7 research outputs found
Role of forest fires in Holocene stand-scale dynamics in the unmanaged taiga forest of northwestern Russia
Fossil pollen, conifer stomata, and charcoal records for the last 10,000 years were studied from three small hollow sites (Larix Hollow, Mosquito Hollow,
and Olga Hollow) located at the modern western range limit of Siberian larch (Larix sibirica) in northwestern Russia to investigate the role of forest fires
in stand-scale dynamics of taiga vegetation. Wavelet coherence analysis was utilized to reveal the significance of fire on the vegetation composition at
different timescales by assessing the phase and strength of the relationship between forest fires and most common boreal tree taxa in a time–frequency
window. Pollen and stomata data show that all of the modern-day common tree taxa, including Norway spruce (Picea abies) and Siberian larch, have been
present in the study region since the early Holocene. The absence of charcoal layers at Mosquito Hollow suggests that this site has acted as a fire-free
refugium with continuous dominance of spruce throughout the Holocene. Meanwhile, the Larix Hollow record indicates frequent local fire events and as
a consequence, a more variable tree species composition. The wavelet coherence results show that the impact of forest fires on vegetation varies from
short-term (<200-year periods) changes in individual tree taxa to long-term (400–800 years) changes in forest composition, such as the expansion of
spruce population after local high-intensity fires around 7500–7000 cal. yr BP and the increase in abundance of birch and alder during periods of high fire
frequency. Our results suggest that Holocene fire histories can be markedly different within a small geographical area, demonstrating the importance of
site-specific factors in the local fire regime in the unmanaged taiga forest
Population genetics of the wood-decay fungus Phlebia centrifuga P. Karst. in fragmented and continuous habitats
Long-term forest composition and its drivers in taiga forests in NW Russia
Understanding the processes behind long-term
boreal forest dynamics can provide information that assists
in predicting future boreal vegetation under changing
environmental conditions. Here, we examine Holocene
stand-scale vegetation dynamics and its drivers at the
western boundary of the Russian taiga forest in NW Russia.
Fossil pollen and conifer stomata records from four small
hollow sites and two lake sites are used to reconstruct local
vegetation dynamics during the Holocene. Variation partitioning
is used to assess the relative importance of the
potential drivers (temperature, forest fires and growing site
wetness) to the long-term stand-scale dynamics in taiga
forest. All the main tree taxa, including the boreal keystone
species Picea abies (Norway spruce) and Larix sibirica
(Siberian larch), have been locally present since 10,000 cal
yr BP. The constant Holocene presence of L. sibirica at
three small hollow sites suggests a fast postglacial immigration
of the species in northern Europe. Picea was present
but not dominant at all study sites until its expansion
between 8,000 and 7,000 cal yr BP markedly changed the
forest structure through the suppression of Betula (birch),
Pinus (pine) and Larix. Our results demonstrate that in
general, the Holocene forest dynamics in our study region
have been driven by temperature, but during short intervals
the role of local factors, especially forest fires, has been
prominent. The comparison between sites reveals the
importance of local factors in stand-scale dynamics in taiga
forests. Therefore, the future responses of taiga forest to
climate change will be predominantly modulated by the
local characteristics at the site