Naidina and Bauch: Distribution of Pollen and Svores in Surface Sediments
581
cedar pine pollen and sphagnum spores whereas the coastal zone yielded herbaceous pollen and
spores of green mosses. The latter two are of local origin and therefore much more closely
linked to the coastal vegetation. This implies that specific hydrodynamic processes which occur
along the pathway of the main river runoff may be responsible for this distinction and, further,
that along the coastal zones and away from the river mouths such processes have less influence
on the distribution.
Discussion and conclusions
The composition of pollen and spore spectra in surface sediments of the Laptev Sea can be
regarded as a result of transportation. This particularly applies to the occurrence of coniferous
pollen grains which do not reflect the typical vegetation on land adjacent to the Laptev Sea.
Therefore, these grains were brought into the shelf region either by offshore winds (Figure 3)
or by the riverine freshwater runoff. Owing to their special morphology, pollen grains of pine
are easily transported for longer distances by wind and rivers. It has been shown that the
boundary of the forest-tundra zone in the Lower Yana region shifted northward in more recent
times (Aleksandrova, 1953). As a result, forest tundra is now located in this area to within 50
km south of the coast (Figure 2). The flowering period for trees along this northern forest
boundary is often accompanied by northerly directed winds. These winds may then account for
the transfer of pollen to the Arctic from the forest-tundra and northern taiga. Interestingly in this
context, the Ary-Mas forest as a major potential source is situated just along the pathway of the
cyclones (Figure 3). Organic matter, which is made up of pollen, spores and other organic
fibres, is one of the main components of aerosols over the Laptev Sea (Shevchenko et a!.
1995). Previous studies of pollen-spore numbers and composition in Arctic Ocean surface
water and seabed sediments (Mudie and Matthiessen, 1988) indicate a primary aeolian
transportation, with the circum-Arctic and boreal-tundra vegetation being the main source.
Figure 2 shows that there are several other possible sources of pollen and spores from
various tundra areas: 1) terraces along the Lena River valley, 2) plains and terraces of the
Lower Khatanga River (the eastern part of the Northern Siberian Lowland), and 3) the mouth
lowland of the Yana River (the western part of the Yana-Indigirka Lowland). In this area, the
particular vegetation cover connected with the existence of the perennially frozen ground and
specific thermokarst forms of tundra-relief, so-called alases, form favourable conditions for the
accumulation and preservation of pollen (Naidina, 1995). But pollen preservation is not always
perfect. In Northern Yakutia, one of the most widespread trees is Larix. Single undersized
specimens of Larix grow in the tundra of the Yana lowland (Khotinsky et aI., 1971) and
together with Betula exilis and Salix rep tans form the majority of the northernmost part of the
Ary-Mas forest (Anonymous, 1978). But Larix pollen are practically absent in palynological
spectra (Khotinsky et aI., 1971; Kupriyanova, 1951; this study). This accounts for the
complete decomposition of these pollen grains due to maceration.
Siberian rivers transport large amounts of dissolved and particulate material onto the shelf
area, where it accumulates and/or from which area it is further transported towards the Arctic
Ocean by, for example, sea-ice (e.g. Eicken et aI., 1997). Due to the influence of the Lena
River, the eastern Laptev Sea receives considerably higher amounts of freshwater than the
western part (Timokhov, 1994). This distinction is also recognized in many other
sedimentological, geochemical and biological proxy data (e.g. Dehn et a!., 1995; Holeman et
a!., 1995; Letolle at a!., 1993). Therefore, it is reasonable to conclude that the river runoff also
accounts for the observed higher relative abundances of pollen and spore grains within the
eastern Laptev Sea.
581
cedar pine pollen and sphagnum spores whereas the coastal zone yielded herbaceous pollen and
spores of green mosses. The latter two are of local origin and therefore much more closely
linked to the coastal vegetation. This implies that specific hydrodynamic processes which occur
along the pathway of the main river runoff may be responsible for this distinction and, further,
that along the coastal zones and away from the river mouths such processes have less influence
on the distribution.
Discussion and conclusions
The composition of pollen and spore spectra in surface sediments of the Laptev Sea can be
regarded as a result of transportation. This particularly applies to the occurrence of coniferous
pollen grains which do not reflect the typical vegetation on land adjacent to the Laptev Sea.
Therefore, these grains were brought into the shelf region either by offshore winds (Figure 3)
or by the riverine freshwater runoff. Owing to their special morphology, pollen grains of pine
are easily transported for longer distances by wind and rivers. It has been shown that the
boundary of the forest-tundra zone in the Lower Yana region shifted northward in more recent
times (Aleksandrova, 1953). As a result, forest tundra is now located in this area to within 50
km south of the coast (Figure 2). The flowering period for trees along this northern forest
boundary is often accompanied by northerly directed winds. These winds may then account for
the transfer of pollen to the Arctic from the forest-tundra and northern taiga. Interestingly in this
context, the Ary-Mas forest as a major potential source is situated just along the pathway of the
cyclones (Figure 3). Organic matter, which is made up of pollen, spores and other organic
fibres, is one of the main components of aerosols over the Laptev Sea (Shevchenko et a!.
1995). Previous studies of pollen-spore numbers and composition in Arctic Ocean surface
water and seabed sediments (Mudie and Matthiessen, 1988) indicate a primary aeolian
transportation, with the circum-Arctic and boreal-tundra vegetation being the main source.
Figure 2 shows that there are several other possible sources of pollen and spores from
various tundra areas: 1) terraces along the Lena River valley, 2) plains and terraces of the
Lower Khatanga River (the eastern part of the Northern Siberian Lowland), and 3) the mouth
lowland of the Yana River (the western part of the Yana-Indigirka Lowland). In this area, the
particular vegetation cover connected with the existence of the perennially frozen ground and
specific thermokarst forms of tundra-relief, so-called alases, form favourable conditions for the
accumulation and preservation of pollen (Naidina, 1995). But pollen preservation is not always
perfect. In Northern Yakutia, one of the most widespread trees is Larix. Single undersized
specimens of Larix grow in the tundra of the Yana lowland (Khotinsky et aI., 1971) and
together with Betula exilis and Salix rep tans form the majority of the northernmost part of the
Ary-Mas forest (Anonymous, 1978). But Larix pollen are practically absent in palynological
spectra (Khotinsky et aI., 1971; Kupriyanova, 1951; this study). This accounts for the
complete decomposition of these pollen grains due to maceration.
Siberian rivers transport large amounts of dissolved and particulate material onto the shelf
area, where it accumulates and/or from which area it is further transported towards the Arctic
Ocean by, for example, sea-ice (e.g. Eicken et aI., 1997). Due to the influence of the Lena
River, the eastern Laptev Sea receives considerably higher amounts of freshwater than the
western part (Timokhov, 1994). This distinction is also recognized in many other
sedimentological, geochemical and biological proxy data (e.g. Dehn et a!., 1995; Holeman et
a!., 1995; Letolle at a!., 1993). Therefore, it is reasonable to conclude that the river runoff also
accounts for the observed higher relative abundances of pollen and spore grains within the
eastern Laptev Sea.