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| Titel |
Holocene fire activity in the Carpathian region: regional climate vs. local controls |
| VerfasserIn |
Gabriela Florescu, Angelica Feurdean |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250101446
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| Publikation (Nr.) |
 EGU/EGU2015-589.pdf |
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| Zusammenfassung |
| Introduction. Fire drives significant changes in ecosystem structure and function, diversity,
species evolution, biomass dynamics and atmospheric composition. Palaeodata and
model-based studies have pointed towards a strong connection between fire activity, climate,
vegetation and people. Nevertheless, the relative importance of these factors appears to be
strongly variable and a better understanding of these factors and their interaction needs a
thorough investigation over multiple spatial (local to global) and temporal (years to
millennia) scales. In this respect, sedimentary charcoal, associated with other proxies of
climate, vegetation and human impact, represents a powerful tool of investigating changes
in past fire activity, especially in regions with scarce fire dataset such as the CE
Europe.
Aim. To increase the spatial and temporal coverage of charcoal records and facilitate a
more critical examination of the patterns, drivers and consequences of biomass burning
over multiple spatial and temporal scales in CE Europe, we have investigated 6
fossil sequences in the Carpathian region (northern Romania). These are located
in different geographical settings, in terms of elevation, vegetation composition,
topography and land-use. Specific questions are: i) determine trends in timing and
magnitude of fire activity, as well as similarities and differences between elevations;
ii) disentangle the importance of regional from local controls in fire activity; iii)
evaluate ecological consequences of fire on landscape composition, structure and
diversity.
Methods. We first determine the recent trends in fire activity (the last 150 years) from
charcoal data and compare them with instrumental records of temperature, precipitation, site
history and topography for a better understanding of the relationship between sedimentary
charcoal and historical fire activity. We then statistically quantify centennial to millennial
trends in fire activity (frequency, magnitude) based on Holocene sedimentary charcoal
records and compare these with pollen-based information of vegetation cover and
diversity, climate records and archaeological data in order to disentangle between
drivers.
Discussion. Our preliminary results indicate a recent enhancement in fire activity at all
mountain sites between 1880 and 1920 AD, which contrasts with a markedly reduced burning
over the past 60 years. Regression analysis with instrumental climate records reveals that the
influence of climate on fire regime becomes negligible from the 60’s. This recent drop in fire
activity is perhaps reflecting fire suppression in land-use practices. In contrast,
in the lowlands fire activity is increasing over the past decades, likely associated
to post-socialist land abandonment and fuel accumulation. On a longer temporal
scale, fire activity is highest in the early Holocene in lowlands and alpine areas,
while at coniferous dominated sites burning is minimum. For the mid Holocene
(7000-4800 BP) enhanced fire activity in uplands contrasts to lowest burning in
lowlands. Trends in fire activity over the last 3500 BP are homogenous only across
alpine sites. Our results point towards an increase in fire activity with fuel load and
flammability related to climate conditions (warm and dry). Results also suggest that other
local factors (e.g. vegetation type, exposure) might be locally more important fire
controllers than climate. Humans enhance biomass burning earlier in lowlands than in
mountains.
Conclusions. Our findings provide new insights into understanding trends in fire activity
and its controllers at smaller spatial scale. |
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