324
Land-Ocean Systems in the Siberian Arctic: Dynamics and History
pebble banks with mesic herbaceous meadows, up to 30-50 % cover (Oxytropis middendorffii,
Astragalus tolmaczewii, A aipinus, Pedicularis amoena, Festuca rubra subsp. arctica et al.)
on Dystric Fluvisols; C) High altitude sites with dry-mesic moss-herb-dryas short grass
meadows (cover up to 90 %). They are present here as fragments only; the species composition
is similar to that of the previous level, but here Dryas punctata dominates and there fragments of
a moss layer (Sanionia uncinata); the soils are Fluvisols; D) High altitude locations with
continuous mesic shrub-moss vegetation in fragments (Salix reptans, S.lanata, Poa alpigena,
Saxifraga nelsoniana et al.; the continuous moss layer is almost only Tomentypnum nitens); the
soils are the same; E) Moss-grass homogeneous bogs of the flood plain and terrace recesses
(Carex concolor, Eriophorum medium, E. polistachyon, Dupontia fisheri et al.; in the
fragmented mosslayer: Meesia triquetra, Limprichtia revolvens); the plant cover is continuous;
the soils are Fibri-gelic Histosols. Mud banks with thickets of Carex saxatilis subsp.laxa, C.
maritima, funcus castaneus et al. occur occasionally; the cover here is not more 30 %; the soils
are Mollic Fluvisols.
26- Gravelly alluvial fans with angles of inclination 10-20°, with hummocky nanorelief
The fans belong to ancient watercourses and there are no modern channels. They support mesic
herb-dwarf shrub-moss tundra with up to 70 % cover (Carex arctisibirica, C.misandra, Dryas
punctata, Salix polaris, Salix arctica; in the moss layer: Hylocomium splendens
var.obtusifolium). The soils are Molli-gelic Gleysols.
27 - Fine grained alluvial fans with angles of inclination 3-8=83 and spotty-hummock
nanorelief.
These fans often form part of the lakeshore and are frequently complicated by fragments of low
lake terraces. This unit included 2 vegetation elements: A) The main surface with sedge-dwarf
shrub-moss tundra, up to 80 % cover (Carex arctisibirica, C. misandra, Dryas punctata, Salix
polaris; moss layer: Tomentypnum nitens); the soils of the hummocky regions are Molli-gelic
Gleysols and between hummocks they are Umbri-gelic Gleysols. The presence of such species
as Oxytropis mertensiana, Eriophorum callitrix, Minuartia stricta indicate a high level of
nitrogen and available organic material in the soils; B) Channels with moist forb-dryas or dryasforb meadows (Dryas punctata, Poa alpigena, Carex tripartita, Gastrolychnis ape tala,
Artemisia tilesii et al.) on Molli-gelic Leptosols with 20-40 % cover.
28 - Alluvial fans with angles of inclination of 0_5°, with pebbly banks and tundra between
them
Such fans occur along the larger channels of small rivers. This landscape unit characterizes
many of the older channels and indicates intense modern accumulation. Stone-loam spottyhummocky tundra with small shallow thermocarst depressions and striped ground is found
between the older channels. The vegetation forms 3 distinct elements: A) Pebbly sites proximal
to channels with mesic forb-dryas vegetation (Dryas punctata, Oxytropis middendorffii, O.
arctica subsp. taimyrensis, et al.) with about 50 % cover on Fluvisols; B) Mesic spottyhummocky sedge-dwarf shrub-moss tundra (Carex misandra, , Dryas punctata, Cassiope
tetragona, the moss layer is polydominant), 60-80 % cover, the soils surrounding spots are
Molli-gelic Gleysols and in the depressions between borders they are Skeletic Cryosol; C)
Thermokarst depressions with a continuous wet shrub-sedge-moss vegetation (Salix rep tans.
Carex conca/or, C. arctisibirica; in the moss layer Tomentypnum nitens dominated), the soils
are Fibri-gelic Histosols.
