Effect of increased fire activity on global warming in the boreal forest

2014 ◽  
Vol 22 (3) ◽  
pp. 206-219 ◽  
Author(s):  
France Oris ◽  
Hugo Asselin ◽  
Adam A. Ali ◽  
Walter Finsinger ◽  
Yves Bergeron
Keyword(s):  
Global Warming ◽  
Boreal Forest ◽  
Forest Fires ◽  
Positive Feedback ◽  
Carbon Stock ◽  
Surface Albedo ◽  
Fire Regime ◽  
Integrative Approach ◽  
Boreal Region ◽  
Fire Activity

Forest fires are an important disturbance in the boreal forest. They are influenced by climate, weather, topography, vegetation, surface deposits, and human activities. In return, forest fires affect the climate through emission of gases and aerosols, and changes in surface albedo, soil processes, and vegetation dynamics. The net effect of these factors is not yet well established but seems to have caused a negative feedback on climate during the 20th century. However, an increase in boreal forest fires is predicted by the end of the 21st century, possibly changing the effect of fires on climate change to a positive feedback that would exacerbate global warming. This review presents (1) an overview of fire regimes and vegetation succession in boreal forests; (2) the effects on climate of combustion emissions and post-fire changes in ecosystem functioning; (3) the effects of fire regime variations on climate, especially on carbon stock and surface albedo; (4) an integrative approach of fire effects on climate dynamics; and (5) the implications of increased fire activity on global warming by calculating the radiative forcing of several factors by 2100 in the boreal region, before discussing the results and exposing the limits of the data at hand. Generally, losses of carbon from forest fires in the boreal region will increase in the future and their effect on the carbon stock (0.37 W/m2/decade) will be greater than the effect of fire on surface albedo (−0.09 W/m2/decade). The net effect of aerosol emissions from boreal fires will likely cause a positive feedback on global warming. This review emphasizes the importance of feedbacks between fires and climate in the boreal forest. It presents limitations and uncertainties to be addressed in future studies, particularly with regards to the effect of CO2 fertilization on forest productivity, which could offset or mitigate the effect of fire.

Forest fire occurrence and climate change in Canada

2010 ◽  
Vol 19 (3) ◽  
pp. 253 ◽  
Author(s):  
B. M. Wotton ◽  
C. A. Nock ◽  
M. D. Flannigan
Keyword(s):  
Climate Change ◽  
Boreal Forest ◽  
Forest Fire ◽  
Forest Fires ◽  
General Circulation ◽  
Fire Regime ◽  
General Circulation Models ◽  
Fire Occurrence ◽  
Fire Activity ◽  
In Fire

The structure and function of the boreal forest are significantly influenced by forest fires. The ignition and growth of fires depend quite strongly on weather; thus, climate change can be expected to have a considerable impact on forest fire activity and hence the structure of the boreal forest. Forest fire occurrence is an extremely important element of fire activity as it defines the load on suppression resources a fire management agency will face. We used two general circulation models (GCMs) to develop projections of future fire occurrence across Canada. While fire numbers are projected to increase across all forested regions studied, the relative increase in number of fires varies regionally. Overall across Canada, our results from the Canadian Climate Centre GCM scenarios suggest an increase in fire occurrence of 25% by 2030 and 75% by the end of the 21st century. Results projected from fire climate scenarios derived from the Hadley Centre GCM suggest fire occurrence will increase by 140% by the end of this century. These general increases in fire occurrence across Canada agree with other regional and national studies of the impacts of climate change on fire activity. Thus, in the absence of large changes to current climatic trends, significant fire regime induced changes in the boreal forest ecosystem are likely.

Fire Trends in the Alaskan Boreal Forest

2006 ◽  
Author(s):  
Eric S. Kasischke ◽  
David L. Verbyla
Keyword(s):  
Boreal Forest ◽  
Forest Fires ◽  
Fire Regime ◽  
Climatic Factors ◽  
Forest Type ◽  
Dominant Factor ◽  
Forest Types ◽  
Natural Fire ◽  
Plant Parts ◽  
Crown Fires

