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Frog-friendly backyard

How to attract amphibians to your pond.

Your wetland is designed for your pleasure and to benefit wildlife, therefore special consideration should be given to the species of animals you wish to attract. Although most ponds are specialized for fish and waterfowl, a few adjustments to your wetland could transform it into a habitat for endangered amphibian species.

Besides bringing diversity to your garden, amphibians are good controllers of unwanted insects.


fig44-1 Amphibians are good controllers of unwanted insects.

Amphibians are completely carnivorous eating only insects such as: slugs, beetles, cutworms, flies, grasshoppers, Gypsy moths, sowbugs, pill bugs, centipedes, millipedes, mole crickets, ants and earwigs. A single toad might eat up to 1,500 earwigs in a summer! In addition to the above insects, larger female toads also tackle Japanese beetles and June bugs. Al though a toad will unfortunately eat the occasional beneficial insect, over 81% of its diet consists of unwanted insects (Organic Gardening, May/June 1994). Toads are not the only amphibians that can help a gardener. If you are close to a permanent body of water you might lure insect eating frogs to your yard. Salamanders, and their larvae, will eat slugs, grubs, worms, spiders, beetles, ants, mosquitoes and many other insects.

The American toad is our model urban amphibian. It spends most of its adult life on land and thrives in our gardens. Toads hibernate on land below the frost line and breed in warm, shallow temporary ponds or the shallow shorelines of larger wetlands. Our choices for model rural amphibians include the American toad and the green frog. The green frog requires permanent water because the tadpole takes two years to develop into a mature frog. The tadpole and adult frog thrive in deep, warm wetlands and ponds like those often found around farms. They hibernate underwater and require water that does not freeze to the bottom.

Vegetation

All ponds need time to develop into good amphibian habitat. New ponds cannot replace the complex ecosystems of established wetlands. This is why it is best to protect existing ponds and wetlands. The quality of habitat improves when plants and algae are established, and when decomposed plant and animal matter has settled to the bottom, forming a source of nutrients for tadpoles and aquatic life. Submerged, aquatic plants are important egg laying sites and provide cover for frogs and tadpoles.


fig44-2 Lilies can be planted in pots with layers of loam, sand, and pebbles.

Plants provide sources of food and shelter for a number of animal species. Plants must suit the soil type, moisture levels, and how much sunlight is received in your garden.

Planting should be done in moistened soils and with plants dug no more than two days prior (and kept cool and damp). If you are removing plants from a wetland destined for destruction remove strips of vegetation including the underlying soil profile if mechanical removal is possible. If you are planting individual plants, Picov's Watergardens suggests that one 10 cm potted aquatic plant every 2 metres squared would be adequate. Other sources suggest one water lily and three bunches of pond plants per square meter of pond surface. Slowly raise water levels to match the growth rate of plants or elevate plants on bricks until they grow enough to be lowered into deeper water. If the new plants are "topped" with water they become stressed and will grow poorly or die (However, this is one way of eliminating invasive plants like cattails). The shoreline needs to be graded to provide a variety of elevations that match the depth tolerances of the plants you want to grow. Remember that your long term objective is to take individual plants and create a plant commu nity that reflects the local hydrological conditions.

If your pond contains insufficient sediment to grow rooted plants, potted plants can be placed along the edges. You should place your plants in pots with 8 cm of organic material and top it off with 2-5 cm of coarse clean sand. Placing your plants in pots also prevents them from taking over your pond. If you have insufficient sand on the bottom to root plants, wrap the plant roots and soil ball in burlap with a few stones to weight it down. Sew up the sides. Roots will grow through the burlap and into the sand as the burlap decays and the soil ball will be contained by the plant's roots.

To improve the area around the pond, place native emergent plants around the edge to provide cover for adults and emerging toadlets and froglets. Sandy soils are nutrient poor and attract different plants than clays or rich organic soils,that may originate in your compost bin. Large emergent plants should be placed on the north side and at the back of the pond so that they do not hinder your view. If you are worried about the safety of children and/or pets, a thick boundary of plants around your pond will discourage them from approaching the edge. Trees should be planted some distance from the southern edge of the pond because excessive shading reduces wild life diversity and productivity. Any dead timber should be left standing since it provides habitat for such species as beetles and woodpeckers.

Aquatic plants rarely grow below 2 meters, unless the water is very clear. Most emergents are found in water 5 to 30 cm deep. Most emergents including trees and shrubs tolerate spring and fall flooding but suffer during the growing season if water levels do not drop. Grasses tolerate shallow flooding (2-5 cm). Submerged plants typically are found in a zone 0.5 to 1.0 metres deep. If excess nutrients become a problem, let duck weed grow to shade out algae and rake off periodically for nutrient rich compost.

Trees, shrubs, flowers and water plants that are native to Ontario are, generally speaking, better adapted to local climate and soil conditions and more resistant to local disease and pests than are exotic species. Native stock requires less of your time and money to maintain, and stands a better chance of healthy growth than most exotic species. Exotic or non-native plants often provide little or no value to wild life as a food source. However, non-invasive ornamentals are quite appropriate where your goal is to provide a water feature as part of a backyard garden. Exotics are often aggressive due to the lack of natural controls in their new habitat. In turn, non-native plant species often outcompete or choke-out our native species. Invasive plant species include Flowering Rush, Eurasian Water Milfoil and Purple Loosestrife.

Purple Loosestrife is threatening wetland habitats by taking over the wetland and choking out all native plant species and animals which feed them. Purple Loosestrife is a deep -rooted perennial, 1-2 meters tall, and has several square and woody stalks per plant. The entire plant must be removed to minimize the chance for regrowth. Dig out the root mass, making sure you have removed all pieces. Once removed, it must be dried in a safe place (plastic bag) and then either burned, packaged for disposal or composted. If it's not feasible to remove the plant then you can retard its spread by removing the flowers before they seed. If you like the "look" of the plant, you may replace Purple Loosestrife with Spiked Speedwell, Spiked Gayfeather or Garden Sage. Ducks Unlimited Canada has produced a pamphlet containing a "report form" to be filled out when you see Purple Loosestrife. Delay drawdowns to late summer as loosestrife thrives in the mudbanks of early summer drawdowns.


fig45-1 Purple Loosestrife pamphlets published by Ducks Unlimited.

We do not recommend that you take plants from a local wetland. In doing so you bring some beneficial plants and invertebrates to your ecosystem, but you may also bring over unwanted plant and animal species.

Look at local wetlands for species likely to grow in your area and buy local stock grown in soils with a similar water regime.

Select a variety of marsh and swamp species depending on the desired habitat. Most emergents germinate from seed banks exposed in warm muds as water recycles. Seed banks take 3 to 4 years to fully develop and the first animal communities to establish.

To control weedy species, such as Typha and Phragmites, deeper water contours will prevent invasion; flooding to 40-50 cm will prevent expansion of cattails; or cutting stalks (prefer able cut off at ground level) and then topping by raising water levels above the cut stems for several weeks (or over winter) will kill extensive stands of the plants.

It may be necessary to temporarily flood the newly seeded area or developing seed bank species with 2-5 cm of water to kill terrestrial invaders . After inundation for one week, water levels are lowered. This lowering and raising of water levels will determine which species survive as long as care is taken not to flood desirable emergents. The control of terrestrial invaders in wetlands may be accomplished by increasing the frequency, but not the depth or duration, of flooding


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