scholarly journals Evidence that modern fires may be unprecedented during the last 3400 years in permafrost zone of central Siberia, Russia

Author(s):  
Elena Yu Novenko ◽  
Dmitry A. Kupryanov ◽  
Natalia G. Mazei ◽  
Anatoly Prokushkin ◽  
Leanne N. Phelps ◽  
...  

Abstract Recent climate change in Siberia is increasing the probability of dangerous forest fires. The development of effective measures to mitigate and prevent fires is impossible without an understanding of long-term fire dynamics. This paper presents the first multi-site palaeo-fire reconstruction based on macroscopic charcoal data from peat and lake sediment cores located in different landscapes across the permafrost area of Central Siberia. The obtained results show similar temporal patterns of charcoal accumulation rates in the cores under study, and near synchronous changes in fire regimes. The paleo-fire record revealed moderate biomass burning between 3.4 and 2.6 ka BP, followed by the period of lower burning occurring from 2.6 to 1.7 ka BP that coincided with regional climate cooling and moistening. Minimal fire activity was also observed during the Little Ice Age (0.7 – 0.25 ka BP). Fire frequencies increased during the interval from 1.7 to 0.7 ka BP and appears to be partly synchronous with climate warming during the Medieval Climate Anomaly. Regional reconstructions of long-term fire history show that recent fires are unprecedented during the late Holocene, with modern high biomass burning lying outside millennial and centennial variability of the last 3400 years.

2020 ◽  
Vol 29 (7) ◽  
pp. 602
Author(s):  
Grant L. Harley ◽  
Emily K. Heyerdahl ◽  
James D. Johnston ◽  
Diana L. Olson

Riparian forests link terrestrial and freshwater communities and therefore understanding the landscape context of fire regimes in these forests is critical to fully understanding the landscape ecology. However, few direct studies of fire regimes exist for riparian forests, especially in the landscape context of adjacent upland forests or studies of long-term climate drivers of riparian forest fires. We reconstructed a low-severity fire history from tree rings in 38 1-ha riparian plots and combined them with existing fire histories from 104 adjacent upland plots to yield 2633 fire scars sampled on 454 trees. Historically (1650–1900), low-severity fires burned more frequently in upland than in riparian plots, but this difference was not significant (P=0.15). During more than half of the fire years at both sites, fires were extensive and burned synchronously in riparian and upland plots, and climate was significantly dry during these years. However, climate was not significantly dry when fires burned in only one plot type. Historically, entire riparian zones likely burned in these two study sites of the Blue Mountains during dry years. This study suggests that riparian and upland forests could be managed similarly, especially given the projected increases to fire frequency and intensity from impending climate change.


2008 ◽  
Vol 17 (1) ◽  
pp. 84 ◽  
Author(s):  
Jennifer Pierce ◽  
Grant Meyer

Alluvial fan deposits are widespread and preserve millennial-length records of fire. We used these records to examine changes in fire regimes over the last 2000 years in Yellowstone National Park mixed-conifer forests and drier central Idaho ponderosa pine forests. In Idaho, frequent, small, fire-related erosional events occurred within the Little Ice Age (~1450–1800 AD), when greater effective moisture probably promoted grass growth and low-severity fires. This regime is consistent with tree-ring records showing generally wetter conditions and frequent fires before European settlement. At higher elevations in Yellowstone, cool conditions limited overall fire activity. Conversely, both Idaho and Yellowstone experienced a peak in fire-related debris flows between ~950 and 1150 AD. During this generally warmer time, severe multidecadal droughts were interspersed with unusually wet intervals that probably increased forest densities, producing stand-replacing fires. Thus, severe fires are clearly within the natural range of variability in Idaho ponderosa pine forests over longer timescales. Historical records indicate that large burn areas in Idaho correspond with drought intervals within the past 100 years and that burn area has increased markedly since ~1985. Recent stand-replacing fires in ponderosa pine forests are likely related to both changes in management and increasing temperatures and drought severity during the 20th century.


2010 ◽  
Vol 19 (8) ◽  
pp. 1015 ◽  
Author(s):  
Laurent Bremond ◽  
Christopher Carcaillet ◽  
Charly Favier ◽  
Adam A. Ali ◽  
Cédric Paitre ◽  
...  