Fire is ubiquitous throughout the global boreal forest (Wein 1983, Payette 1992, Goldammer and Furyaev 1996, Kasischke and Stocks 2000). The inter- and intra-annual patterns of fire in this biome depend on several interrelated factors, including the quantity and quality of fuel, fuel moisture, and sources of ignition. Fire cycles in different boreal forest types vary between 25 and >200 years (Heinselman 1981, Yarie 1981, Payette 1992, Conard and Ivanova 1998). Although the increased presence of humans in some regions of boreal forest has undoubtedly changed the fire regime (DeWilde 2003), natural fire is still a dominant factor in ecosystem processes throughout this biome. Boreal forest fires are similar to those of other forests in that they vary between surface and crown fires, depending on forest type and climatic factors. Surface fires kill and consume most of the understory vegetation, as well as portions of the litter or duff lying on the forest floor, resulting in varying degrees of mortality of canopy and subcanopy trees. Crown fires consume large amounts of the smaller plant parts (or fuels) present as leaves, needles, twigs, and small branches and kill all trees. These fires are important in initiating secondary succession (Lutz 1956, Heinselman 1981, Van Cleve and Viereck 1981, Van Cleve et al. 1986, Viereck 1983, Viereck et al. 1986). Unlike fires in other forest types, smoldering ground fires in the boreal forest can combust a significant fraction of the deep organic (fibric and humic) soils in forests overlying permafrost (Dyrness and Norum 1983, Landhauesser and Wein 1993, Kasischke et al. 2000a, Miyanishi and Johnson 2003). During periods of drought, when water tables are low, or prior to spring thaw, organic soils in peatlands can become dry enough to burn, as well (Zoltai et al. 1998, Turetsky and Wieder 2001, Turetsky et al. 2002).

The potential and limitations of long-term fire regime reconstructions in Eastern Siberia based on sedimentary charcoal and low-temperature fire markers 

2021 ◽  
Author(s):  
Elisabeth Dietze ◽  
Kai Mangelsdorf ◽  
Jasmin Weise ◽  
Heidrun Matthes ◽  
Simeon Lisovski ◽  
...  
Keyword(s):  
Low Temperature ◽  
Boreal Forest ◽  
High Latitude ◽  
Forest Fires ◽  
Fire Regime ◽  
Fire Regimes ◽  
Transport Processes ◽  
Eastern Siberia ◽  
Climate Data

<p>Forest fires are an important factor in the global carbon cycle and high latitude ecosystems. Eastern Siberian tundra, summergreen larch-dominated boreal forest on permafrost and evergreen boreal forest have characteristic fire regimes with varying fire intensities. Yet, it is unknown which role fire plays in long-term climate-vegetation-permafrost feedbacks and how high-latitude fire regimes and ecosystems will change in a warmer world. To learn from fire regime shifts during previous interglacials, prior to human presence, we use lake-sedimentary charcoal as proxy for high-intensity forest fires and monosaccharide anhydrides (i.e. levoglucosan, mannosan, galactosan: MA) as molecular proxies for low-temperature biomass burning, typical for surface fires in modern larch forest. However, MA pathways from source to sink and their stability in sediments are very poorly constrained. Recently, Dietze et al. (2020) found MA in up to 420 kyr old sediment of Lake El’gygytgyn (ICDP Site 5011-1), NE Siberia, suggesting that they are suitable proxies for fires in summergreen boreal forests. Surprisingly, the ratios of the MA isomers were exceptionally low compared to published emission ratios from modern combustions.</p><p>To understand what MA from Arctic lake sediments tell us, we have analyzed the MA and charcoal composition in modern lake surface sediments of Lake El’gygytgyn and three East Siberian lakes and we compare them to late glacial-to-interglacial El’gygytgyn records. The three Siberian lakes were chosen to represent spatial analogues to the El’gygytgyn conditions during MIS 5e and 11c. We discuss first results of the modern sediments in context of recent MODIS- and Landsat-based fire extents and biome-specific land cover data, a wind field modelling using climate data over eastern Siberia, and lake-catchment configurations from TDX-DEM analysis to assess potential fire proxy source areas and regional-to-local transport processes. Thereby, we provide insights into the meaning of sedimentary fire proxies, crucial for a sound reconstruction of long-term fire regime histories.</p>

Influence of landscape structure on patterns of forest fires in boreal forest landscapes in Sweden

2004 ◽  
Vol 34 (2) ◽  
pp. 332-338 ◽  
Author(s):  
Erik Hellberg ◽  
Mats Niklasson ◽  
Anders Granström
Keyword(s):  
Boreal Forest ◽  
Forest Fires ◽  
Landscape Structure ◽  
Fire Regime ◽  
Spatial And Temporal Patterns ◽  
Fire Scars ◽  
Maximal Interval ◽  
Landscape Types ◽  
Fire Intervals ◽  
Cross Dating

