire suppression with local and regional authorities. Under severe fire conditions, military detachments and local populations are recruited.

Operational policy and logistical allocation follow fire danger predictions, which are based on weather and climatic conditions. The Nesterov fire index, similar to the Canadian Forest Fire Danger Rating System or the US National Fire Danger Rating System, is used for prediction. Aircraft patrols and resource deployments are based on the fire index predictions. A severe limitation to successful fire management has been a lack of funding – in 1998, only US$ 0.06 per hectare was allocated to fire suppression[40]. In addition, a lack of advanced technology equipment (i.e., satellite monitoring, radios, etc.), aircraft, and State Forest Guard personnel, as well as unfavorable land-use practices, have been identified as major weaknesses in the current system.

Canada (14.9.2.2)

Canadian fire management agencies developed a large-fire database for all fires larger than 200 ha for the period 1959 to the present[41]. Fires larger than 200 ha represent only 3.5% of the total number of fires, but 97% of the total area burned over this period[42]. The fire perimeters were digitized and mapped in a geographic information system, and the database includes ancillary information such as ignition location and date, size, cause, and suppression action(s) taken. This database has been expanded into the past where data exist (as far back as 1918), and is continuously updated with each passing fire season. Total area burned in Canada has more than doubled since the 1970s, and the upward trend is well explained by warmer [[temperature]s][43].

Lightning-caused fires predominate throughout the fire record and account for almost all large fires in the northern portions of Canada. From 1959 to 1997, lightning ignited approximately 68% of all fires, and those fires accounted for approximately 79% of the total area burned[44]. Temporal trends show a steady increase in the number of lightning fires and their contribution to total area burned from the 1960s through the 1990s, which fire managers attribute to technology improvements in fire detection and monitoring. Anthropogenic fires are a significant contributor to the total number of fires almost exclusively in populated areas and along the road network, and suppression of these fires is effective in limiting the total area burned. Temporal trends show a steady decrease in total area burned due to anthropogenic ignitions, attributed to aggressive fire suppression tactics.

The average annual area burned between 1959 and 1997 was approximately 1.9 million ha, with interannual variability ranging from 270,000 to 7.5 million ha burned[45]. Spatial trends identified a few ecozones (taiga plains, taiga shield, boreal shield, and boreal plains; see Wiken[46] for definitions) that accounted for the majority (88%) of total area burned between 1959 and 1997, primarily because these ecozones have a continental climate that is conducive to extreme fire danger conditions and have large uninhabited areas with low values-at-risk, so fires are allowed to burn unimpeded[47].

Organized fire suppression and management has operated in Canada since the early 1900s, initiated as a response to large catastrophic fires, much like those experienced in the United States. Canada is recognized worldwide for its advanced technologies and operational efficiencies in both fire prevention and suppression. The Canadian Forest Fire Danger Rating System (CFFDRS) was first developed in 1968 and consists of two subcomponents: the Canadian Forest Fire Weather Index (FWI) system, which provides a quantitative rating of relative fire potential for standard fuel types based upon weather observations; and the Canadian Forest Fire Behavior Prediction system, which accounts for fire behavior variability of fuel types based on topography and components of the FWI. The CFFDRS is used for training, prevention, operational planning, prescribed burning, and suppression tactics. In addition, researchers use CFFDRS for investigating fire growth modeling, fire regimes, and potential climate change impacts. The system is used extensively in Alaska in place of the US Fire Danger Rating System – a system developed primarily for the lower 48 states.

Aerial reconnaissance in conjunction with lightning detection systems has been employed heavily since the 1970s throughout the North American boreal forest (including Alaska). The lightning detection system identifies areas of high lightning strike density and allows for focused aerial detection operations. This has greatly increased detection efficiencies over remote regions.

United States (Alaska) (14.9.2.3)

The fire record for the Alaskan boreal forest has evolved over time and consists of three datasets[48]. The first is a tabular summary of total annual area burned since 1940. The second is a tabular database that contains the location, ignition source, size, management option, and initiation and extinguishment date for all fires since 1956. The third is a geographic information system database of the boundary of fires since 1950. The spatial database includes all fires larger than 400 ha occurring from 1950 to 1987, and all fires larger than 25 ha occurring since 1988.

Early studies minimized the importance of lightning as an ignition source in the Alaskan boreal forest because anthropogenic ignitions were thought to be more important[49]. However, the implementation of digital electronic lightning detection systems along with a more thorough review of fire statistics led to the realization that lightning is not only widespread throughout the growing season in Interior Alaska, but is responsible for igniting the fires that burn most of the area[50]. Analysis of fire statistics from the Alaska Fire Service shows that while humans start more than 61% of all fires, these fires are responsible for only 10% of the total area burned[51]. The remaining fires are the result of lightning ignitions.

