Subarctic Riparian Woodland and Boreal Shrubland Mosaic - Code: Ne3G

A common misconception is that conifers are the northernmost trees. But on the southern edge of the tundra, where there is an extremely short growing season (Koppen Et), permafrost below, abundant snow, and high exposure to wind an Arctic scrub of birch and aspen groves, not evergreen conifers, grows in the most protected areas. These shrublands  of  Dwarf Birch (betula nana), Balsam Poplar (Populus balsamifera) and paper birch (Betula papyrifera) are the same general assemblage as the Riperian Woodlands and the small grass-shrublands in disturbed areas of the northern BOREAL CONIFER WOODLANDS. Where these groves exist between the conifers and tundra, they expand in favorable years and contract in more severe years. In the toughest conditions, conifers such as spruce and fir are unable to survive through the winter, due to the fact that they are evergreen. Any tree that carries leaves at all, and that needs to eke out water from the permafrost during the winter months, finds it difficult to survive, so are replaced by colonist deciduous angiosperms and deciduous conifers, such as Tamarack Larch (Larix laricina). These groves are generally  very open, with a krummholz (wind blown to one direction), canopy usually  around 4 ft tall on exposed areas and 20 ft tall in more protected areas, especially where there are snowbanks.  The lowest shrubs are doiminated by European Blueberry (Vaccinium myrtillus) and Bog Bilberry (Vaccinium uliginosum) In contrast to the soils of the tundra, these shrublands cause a strong podzol soil (heavily leached at surface in an acidic environment) to develop underneath which is typical of the conifer forests to the south.
 In the boreal areas to the south with a more moderate climate, Koppen (Dsd) along riverine areas and in recently disturbed environments, as perhaps say after severe storms, those same Balsam Poplar and paper birch are joined by Black Spruce, and closed stands of quaking aspen that together make a mixed woodland with a canopy of around 60-90 ft (20-30m), with generally a straight woodland without krumholtzing of the canopy. The understory of these woodlands is dominated by dwarf shrubs, many of which are circumpolar and familiar to people from northern Europe such as alpine bearberry Arctostaphylos alpina, Crowberry Empetrum nigrum, and Blue mountainheath (Phyllodoce coerulea), as well as subshrubs such as Twinflower Linnaea borealis. The ground is covered with lichens and mosses such as glittering woodmoss, Hylocomium splendens,  and red-stemmed feathermoss (Pleurozium schreberi)
There are many small glades in this habitat which have fields of mixed small shrubs mentioned above, but joined with grasses and forbes such as Edlund's fescue Festuca edlundiae, wavy hair-grass (Deschampsia flexuosa), Lappland reedgrass (Calamagrostis lapponica), Bigelow's sedge (Carex bigelowii), and Lapland lousewort (Pedicularis lapponica). In marshy areas Highland Rush (Oreojuncus trifidus) can become dominant. At first pass, the nature of these fields may suggest that they are classified as TALLGRASS PRAIRIES, but they lack the bird or animal assemblages of those grasslands to the south, and are better regarded as “light breaks” within the broader riparian and shrubland habitat.