An original method is proposed for estimating past carbon emissions from fires in order to understand long-term changes in the biomass burning that, together with vegetation cover, act on the global carbon cycle and climate. The past carbon release resulting from paleo-fires during the Holocene is examined using a simple linear model between measured carbon emissions from modern fires and sedimentary charcoal records of biomass burning within boreal and cold temperate forests in eastern Canada (Quebec, Ontario). Direct carbon emissions are estimated for each ecozone for the present period and the fire anomaly per kilo annum (ka) v. present day (0 ka) deduced from charcoal series of 46 lakes and peats. Over the postglacial, the Taiga Shield ecozone does not match the pattern of fire history and carbon release of Boreal Shield, Atlantic Maritime, and Mixedwood Plains ecozones. This feature results from different air mass influences and the timing of vegetation dynamics. Our estimations show, first, that the contribution of the Mixedwood Plains and the Atlantic Maritime ecozones on the total carbon emissions by fires remains negligible compared with the Boreal Shield. Second, the Taiga Shield plays a key role by maintaining important carbon emissions, given it is today a lower contributor.


Author(s):  
Cathy Barnosky

The research underway has focused on two different aspects of the environmental history of the Yellowstone/Grand Teton region. One objective has been to examine the long-term vegetational and climatic history of Jackson Hole, the Pinyon Peak Highlands, and Yellowstone Park since the end of late Pinedale glaciation, about 14,000 years ago. Fossil pollen in sediment cores from lakes in the region is being analyzed to clarify the nature and composition of ice-age refugia, the rate and direction of plant migrations in the initial stages of reforestation, and the long-term stability of postglacial communities. Sedimentary charcoal also is being examined to reconstruct fire frequency during different climatic regions and different vegetation types in the past. This information is necessary to assess the sensitivity of plant communities to environmental change and to understand postglacial landscapes of the northern rocky Mountains. The second objective has been a multidisciplinary investigation of the relationship of climate to sedimentation rates in lakes and ponds in Yellowstone, undertaken with Drs. Wright, D.R. Engstrom and S.C. Fritz of the University of Minnesota. This facet of the research examines the relative importance of climate, fire, hillslope erosion induced by overgrazing, and nutrient enrichment in the last 150 years, as recorded in selected lakes in the northern range of Yellowstone. Populations of elk and bison are known to have fluctuated greatly during this interval, and slight climatic changes are suggested from other lines of research. In this study pollen, diatoms, charcoal, sediment chemistry, and sediment accumulation rates are analyzed in short cores from small lakes.


2021 ◽  
Author(s):  
Ramesh Glückler ◽  
Elisabeth Dietze ◽  
Josias Gloy ◽  
Ulrike Herzschuh ◽  
Stefan Kruse

<p>Wildfires are an essential ecological process, located at the interface between atmosphere, biosphere, and geosphere. Climate-related changes in their appearance and frequency will shape the boreal forest of tomorrow, the largest terrestrial biome responsible for numerous important ecosystem functions. Changing fire regimes could also increase pressure on fire management and become a threat for humans living in Siberia. However, a lack of long-term fire reconstructions complicates the understanding of the main drivers in the larch-dominated forests of eastern Siberia. At the same time, this lack of long-term understanding also aggravates the validation of fire-vegetation models, and thus predictions of future changes of fire regimes in this vital region.</p><p>Here, we present a new fire module being built for the individual-based, spatially explicit vegetation model LAVESI (<em>Larix</em> Vegetation Simulator). LAVESI is able to simulate fine-scale interactions in individual tree’s life stages and detailed population dynamics, now expanded by the ability of wildfires igniting and damaging biomass. Fire-vegetation simulations were computed around the catchment of Lake Khamra (SW Yakutia), which experienced forest fires in the years 2007 and 2014 according to remote sensing imagery. From the lake, we previously contributed a new, sedimentary charcoal-based fire reconstruction of the late Holocene. Testing the fire module at a current study site, where modern and historic data has already been collected, allows us to improve it, and look into ways in which the fire reconstruction might help inform the model, before eventually scaling it up to cover larger regions. This represents a first step towards a reliable fire-vegetation model, able to predict future impacts of fires on both the forests of eastern Siberia, as well as the humans living there.</p>


2017 ◽  
Author(s):  
Fátima Abrantes ◽  
Teresa Rodrigues ◽  
Marta Rufino ◽  
Emília Salgueiro ◽  
Dulce Oliveira ◽  
...  