To analyze the effect of landscape structure (viz. amount of wetlands) on the past forest fire regime in boreal Sweden, we reconstructed detailed fire histories by cross-dating fire scars in living and dead Scots pine (Pinus sylvestris L.) in two different landscape types: mire-free landscapes with a low proportion (1%–2%) of mires and mire-rich landscapes with a high proportion (21%–33%) of mires. Two localities were selected and at each one, adjacent mire-free and mire-rich areas of 256–601 ha were sampled. Over the studied 650-year period, the two landscape types differed primarily in the fire intervals and sizes of fires. In the mire-rich landscapes, fires had frequently stopped against mire elements. The net effect was significantly longer fire intervals in the mire-rich than in the mire-free landscape (on average, 32 versus 56 years). The mire-rich areas also had a tail of very long fire intervals lacking in the mire-free areas (maximal interval 292 years). We conclude that mires can have a profound effect on both spatial and temporal patterns of forest fires in the boreal forest, but only when they are effective fuel breaks (i.e., they are wet enough) at the time the fires burn and if they truly dissect the nonmire portion of the forest landscape.

scholarly journals Stand age and species composition effects on surface albedo in a mixedwood boreal forest

2019 ◽  
Author(s):  
Mohammad Abdul Halim ◽  
Han Y. H. Chen ◽  
Sean C. Thomas
Keyword(s):  
Species Composition ◽  
Boreal Forest ◽  
Forest Fires ◽  
Surface Albedo ◽  
Stand Age ◽  
Ground Vegetation ◽  
Post Harvest ◽  
Age Related ◽  
Mixedwood Boreal Forest ◽  
Broadleaf Species

Abstract. Surface albedo is one of the most important processes governing climate forcing in the boreal forest and is directly affected by management activities such as harvesting and natural disturbances such as forest fires. Empirical data on effects of these disturbances on boreal forest albedo are sparse. We conducted ground-based measurements of surface albedo from a series of instrument towers over four years in a replicated chronosequence of mixedwood boreal forest sites differing in stand age (year since disturbance) in both post-harvest and post-fire stands. We investigated the effects of stand age, canopy height, tree species composition, and ground vegetation cover on surface albedo through stand development. Our results indicate that winter and spring albedo values were 63 and 24 % higher, respectively, in post-harvest stands than in post-fire stands. Winter and summer albedos saturated at ~ 50 years of stand age in both post-harvest and post-fire stands. Albedo differences between post-harvest and post-fire stands were most pronounced during winter and spring in young stands (0–19 years post-disturbance). The proportion of deciduous broadleaf species showed a strong positive relationship with seasonal albedo in both post-harvest and post-fire stands. Given that stand composition in mixedwood boreal forests generally shows a gradual replacement of deciduous trees by conifers, our results suggest that successional changes in species composition are likely a key driver of age-related patterns in albedo. Our findings also suggest the efficacy of increasing the proportion of deciduous broadleaf species as a silvicultural option for climate-friendly management of boreal forest.

scholarly journals Stand age and species composition effects on surface albedo in a mixedwood boreal forest

2019 ◽  
Vol 16 (22) ◽  
pp. 4357-4375 ◽  
Author(s):  
Mohammad Abdul Halim ◽  
Han Y. H. Chen ◽  
Sean C. Thomas
Keyword(s):  
Species Composition ◽  
Boreal Forest ◽  
Forest Fires ◽  
Surface Albedo ◽  
Stand Age ◽  
Ground Vegetation ◽  
Post Harvest ◽  
Age Related ◽  
Mixedwood Boreal Forest ◽  
Broadleaf Species

Abstract. Surface albedo is one of the most important processes governing climate forcing in the boreal forest and is directly affected by management activities such as harvesting and natural disturbances such as forest fires. Empirical data on the effects of these disturbances on boreal forest albedo are sparse. We conducted ground-based measurements of surface albedo from a series of instrument towers over 4 years in a replicated chronosequence of mixedwood boreal forest sites differing in stand age (to 19 years since disturbance) in both post-harvest and post-fire stands. We investigated the effects of stand age, canopy height, tree species composition, and ground vegetation cover on surface albedo through stand development. Our results indicate that winter and spring albedo values were 63 % and 24 % higher, respectively, in post-harvest stands than in post-fire stands. Summer and fall albedo values were similar between disturbance types, with summer albedo showing a transient peak at ∼10 years stand age. The proportion of deciduous broadleaf species showed a strong positive relationship with seasonal averages of albedo in both post-harvest and post-fire stands. Given that stand composition in mixedwood boreal forests generally shows a gradual replacement of deciduous trees by conifers, our results suggest that successional changes in species composition are likely a key driver of age-related patterns in albedo. Our findings also suggest the efficacy of increasing the proportion of deciduous broadleaf species as a silvicultural option for climate-friendly management of the boreal forest.

