Riparian Zones

Some of PEI’s natural habitats punch well above their weight – their importance far exceeds the area they occupy in the landscape. Today’s Island habitat is one of our most important and most misunderstood: riparian zones.

Photo 1: A healthy riparian zone along the Trout River in Prince County, PEI.

Riparian zones are transitional areas between land and streams or rivers. Although they are sometimes referred to as ‘buffer zones’, I don’t like that term. Riparian zones do far more than buffer our waterways, and – ecologically – are wider than the area protected under buffer zone legislation.  We often think of healthy riparian zones as forested (Photo 1), but these areas can also host natural wetlands, meadows, bogs, shrublands, and other habitats.

For a small island, PEI has a lot of streams: more than 5,100 km (about 3,170 miles), greater than the distance from Halifax to Vancouver!  While riparian zones represent only about 4.5% of our landscape, virtually all our wild animals use these areas at some point in their lives and you can find a greater diversity of plant species here than in any other habitat.

As transitional areas, riparian zones are important to both aquatic and terrestrial wildlife. They filter silt and other contaminants from runoff, provide shade to keep streams cool, and drop organic matter such as insects, leaves, and plant debris into streams where they become critical food for fish and other aquatic organisms. While the importance of riparian zones to fish and healthy waterways may seem obvious, their contributions to terrestrial wildlife are often less so.  

Photo 2: Dutchman's Breeches (Dicentra cucullaria) is one of the many rare plants that can be found in PEI's riparian zones.

In some parts of the Island, lands along streams and rivers were the only areas left unfarmed, which means their important forest soils, seedbanks, and fungi remain. This, coupled with rich floodplain soil, makes riparian zones home to not only a high number of plant species, but also some of our rarest.  If I want to see uncommon remnant trees such as Black Ash, Elm, and Ironwood or rare Island plants such as Dutchman’s Breeches (Dicentra cucullaria, Photo 2), Wood Nettle (Laportea canadensis, Photo 3), and dozens of others, I head to a healthy riparian zone.

Photo 3: The lovely and rare Wood Nettle (Laportea canadensis) has a bite more severe than its cousin, Stinging Nettle (Urtica dioica). I've had this plant sting me through my clothing!

For animals, these areas provide travel corridors – something that is especially important in a highly developed landscape such as PEI.  As areas where land and freshwater meet, riparian zones are ideal spots to find amphibians and reptiles. They also host disproportionately high numbers of flying insects, including important native pollinators such as Bees, Wasps, Butterflies, and Moths. Where there are insects, there are insect-eaters, and so the Island’s riparian zones are important for our endangered Bats as well as insectivorous birds such as Warblers, Flycatchers, and Tree Swallows. Bald Eagle nests can be found in large riparian White Pines, and dead trees provide habitat for cavity nesters from Chickadees to Barred Owls.

Hidden among all this species diversity is an amazing complexity of interactions. Ants are spreading seeds of those Dutchman’s Breeches, as well as Trillium, Violets, and many other wildflowers. Flying Squirrels are eating fungi and spreading spores that help trees absorb water and nutrients. Woodpeckers’ bills are spreading fungi that helps trees decay, both contributing to nutrient cycling and helping other birds, amphibians, and insects that need dead wood.

There is far more to riparian zones than meets the eye.  The next time you are fishing, hiking, or just passing by one of these important areas, take a moment to thank it for everything it contributes to PEI untamed!