Vital Vernal Pools
Vernal pools are temporary wetlands formed in depressions, thanks to rain and melting spring snow. Some are puddle-sized. Others, like prairie potholes, are relatively large. These short-lived soggy spots last anywhere from a few days to three or four months before drying up. Yet they are critical to the life cycles of many amphibians and invertebrates.
The imperilled mountain dusky salamander and great basin spadefoot toad both rely on vernal pools to reproduce. A host of other wildlife, like tiny, transparent fairy shrimp and water striders, also live part-time in vernal pools. As the water dries up, some inhabitants simply move on. With luck, tadpoles will now be tiny toads, ready to hop on to the next stage of their lives. Survival is a race against time for inhabitants of vernal pools. But the absence of predators, such as fish and reptiles found in permanent water bodies, makes the rush worthwhile.
To add to the challenge, these critical habitats are being paved over by spreading suburbs. Larger vernal pools, such as prairie potholes, are often considered wasted land and are, therefore, drained and cultivated. Elsewhere, vernal pools are "improved" by dredging and fish-stocking. Cattle and all-terrain vehicles can crush inhabitants and churn up mud, which clogs the gills of salamander larvae and developing tadpoles.
Vernal pools are not protected or even acknowledged by the Canadian Wetland Classification System. You can be a huge help to aquatic creatures by educating yourself and the public about these special spots. Ask naturalists and biologists for more information. Visit a vernal pool this spring. Prepare and distribute fact-sheets alerting landowners, developers, schools, and community groups about the importance of these habitats.
Of Canada’s frog, toad, and salamander species, 17 are in decline. Scientists have documented an alarming number of deformed frogs in Quebec and believe that farm pesticides are to blame. Wherever you live, you can help solve this mystery by reporting amphibian deformities to us at the Canadian Wildlife Federation.
Whip up a Wetland
Wetlands include, among other waterlogged wonders, swamps, fens, marshes, muskeg, peat bogs, and potholes. Countless species, from mallards to mud puppies, mate, lay eggs, hatch, swim, hunt, and grow in these habitats. Wetlands act as filters by breaking down sewage and harmful contaminants, leaving clean soil and water behind. Common cat-tails and bulrushes absorb toxic metals such as mercury and lead. Wetlands soak up rain and snow like sponges and help to prevent erosion and flooding.
Creating a mini-wetland in your schoolyard is surprisingly simple. It may be your key to attracting a host of wet and wild creatures.
- Choose a likely location. Your school grounds may already have a low-lying soggy spot that never entirely dries up. Consult with maintenance staff to see if weeping tiles or pipes have been laid to drain the "problem" site. If so, seek permission to have them removed. Then let the wetland work its wonders.
- If there are no naturally wet areas in your schoolyard, create your own. If possible, pick a spot in partial shade.
- Outline the shape of the wetland you want with a length of twine or garden hose. Any size is worthwhile, depending on space available and the energy of volunteer diggers. Even a small wetland will add surprising wildlife diversity.
- Remove any sod and dig a hole 30 to 90 cm deep.
- Line the hollow with a sturdy plastic sheet. If your area gets a lot of rain, puncture the liner in several places to allow slow drainage. If your site is a naturally soggy one, you needn't put down plastic at all.
- Layer 5 cm of pebbles on top of the liner, then 5 cm of damp peat moss and some roughly chopped sod. Make sure the peat moss feels damp when you open the bag. It won't work if it's crumbly and dry.
- Now for the plants. Always use native wetland species. Don't collect them from the wild unless an area is slated for development. Otherwise, purchase plants from a reputable nursery. Wildflowers that thrive along the edges of moist areas include marsh marigold, cardinal flower, blue flag, pickerel weed, and bottle and closed gentian. You can also plant a moisture-loving shrub or two, such as red-osier dogwood or buttonbush, along the edges of your little wetland.
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