Convective storms and associated lightning can range in size from individual clouds to synoptic thunderstorms covering thousands of square kilometers. A single thunderstorm may produce most of the annual lightning strikes in an area[52]. In Interior Alaska, the lightning density gradient generally runs from high in the east to low in the west, parallel with the warmer summer climate in the interior continental areas and cooler maritime summer climate near the coast[53]. However, mapped fires that originate from lightning strikes are well distributed throughout the interior of the state. In contrast to lightning ignitions that are uniformly distributed between the Brooks and Alaska Ranges, anthropogenic fire ignitions are centered around major population centers (Fairbanks and Anchorage), as well as along the major road networks[54].

The presence of the boreal forest landscape may promote convective thunderstorms. In central Alaska, the density of lightning strikes is consistently highest within boreal forest compared to tundra and shrub zones across a climatic gradient[55]. Within the tundra, the number of lightning strikes increases closer to the boreal forest edge. The paleo-fire record indicates that wildfires increased once black spruce became established in Interior Alaska (despite a cooler, moister climate). This may have been due to two factors: 1) increased landscape heterogeneity and higher sensible heat fluxes (see Section 14.2.5, BOREAS results (Climate change and fire in the Arctic)) leading to increased convective thunderstorms; and 2) increased fuel flammability associated with the black spruce vegetation type[56]. These results suggest that climate changes that promote the expansion or increase in density of conifer forest are likely to increase the incidence of fire, but that climate changes that decrease conifers (too-frequent burning, aridification) are likely to decrease subsequent burning.

The annual area burned in Alaska exhibits a bimodal distribution, with years of high fire activity (ignitions and area burned) punctuating a greater number of years of low activity. For the Alaskan boreal forest region, 55% of the total area burned between 1961 and 2000 occurred in just 6 years. The average annual area burned during these episodic fire years was seven times greater than the area burned in the low fire years.

With the observed increase in air temperature and lengthening of the growing season over the past several decades in the North American boreal forest region, a corresponding increase in fire activity between the 1960s and 1990s might be expected[57]. For the Alaskan boreal forest region (which was less affected by fire suppression efforts than southern boreal areas), such an increase in fire activity was not apparent until the summer of 2004, in which a record 2.71 million ha burned. That summer (May–August) also had the highest mean monthly temperatures recorded at Fairbanks since observations began in 1906. A record 1.84 million ha also burned in 2004 in the adjacent Yukon Territory, amounting to about 12.4% of all forest land in the Yukon. Between 1981 and 2000 there was only a slight (7%) rise in the annual area burned (297,624 ha/yr) compared to the period between 1961 and 1980 (276,624 ha/yr)[58]. These extensive 2004 fires have clearly established a significant upward trend in the area burned during the period of record. The frequency of large fire years has been greater since 1980 (five large fire years) than before 1980 (two large fire years), and the increase in average annual area burned between these periods is due to the increase in frequency of large fire years and the decrease in fire-fighting activities in remote areas. The fire data record for Alaska is consistent with an increase in large fires in response to recent climate warming, but not sufficient to determine definitively whether the increase is outside the range of natural variability. The official fire statistics for Alaska show that there were two large fire years per decade in the 1940s and 1950s, indicating that the frequency of large fire years has been relatively constant over the past 60 years, although this entire period is distinctly warmer than preceding centuries.

The number and size distribution of fires in the Alaskan boreal forest region is different during low and severe fire years. During low fire years between 1950 and 1999, an average of 17 fires greater than 400 ha occurred per year, with an average size of 7,800 ha. In contrast, during high fire years an average of 66 fires greater than 400 ha occurred, with an average size of 20,300 ha[59]. In low fire years, 73% of the total area burned occurred in fires larger than 50,000 ha. In high fire years, 65% of the total area burned occurred in fires larger than 50,000 ha. In low fire years, 9% of the total area burned in fires larger than 100,000 ha, with no fires larger than 200,000 ha. In contrast, during high fire years, 33% of the total area burned in fires larger than 100,000 ha.

Fire managers in Alaska typically recognize two fire seasons[60]. The major fire season typically occurs after mid-June when the surface of the earth becomes warm enough to drive convective thunderstorm activity. However, there is an earlier fire season throughout the state associated with the extremely dry fuel conditions that occur immediately after snowmelt and before leaf-out in late spring. At this time, precipitation levels are low, and fuel moisture conditions are extremely low because of the curing of dead vegetation during winter and the lack of green vegetation. During this period, human activities result in the majority of fire ignitions.

