The broad TRRP goal for riparian vegetation is to “establish and maintain riparian vegetation that supports fish and wildlife.” The TRRP can achieve the riparian vegetation goal through promoting diverse native riparian vegetation on different geomorphic surfaces that contributes to complex channel morphology and high quality aquatic and terrestrial habitat.
This must be done in the context of how flow regulation has affected riparian vegetation, primarily by enabling vegetation to grow densely along the low-water edge (see the overview page on restoration flows). The general pattern of TRRP’s revegetation efforts is to encourage riparian vegetation at a higher elevation, appropriate to restoration flow releases.
There are two ways to achieve the riparian vegetation goals, natural recruitment and revegetation. Physical designs can affect the location where plants can successfully initiate (e.g., grow from a root fragment or seed) and then establish (e.g., grow into a mature plant). Physical designs also affect the location and elevation where riparian plantings should occur via the construction of specific ground elevations, planform locations, and soil placement. Physical designs should also be able to inhibit detrimental riparian encroachment on the river channel. Benches at or below the floodplain exposed at different characteristic ROD discharges
(e.g., 6,000 cfs, 4,500 cfs, 2,000 cfs, etc) and with variable microtopography can promote the successful initiation of multiple riparian hardwoods beyond just narrowleaf willow.
Presently TRRP’s revegetation goal consists of a 1:1 replacement of riparian vegetation removed by rehabilitation site construction. The replacement goal also includes a 50/50 ratio of natural recruitment versus planting. Revegetation efforts focus on perennial species; the grass seed distributed at the end of construction is for erosion and weed control rather than revegetation.
The logic supporting the overall programmatic riparian vegetation goals and objectives is detailed in the Integrated Assessment Plan and a riparian revegetation guide is under development. Success of riparian revegetation is monitored, primarily within the Integrated Habitat Assessment Project (IHAP) – see Riparian Vegetation within the Science and Monitoring area of the website.