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Lowenfels: Brilliant and beneficial lichens enhance fall colors

Jeff Lowenfels
Bob Hallinen

It's hard for me to not notice our trees this time of year. To me, they are the bellwether of fall. This week, I note there are still lots of green leaves on our trees. In fact, they are almost all still green. This seems a bit late and brings back bad memories of freezing rains, frozen leaves and tremendous loss of limbs and shrubbery after the storm. Of course, that won't happen this year. That would cap off the weird weather streak we seem to be experiencing.

On the other hand, I am pleased to see that, even without a campaign to spray all the trees in Southcentral Alaska, the leaf miners, which had been causing leaves to prematurely turn yellow and even drop, have subsided. It is just one more testimony that most of the time nature balances herself; we don't need to interfere.

What catches my eye more than anything, however, is what has happened to the bark, particularly that of our birch trees. It has rained quite a bit, as it always does in August and early September. Take the time to look and you to will see just how much of the bark of these trees is covered with lichens. In fact, the characteristic texture and colors of birch, caught so aptly by Alaskan artists from Sydney Laurence to Steve Gordon are not actually the bark, but the lichens that reside all over it.

Lichens are actually two types of organisms in a symbiotic relationship: fungi and a photosynthesizing partner, either a cyanobacterium or a green alga. They are all over, not just on trees. And because of the rain this time of year lichens (and mosses) are pretty much at their peak colors.

This is primarily because of two things. First, the fungal "mat," technically called the "thallus," has absorbed rain and nutrients and is providing its photosynthesizing partners the perfect environment. They are cranking away making food. In fact, some folks compare the fungus partner to a farmer. It traps nutrients and then feeds these to the algae or cyanobacteria which in turn produce carbon using the sunlight, much of which not only feeds the fungi carbon but also release carbon into the environment. These light gathering partners are operating at their peak right now.

Second, many lichens develop mushroom-like fruiting bodies and these often contain beautiful colors. In fact if you look around your property, trees, rocks, wooden fences and other structures you will notice that the birch are not the only surfaces upon which lichens are growing and that many have colors other than army green, due to reproduction that accompanies good times.

Lichens are everywhere in Alaska (and elsewhere). And they come in all sorts of shapes and colors. Nonetheless you can group them all into three types: foliose, fruticose and crustose. Foliose, as the name suggests, look leaf-like. Fruticose lichens are stringy or hair-like. Crustose lichens look like they were painted on. I highly urge you to spend a bit of time using a search engine and the words "Alaska lichens." Then go forth and learn what you have in your own yard.

Most lichens are incredibly beautiful, at least when you look at them with a magnifying lens, a macroscope or just a jeweler's loupe. The colors can be amazing. One, known commonly as "British soldiers," has beautiful, red-capped, fruiting bodies atop white "uniforms," obviously reminiscent of British troops. Then there is "orange chocolate chip," which looks as you might expect from the name. "Gray reindeer" does indeed looks like a herd of reindeer, the thallus consisting of tiny, exact replicas of reindeer antlers. Some lichens, often orange, habituate areas where animals have deposited nitrogen

Are lichens a good thing? You bet. First, they are pioneer organisms. Those with cyanobacteria fix nitrogen which then gets distributed to soil and thus other plants when it rains. They do trap particles and can help start the process of soil building. They are very sensitive to some air- and rain-born materials, as is the fungus, which provides protection for its partner, which, really doesn't have much protection itself. Because of this they are used to monitor air pollution.

While these partnerships do attach themselves to all sorts of surfaces, they don't harm them as they grow. Oh, sure, a bit of rock may get dissolved over a few hundred years, but who is counting? You don't have to worry about that fence or tree rotting away due to lichens.

One of the great things about lichens is that they are around all year long and, at least in Southcentral, they are everywhere. This means you can explore your yard, the cross country ski trail, your favorite tennis court or while getting that fishing fly you snagged in an alder branch. Lichens are everywhere. Studying them can be a great adjunct to gardening.

GARDEN CALENDAR

Spring-flowering bulbs: Buy and plant as many as you can. Follow directions. Mulch with grass clippings, if possible, immediately after planting. Do not fertilize or use bone meal. All the bulbs need are inside already.

Harvest: People! Nation! Awake and stop waste of hard-grown food!

Alaska Botanical Garden: A great place to see lichens, mushrooms and much more. Go. Better yet, join and go. Find out more online at alaskabg.org.

Nurseries: Great time to plant if you can find stuff. Visit. Look for sales.

Jeff Lowenfels is co-author of "Teaming With Microbes" and author of "Teaming With Nutrients," available at tinyurl.com/TeamingWithMicrobes and tinyurl.com/TeamingWithNutrients.

 


By Jeff Lowenfels
Gardening