Fire management and suppression is a relatively new concept in Alaska and did not become an organized effort until 1939. In the early 1980s, fire-management efforts in Alaska were coordinated under the direction of an interagency team. Beginning in 1984, fire-management plans were developed for thirteen planning areas. The fire plans provide for five separate suppression options:

  • Critical protection is provided for areas of human habitation or development. These areas receive immediate initial attack and continuing suppression action until the fire is extinguished.
  • Full protection is provided for areas of high resource values. Fires receive immediate initial attack and aggressive suppression to minimize area burned.
  • Modified action provides for initial attack of new fires during the severe part of the fire season (May 1–July 10). Escaped fires are evaluated by the land manager and suppression agency for appropriate suppression strategies. On specified dates (generally after July 10), the modified action areas convert to limited action.
  • Limited action is provided for areas of low resource values or where fire may actually serve to further land management objectives. Suppression responses include the monitoring of fire behavior and those actions necessary to ensure it does not move into areas of higher values.
  • Unplanned areas exist where land managers declined participation in the planning process. These few unplanned areas receive the equivalent of full protection.

The formation of these plans radically changed wildland fire management in Alaska. The adoption of these cooperative plans created areas where fires were no longer aggressively attacked due to the low economic resource value of those lands. The primary goals of the plans are to restore the natural fire regime to the boreal forest ecosystem and to reduce suppression costs.

Fennoscandia (14.9.2.4)

Finland, Sweden, and Norway account for a very small percentage of total area burned in the boreal forest and generally have not experienced large fires in modern times. This can be attributed to the ease of access throughout these relatively small countries and their highly managed forest systems. In addition, lightning fires are not a major factor, accounting for less than 10% of all fires[61]. Fire statistics for this region of the boreal forest are limited and discontinuous. The lack of natural fire is one of the principal causes of endangerment of a set of fire-dependent species in northern Fennoscandia[62].

Finland reported an annual average of 800 ha burned during the 1990s[63]. Since record keeping began in 1952, there has been a steady decrease in average annual area burned from a high of 5,760 ha in the 1950s to 1,355 ha in the 1960s to less than 1,000 ha from 1971 to 1997[64]. An average of 2,224 fires per year occurred during the period 1995 to 1999. Anthropogenic fires accounted for 61% of all fires, followed by 29% of unknown cause, and 10% caused by lightning[65].

Boreal forest covers most of Sweden and includes a mix of flammable conifer trees, shrubs, and mosses. Sweden reported an annual average of 1,600 ha burned during the 1990s[66]. Humans are the major cause of fires accounting for approximately 65%[67] of the annual average of 3,280 fires during the 1990s[68]. Norway reported an average of 564 ha burned annually between 1986 and 1996[69]. The highest frequency of fires occurs in the boreal forest region of the eastern lowlands[70]. On average, there were only 513 fires per year in Norway during the 1990s[71].

Forest fires are virtually absent from the sparsely forested regions of Iceland and Greenland. No fire statistics were reported to the FAO for the period 1990 to 1999.

Possible impacts of climate change on fire (14.9.3)

Rupp et al.[72] used a spatially explicit model to simulate the transient response of subarctic vegetation to climatic warming in northwestern Alaska near the treeline. In the model simulations, a warming climate led to more and larger fires. The vegetation and fire regime continued to change for centuries in direct response to a 2 to 4 °C increase in mean growing-season temperature. Flammability increased rapidly in direct response to temperature increases and more gradually in response to simulated climate-induced vegetation change. In the simulations, warming caused as much as a 228% increase in the total area burned per decade, which led to a landscape dominated by an increasingly early successional and more homogenous deciduous forest.

Turner M. et al.[73] used the same model[74] to simulate fire-regime sensitivity to precipitation trends. Precipitation projections from global climate models have the largest associated errors and the highest variability between models. A simulated instantaneous 2 °C increase in average growing-season temperature was applied with two different precipitation regimes (a 20% increase and a 20% decrease from current precipitation levels) to explore the possible influence of climate change on long-term boreal forest ecosystem dynamics. Both scenarios projected an increase in the total number of fires compared to current climate. However, the distribution of fire sizes was surprising. As expected, the warmer and drier scenario resulted in fewer small fires and an associated shift toward larger fires. Also as expected, the warmer and wetter scenario resulted in fewer large fires and an associated shift toward smaller fires. However, the distribution of very large fires (burning >25% of the total landscape area) was unexpected. The warmer and wetter scenario produced more very large fires compared to the warmer and dryer scenario. The warmer and dryer climate scenario experienced frequent medium-sized fires, which prevented fuels from building up across the landscape and limited the number of large fires. In contrast, the warmer and wetter climate scenario led to frequent small fires, which allowed the development of well-connected, highly flammable late-successional stands across the landscape.