Abstract. The Iberian Peninsula, at North Atlantic mid-latitude and the western extreme of the European continent, is a key point for climate reconstructions. This work provides multi-proxy records measured in 8 inner-shelf sediment cores from 5 sites located between South Portugal (Algarve) and Northwest Spain (Galiza) (36 to 41º N) and target a regional reconstruction of climate variability during the Historic period (last 2 ky). The SST records reveal a long-term scale cooling (±1 ºC/2 ky) that ends at the beginning of the 20th century at all latitudes. This cooling is a follow up of the cooling process that started in the early Holocene driven by a decrease in summer insolation in the Northern Hemisphere. Within this long term SST variability multi-decadal/centennial scale variability is detected along Iberia. The different latitudinal SST reconstructions jointly with a determined regional SST stack were compared to on-land precipitation from higher plant n-alkanes and pollen data, to assess the relationship between hydroclimate (drought and/or precipitation) and SST. Regional variability is overall in consonance with NE Spain, and other European and north Hemisphere reconstructions. Warm conditions prevailed throughout 1300 yr, encompassing the Roman Period (RP), the Dark Ages (DA) and the Medieval Warm Period (MWP). The initial cooling at 1300 CE leads to 4 centuries of ±1 ºC colder mean SSTs contemporaneous with the Little Ice Age (LIA). The transition towards the Industrial Era starts by 1800 CE with a rise to pre-LIA SSTs. Climate specificities have been detected in western Iberian margin records and reveal the existence of two distinct phases within the MWP and a two-step SST increase towards the Industrial Era. The intense precipitation/flooding and warm winters but cooler intermediate seasons observed for the early MWP imply the interplay of internal oceanic variability with the three known atmospheric circulation modes, AMO, EA and SCAND in a positive phase. The late MWP, typified by drier and cooler winters and warmer intermediate seasons calls for a change in sign of the SCAND. A stronger mark of oceanic influences on western Iberian Peninsula (IP) starts with the transition to the Industrial Era.


2008 ◽  
Vol 17 (1) ◽  
pp. 72 ◽  
Author(s):  
Cathy Whitlock ◽  
Jennifer Marlon ◽  
Christy Briles ◽  
Andrea Brunelle ◽  
Colin Long ◽  
...  

Pollen and high-resolution charcoal records from the north-western USA provide an opportunity to examine the linkages among fire, climate, and fuels on multiple temporal and spatial scales. The data suggest that general charcoal levels were low in the late-glacial period and increased steadily through the last 11 000 years with increasing fuel biomass. At local scales, fire occurrence is governed by the interaction of site controls, including vegetation, local climate and fire weather, and topography. At subregional scales, patterns in the long term fire-episode frequency data are apparent: The Coast Range had relatively few fires in the Holocene, whereas the Klamath–Siskiyou region experienced frequent fire episodes. Fire regimes in the northern Rocky Mountains have been strongly governed by millennial- and centennial-scale climate variability and regional differences in summer moisture. At regional scales, sites in present-day summer-dry areas show a period of protracted high fire activity within the early Holocene that is attributed to intensified summer drought in the summer-dry region. Sites in summer-wet areas show the opposite pattern, that fire was lower in frequency than present in the early Holocene as result of strengthened monsoonal circulation then. Higher fire-episode frequency at many sites in the last 2000 years is attributed to greater drought during the Medieval Climate Anomaly and possibly anthropogenic burning. The association between drought, increased fire occurrence, and available fuels evident on several time scales suggests that long-term fire history patterns should be considered in current assessments of historical fire regimes and fuel conditions.