scholarly journals Twenty-first century droughts have not increasingly exacerbated fire season severity in the Brazilian Amazon

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. Libonati ◽  
J. M. C. Pereira ◽  
C. C. Da Camara ◽  
L. F. Peres ◽  
D. Oom ◽  
...  
Keyword(s):  
Forest Fires ◽  
Brazilian Amazon ◽  
First Century ◽  
Fire Season ◽  
Fire Intensity ◽  
Amazon Forest ◽  
Active Fire ◽  
Fire Activity ◽  
Twenty First Century ◽  
In Fire

AbstractBiomass burning in the Brazilian Amazon is modulated by climate factors, such as droughts, and by human factors, such as deforestation, and land management activities. The increase in forest fires during drought years has led to the hypothesis that fire activity decoupled from deforestation during the twenty-first century. However, assessment of the hypothesis relied on an incorrect active fire dataset, which led to an underestimation of the decreasing trend in fire activity and to an inflated rank for year 2015 in terms of active fire counts. The recent correction of that database warrants a reassessment of the relationships between deforestation and fire. Contrasting with earlier findings, we show that the exacerbating effect of drought on fire season severity did not increase from 2003 to 2015 and that the record-breaking dry conditions of 2015 had the least impact on fire season of all twenty-first century severe droughts. Overall, our results for the same period used in the study that originated the fire-deforestation decoupling hypothesis (2003–2015) show that decoupling was clearly weaker than initially proposed. Extension of the study period up to 2019, and novel analysis of trends in fire types and fire intensity strengthened this conclusion. Therefore, the role of deforestation as a driver of fire activity in the region should not be underestimated and must be taken into account when implementing measures to protect the Amazon forest.

Airborne measurements of surface albedo and leaf area index of snow‐covered boreal forest

2021 ◽  
Author(s):  
Terhikki Manninen ◽  
Jean‐Louis Roujean ◽  
Olivier Hautecoeur ◽  
Aku Riihelä ◽  
Panu Lahtinen ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Surface Albedo ◽  
Area Index ◽  
Airborne Measurements

scholarly journals Global warming in Amazonia: impacts and Mitigation

2009 ◽  
Vol 39 (4) ◽  
pp. 1003-1011 ◽  
Author(s):  
Philip Martin Fearnside
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Forest Fires ◽  
El Niño ◽  
El Nino ◽  
Cost Effective ◽  
Climatic Conditions ◽  
Carbon Accounting ◽  
Amazon Forest ◽  
Temperature Oscillations

Global warming has potentially catastrophic impacts in Amazonia, while at the same time maintenance of the Amazon forest offers one of the most valuable and cost-effective options for mitigating climate change. We know that the El Niño phenomenon, caused by temperature oscillations of surface water in the Pacific, has serious impacts in Amazonia, causing droughts and forest fires (as in 1997-1998). Temperature oscillations in the Atlantic also provoke severe droughts (as in 2005). We also know that Amazonian trees die both from fires and from water stress under hot, dry conditions. In addition, water recycled through the forest provides rainfall that maintains climatic conditions appropriate for tropical forest, especially in the dry season. What we need to know quickly, through intensified research, includes progress in representing El Niño and the Atlantic oscillations in climatic models, representation of biotic feedbacks in models used for decision-making about global warming, and narrowing the range of estimating climate sensitivity to reduce uncertainty about the probability of very severe impacts. Items that need to be negotiated include the definition of "dangerous" climate change, with the corresponding maximum levels of greenhouse gases in the atmosphere. Mitigation of global warming must include maintaining the Amazon forest, which has benefits for combating global warming from two separate roles: cutting the flow the emissions of carbon each year from the rapid pace of deforestation, and avoiding emission of the stock of carbon in the remaining forest that can be released by various ways, including climate change itself. Barriers to rewarding forest maintenance include the need for financial rewards for both of these roles. Other needs are for continued reduction of uncertainty regarding emissions and deforestation processes, as well as agreement on the basis of carbon accounting. As one of the countries most subject to impacts of climate change, Brazil must assume the leadership in fighting global warming.

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