Additional model simulations suggest that vegetation effects are likely to cause significant changes in the fire regime in Interior Alaska[75]. Landscapes with a black spruce component were projected to have more fires and more area burned than landscapes with no black spruce component. Black spruce landscapes were also projected to experience numerous fires consuming extensive portions (more than 40%) of the landscape. These results agree with observations in the Canadian boreal forest where 2% of the fires account for 98% of the total area burned[76]. Large-scale fire events need to be realistically represented in ecosystem models because they strongly influence ecosystem processes at landscape and regional scales. These results have strong implications for global-scale models of terrestrial ecosystems. Currently, these models consider only plant functional types distinguished by their physiological (C3 versus C4 photosynthesis), phenological (deciduous versus evergreen), and physiognomic (grass versus tree) attributes. The fire-modeling results suggest the need for a finer resolution of vegetation structure and composition related to flammability in order to accurately simulate the dynamics of the fire regime, and to understand how different climate changes are likely to change ecosystems at several different scales.

Modeling results show that fire regime plays an important role in determining the overall relative abundance of ecosystem types at any given time, and that different fire regimes create qualitatively different patterns of ecosystem placement across the landscape[77]. One process is "contagion" or the spread of effects into one type largely due to its juxtaposition with another. Simulation results in a typical Alaska black spruce landscape projected increases in the total amount of deciduous forest that burned in two landscapes that contained a black spruce component. The results indicated a much shorter fire return interval for deciduous forest in a landscape dominated by black spruce, and the fire return times were similar to actual fire intervals calculated by Yarie[78] for deciduous forest in Interior Alaska[79]. Landscape-level changes in the fire return interval of specific fuel types is an important effect of spatial contagion that currently cannot be addressed by statistical formulation within a global vegetation model. Although there is an excellent quantitative understanding of fire behavior as a function of climate/weather and vegetation at the scale of hours and meters[80], the dynamic simulation of fire effects at landscape or regional scales remains rudimentary[81]. A long-term potential consequence of intensified fire regimes under increasing temperatures is that fire-induced changes in vegetation are likely to lead to a more homogenous landscape dominated by early-successional deciduous forest[82]. This has significant implications for the regional carbon budget and feedbacks to climate (Section 14.10.2 (Climate change and fire in the Arctic)). A shift from coniferous to deciduous forest dominance is very likely to have a negative feedback to temperature increases due to changes in albedo and energy partitioning[83].

Stocks et al.[84] used outputs from four GCMs (General Circulation Models) to project forest-fire danger in Canada and Russia in a warmer climate. Temperature and precipitation anomalies between runs forced with current atmospheric CO2 concentrations and those forced with doubled atmospheric CO2 concentrations were combined with observed weather data for 1980 to 1989 in both Canada and Russia. All four models projected large increases in the areal extent of extreme fire danger in both countries under the doubled CO2 scenarios. A monthly analysis identified an earlier start date to the fire seasons in both countries and significant increases in total area experiencing extreme fire danger throughout the warmest months of June and July. Scenarios are still of limited use, however, in projecting changes in ignitions.

Model projections of the spatial and temporal dynamics of a boreal forest under climate change were made for the Kas-Yenisey erosion plain in the southern taiga of western Siberia[85]. This study projected that the number of years in which there are severe fires would more than double under a summer temperature increase from 9.8 to 15.3 °C, the area of forests burned annually would increase by 146%, and average stored wood mass would decrease by 10%.

Flannigan and Van Wagner[86] also investigated the impact of climate change on the severity of the forest fire season in Canada. They used projections from three GCMs forced with doubled atmospheric CO2 concentrations to calculate the seasonal severity rating across Canada. Their results suggest a 46% increase in seasonal severity rating, with a possible similar increase in area burned, in a doubled CO2 climate.

Flannigan et al.[87] looked at future projections of wildfire in circumpolar boreal forests in response to scenarios of climate change. Simulations were based on GCM outputs for doubled atmospheric CO2 concentrations. The simulation and fire history results suggested that the impact of climate change on northern forests as a result of forest fires may not be as severe as previously suggested, and that there may be large regions of the Northern Hemisphere with a reduced fire frequency. These simulation results are attributed to a switch from using monthly to using daily GCM output. The scenarios still produced areas where the interval between fires is likely to decrease (i.e., more frequent fires), but they also produced regions of no change or with greater probability of an increasing interval (i.e., less frequent fires).

Chapter 14: Forests, Land Management, and Agriculture
14.1. Introduction (Climate change and fire in the Arctic)
14.2. The boreal forest: importance and relationship to climate
14.3. Land tenure and management in the boreal region
14.4. Use and evaluation of the ACIA scenarios
14.5. Agriculture (Agriculture in the Arctic)
14.6. Tree rings and past climate
14.7. Direct climate effects on tree growth
14.8. Climate change and insects as a forest disturbance
14.9. Climate change and fire
14.10. Climate change in relation to carbon uptake and carbon storage
14.11. Climate change and forest distribution
14.12. Effects of ultraviolet-B on forest vegetation
14.13. Critical research needs