2014 ◽  
Vol 44 (11) ◽  
pp. 1331-1343 ◽  
Author(s):  
Elizabeth A. Lynch ◽  
Randy Calcote ◽  
Sara C. Hotchkiss ◽  
Michael Tweiten

We reconstructed vegetation and fire histories from four sites located on a sandy outwash plain in northwestern Wisconsin (USA) to test whether lakes and wetlands have influenced how vegetation and fire regimes in pine–oak forests responded to late-Holocene climatic changes. Because of positive feedbacks between jack pine (Pinus banksiana Lamb.) and fire, communities with few fire breaks should be more resilient to changing climatic conditions. Pollen and charcoal from lake-sediment cores were used to reconstruct vegetation changes at 50- to 100-year intervals and forest fire history at decadal time scales for the past 2500 years. The presence of fire breaks affected both fire regimes and the response of vegetation to climatic changes. Areas with more fire breaks had smaller charcoal peaks and the vegetation was more responsive to climate changes. The vegetation in areas with few fire breaks was more resilient, maintaining higher amounts of jack pine and (or) red pine than the more protected sites. We interpret these findings as evidence that positive feedbacks between fire and jack pine forests stabilized vegetation at sites where fire breaks were absent, and that such sites may be relatively resilient to future climate changes, until jack pine is no longer able to regenerate under the regional climatic conditions.


2019 ◽  
Vol 11 (5) ◽  
pp. 1305 ◽  
Author(s):  
Margherita Carlucci ◽  
Ilaria Zambon ◽  
Andrea Colantoni ◽  
Luca Salvati

Empirical studies investigating long-term trends in wildfires’ frequency and severity have been relatively scarce in Europe. Number of fire events, total burnt area and average fire size were studied between 1961 and 2017 in Italy with the aim to identify homogeneous time periods with similar wildfire frequency and severity and correlate them with the background socioeconomic context. Fire attributes had a diverging behavior over time: the number of fires was the highest in the 1970s and the early 1980s; total burnt area was relatively more constant over time with a peak in the 1980s; and, finally, average fire size decreased quite homogeneously from the peak observed in the 1960s and early 1970s. The number of fires and average fire size were significantly influenced by the value of the same variable one year before. Investigating long-term historical outlines of forest fires, a mixed approach based on time-series statistical analysis, multivariate techniques and regressive models intended to define changes in fire regimes and socioeconomic development. In fact, the comparative valuation of the socioeconomic aspects and wildfire trends can reveal a key step to recognizing mitigation and preventive possibilities. Through a multivariate analysis, a substantial difference in the socioeconomic profile can emerge by decade, evidencing a (more or less) rapid socioeconomic development in relation to the evolution of forest fires in Italy.


The Holocene ◽  
2019 ◽  
Vol 29 (9) ◽  
pp. 1480-1490 ◽  
Author(s):  
Normunds Stivrins ◽  
Tuomas Aakala ◽  
Liisa Ilvonen ◽  
Leena Pasanen ◽  
Timo Kuuluvainen ◽  
...  

Fire is a major disturbance agent in the boreal forest, influencing many current and future ecosystem conditions and services. Surprisingly few studies have attempted to improve the accuracy of fire-event reconstructions even though the estimates of the occurrence of past fires may be biased, influencing the reliability of the models employing those data (e.g. C stock, cycle). This study aimed to demonstrate how three types of fire proxies – fire scars from tree rings, sedimentary charcoal and, for the first time in this context, fungal spores of Neurospora – can be integrated to achieve a better understanding of past fire dynamics. By studying charcoal and Neurospora from sediment cores from forest hollows, and the fire scars from tree rings in their surroundings in the southern Fennoscandian and western Russian boreal forest, we produced composite fire-event data sets and fire-event frequencies, and estimated fire return intervals. Our estimates show that the fire return interval varied between 126 and 237 years during the last 11,000 years. The highest fire frequency during the 18th–19th century can be associated with the anthropogenic influence. Importantly, statistical tests revealed a positive relationship between other fire event indicators and Neurospora occurrence allowing us to pinpoint past fire events at times when the sedimentary charcoal was absent, but Neurospora were abundant. We demonstrated how fire proxies with different temporal resolution can be linked, providing potential improvements in the reliability of fire history reconstructions from multiple proxies.


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