Alvars are globally rare ecosystems that occur along the edges of the Canadian Shield in Canada. This ecosystem is characterized by sparse tree cover and thin soils over a limestone bedrock that makes it a harsher environment. Only drought and flood tolerant species can survive here which makes it a very interesting ecosystem to study for plants. I have had the pleasure of completing my masters research in the Interlake region of Manitoba studying the plants that live on alvars.
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| Hoary Puccoon - Lithospermum canescens |
In the spring, flowers such as
Lithospermum canescens and
Cyprepedium parviflorum attract pollinators with bright yellow flowers. Later in the season when the spring flowers are finished, Gaillardia aristata speckles the field again with yellow-orange flowers.
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| Lesser Yellow Lady Slipper - Cyprepedium parviflorum |
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| Blanketflower - Gaillardia aristata |
Often the first things to colonize an area of open rock are lichens and mosses. These are very common on alvars since ecological processes maintain the openness and allow them to thrive.
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| Granite Erratic With Moss and Lichens |
They grow on both rock and tree bark often covering most of the rock or trees surface as seen above and below. These organisms often grow quite slowly indicating that these habitats remain open for long periods of time.
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| Bur Oak With Lichens |
Unfortunately not all alvars remain pristine. Here you can see nicer green alvar vegetation fading into a field of encroaching
Poa pratensis. This invasive grass is commonly found in pastures and since alvars are so barren grazing usually requires providing cattle with hay bails that introduce invasive species to the area.
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| Poa pratensis Encroaching On Alvar Vegetation |
Even admist the disturbances of grazing many alvar species can still find small pockets where the soil is to thin to support invasives.
Myosurus minimus is a rare species to find in Manitoba since it reaches it most northern tip of its range here. On the alvars in Manitoba
, Myosurus minimus is restricted to lower lying depressions on bare limestone pavement with extremely thin soils.
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| Tiny Mousetail - Myosurus minimus |
