Functional type |
Height (cm) |
Patch size (m2) |
Description & distributional patterns |
Lichens |
0–5 |
0.001–100 |
Diverse nonvascular plants consisting of
fungal and algal symbionts, often distinguished by growth form (foliose,
fruticose, crustose) or color group. Intermixed “reindeer lichens”
(Cladonia spp.) and other fruticose taxa (e.g.,
Flavocetraria, Alectoria, and Bryoria spp.) can form
extensive mats on undisturbed, well drained sites. |
Bryophytes |
0–5 |
0.001–100 |
Nonvascular plants including mosses and
liverworts. Found throughout Arctic; common mesic taxa include branched
“feathermosses” (e.g., Hylocomnium splendens, Pleurozium
schreberi) and single-stemmed mosses (e.g., Dicranum and
Polytrichum spp.). Peat mosses (Sphagnum spp.) can form
continuous carpets in wet areas. Liverworts much less abundant, but form
extensive cryptogamic crusts in High Arctic. |
Graminoids |
10–70 |
0.01–0.25 |
Sedges and grasses. Sedges common
throughout tundra except in coldest parts of High Arctic. Tall
cottongrass (Eriophorum angustifolium) and water sedge
(Carex aquatilis) often dominate wet sites. Large areas of
tussock tundra dominated by Arctic cottongrass (Eriophorum
vaginatum) occur in Low Arctic on mesic soils. Grasses superficially
resemble sedges and occur throughout Arctic, but cover is usually low;
most common on floodplains and disturbed sites. Pendantgrass
(Arctophila fulva) is a common marsh species. |
Forbs |
0–50 |
0.01–0.05 |
Diverse group of non-graminoid herbaceous
flowering plants found throughout the Arctic, but cover is typically
low. Common forbs include Arctic lupine (Lupinus arcticus),
Arctic sweet coltsfoot (Petasites frigidus), and “cushion”
plants such as purple mountain saxifrage (Saxifraga
oppositifolia). |
Deciduous shrubs |
0–500 |
0.01–100 |
Multi-stemmed, broadleaf woody
plants; common erect species include dwarf birch (Betula
nana), diamondleaf willow (Salix pulchra), and bog
blueberry (Vaccinium uligonosum). Dwarf shrubs such as Arctic
willow (Salix arctica) occur throughout tundra biome except in
coldest parts of High Arctic. Tall stands are restricted to warmer parts
of Low Arctic, where typically found on floodplains (e.g., feltleaf
willow Salix alaxensis) and mesic slopes (e.g., Siberian alder
Alnus viridis ssp. fruticosa). |
Evergreen shrubs |
0–20 |
0.01–10 |
Widespread dwarf shrubs, except in
High Arctic. Common species include entireleaf mountain-avens
(Dryas integrifolia), mountain heather (Cassiope
tetragona), lingonberry (Vaccinium vitis-idaea), and
Labrador tea (Ledum decumbens). |
Deciduous trees |
150–1,000 |
1–25 |
The deciduous conifer, larch
(Larix spp.), is the dominant tree in Siberian taiga-tundra
ecotones. Poplar (Populus balsamifera) can occur on Low Arctic
floodplains and south-facing slopes. Trees are typically widely spaced.
Conifers typically have columnar growth form with small canopies;
broadleaf trees often have larger canopies. |
Evergreen trees |
150–1,000 |
1–10 |
Evergreen conifers such as spruce
(Picea spp.) are dominant in North American and European
taiga-tundra ecotones. |