Ministry of Environment Sensitive Ecosystems Inventories

Central Okanagan Riparian (RI)

• Structural stages
• Bench riparian
• Gully riparian
• Fringe riparian
• River riparian
• Status of riparian ecosystems

'Riparian' refers to areas adjacent to a water body, including lakes, rivers, streams and ponds.

For the purposes of the SEI, riparian ecosystems are defined as ecosystems adjacent to water bodies (except wetlands) that are significantly influenced by that water body. These sites are moister and support a plant community that is distinct from the surrounding upland. Riparian ecosystems are typically linear in nature.

Structural stages of riparian ecosystems

The Central Okanagan SEI classifies riparian ecosystems into seven structural stages, to identify habitat values and the condition of the site.

Subtypes of Riparian Ecosystems

Riparian ecosystems are also classified into four subtypes: bench, gully, fringe, and river riparian ecosystems.

Bench Riparian Ecosystems (RI:fp)

Bench riparian ecosystems are flood or fluvial ecosystems with distinct characteristics that are associated with moving water such as creeks, streams and rivers. They are influenced by flooding, deposition of sediments, erosion, and often subterranean irrigation. Such sites include active floodplains, where seasonal flooding adds inputs of organic matter and fine soil materials, as well as river and stream terraces that are occasionally flooded.

Bench riparian ecosystems are rich in nutrients and species. Generally, these sites are productive and develop more quickly after disturbance than adjacent upland sites. These ecosystems have high vegetation structural diversity. They usually have a mix of coniferous and deciduous trees in the overstory, with shrubby understories. Soils of this ecosystem type are typically sandy and gravely, and are poorly developed. These soils are saturated for only part of the growing season, but this still has a strong influence on plant composition.

Typically, bench riparian ecosystems occur as a band on either side of a creek and often form natural corridors through the landscape.

Gully Riparian Ecosystems (RI:gu)

Gully riparian ecosystems occur at the base and lower slopes of moderate to steep-sided linear sites (small valleys or ravines) with significant moisture. These ecosystems have either permanent or intermittent surface water flow, or significant subsurface flow, but are usually not subject to flooding.

These are rich and productive sites, forming natural corridors through the study area and providing habitat that is distinctly different from the surrounding landscape. These ecosystems usually have a mixed coniferous and deciduous overstory with shrubby understories.

Fringe Riparian Ecosystems (RI:ff)

Lakes and ponds typically have fringe riparian ecosystems associated with their shorelines. Sandy, gravely soils are common in these ecosystems and soils are often gleysols or mottled. This class also includes sites on fluvial fans, and sites with significant seepage that are sensitive to soil and hydrological disturbances; soils are typically medium-textured on these sites.

Within the study area, fringe riparian ecosystems are commonly associated with the Okanagan Lake foreshore, pond fringes, and moist seepage slopes. These ecosystems usually have mixed coniferous and deciduous overstories with shrubby understories.

River Riparian Ecosystems (RI:ri)

These are river ecosystems that include the flowing water and unvegetated sandbars, gravel bars and banks of the river. These ecosystems were mapped but were not field verified.

Status of Riparian Ecosystems

Riparian ecosystems were found to occupy 4.3% (1,315 ha) of the study area; predominantly bench (493 ha) and gully (574 ha) ecosystems with some fringe (215 ha) ecosystems and occasional river ecosystems (33 ha). Only 7% of riparian ecosystems in the study area were in the old forest and structural stage. Another 39% was mature forest and 43% young forest.

For more detail see the Technical Report.