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Northland Nature: Opportunistic lichens thriving in the recent rain

After a month of colder-than-normal temperatures, the thaw of the last few days of December came as a surprise. A respite from the chill is often welcomed, but with these days filled with rain, many Northlanders would have preferred the cold.

Lichens
Lichens (pronounced "likens") are rather strange organisms that are quite common in the North Country. Submitted photo

After a month of colder-than-normal temperatures, the thaw of the last few days of December came as a surprise. A respite from the chill is often welcomed, but with these days filled with rain, many Northlanders would have preferred the cold.

In response to the wet warmth, snow became sticky and slushy, putting a damper on many of our outdoor winter sports. And the road conditions changed travel plans as well.

As I watched the birds and squirrels in the yard dealing with this rainy day, it looked like they were struggling, too. Feathers and fur can handle the moisture quite well but, at those kinds of temperatures, they can lose the body heat that is so critical to them now. Fewer of the feeder regulars arrived; many stayed in their shelters. For the first time in a month, no flying squirrels came to their feeding platform as the rainy night began. But, as often happens in nature, what may be a hard time for some is a blessing for others.

Walking in the woods, I noted some situations that benefited from the rain. During the snowstorm in late November, many small trees (hazel, dogwoods and alders) were bent over by the heavy wet snow. Defying the weather of the following weeks, this cold shroud hung on. It looked like maybe some of the bent trees would remain in this position. Weeks later, in the waning days of December, however, nature relented.

Winds caused much snow to fall, and this was followed by warming temperatures and the rain. Under these conditions, the weighted white coat was shed and the trees began to return to their earlier, and more normal, pose -- making movement through the woods much easier. I, as well as other winter woods wanderers, can go through the forests with fewer barriers now. This rain helped to set the trees free from the blizzard bondage.

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But the biggest opportunists during the rainy time of late December were the lichens (PICTURED). Lichens (pronounced "likens") are rather strange organisms that are quite common in the North Country. Composed of fungi and algae in a mutualistic relationship, lichens grow on a variety of substrates here. Though some do well on the ground, many flourish on rocky surfaces. But the lichens that we see most in winter are those growing on tree trunks. On these sites, the hardy lichens will spend winter out in the open, handling the cold and dry environment in a dormant phase. The algal portion requires sunlight to make food, while the fungal component holds the moisture.

On the tree trunks in winter, lichens will get plenty of light, but in the cold arid air of winter, the lichens will shrivel and appear to be dead.

However, these slow-growing fixtures that have lasted for many years are patiently waiting for the right conditions to get rehydrated. And the situation was right during the last days of December 2010.

Above-freezing temperatures allowed the precipitation in the form of rain.

And though it may have been under-appreciated by us, the lichens absorbed it and thrived.

While walking in the woods during this wet time, I was amazed at how these dried and shriveled, gray-green lichens suddenly took on moisture and stood out by appearing much larger and greener.

Bigger, more colorful and easy to see, it was apparent how common these often-overlooked growths on the trees are. The lichens took the available water, but, with more cold temperatures, winter quickly returned and they settled back in the dormant phase waiting for the next time moisture will return.

Retired teacher Larry Weber is the author of several books that are available now, including "Butterflies of the North Woods," "Spiders of the North Woods" and "Webwood."

Related Topics: SCIENCE
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