See Also

Citation

International Arctic Science Committee (2012). Climate change and fire in the Arctic. Encyclopedia of Earth. National Council for Science and Environment. Washington DC. Retrieved from http://editors.eol.org/eoearth/wiki/Climate_change_and_fire_in_the_Arctic
== References ==
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  2. ↑ Neilson, R.P., 1993. Transient ecotone response to climatic change: some conceptual and modeling approaches. Ecological Applications, 3:385–395.–Noble, I.R., 1993. A model of the responses of ecotones to climate change. Ecological Applications, 3:396–403.
  3. ↑ Gardner, R.H.,W. W. Hargrove, M.G. Turner and W.H. Romme, 1996. Global change, disturbances and landscape dynamics. In: B. Walker and W. Steffen (eds.). Global Change and Terrestrial Ecosystems, pp. 149–172. Cambridge University Press.–Rupp,T.S., F.S. Chapin III,A.M. Starfield and P. Duffy, 2002. Modeling boreal forest dynamics in interior Alaska. Climatic Change, 55:213–233.–Turner, M.G., S.L. Collins, A.L. Lugo, J.J. Magnuson, T.S. Rupp and F.J. Swanson, 2003. Disturbance dynamics and ecological response: the contribution of long-term ecological research. BioScience, 53(1):46–56.
  4. ↑ Turner, D.P., G.J. Koerper, M.E. Harmon and J.J. Lee, 1995. A carbon budget for forests of the conterminous United States. Ecological Applications, 5(2):421–436.–Rupp,T.S.,A.M. Starfield and F.S. Chapin III, 2000a. A frame-based spatially explicit model of subarctic vegetation response to climatic change: comparison with a point model. Landscape Ecology, 15:383–400.–Rupp,T.S., F.S. Chapin III and A.M. Starfield, 2000b. Response of subarctic vegetation to transient climatic change on the Seward Peninsula in northwest Alaska. Global Change Biology, 6:541–555.
  5. ↑ Stocks, B.J., M. A. Fosberg, M.B. Wotton, T.J. Lynham and K.C. Ryan, 2000. Climate change and forest fire activity in North American boreal forests. In: E.S. Kasischke and B.J. Stocks (eds.). Fire, Climate Change, and Carbon Cycling in the Boreal Forest, pp. 368–376. Springer-Verlag.
  6. ↑ Murphy, P.J., J.P. Mudd, B.J. Stocks, E.S. Kasischke, D. Barry, M.E. Alexander and N.H.F. French, 2000. Historical fire records in the North American boreal forest. In: E.S. Kasischke and B.J. Stocks (eds.). Fire, Climate Change, and Carbon Cycling in the Boreal Forest, pp. 274–288. Springer-Verlag.
  7. ↑ Kasischke, E.S., T.S. Rupp and D.L.Verbyla, in press. Fire trends in the Alaskan boreal forest. In: F.S. Chapin III, J. Yarie, K.Van Cleve, L. A.Viereck, M. W. Oswood and D.L.Verbyla (eds.). Alaska’s Changing Boreal Forest. Oxford University Press.
  8. ↑ Chapin, F.S. III, T.S. Rupp, A.M. Starfield, L. Dewilde, E.S. Zavaleta, N. Fresco, J. Henkelman and A.D. McGuire, 2003. Planning for resilience: modeling change in human-fire interactions in the Alaskan boreal forest. Frontiers in Ecology and the Environment, 1:255–261.
  9. ↑ Baldocchi, D.D. and C. A.Vogel, 1995. Energy and CO2 flux densities above and below a temperate broad-leaved forest and boreal pine forest. Tree Physiology, 16:5–16.
  10. ↑ Viereck, L. A., 1970. Forest succession and soil development adjacent to the Chena River in interior Alaska. Arctic and Alpine Research, 2:1–26.
  11. ↑ Crawford, R.M.M., C.E. Jeffree and W.G. Rees, 2003. Paludification and forest retreat in northern oceanic environments. Annals of Botany, 91:213–226.
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  13. ↑ Paré, D. and Y. Bergeron, 1995. Above-ground biomass accumulation along a 230-year chronosequence in the southern portion of the Canadian boreal forest. Journal of Ecology, 83:1001–1007.
  14. ↑ Wright, H.E. Jr., 1974. Landscape development, forest fires, and wilderness management. Science, 186:487–495.
  15. ↑ Mann, D.H. and L.J. Plug, 1999.Vegetation and soil development at an upland taiga site, Alaska. Ecoscience, 6(2):272–285.
