Treatment of annual and perennial non-native weeds will occur as needed throughout the project period. A combination of mechanical and herbicide treatment techniques will be used to treat weed populations depending on their growth stage and proximity to native vegetation. During the first year of the project, removal of invasive weeds will occur prior to revegetation efforts to avoid impacts to pole cuttings.
All target invasive species shall be removed or treated with herbicide before they set seed. Cut and daub herbicide treatments or hand pulling methods shall be used to treat weeds growing near native trees to prevent overspray on non-target vegetation. Dead biomass may be removed if it is determined the biomass will interfere with revegetation activities. Re-treatment of weed populations shall occur as needed. Quarterly weed surveys will be completed in order to monitor and prevent weeds from re-establishing.
Pre-work biological surveys for sensitive species and wildlife issues (such as nest sites and presence of vertebrates) shall be performed by staff before herbicide applications begins. Any mechanical biomass removal activities shall only be conducted outside bird breeding season as required by regulatory permitting.
Revegetation using native pole cuttings shall be focused in designated planting areas where current plant cover is low and natural recruitment is not expected to provide necessary cover. Cuttings will be collected from riparian tree species commonly used in riparian restoration including red willow (Salix laevigata), arroyo willow (Salix lasiolepis), Fremont’s cottonwood (Populus fremontii) and black cottonwood (Populus trichocarpa). All cuttings shall be collected from populations within the Santa Clara River watershed. Cuttings will be collected from mature trees in the immediate vicinity of the project area as well as from populations occurring at higher elevations within the watershed where trees have adapted to survive in warmer and drier conditions. Collecting from different sites throughout the watershed will insure genetic diversity. Cuttings will be collected from healthy parent trees and observed for any pathogens or blemishes. All cuttings will be collected from medium to large diameter branches (4 to 8 cm) and trimmed to a standard length (60 to 90 cm). Planting depth and timing shall occur to take advantage of seasonal increases in soil moisture. An estimated two thousand pole cuttings will be installed per acre in designated planting areas (1 pole cutting every 2 square meters). In areas where native understory growth is insufficient, container plantings may be installed.