It is late December, a week after the seasonís first blizzard dumped eighteen inches of snow on Cape Cod. However, today it is mild, temperature in the mid-40ís after a heavy rainstorm. Now a misty, soft fog is circulating through the Mashpee River Woodlands where I have decided to walk. Connected to Popponesset Bay, this brackish system is home to both fresh and salt water plants and animals.
But itís the woods surrounding the river that gets my attention. Because of the rain and fog I notice large populations of lichens glistening on the bark of living trees and fallen logs. Lichens are fascinating organisms. Each lichen consists of a fungus and an alga living in a symbiotic relationship. There are three major groups of lichens based on their appearance. Flattened against the bark are the crustose lichens. The leafy ones are called foliose lichens, and the branching types hanging from trees are the fruticose lichens.
Lichens grow very slowly and live for many years. They are ecologically important as the first, pioneer species on rocks, stone walls, and dead trees where they break apart the material creating an environment for small mosses and plants to colonize. Their presence is also a sign of good air quality as they are sensitive to sulfur dioxide.
Lichens also have the ability to absorb moisture from the atmosphere and that was evident today. With most plants in their winter state, the abundant lichens were conspicuous in their green, gray, and even pink colors. Out of the corner of my eye I spotted a large tree that had fallen over many years ago. It seemed coated in green and so I went over to examine it more closely. I was amazed to see it covered with the beautiful British soldier lichen with its recognizable red tips. Also, several foliose lichens, including the common pale shield lichen were present. The entire branch was covered with a series of crustose forms, many producing small dark fruiting structures. I counted seven different kinds of lichens on this one branch, most of which were also producing their reproductive structures.
I have walked these trails dozens of times and have always noticed the lichens, but this was my first visit in which they seemed so abundant and common. Whether hanging from trees, or clinging to the surface of logs, or carpeting the forest floor, this diverse group of life forms revealed a healthy, dynamic system within this important conservation parcel.
Copyright Gil Newton 2009 Thanks to Chris Dumas for logo image.