Book SectionsTable of Contents
The Problem Puddle Power Frog-Friendly Backyard Why are we concerned about amphibians?
Wetlands - function/type Wetland issues
How to help amphibians
Community Green Plans
Ecological planning beyond the birdbath Before you start Urban Wetlands Marshes
Drainage ditches Stormwater retention ponds Ephemeral ponds River valleys
Swamps Wet meadows Beaver pond Management
Ecological planning beyond the birdbath
We spoke earlier of the bioregion concept...the geological, natural and human history that has shaped the development of your region. It is also important to understand that your bioregion determines the type of wetlands and wild life that characterize your community. You cannot attract certain species to restored habitats unless you understand there are forces larger than your backyard which determine the plants and animals that can live in your area.
The most important aspect of wetland creation is actually the management or restoration of the local hydrology. Rather than beginning anew it is best to seek areas of former wetlands that have been drained or which have had their water supply disrupted. These will be in areas which have historically held water and which "fit" the landscape and local hydrology. Determine which factors have resulted in the loss of the wet land. These areas may also have remnants of the original seed bank to seed your newly flooded area.
Plant community structure is determined by adaptations to saturated soils or tolerance of inundation. Although standing water may not always be present, the underlying soils still can hold enough water for the germination and growth of emergent aquatic plants. Fewer species can tolerate complete inundation. Plant a variety of emergent shoreline plants if diversity is your goal. However, we should not always judge the value of our wetland by its diversity alone. Plant diversity does not equal productivity.
Most wetlands are nutrient poor. It is a surplus of new nutrients that causes excessive plant growth and an enrichment or eutrophication of wetlands. Permanent water tends to tie up nutrients in the bottom sediments. These wetlands may not be as productive as those which occasionally dry and release the nutrients bound in the sediments. There is a tendency to discount the importance of nutrient poor wetlands even though there are a number of plant and animal species adapted to these systems. Wetland succession progresses at different rates and a variety of nutrient levels reflect this process. Wetlands located in areas where unpredictable flood or drying provides the opportunity for renewed successional opportunities.
Attempts to maintain habitats out of context, especially in urban areas, will always be expensive and not self-sustaining. We encourage you to design with nature taking advantage of local landforms and established plant communities. You can add value to low lying areas that currently hold or drain water. Wetlands are unique to each community and, when preserved, lend local character to your community. You will not find all species in every community- nor should this be the goal.
Natural succession will not be the same at every site and each community will evolve a character and structure of its own. Remember it is a landscape composed of different types of communities that contributes to the wild life features of your entire bioregion.
You should take stock (inventory) of what you have and what is required to sustain the local wild life already found in your community. You may then determine what actions are appropriate to maintain, enhance, or create additional habitat. Remember the importance of linkages so that wild life can expand their ranges into new habitats in good years. In bad years of drought or cold their ranges contract to the habitats that sustain them through the natural cycles. Your backyard habitat is part of a dynamic ecosystem and, although you may not provide all the habitat features necessary to sustain a species for the whole year, you may provide those habitats essential to its survival for part of its life history. While you may not have a certain species in your backyard for several years, your role may be to provide a healthy habitat linkage between other habitats needed by a species. Or even if a species of frog breeds in your yard, they may actually feed and overwinter somewhere else. You will have the benefit of a spring chorus of frogs but this may only last a few weeks. Nevertheless, without your breeding habitat or overwintering habitat the species could not survive. It is best to understand your role at the community level. It may be too much to ask any individual to provide resources to sustain a species for the whole community. But we can all contribute to a healthy community by providing pieces of a puzzle that together join to form a picture of a healthy sustain able community.
The first step in planning your backyard habitat is to decide which plants and animals will live as a community in your backyard. Animals are attracted to a specific habitat by its ability to provide shelter, food, water and/or breeding grounds for a specific species.
Ideally, we would want to locate wetlands in areas large enough for them to function without management reflecting the hydrological resources of the bioregion. For example, some bottomland wetlands receive water as overflow from streams which peak during spring flooding and after heavy rainfall. Often our urban or created wetlands have an elevated nutrient load entering from surface runoff. Most of these wetlands are too small to demonstrate long term succession after an initial period of balancing has occurred. As a result, there is reduced opportunity for diverse plant communities to develop. Very few wetlands are supported by precipitation alone and ground water supplies are what maintains most wetlands. Those that are supported by precipitation will most likely be ephemeral in nature, drying up as spring meltwater disappears and evaporation increases in the summer. Even these temporary ponds are important breeding sites for many species.
If you decide to build a pond in your backyard, you will have to determine its purpose. Will it be used for irrigation? Storm water? Attracting wild life? Fish? Bird Bath? Waterlilies? Or all of these? When building a pond for wild life, the animal species you wish to attract will determine its size and depth. A bucket of water will do for some water insects, while a large pond over a 100 square metres and 2 metres deep will be required for a sustainable green frog population. Soil type and moisture content of the soil will determine if you require an artificial pond liner or not. The location of the pond in your backyard will be determined by the source of water, local pollution sources, hydro, telephone, water and gas lines (AL WAYS CONFIRM THEIR LOCATION BEFORE DIGGING); number of hours of light per day, and existing habitats.
Construct your wetland and let succession take place. Those constructed as part of new developments or to mitigate the loss of existing wetlands, should factor in the need for return visits to manipulate some aspects of the wetland succession to meet project goals. As the wetland stabilizes you can then manage those sections towards the planned landform. This may be as simple as removing aggressively growing cattails. However, it is more appropriate to design the wetland with depth con tours that preclude cattails taking over the whole surface of the wetland.
It is best to visit local wetlands to review what grows locally and to serve as a model for the size of your site. Adjacent habitats contribute to the mosaic of habitats and these must be taken into consideration for no wetland exists in isolation from the surrounding ecosystem (old field, pioneer trees, or old forest). You may manage individual habitats separately, but you must recognize their ecological interdependence with the surrounding countryside. The object is not to create a wetland at any cost but to integrate it into the landscape.
Each restoration project should have clearly established goals with monitoring and follow-up to evaluate the success of the project. Success is best measured not by the vegetation alone but by patterns of succession, soil profiles, if it functions like a natural system, relationship to watershed hydrology, and persistence of species. The success of some restoration functions are unpredictable. This includes infiltration rates, recharge and discharge, and hydroperiod. Soil permeability may change with time as less porous organic soils are deposited over mineral soil.
Short term success is not indicative of long term persistence as existing natural wetlands have themselves gone through a long evolutionary history of drying and flooding and are survivors in the watershed. Created wetlands only reflect the existing hydrologies and have not been tested within a fluctuating environment.
Consider giving a donation to the Nature Conservancy of Canada wetland purchase programme to match your own backyard wetland. Support the many other organizations which are dedicated at least in part to wetland conservation.
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