Abstract: Session B 8:55 am (Back to Session B)
Riparian Restoration—Simple Designs that Substantially Increase Ecological Lift for Stream Restoration Projects
AloTerra Restoration Services, LLC
Fort Collins, CO
Restoring a stream’s proper dimension, pattern, and profile is fundamental to restoring the ecological health of floodplains. Further, the health of riparian communities along the stream bank, overbank, and other geomorphic positions in a floodplain is essential to the integrity of a floodplain, including bank stability, surface roughness, and adequate resilience in the face of annual scour events and larger flood events. A significant proportion of our stream corridors in the Western US exhibit highly degraded riparian conditions (e.g., low biological diversity, reduced structural diversity, dominance of weed species, etc.), offering potential for significant ecological uplift during a stream restoration project. For a variety of budgetary and other reasons, the limits of revegetation that occurs on a great number of stream restoration projects includes only willow transplants and/or sod transplants, with little active seeding, planting of container stock, poles, cuttings, or other treatments. Or, such treatments are an afterthought. Following good geomorphic restoration, substantial ecological lift can occur with some basic revegetation design techniques that go beyond transplanting existing vegetation. Some concerns a transplant only revegetation plan include: a) the spread of non-native species such as Salix fragilis – crack willow, Phalaris arundinaceae – reed canary grass, and many others across the floodplain; b) high degree of barren areas across a restoration area due to lack of transplant material; and c) on-site transplants are not adapted to the full range of hydrologic conditions existing in a floodplain. Considering the need for efficient design, planning, and construction processes, the use of a formulaic riparian zonation system that relates plant palettes and seed mixes to a hydrologic point of reference (i.e., bankfull, normal pond, etc.) has practical implications. Such formulaic design processes lend themselves well to adaptation by engineers and others seeking to bring ecological lift to their stream restoration project. This talk will present an approach to defining riparian revegetation designs based on over 20 stream restoration projects in the Southern Rockies Ecoregion. Simple methods for designing and communicating plant palettes and seed mixes for the multiple hydroseres (i.e., hydrologic zones) that exist across a floodplain will be presented, along with case studies.