What Makes a Healthy Riparian Area?

"The Riparian Zone" the distinctively lush green ribbon between streams and uplands, is home to diverse communities of plants and animals. It also preforms many valuable ecological functions. Although occupying only a small area of the total land base, management of riparian areas influences watershed function and has important economic and environmental consequences.

Both the streambank and the floodplain make up the transition zone between water and uplands which we call the riparian ecosystem. The uplands support drought tolerant plants whereas plants in riparian areas tend to love moisture and grow vigorously in response to the greater availability of moisture and nutrients.

Each Stream is Unique

Streams are controlled by climate, geology, topography, vegetation and land use. The relationships are incredibly complex and dynamic. Streams and streambanks are continually being reshaped by flooding, deposition and erosion.

Over time, streams shape their own channels. This natural process is dynamic, as the stream continually seeks a balance between its abilities to erode a new channel and to carry and deposit sediment. Both are related to the speed of the water and the size of the particles being eroded or transported.

Each stream is different. The riparian area along a seasonal stream fed by melting snow in southwestern Saskatchewan differs from the riparian area associated with a spring-fed stream in the central part of the province.

Neither has precisely the same characteristics as the lands fronting the South Saskatchewan River. The volumes are different; the plant, insect and animal life around the naturally differ as well.

Did you Know that Healthy Riparian Areas Provide Many Benefits?

• purify water
• reduce excessive erosion
• maintain perennial stream flow
• recharge ground water
• provide critical habitat for wildlife, birds, fish and other aquatic organisms
• produce abundant, high quality forage for livestock and wildlife

Many Characteristics Many Functions

Despite their differences, healthy riparian areas share many common characteristics if they are functioning properly.

A narrow, meandering channel with a broad floodplain and overhanging vegetation on the banks typically indicates a healthy riparian area, particularly if the vegetation includes woody, deep- rooted plants such as willow. By binding the soil, deep-rooted vegetation reduces erosion and stabilizes streambanks. Although woody species are particularly important, grasses, sedges and rushes also contribute to the root mat and absorb nutrients. Healthy above-ground vegetation reduces the velocity of flood water and surface runoff. Consequently, water infiltration into the soil is increased and ground water is recharged. Downstream flooding and flood peaks are reduced. The higher water table provides more seepage back to the streams, thus stabilizing flows. Streams will flow for a longer period and seasonal flows will be less variable. In this way, the riparian area acts like a sponge, holding water in the ground table and then releasing it back into the streams later in the season.

Water quality is improved as sediment and nutrient rich organic matter are 'trapped' and nutrients are filtered out.

This filtering function has become even more crucial in modern times, when runoff may contain fertilizers, pesticides, heavy metals or other pollutants. Increased nutrient levels may stimulate algal growth. Decomposition of the dense algal blooms may reduce oxygen availability and create toxic conditions for some aquatic organisms.

Water quality also affects habitat quality. A gravel stream bed, free of fine sediment, is required by some fish for spawning. Cloudiness of the water can reduce the growth of the stream microorganisms and invertebrates that are the foundation of several food chains. Shade, from overhanging vegetation, optimizes water temperatures for fish habitat.

Dead twigs, leaves and needles also have important functions. This "litter" provides an essential source of food for aquatic organisms. The organic carbon in the litter aids in nutrient cycling and decline of algal growth. Litter also prevents algal blooms and toxicity problems by acting as a sink for phosphorus, residues and other contaminants, pesticides and heavy metals.

Characteristics of Degraded Riparian Areas

Signs of a streambank degradation include:

• reduced or seasonal flow but increased flood peaks (relative to usual patterns)
• shallow-rooted vegetation with relatively low productivity, lacking woody species
• lack of shade and overhanging vegetation
• streambank collapse and excessive down cutting
• a wide stream channel with shallow, muddy water
• exposed soil on bank or flood plain
• invasion of undesirable plant species

Flooding is Natural

A floodplain that is flooded annually is not a sign of a stream out of control.

Overbank flooding is a natural process, critical for streambank building and maintenance. Several plant species require flooding for seeding establishment. Cottonwoods, for example, have very specific flooding requirements to regenerate. Trees and shrubs of diverse sizes and ages indicate that populations are being rejuvenated.

The floodplain allows a stream to dissipate its energy naturally. As the width of flooded area increases, velocity of the water decreases, as does its abilities to erode and carry sediment.

Recharged regularly with new soil, nutrients and moisture, floodplains support vigorous plant growth. It is no accident that floodplains are among the most fertile areas in the world.

Why Protect and Conserve Riparian Areas?

With water so scarce in the arid prairie environment, riparian areas have generally been intensively used, and often degraded. It is now apparent that maximizing and sustaining the productivity of this rich ribbon will come from careful, moderate management rather than intensive use. Maintaining the functions of riparian areas will yield benefits felt far beyond the immediate and manager and will outweigh the cost or inconvenience of doing so.

Those who use these areas for pasture stand to see better livestock performance from improved forage production and better water quality.

Improved reserves of sub-soil moisture will increase crop and forage yields, providing a direct benefit to farmers. Weed invasions are less likely in healthy riparian vegetation.

Many food chains are dependent upon the plant and invertebrate life of riparian areas. Humans, wildlife, fish, water fowl, upland birds, raptors, amphibians and mammals are all part of a complex interdependent web. Understanding the function of riparian areas helps us as human beings take a responsible place in this ecosystem.

We gratefully acknowledge the support of the following funding partners of the Streambank Stewardship Program.

Canada - Saskatchewan Agri-food Innovation Agreement, Environment Canada, Action 21, Prairie Farm Rehabilitation Administration with special thanks to Bill Bristol for his assistance in technical editing, Saskatchewan Grazing and Pasture Technology Program, and to the contributions to riparian activities through support of the Saskatchewan Prairie Shores program by the California Waterfowl Association, The Nature Conservatory (US), Nebraska Game and Parks Commission, North America Wetlands Conservation Council, Pheasants Forever, Inc., Wildlife Habitat Canada and Wyoming Game and Fish Department.

The Saskatchewan Watershed Authority and its partners in the Streambank Stewardship Program have developed a planning guide to help landowners develop their own stewardship plans. The planning guide is available from the web site above.