  16. ↑ Kasischke, E.S., N.L. Christensen and B.J. Stocks, 1995. Fire, global warming, and the carbon balance of boreal forests. Ecological Applications, 5:437–451.–Kurz, W. A. and M.J. Apps, 1999. A 70-year retrospective analysis of carbon fluxes in the Canadian forest sector. Ecological Applications, 9(2):526–547.
  17. ↑ Flannigan, M.D. and J.B. Harrington, 1988. A study of the relation of meteorological variables to monthly provincial area burned by wildfire in Canada (1935–80). Journal of Applied Meteorology, 27:441–452.–Flannigan, M., I. Campbell, M. Wotton, C. Carcaillet, P. Richard and Y. Bergeron, 2001. Future fire in Canada’s boreal forest: Paleoecology results and general circulation model – regional climate model simulations. Canadian Journal of Forest Research, 31(5):854–864.–Johnson, E. A., 1992. Fire and Vegetation Dynamics: Studies from the North American Boreal Forest. Cambridge University Press, 129p.
  18. ↑ Flannigan, et. al., 2001, Op. cit.
  19. ↑ Flannigan, M.D. and J.B. Harrington, 1988. Op. cit
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  21. ↑ Newark, M.J., 1975. The relationship between forest fire occurrence and 500 mb longwave ridging. Atmosphere, 13:26–33.
  22. ↑ Nimchuk, N., 1983. Wildfire Behavior Associated with Upper Ridge Breakdown. Alberta Energy and Natural Resources Report Number T/50, Forest Service, Alberta.
  23. ↑ Flannigan, M.D., B.J. Stocks and B.M. Wotton, 2000. Climate change and forest fires. Science of the Total Environment, 262(3):221–229.–Johnson, E. A. and D.R. Wowchuk, 1993. Wildfires in the southern Canadian Rocky Mountains and their relationship to mid-tropospheric anomalies. Canadian Journal of Forest Research, 23:1213–1222.–Swetnam, T. W. and J.L. Betancourt, 1990. Fire-Southern Oscillation relations in the Southwestern United States. Science, 249:1017–1020.
  24. ↑ Flannigan, et. al., 2001, Op. cit.
  25. ↑ Flannigan, et. al., 2000, Op. cit.
  26. ↑ Egler, F.E., 1954. Vegetation science concepts. I. Initial floristic composition, a factor in old-field vegetation development. Vegetatio, 4:412–417.
  27. ↑ Greene, D.F., J.C. Zasada, L. Sirois, D. Kneeshaw, H. Morin, I. Charron and M.-J. Simard, 1999. A review of the regeneration dynamics of North American boreal forest tree species. Canadian Journal of Forest Research, 29:824–839.–Mann, D.H. and L.J. Plug, 1999.Vegetation and soil development at an upland taiga site, Alaska. Ecoscience, 6(2):272–285.
  28. ↑ Whelan, R.J., 1995. The Ecology of Fire. Cambridge University Press, 346p.
  29. ↑ Johnson, E. A., 1992. Fire and Vegetation Dynamics: Studies from the North American Boreal Forest. Cambridge University Press, 129p.
  30. ↑ Johnson, E. A., 1992. Fire and Vegetation Dynamics: Studies from the North American Boreal Forest. Cambridge University Press, 129p.–Swetnam,T. W., C. D. Allen and J. L. Betancourt, 1999. Applied historical ecology: Using the past to manage for the future. Ecological Applications, 9(4):1189–1206.
  31. ↑ FAO, 2001. Global Forest Resources Assessment 2000. Main Report.–Stocks, B.J., 1991. The extent and impact of fires in northern circumpolar countries. In: J.S. Levine (ed.). Global Biomass Burning: Atmospheric, Climatic, and Biospheric Implications, pp. 197–202.
  32. ↑ FAO, 2001. Global Forest Resources Assessment 2000. Main Report.
  33. ↑ Shetinsky, E. A., 1994. Protection of forests and forest pyrology. Ecology, Moscow, 209 p. (In Russian)
  34. ↑ FAO, 2001. Op. cit
  35. ↑ Ibid.
  36. ↑ Shvidenko, A.Z. and S. Nilsson, 2000. Extent, distribution and ecological role of fire in Russian forests. In: E.S. Kasischke and B.J. Stocks (eds.). Fire, Climate Change, and Carbon Cycling in the Boreal Forest, pp. 132–150. Springer-Verlag.
  37. ↑ Cahoon, D.R. Jr., B.J. Stocks, J.S. Levine, W.R. Cofer III and J.M. Pierson, 1994. Satellite analysis of the severe 1987 forest fires in northern China and southeastern Siberia. Journal of Geophysical Research, 99(D9):18627–18638.
