416
Land-Ocean Systems in the Siberian Arctic: Dynamics and History
climatic conditions at least as favourable as those of today.
Interstadial 1 (LLA) is a longer-lasting thermomer. Assuming similar sedimentation rates to
those of the Holocene, it may comprise more than 1000 years. High values of Betula, Alnus
and Cyperaceae and low values of Artemisia can be regarded as a signal for increased humidity.
A shrub tundra composed of Betula and Alnus species likely spread in the southern parts of the
Taymyr Peninsula. However, it probably did not reach the Levinson-Lessing Lake area,
because a comparison to the present-day situation indicates a graminoid-herb vegetation for the
surroundings of the lake.
Interstadial 2 (LLC) comprises three samples with AP concentrations of 40 to 50 % . An
intervening sample with a stadial character (AP <10 %) indicates that Interstadial 2 is built up of
two very short thermomers of a few hundred years maximum duration. They are characterized
by the presence of birch and alder shrubs. The occurrence of elm and, to a greater degree, hazel
(about 3.5 %), are only recorded here and argue for an authochtonous deposition. An advance
of Corylus cornuta and Ulmus pumila can be taken into consideration. They are known to have
settled this area in the Middle Weichselian period (Ukraintseva, 1993).
In the intermittent stadial periods (LLD, LLB, LLl) very low pollen concentrations and AP
values of less than 5 % indicate extremely cold and dry conditions. Artemisia, Poaceae and
numerous taxa typical for a high-arctic environment, such as Caryophyllaceae, Asteraceae,
Thalictrum, Saxifragaceae, and Rumex arcticus, covered favourable slopes and depressions in
a predominant arctic desert.
The borders between the stadial and interstadial Middle Weichselian periods are characterized
by rapid changes rather than gradual transitions in the AP pollen contents and, less pronounced,
in the total pollen concentrations (Figure 3). Sample intervals of 10 cm at the corresponding
depths, which probably represent about 100 years, indicate abrupt changes in the climatic
conditions at the transitions both to and from the interstadials, and a rapid vegetation response.
Late Weichselian
The Late Weichselian in Siberia was charcterized by a very cold climate (Velichko, 1993). This
period, as well as all following intervals, are well represented, not only in the core PG 1228
from Levinson-Lessing Lake (Figure 3), but also in the lower part of the core PG 1111 from
Lama Lake (Figure 2). In both cores, the vegetation was strongly reduced during Stadial 1 and
Oldest Dryas (LLl and Ll). A cold and dry climate, similar to that of the Middle Weichselian
stadial periods, led to arctic desert at Levinson-Lessing Lake and graminoid-herb-Artemisia
tundra at Lama Lake. At the end of the oldest Dryas, a slight increase in moist habitats is
indicated in both cores by a spread of Cyperaceae communities.
The Late WeichselianlHolocene transition (PAZs LLl - LL6 and Ll - L6) is represented by
the thermomers B011ing, AlIer0d, and Preboreal, interrupted by the stadials Older Dryas and
Younger Dryas. The specific PAZ boundaries for these periods have developed more clearly
than they do in certain European sequences (e.g., Hahne, 1992). This is probably due to the
more continental climate of Central Siberia, leading to more distinct vegetation changes as a
result of even small climatic fluctuations during the Late Weichselian.
The B!/llling interstadial (LL 2 and L 2) is very well developed in the Lama Lake diagram. In
Levinson-Lessing Lake, in contrast, a slight increase of the birch curve is restricted to only one
sample. The spread of Cyperaceae and a decrease of the Artemisia values in several samples,
however, support the correlation. Hence, during the B011ing period a dense graminoid-herb
tundra likely developed on the southern Taymyr Peninsula, whilst sparsely growing grass
communities existed in a predominant arctic desert on the northern peninsula.
The climatic deterioration of the Older Dryas is recorded in both diagrams (LL3 and L3). This
event is often difficult to identify due to its short duration (up to 300 years). In the diagram
Land-Ocean Systems in the Siberian Arctic: Dynamics and History
climatic conditions at least as favourable as those of today.
