Lichens

Description:

Lichens growing on trees, on ground and on rocks in this picture taken within the Tongass National forest near Juneau, Alaska. It is reported that there are well over 400 species of lichen in Alaska. Lichens have two symbiotic relations. First, the fungus gives the alga a home by forming the thallus, or body, of the lichen. The alga (or sometimes cyanobacterium), sandwiched In between fungal layers, supplies food to the fungus through the process of photosynthesis. The lichen then forms a second, symbiotic relationship with trees. The trees provide the home area and the lichen in turn trap moisture and wind blown particles to establish a soil layer.

Habitat:

The temperate rain forest of southern Alaska. The forest occupies 17 million acres.

Notes:

I have observed tree roots being sheltered and nourished by lichen atop of a 5 foot high boulder. If you take a trip to Alaskan rain forest, I recommend the online field guide that I use a third reference.