1/28/2011

Major Moss In B.C.'s Coastal Forests

This giant Douglas-fir snag makes a perfect scaffold for the moss

Fluorescent green flashes catch my eye whenever I am out in the forest. It is not surprising as anything that doesn't move in the coastal forest gets covered in deep, luxurious moss. Actually, I can say that even things that roll grow moss in the rain forest - my vehicle is slowly turning green. If left long enough it would disappear entirely, as would I if I ever fell on a hike and couldn't get up.

Detail of tree above showing a Western hemlock seedling growing out of the moss

British Columbia possesses the richest diversity of mosses, or bryophytes, in Canada. The amazing diversity of this large group of special non-flowering green plants is due to the varied terrain  of the province, as well as historical developments that led to holdovers surviving from before the last ice age. B.C.'s huge collection of mosses is greater than the combined mosses of all of the U.S. west of the Rocky Mountains. That's major moss.

The moss on big trees can be several centimetres thick, and cover the bark completely

This time of year the mosses are hydrated and at their colourful best. Moss can hold a whopping 25 times its own weight in moisture. They are efficient sponges which can add tons of weight to the limbs of an old tree, making them more susceptible to wind damage.

Old Bigleaf maple branches grow a covering of moss and ferns

Mosses are a special kind of green plant because they are non-vascular, meaning they do not have xylem or phloem (tissues that transport water and nutrients) like trees and other vascular plants. The Bryophytes are sometimes referred to as "lower" plants because they evolved earlier in the history of green stuff on the planet.

Winter, when trees don't have leaves, is a good time to see the full extent of the moss

The mosses shown here are all epiphytes, meaning that they do not harm the trees they are growing on. The base of trees provide a scaffold for the moss, but the moss derives all its nutrients from the air and rain, not from the tree. Mosses do not have true roots, only root-like threads called rhizoids. In the summer, mosses can dry right out. They survive by lowering their metabolism until the rains come again to fluff up the green cushions.


Could it be Amblystegium serpens, or Creeping feather moss?

Sometimes moss seems like it is from a different planet. Mosses are a varied, wonderful, and ubiquitous part of the coastal forest. So many different types of moss growing in so many different shades of fluorescent green. Just remember to keep moving out here or you may find yourself turning green.

Resources

For a good introduction to B.C. mosses see:

Schofield, W. B. 1992. Some Common Mosses of British Columbia. Royal BC Museum Handbook. Queen's Printer, Victoria, BC. 394 pages. Illustrated.

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