  38. ↑ Cahoon, D.R. Jr., B.J. Stocks, J.S. Levine, W.R. Cofer III and J.M. Pierson, 1996. Monitoring the 1992 forest fires in the boreal ecosystem using NOAA AVHRR satellite imagery. In: J.L. Levine (ed.). Biomass Burning and Climate Change - Vol 2: Biomass Burning in South America, Southeast Asia, and Temperate and Boreal Ecosystems, and the Oil Fires of Kuwait, pp. 795–802. MIT Press.
  39. ↑ FAO, 2001. Op. cit.
  40. ↑ Ibid.
  41. ↑ Stocks, B.J., M. A. Fosberg, M.B. Wotton, T.J. Lynham and K.C. Ryan, 2000. Climate change and forest fire activity in North American boreal forests. In: E.S. Kasischke and B.J. Stocks (eds.). Fire, Climate Change, and Carbon Cycling in the Boreal Forest, pp. 368–376. Springer-Verlag.
  42. ↑ Ibid.
  43. ↑ Gillett, N.P., A.J. Weaver, F. W. Zwiers and M.D. Flannigan, 2004. Detecting the effect of climate change on Canadian forest fires. Geophysical Research Letters, 31:L18211, doi:10.1029/ 2004GL020876.
  44. ↑ Stocks, et. al. 200, Op. cit
  45. ↑ Ibid.
  46. ↑ Wiken, E.B., 1986. Terrestrial Ecozones of Canada. Ecological Land Classification, Series No. 19. Environment Canada, Hull, Quebec. 26p.+map.
  47. ↑ Stocks, et. al. 200, Op. cit
  48. ↑ Kasischke, E.S., T.S. Rupp and D.L.Verbyla, in press. Fire trends in the Alaskan boreal forest. In: F.S. Chapin III, J. Yarie, K.Van Cleve, L. A.Viereck, M. W. Oswood and D.L.Verbyla (eds.). Alaska’s Changing Boreal Forest. Oxford University Press.
  49. ↑ Lutz, H.J., 1956. Ecological Effects of Forest Fires in the Interior of Alaska. United States Department of Agriculture Technical Bulletin 1133, United States Government Printing Office, 121p.
  50. ↑ Barney, R.J. and B.J. Stocks, 1983. Fire frequencies during the suppression period. In: R. W. Wein and D. A. MacLean (eds.). The Role of Fire in Northern Circumpolar Ecosystems, pp. 45–62. John Wiley and Sons.–Gabriel, H. W. and G.F. Tande, 1983. A Regional Approach to Fire History in Alaska. U.S. Bureau of Land Management,Technical Report 9, 34p.
  51. ↑ Kasischke, E.S., T.S. Rupp and D.L.Verbyla, in press. Fire trends in the Alaskan boreal forest. In: F.S. Chapin III, J. Yarie, K.Van Cleve, L. A.Viereck, M. W. Oswood and D.L.Verbyla (eds.). Alaska’s Changing Boreal Forest. Oxford University Press.
  52. ↑ Nash, C.H. and E. A. Johnson, 1996. Synaptic climatology of lightning-caused forest fires in subalpine and boreal forests. Canadian Journal of Forest Research, 26:1859–1874.
  53. ↑ Kasischke, E.S., T.S. Rupp and D.L.Verbyla, in press. Fire trends in the Alaskan boreal forest. In: F.S. Chapin III, J. Yarie, K.Van Cleve, L. A.Viereck, M. W. Oswood and D.L.Verbyla (eds.). Alaska’s Changing Boreal Forest. Oxford University Press.
  54. ↑ Ibid.
  55. ↑ Dissing, D. and D.L. Verbyla, 2003. Spatial patterns of lightning strikes in interior Alaska and their relations to elevation and vegetation. Canadian Journal of Forest Research, 33(5):770–782.
  56. ↑ Chambers, S.D. and F.S. Chapin III, 2003. Fire effects on surfaceatmosphere energy exchange in Alaskan black spruce ecosystems: Implications for feedbacks to regional climate. Journal of Geophysical Research, 108(D1): doi:10.1029/2001JD000530.–Dissing, D. and D.L.Verbyla, 2003. Spatial patterns of lightning strikes in interior Alaska and their relations to elevation and vegetation. Canadian Journal of Forest Research, 33(5):770–782.–Kasischke, E.S., T.S. Rupp and D.L.Verbyla, in press. Fire trends in the Alaskan boreal forest. In: F.S. Chapin III, J. Yarie, K. Van Cleve, L. A. Viereck, M. W. Oswood and D.L. Verbyla (eds.). Alaska’s Changing Boreal Forest. Oxford University Press.–Lynch, J. A., J.S. Clark, N.H. Bigelow, M.E. Edwards and B.P. Finney, 2003. Geographic and temporal variations in fire history in boreal ecosystems of Alaska. Journal of Geophysical Research, 108(D1): doi:10.1029/2001JD000332.
  57. ↑ Stocks, B.J., 2001. Fire Management in Canada. Section 6.1.2. In: Global Forest Fire Assessment 1990–2000. Forest Resources Assessment - WP 55. U.N. Food and Agriculture Organization.