Interstadial 1 (LLA) is a longer-lasting thermomer. Assuming similar sedimentation rates to
those of the Holocene, it may comprise more than 1000 years. High values of Betula, Alnus
and Cyperaceae and low values of Artemisia can be regarded as a signal for increased humidity.
A shrub tundra composed of Betula and Alnus species likely spread in the southern parts of the
Taymyr Peninsula. However, it probably did not reach the Levinson-Lessing Lake area,
because a comparison to the present-day situation indicates a graminoid-herb vegetation for the
surroundings of the lake.
Interstadial 2 (LLC) comprises three samples with AP concentrations of 40 to 50 % . An
intervening sample with a stadial character (AP <10 %) indicates that Interstadial 2 is built up of
two very short thermomers of a few hundred years maximum duration. They are characterized
by the presence of birch and alder shrubs. The occurrence of elm and, to a greater degree, hazel
(about 3.5 %), are only recorded here and argue for an authochtonous deposition. An advance
of Corylus cornuta and Ulmus pumila can be taken into consideration. They are known to have
settled this area in the Middle Weichselian period (Ukraintseva, 1993).
In the intermittent stadial periods (LLD, LLB, LLl) very low pollen concentrations and AP
values of less than 5 % indicate extremely cold and dry conditions. Artemisia, Poaceae and
numerous taxa typical for a high-arctic environment, such as Caryophyllaceae, Asteraceae,
Thalictrum, Saxifragaceae, and Rumex arcticus, covered favourable slopes and depressions in
a predominant arctic desert.
The borders between the stadial and interstadial Middle Weichselian periods are characterized
by rapid changes rather than gradual transitions in the AP pollen contents and, less pronounced,
in the total pollen concentrations (Figure 3). Sample intervals of 10 cm at the corresponding
depths, which probably represent about 100 years, indicate abrupt changes in the climatic
conditions at the transitions both to and from the interstadials, and a rapid vegetation response.
Late Weichselian
The Late Weichselian in Siberia was charcterized by a very cold climate (Velichko, 1993). This
period, as well as all following intervals, are well represented, not only in the core PG 1228
from Levinson-Lessing Lake (Figure 3), but also in the lower part of the core PG 1111 from
Lama Lake (Figure 2). In both cores, the vegetation was strongly reduced during Stadial 1 and
Oldest Dryas (LLl and Ll). A cold and dry climate, similar to that of the Middle Weichselian
stadial periods, led to arctic desert at Levinson-Lessing Lake and graminoid-herb-Artemisia
tundra at Lama Lake. At the end of the oldest Dryas, a slight increase in moist habitats is
indicated in both cores by a spread of Cyperaceae communities.
The Late WeichselianlHolocene transition (PAZs LLl - LL6 and Ll - L6) is represented by
the thermomers B011ing, AlIer0d, and Preboreal, interrupted by the stadials Older Dryas and
Younger Dryas. The specific PAZ boundaries for these periods have developed more clearly
than they do in certain European sequences (e.g., Hahne, 1992). This is probably due to the
more continental climate of Central Siberia, leading to more distinct vegetation changes as a
result of even small climatic fluctuations during the Late Weichselian.
The B!/llling interstadial (LL 2 and L 2) is very well developed in the Lama Lake diagram. In
Levinson-Lessing Lake, in contrast, a slight increase of the birch curve is restricted to only one
sample. The spread of Cyperaceae and a decrease of the Artemisia values in several samples,
however, support the correlation. Hence, during the B011ing period a dense graminoid-herb
tundra likely developed on the southern Taymyr Peninsula, whilst sparsely growing grass
communities existed in a predominant arctic desert on the northern peninsula.
The climatic deterioration of the Older Dryas is recorded in both diagrams (LL3 and L3). This
event is often difficult to identify due to its short duration (up to 300 years). In the diagram