Monday, January 05, 2009

A few good lichens

The lichens on this rock are amazing. So many colors, such interesting patterns. It’s even more interesting to look at them up close, with a microscope or a good hand lens. To me, they look like a coral reef, with all sorts of interesting shapes, some feathery, some hairy. Lichens can "make a living" where virtually nothing else can. They don’t have roots, so they draw water and nutrients directly from the air. When conditions are poor, they simply close up shop and wait for things to get better.

Many insects live in or on them and later become food for larger animals, so lichens are a critical part of the food chain. In some places, large animals forage on the lichens in winter. Birds and small animals often collect them for nesting materials.

And yet, lichens are not widely studied. Let’s face it, they’re not the most exciting thing on the planet. The don’t even grow very fast, perhaps just a millimeter or so a year. So when an area of them is wiped out, it can take decades, even centuries, for them to recolonize that area. And changes to a forest bring changes to lichens. Something like the end of the chestnut trees brought entirely new group of lichens to the forest.

In Pennsylvania, some 30% of the identified lichens are found in two or fewer counties. Many species are thought to be in trouble, but they are so poorly studied that no one knows how much trouble they are in. They have been called the "canaries in the mine" because they are one of the first organisms to go when something is wrong in a habitat. Identifying them is almost impossible for an average person like me. For one thing, more than 15,000 species have been identified, which makes a good field guide nearly impossible. And the differences between species are often minute, requiring both testing and a microscope.

So what are these lichens? Well, I can safely call them a crustose-type, which essentially means they are deeply fixed into the rock and are basically 2-dimensional. They form circular colonies and are some of the slowest growers—in that one-millimeter a year range. Other types are foliose, which means they are leaf-shaped and 3-dimensional, and fructicose, which stand upright, often with a cupped shape. They are usually found on trees, not rocks.

Around my cabin, I have a lot of rocks and a lot of lichens. To me the lichens look pretty healthy, as best I can tell. Of course, my best in this one isn’t very good. But if they start to disappear, I’ll let you know.

3 comments:

Cicero Sings said...

Lichens are so interesting. We have a good number around here but we are an arid area so not as many as in the Fraser Valley area ... where there are any woods left!

The-Grizzled-But-Still-Incorrigible-Scribe-Himself! said...

I was just out this morning, ambling through an old field, taking a few photos, some of which were of lichens. I was thinking I knew virtually nothing about them, and that I should get a good field guide and begin learning.

Guess the field guide notion is out…and the learning will be harder than I thought. But I still think they're interesting, worth looking at and photographing, and if this old dog can still be taught a few tricks, learning at least a little bit about.

I very much enjoyed your blog entry and photo. Thank you.

Carolyn H said...

Cicero: I think lichens are cool too. They're a lot easier to see in the winter than in the green season, for the most part. I don't think I have all that many different ones around here, either, but I lie the ones I have.

TGBSISH: Thanks for stopping by...and if you find a decent or even half-decent field guide for lichens, be sure to let me know.

Carolyn H.