Plants of Niwot Ridge

Krummholz Tree Form or "Tree Islands"

Krummholz Tree Forms or "Tree Islands" are generally Subalpine Fir (Abies lasiocarpa) or Engelmann Spruce (Picea engelmannii), but sometimes you can find a Limber Pine (Pinus flexilis) or a Lodgepole Pine (Pinus contorta). Many of these trees are actually capable of slowly sliding across the tundra surface. The windward sides are scoured away, and the tree grows to the leeward (the left side in this photo). The tree is capable of forming new roots by the burial of stem materials in organic matter that's collected inside of the tree!

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