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Peat Bogs

Peat Bogs (Photo 1) are one of the oldest habitats on the Island; we can trace their beginnings back to the end of the last Ice Age more than 10,000 years ago.

Ellerslie Bog, Prince Edward Island

The massive glaciers that scraped across our landscape erased all previous vegetation and most landforms. When they retreated, those ice sheets left some areas piled high with glacial till (sediment left by the glaciers) and others with nothing but low-lying bedrock and no drainage. In these latter sites, water accumulated and algae began to grow, beginning the slow process of Peat Bog formation.

The algae that colonized these damp depressions formed a sort of ooze that provided enough organic matter for plants such as sedges, grasses and - most notably - Sphagnum mosses to establish. Sphagnum mosses are very good at holding water; they trap rainfall and snowmelt, preventing it from evaporating. As water accumulated, mosses continued to grow outward and upward while the older, lower levels died and began to slowly decompose. With so little oxygen in this water-saturated environment, decomposition happens very slowly. Decayed Sphagnum moss - called peat - forms at a rate of about one millimetre per year.

Over thousands of years, Sphagnum continued to grow and peat continued to accumulate. Some PEI bogs have peat deposits more than 6.5 metres (21 feet) deep! Eventually, other plants started to grow in this water-logged, acidic, and nutrient-poor environment, including low-pH-loving Small Cranberries (Vaccinium oxycoccus, Photo 2) and Labrador Tea (Rhodendron groenlandicum, Photo 3). Black Spruce (Picea mariana) and Eastern Larch (Larix laricina) are the main trees of Island bogs, but the tough environment means they grow slowly. A stunted Spruce or Larch could easily be many decades old.

Small Cranberry (Vaccinium oxycoccus) in flower. Peat bogs are naturally acidic, with a pH in the range of 3-3.5 (roughly the same as vinegar). Cranberries are members of the Heath Family (Ericaceae), many of which thrive in acidic soils.

Labrador Tea (Rhododendron groenlandicum) is another member of the Heath Family (Ericaceae). I collect these leaves in fall and dry them. As its name suggests, Labrador Tea makes a pleasant hot drink.

Peat Bogs are so nutrient poor that some of their plants have compensated by becoming carnivorous. Pitcher Plant (Sarracenia purpurea, Photo 4) and Round-leaved Sundew (Drosera rotundifolia, Photo 5), are two examples that trap and digest insects and other small animals to get needed nutrients, especially nitrogen.

Pitcher Plant (Sarracenia purpurea) has adapted to this nutrient-poor environment by becoming carniverous. It traps insects in its cup-shaped leaves and digests them.

Round-leaved Sundew (Drosera rotundifolia) may be tiny, but is also carniverous! It traps insects on those sticky stalks on its leaves.

Peat Bogs are used by many Island birds, mammals, amphibians, reptiles and invertebrates. They are home to dozens of uncommon plant species (I’ll show you some beautiful bog orchids next week). They filter water, mitigate flooding, and store far more carbon than forests do. They take thousands of years to form and are one of the Island’s oldest habitats. Peat Bogs are unquestionably a cool PEI landscape!

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