Riparian and Creek Ecosystems (RI) and (CK)
In the Discovery Islands
• Riparian ecosystems occur along flowing freshwater (creeks) and around the still waters of lakes and ponds and wetlands. Riparian ecosystems are usually narrow and linear. Creeks are separate aquatic communities that have complex inter-relationships with the Riparian ecosystems on their border.
• Riparian ecosystems are constantly changing due to seasonal fluctuations and other effects of freshwater movement, including flooding and exposure, partial drying, erosion, siltation and debris accumulation. Their typically moist soils support distinct plant communities, usually including a lush understory of shrubs and herbs, and flood-tolerant deciduous and coniferous tree species.
• Creeks result from water run-off that is channelled by the underlying geology. Although they are subject to seasonal fluctuations, creeks are home to fish, numerous invertebrates, and various aquatic or semi-aquatic plants.
DIEM has mapped Riparian and Creek Ecosystems together and moss green in the Sensitive Ecosystems Mapping, with creeks represented as lines on top of the riparian which is mapped as the area around the creek.
The same Creek may cascade and flood, or pool and trickle, due to more or less precipitation The flow and course of a creek are also affected by seepage and evaporation, animals (especially beavers), and debris deposition or movement. Creeks provide a local water source, as well as delivering water for riparian and other downstream ecosystems
Riparian Ecosystems are influenced by their adjacent freshwater – and they always surround creeks, ponds, lakes and wetlands. Riparian zones can also occur atop gravel bars, spread over floodplains, in forest gullies where seepage occurs, and as micro-areas in the sprayzone of cascading water. The high variability and long edge of riparian ecosystems provide food, water and shelter that support many species and interactions that result in high productivity and biological diversity. Although natural disturbances are frequent in riparian ecosystems, the roots of riparian vegetation help bind soils and stabilize the edges of moist areas. Riparian vegetation and soils also play a key role as natural water filtration systems and help to regulate the flow and the temperature of fresh waters. The form and size of a riparian zone is determined by the shape and size of surrounding terrain.
In the Discovery Islands, there are three distinct types of Riparian Zone: BENCH FLOODPLAINS are adjacent to watercourses, and are graded according to the amount of flooding. Low benches are flooded at least every other year for extended periods during the growing season. High benches have subsurface flows within the root zone of plants for extended periods, but only periodic brief flooding of the ground surface. FRINGE describes the narrow edge of water courses or water bodies with no floodplain. Plants receive regular subsurface flooding of root zone. GULLIES AND CANYONS are steep V- or U-shaped creek beds with minimal flooding, but influenced by water due to proximity and exposure on steep sides; they may have unique microclimate.
WHEN YOU EXPLORE creeks and riparian areas, try not to disturb banks and roots, as this weakens the soils and dislodges sediments into the water. And be careful if you walk on the creek bed: you’ll likely be disturbing sediment, fish eggs and fish, and you may crush other animals and their eggs or larvae.
Look For Typical & Rare Species in Intertidal Ecosystems
Note: Riparian and Creek ecosystems share many species that live in and around both of these more-or-less moist ecosystems.
TYPICAL FAUNA American dipper, common merganser, common yellow-throat, little brown bat, Lorquin’s admiral, MacGillivray’s warbler, mink, northern-red-legged frog, river otter, rough-skinned newt, Swainson’s thrush, yellow warbler, western toad, northwestern salamander. Aquatic species: Caddis fly larvae, Coho salmon, cutthroat trout, freshwater lamprey, stickleback, water strider, and whirligig beetle
TYPICAL FLORA Big-leaf maple, bitter cherry, black cottonwood, black hawthorn, cascara, coastal leafy moss, devil’s club, goat’s beard, lady-fern, maiden-hair fern, oak fern, Pacific crab apple, red alder, red-osier dogwood, Pacific ninebark, salmonberry, sitka spruce, skunk cabbage, stinging nettle, water parsley, vine maple, western hemlock, western red-alder, western red-cedar, willow species, American bulrush, slough sedge, small-flowered bulrush
SPECIES AT RISK northern red-legged frog (Blue, Special Concern),western toad (Blue, Special Concern), great blue heron (Blue, Special Concern), cutthroat trout (Blue), grizzly bear (Blue, Special Concern), white adder’s-mouth orchid (Blue), pointed rush (Blue),
ECOLOGICAL COMMUNITIES AT RISK western redcedar/Sitka spruce/skunk cabbage; black cottonwood/red alder/salmonberry; Sitka spruce/salmonberry; western redcedar/swordfern
*For comprehensive species lists & rarity explanation, click here.
Some Observations of Local Species
Some Local Riparian & Creek Ecosystems
Creeks in the Discovery Islands are often small and ephemeral, flowing mainly during the rainy season. They may be found in most linear depressions on all of the islands. Data for creeks provided the basis for some of the initial mapping of Riparian Ecosystems in the DIEM project. DIEM participants can enhance the knowledge of Riparian and Creek ecosystems by obtaining on-site creek-records. Observations of species seen, or the breadth and depth of flowing water in various seasons and times will provide significant records.
Familiar Locations: Sonora Island: Christy Creek, Cortes Island: Whaletown Commons, Quadra Island: Hyacinthe Creek, Read Island: Bird Cove Creek, Maurelle Island: Elephant Bay Creek, Stuart Island: Eagle Creek.