Posts Tagged ‘bioindicators’

The first wildflowers to bloom in Nova Scotia every spring are often mistaken for dandelions.  Coltsfoot has small yellow flowers that will appear along the roadside and in moist waste areas as early as March.  Their appearance usually coincides with first sightings of robins and pussywillows.

Non-natives, they were introduced to North America from Europe and are presently widespread across the Eastern Seaboard.  In Europe, their image has sometimes been used as a logo for apothecaries (pharmacies).  The blooms, stems and leaves have been regarded for millennia as a helpful medicinal herb.

Coltsfoot blooms appear long before the leaves.  Once the blooms die away, large hoof-shaped leaves emerge.    Dried leaves from last season can be seen in the image below.  In summer, the leaves are usually a dark green with a velvety white underside.

Like dandelions, coltsfoot blooms close at night and on overcast days.  Their closure often acts as a bioindicator for predicting rain.

Dried coltsfoot leaves have been smoked as a tobacco for relief of asthma and bronchial infections.    As a cough remedy, they’ve also been steeped as a tea.  Recent scientific research indicates that coltsfoot causes toxicity in the livers of rats.  Whether it’s considered a remedy or a poison is likely dependent on dosage.

Downy coltsfoot blooms that have gone to seed are used by goldfinches as a lining for their nests.

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moss 1

Moss brings an enchanted appearance to forests.  Several varieties grow around Flandrum Hill, on the ground, on stones and more than just the north side of tree trunks. 

moss on tree

In recent years, some innovative horticulturalists have suggested that it might be ecologically beneficial for homeowners to consider growing lawns of moss instead of grass.   Here are some reasons why:

  • It grows fast,
  • prevents erosion,
  • repels weeds,
  • doesn’t require fertilizer,
  • doesn’t require watering and 
  • doesn’t require mowing.

That last reason should be enough by itself to convince people to look into the moss option.  Imagine all the labour that would be saved in lawn maintenance!

moss 5

Though mosses thrive in moist, acidic soil, all they really need is a bit of shade.  They’re able to absorb enough moisture from rainfall to allow them to survive without extra watering.



The sphagnum moss shown above is a marvel of nature.  It can absorb several times its own weight in water or oil.  It has many uses in gardening, ie. as a seed starter, and dried, is an excellent insulator, firestarter and dressing for wounds.  

Mosses are often used by scientists as bioindicators, species used to monitor the health of an environment, to identify the presence of heavy metals and other pollutants in an ecosystem.  Their presence here doesn’t just make the woods seem more magical, they reveal the good health of the environment as well.

For more information on moss lawns, see

Moss Makes a Lush, No-care Lawn

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lichens on trees

What if there existed something in nature that could gauge air quality?  There is.  Though they have a preference for rough bark, lichens grow on most of the trees here.  Consequently, most of the tree trunks in the woods around my home are a light grey.  This is a good thing, as lichens are bioindicators of high quality air in the environment.  The more three-dimensional the lichens are, the better the air quality.

lichens in woodsLichens are not plants.  They are a mutually beneficial relationship between a fungus and algae.  For more information about this relationship, see my previous post about Lichens.

When it rains, lichens act as a sponge by absorbing as much water as possible.  After the rain stops, they slowly release the water back into the environment.  This process keeps humidity levels in the forest more stable than if the water was simply allowed to fall directly onto the ground.

The three-dimensional properties of lichens also make them ideal places for arthropods to survive.  It’s no wonder then, that birds are especially attracted to tree trunks covered in lichens.  Even chickadees that have access to seed in the winter will consume arthropods for 50% of their diet.

Considering the above benefits, wouldn’t it be helpful to promote lichen growth on trees in the city?

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Lichenes by Ernst Haeckel

Lichenes by Ernst Haeckel

What in nature could be more easily overlooked than lichens?  They’re so common and unobstrusive, that it’s easy to take them for granted.  In recent years however, scientists have discovered their value as bioindicators of air quality.  Research has shown that strong lichen growth in an area is an indicator of clean air.  Back in 2001, scientists Bibeau and Chevalier from the University of Quebec were able to show a link between lichen growth in areas around Montreal and incidences of hospitalization for respiratory problems in children. 

A lichen is basically an agreement between a fungus and an algae. The fungus provides a stable home and the algae provides the food.  It’s a very productive partnership.  Lichens are especially useful in forests as nitrogen-fixers.  Many birds use lichens for nest building.  In the Arctic lichens provide 90% of the caribou’s winter diet.  Locally, they’re eaten by grouse.  Traditionally they’ve been used as dyes and medicines by native people.  Ernst Haeckel, who created the above picture at the beginning of the 20th century, saw them as artforms in nature.  They are indeed beautiful.

My first encounters with lichens were of the reindeer variety on rocks in Northern Ontario.  They would crunch under my feet in the summer as I was picking blueberries.  Here in Cow Bay, they adorn trees as ‘Old Man’s Beard’ (Usnea hirta), and in a variety of forms can be found on the surfaces of tree bark, stones, as well as the siding on my house.

To find them in abundance is to find a corner of the universe where the environment is still pure and unspoiled.    ~ Irwin M. Brodo, Lichens of North America

Since lichens absorb everything that comes their way in the environment, they prefer unpolluted landscapes.  It’s a comfort to me (and my lungs) to see them thriving around the Flandrum Hill area.

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