Canada and Boreal Forests

Today’s Tree Trivia

• What is considered to be the largest tree on Earth?

  • Depends how you measure it. Pando, a Populus tremuloides, grows clonally and has as many as 47,000 stems

Boreal Forests around the World

• 50-70 degrees North latitude

• Temperature extremes

• 1/3 of worldwide forest area

• Sub-types north > south:

  • tundra/scattered trees

  • closed canopy evergreen forest

  • mixed conifer/deciduous forest

Canada/Boreal Forest

• Environmental Factors

  • cool summers (60 degrees Fahrenheit), cold winters (-20 degrees)

    • 40-60” maritime provinces

    • 40-90” PNW

    • <15” tundra

  • Glaciation (i.e., “youthful topography”)

  • average annual rainfall 14-50”

Glaciation and glacial features

• Student Conservation Association intern—Chugach National Forest, Alaska

• Portage Glacier, Alaska

• What are some features of a glaciated landscape?

  • primary succession—no seedbank (young topography)

  • glacial outwash and soils (infertile, rocky)

  • lakes

• 

Canada/Boreal Forest

• 35% of Canada’s land area is forested

• 90% of forests are publicly owned

• $1.4 billion export in primary wood products

• $15.5 billion exports in pulp and paper products

• $3.6 million exports in maple products (32 billion liters)

• “Boreal” means northern

  • spruce-fir forest

  • bog forests

  • glacial outwash plain

Spruce-Fir Forest

• Principal species:

  • spruce

    • eastern: red spruce

      • found above 5000 ft in NC

      • susceptible to spruce budworm

    • Central: white spruce

      • waxy needles give glaucous appearance, 2” long cones, ranges north to treeline, Canada’s northernmost spruce, favors dry habitats, grows tall

  • fir

    • balsam fir

      • cones borne upright on top branches

      • relatively low timber value; used for Christmas trees

  • other species

    • paper birch

      • important pioneer species on disturbed sites

      • commercial value

      • southernmost stand at Mr. Mitchell

• Forest structure

  • even-aged stands from periodic, catastrophic disturbance

  • fire, insects, or disease

  • pre-colonization: 75-100 year disturbance intervals

  • openings have wildflowers and herbaceous species

Bog Forest

• Wet depressions formed when blocks of ice from glaciers melted into a depression to form lakes

• Principal species:

  • Black spruce

    • Picea mariana

    • Also called bog spruce, swamp spruce

    • Similiar to white spruce; shorter needles and rounded cones

    • important timber species in Canada

    • favors wet habitats and organic soils

  • Larch or tamarack

    • also favors bog habitats; co-occurs with black spruce

    • deciduous; needles borne in short shoots

    • Larx larcina — Family Pinaceae

• Restricted drainage = organic peat soils

• acidic and nutrient-poor

• what is a “quaking bog?”

• Winter timber harvest (why?)

• Sphagnum (peat)

• Carbon sink?

Glacial Outwash Plains

• Glacial outwash pain— glacial sediments deposited by meltwater

• Fire cycle—

  • releases nutrients stored in organic soil

  • reduces competition

• subject to drought

• principal species

  • jack pine, red pine, quaking aspen, grades into white pine, often has blueberry as shrub component

  • jack pine

    • fire-adapted; 50-80 year cycle

    • serotinous cones; produces cones at age 3-4

    • cones point toward the tip

    • thin bark; retains branches

    • often has scraggly form

    • short needles in 2s

    • fire strategy: regeneration

  • red pine:

    • distribution only in the southern part of the region. often occurs with white pine

    • long-lived, straight-trunked, and commercially valuable

    • self-prunes; thick bark

    • more mesic conditions

  • Quaking aspen:

    • one of the widest distributions in NA

    • mainly used for pulpwood

    • fire intolerant

    • grows clonally

Threats

• Some of the frequent or common threats we’ve discussed (deforestation, development) are not an issue

• climate shifts are moving species and causing more frequent insect outbreaks

• more frequent and intense wildfires could release massive amounts of carbon