We studied riparian areas with the Urban School this week. Here is some awesome information we shared with our students to get them thinking about the project!

What is a Riparian Area?

The term “riparian” is defined as “vegetation, habitats, or ecosystems that are associated with bodies of water (for example streams, springs or ponds) or depend on perennial or intermittent surface or subsurface water.” Put more simply, riparian areas are the green ribbons of trees, shrubs, and herbs growing along watercourses. Some riparian features we enjoy include the cottonwood groves where we like to picnic along sandy riverbeds, the green, shady areas next to the stream where we like to fish, and wetlands with ducks, tadpoles and dragonflies.

Riparian areas occur in a wide range of climatic, hydrologic, and ecological environments. Different latitudes and altitudes can support very different riparian communities. This is caused primarily by differences in soil, water and temperature. In the western United States, riparian areas occur from high elevation montane meadows or forests through intermediate elevation woodlands to low elevation shrublands and desert grasslands.

In the western United States, riparian areas comprise less than 1 percent of the land area, but they are among the most productive and valuable natural resources. There is a significant difference between the water-rich riparian areas and the arid uplands. Riparian areas are the major providers of habitat for endangered and threatened species in the western desert areas. In the humid east, the riparian areas are more similar to the uplands. In many areas, the separation of the riparian zone from the upland is not distinct.

Riparian Areas are Ecosystems. An ecosystem is a functional system that includes both abiotic part in the organisms, such as the plants and animals, and an abiotic part, which factors in their immediate environment such as soil and topography. These organisms interact both with each other and with their environment. Each ecosystem is unique because the organisms and the environment differ from other ecosystems.

The three main characteristics that define riparian area ecosystems are hydrology, soils and vegetation. These reflect the influence of additional moisture compared to the adjacent, drier uplands. Riparian areas are the transition zones between aquatic (water-based) systems and terrestrial (land-based) systems, and usually have characteristics of both. These characteristics make it habitat for a larger number of species of plants and animals.

Because riparian areas are at the margin between water and land, their soil was most likely deposited by water and could be washed away by water. Protecting soil, streambanks, or water edges from excess erosion is an important function of riparian plants. Thus, properly functioning riparian areas absorb the water, nutrients, and energy from big events and use them to recover from disturbances while improving water quality. The toughness of riparian plants with dense, strong root systems, stems that slow floodwaters, and maybe woody debris that forms pools, adds to riparian stability and habitat diversity.

Some riparian areas, especially those not functioning properly or in high energy – high sediment locations are very dynamic and disturbance-driven. Plant communities may be susceptible to rapid change, if soil and water conditions change dramatically. These changes might include:

Flooding or lack of flooding either temporary or more long term, as caused by beavers, or man-made structures;

  • Deposition of sediment on streambanks and across floodplains;
  • Dewatering of a site by a variety of means; and
  • Changes in channel location or elevation.

Significant differences in water availability due to precipitation between the eastern and western United States have led to major differences in these regions’ riparian areas. Riparian areas in the arid western United States have different plant composition but are also more lush than their adjacent uplands. Another important difference between the eastern and western United States that influences riparian areas are the pathways that water follows to reach streams. In the eastern United States, more water infiltrates the soil resulting in more subsurface flow reaching the stream and thus, more soil moisture. In the western United States, there is more overland flow reaching the stream.

Riparian Areas: Different but the Same

Although riparian areas can differ greatly, they all have several things in common. They are shadier, cooler, and moister than the adjacent upland environments. A wide variety of animals are attracted to these areas including insects, amphibians, reptiles, fish, birds, and mammals. Suitable habitat (food, water, and shelter) is often provided in riparian areas to support these animals which may not occur in surrounding drier areas.

To find out more, you can read the full article here.

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