Land-Ocean Systems in the Siberian Arctic: Dynamics and History
pebble banks with mesic herbaceous meadows, up to 30-50 % cover (Oxytropis middendorffii,
Astragalus tolmaczewii, A aipinus, Pedicularis amoena, Festuca rubra subsp. arctica et al.)
on Dystric Fluvisols; C) High altitude sites with dry-mesic moss-herb-dryas short grass
meadows (cover up to 90 %). They are present here as fragments only; the species composition
is similar to that of the previous level, but here Dryas punctata dominates and there fragments of
a moss layer (Sanionia uncinata); the soils are Fluvisols; D) High altitude locations with
continuous mesic shrub-moss vegetation in fragments (Salix reptans, S.lanata, Poa alpigena,
Saxifraga nelsoniana et al.; the continuous moss layer is almost only Tomentypnum nitens); the
soils are the same; E) Moss-grass homogeneous bogs of the flood plain and terrace recesses
(Carex concolor, Eriophorum medium, E. polistachyon, Dupontia fisheri et al.; in the
fragmented mosslayer: Meesia triquetra, Limprichtia revolvens); the plant cover is continuous;
the soils are Fibri-gelic Histosols. Mud banks with thickets of Carex saxatilis subsp.laxa, C.
maritima, funcus castaneus et al. occur occasionally; the cover here is not more 30 %; the soils
are Mollic Fluvisols.
26- Gravelly alluvial fans with angles of inclination 10-20°, with hummocky nanorelief
The fans belong to ancient watercourses and there are no modern channels. They support mesic
herb-dwarf shrub-moss tundra with up to 70 % cover (Carex arctisibirica, C.misandra, Dryas
punctata, Salix polaris, Salix arctica; in the moss layer: Hylocomium splendens
var.obtusifolium). The soils are Molli-gelic Gleysols.
27 - Fine grained alluvial fans with angles of inclination 3-8=83 and spotty-hummock
nanorelief.
These fans often form part of the lakeshore and are frequently complicated by fragments of low
lake terraces. This unit included 2 vegetation elements: A) The main surface with sedge-dwarf
shrub-moss tundra, up to 80 % cover (Carex arctisibirica, C. misandra, Dryas punctata, Salix
polaris; moss layer: Tomentypnum nitens); the soils of the hummocky regions are Molli-gelic
Gleysols and between hummocks they are Umbri-gelic Gleysols. The presence of such species
as Oxytropis mertensiana, Eriophorum callitrix, Minuartia stricta indicate a high level of
nitrogen and available organic material in the soils; B) Channels with moist forb-dryas or dryasforb meadows (Dryas punctata, Poa alpigena, Carex tripartita, Gastrolychnis ape tala,
Artemisia tilesii et al.) on Molli-gelic Leptosols with 20-40 % cover.
28 - Alluvial fans with angles of inclination of 0_5°, with pebbly banks and tundra between
them
Such fans occur along the larger channels of small rivers. This landscape unit characterizes
many of the older channels and indicates intense modern accumulation. Stone-loam spottyhummocky tundra with small shallow thermocarst depressions and striped ground is found
between the older channels. The vegetation forms 3 distinct elements: A) Pebbly sites proximal
to channels with mesic forb-dryas vegetation (Dryas punctata, Oxytropis middendorffii, O.
arctica subsp. taimyrensis, et al.) with about 50 % cover on Fluvisols; B) Mesic spottyhummocky sedge-dwarf shrub-moss tundra (Carex misandra, , Dryas punctata, Cassiope
tetragona, the moss layer is polydominant), 60-80 % cover, the soils surrounding spots are
Molli-gelic Gleysols and in the depressions between borders they are Skeletic Cryosol; C)
Thermokarst depressions with a continuous wet shrub-sedge-moss vegetation (Salix rep tans.
Carex conca/or, C. arctisibirica; in the moss layer Tomentypnum nitens dominated), the soils
are Fibri-gelic Histosols.