  58. ↑ Kasischke, et. al, Op. cit.
  59. ↑ Ibid.
  60. ↑ Ibid.
  61. ↑ Stocks, B.J., 1991. The extent and impact of fires in northern circumpolar countries. In: J.S. Levine (ed.). Global Biomass Burning: Atmospheric, Climatic, and Biospheric Implications, pp. 197–202. MIT Press.
  62. ↑ Essen, P. A., B. Ehnstrom, L. Eriscon and K. Sjoberg, 1992. Boreal forests – the focal habitats of Fennoscandia. In: L. Hansson (ed.). Ecological Principles of Nature Conservation. Applications in Temperate and Boreal Environments, pp. 252–325. Elsevier Applied Science.
  63. ↑ FAO, 2001. Op. cit.
  64. ↑ Ibid.
  65. ↑ Ibid.
  66. ↑ Ibid..
  67. ↑ Ibid.
  68. ↑ Ibid.
  69. ↑ Ibid.
  70. ↑ Mysterud, I., I. Mysterud and E. Bleken, 1998. Forest fires and environmental management in Norway. International Forest Fire News, 18:72–75.
  71. ↑ FAO, 2001. Global Forest Resources Assessment 2000. Main Report.
  72. ↑ Rupp,T.S.,A.M. Starfield and F.S. Chapin III, 2000a. A frame-based spatially explicit model of subarctic vegetation response to climatic change: comparison with a point model. Landscape Ecology, 15:383–400.–Rupp, T.S., F.S. Chapin III and A.M. Starfield, 2000b. Response of subarctic vegetation to transient climatic change on the Seward Peninsula in northwest Alaska. Global Change Biology, 6:541–555.
  73. ↑ Turner, M.G., S.L. Collins, A.L. Lugo, J.J. Magnuson, T.S. Rupp and F.J. Swanson, 2003. Disturbance dynamics and ecological response: the contribution of long-term ecological research. BioScience, 53(1):46–56.
  74. ↑ Rupp, T.S., F.S. Chapin III and A.M. Starfield, 2000b. Response of subarctic vegetation to transient climatic change on the Seward Peninsula in northwest Alaska. Global Change Biology, 6:541–555.
  75. ↑ Rupp,T.S., F.S. Chapin III, A.M. Starfield and P. Duffy, 2002. Modeling boreal forest dynamics in interior Alaska. Climatic Change, 55:213–233.
  76. ↑ Stocks, B.J., 1991. The extent and impact of fires in northern circumpolar countries. In: J.S. Levine (ed.). Global Biomass Burning: Atmospheric, Climatic, and Biospheric Implications, pp. 197–202. MIT Press.
  77. ↑ Rupp, T.S., F.S. Chapin III and A.M. Starfield, 2000b. Op. cit.–Rupp,T.S., F.S. Chapin III, A.M. Starfield and P. Duffy, 2002. Modeling boreal forest dynamics in interior Alaska. Climatic Change, 55:213–233.
  78. ↑ Yarie, J., 1981. Forest fire cycles and life tables: a case study from interior Alaska. Canadian Journal of Forest Research, 11(3):554–562.
  79. ↑ Rupp, T.S., F.S. Chapin III and A.M. Starfield, 2000b. Op. cit.–Rupp,T.S., F.S. Chapin III, A.M. Starfield and P. Duffy, 2002. Modeling boreal forest dynamics in interior Alaska. Climatic Change, 55:213–233.
  80. ↑ Johnson, E. A., 1992. Fire and Vegetation Dynamics: Studies from the North American Boreal Forest. Cambridge University Press, 129p.
  81. ↑ Gardner, R.H., W.H. Romme and M.G. Turner, 1999. Predicting forest fire effects at landscape scales. In: D.J. Mladenoff and W.L. Baker (eds.). Spatial Modeling of Forest Landscape Change: Approaches and Applications, pp. 163–185. Cambridge University Press.
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  84. ↑ Stocks, B.J., M. A. Fosberg, T.J. Lynham, L. Mearns, B.M. Wotton, Q. Yang, J.-Z. Jin, K. Lawrence, G.R. Hartley, J. A. Mason and D. W. McKenny, 1998. Climate change and forest fire potential in Russian and Canadian boreal forests. Climatic Change, 38(1):1–13.
  85. ↑ Ter-Mikaelian, M.,V.V. Furyaev and M.I. Antonovsky, 1991. A spatial forest dynamics model regarding fires and climate change. In: Problems of Ecological Monitoring and Ecosystem Modeling, V. 13. Gidrometeoizdat, Leningrad. (In Russian)
  86. ↑ Flannigan, M.D. and C.E. Van Wagner, 1991. Climate change and wildfire in Canada. Canadian Journal of Forest Research, 21(1):66–72.
  87. ↑ Flannigan, et. al. 1998 Op. cit.
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