Article Figures & Data
Figures
- Figure 1.
Nine project sites (A–I) comprised the initiative to restore a large portion of Lake Phalen’s degraded shorelands. Lake Phalen is the central feature of an urban park within the Minneapolis-Saint Paul, Minnesota metropolitan area.
- Figure 2.
Pre-restoration, construction, and post-installation (6 yrs) comparison of Site H. A) Pre-restoration image shows the steep riprapped slope with an informal path (foreground) from a walking path to the water. A portion of the riprap was re-used to make an offshore wave-break. B) A biolog providing secondary wave protection. The bank was regraded, seeded and protected with North American Green S-75BN (upland) and C-350 (toe of the slope) erosion control blankets. Emergent, wet meadow and upland prairie zones established by the sixth year (post-construction). C) Emergent vegetation (primarily Schoenoplectus tabernaemontani; softstem bulrush) colonized and spread between the offshore rock berm and the OHW elevation.
- Figure 3.
Post-restoration changes in the effort (person-hours per year) over time for different types of vegetation management. Year 0 effort consists of actions taken immediately after installation of soil erosion control materials and planting.
- Figure 4.
Change over time in the relative cost of annual management post-restoration (% of total project costs). Year 0 annual management costs are for actions taken immediately after installation of soil erosion control materials and planting.
Tables
- Table 1.
Summary of practices, relative costs, and general outcomes for each restoration site. All parameters related to vegetation are based ranks or categories of numbers of species (see Table 5 for details).
Practices Sites A B C D E F G H I Landform modification none Full offshore berm Partial offshore berm Wetland fill removal Full offshore berm Full offshore berm Full offshore berm Full offshore berm none Soil erosion control PCR + blanket PCR + blanket PCR + blanket blanket PCR + blanket Pre-veg mats + container stock Pre-veg mats + container stock PCR + blanket PCR + blanket Littoral revegetation PCR + container stock, protective fencing PCR + container stock PCR + container stock, protective fencing PCR + container stock, protective fencing PCR + container stock PCR + container stock PCR + container stock PCR + container stock PCR + container stock, protective fencing Upland & wetland revegetation Seeding + seedlings Seeding + seedlings Seeding + seedlings Seeding + seedlings Seeding + seedlings Seeding + seedlings Seeding + seedlings Seeding + seedlings Seeding + seedlings Native species planted-rank (1=high) 9 6 2 7 8 4 1 5 3 Costs Total installation costs per area (rank) (1=high) 7 3 8 9 1 5 2 4 6 Total management costs per area (rank) (1=high) 6 5 1 8 4 2 3 7 9 Outcomes Bank erosion Minor Minor Moderate Minor Minor Minor Minor Minor Minor Path formation One-few Many Many One-few One-few One-few Many Many One-few Native species present-rank (1=high) 9 2 1 6 8 6 5 4 3 Native species-spread (High=20+, Low=1) Low Medium Medium High High Medium Medium Medium Medium Introduced/invasive species present-rank (1=high) 5 1 2 8 9 5 3 3 5 Introduced/invasive species spread High=5+, Low=1 Medium Low 0 0 Medium High Low Medium Low - Table 2.
Installation costs and management labor for each restoration site. Planning and preparation include field surveys, restoration design, securing materials, scheduling contractors and other related project management activities. Landform and soil preparation include heavy equipment contractors, soil, delivery, and labor required to prepare soil for seeding and planting. Plant materials include plants, seeds, and prevegetated mats. Erosion control materials include erosion control blankets, coconut biologs, brush bundles, and temporary fencing. Management hours include site surveillance, management, irrigation, herbicide, and equipment rental necessary for treatments. Hours/area/year is adjusted for number of years post-restoration (see Figure 1). Linear and areal dimensions for each site are also presented in Figure 1.
Sites A B C D E F G H I Total Cost (USD x 1000) 60.2 152.6 316.9 110.7 206.3 138.5 281.7 286.5 131.1 USD linear m−1 563 655 672 683 790 567 673 507 461 USD m−2 63 109 61 49 113 96 112 102 66 Installation Components (USD x 1000) Planning & preparation 7.7 15.4 16.5 10.8 17.5 17.3 20.1 23.3 17.0 Landform & soil preparation 12.3 46.5 61.1 28.9 39.4 37.6 68.7 82.4 30.8 Plant materials 33.1 44.2 200.7 57.8 96.5 27.4 96.2 70.7 43.5 Erosion control materials 7.2 46.4 38.6 13.2 52.9 55.9 96.8 110.2 39.9 Management—Total hours 343 549 1438 551 783 639 1022 825 405 Hours m−2 0.36 0.39 2.85 0.24 0.42 1.17 0.40 0.27 0.06 Hours m−2 yr−1 0.02 0.03 0.17 0.01 0.02 0.06 0.02 0.02 <0.01 - Table 3.
Attributes used to assess shoreland landform restoration and stabilization at each site. Slope (%) was measured from paved pathways to OHW elevation. The berms of five sites (B, E, F, G, H) extend the full shoreline length. The C site berm provides partial protection. Three sites (A, D, I) do not have riprap berms. Note that there was no buffer width lost on any site, no patches of bare soil > 0.1 m2 other than those associated with paths, and no change to riprap berm elevation.
Metrics Sites A B C D E F G H I Slope (%) 22 31 18 7 22 25 27 30 18 Cut-bank drop (cm) 20 0 40 0 0 0 20 0 20 Cut-bank length (m) (% of total) 9 0 179 0 0 0 30 0 93 (8.4) (0) (38) (0) (0) (0) (7.2) (0) (32.7) No. paths with bare soil 1 9 13 2 3 2 10 9 1 Vegetation cover class-berms N/A 1–5% 5–25% N/A 25–50% 50–75% 1–5% 5–25% N/A No. species colonizing berms N/A 1 4 N/A 5 6 6 6 N/A Acorus calamus — — — — X — — — — Bolboschoenus fluviatilis — — X — X X X — — Carex lacustris — — — — X X — X — Schoenoplectus acutus — X X — — X X X — Sparganium eurycarpum — — X — X X X X — Schoenoplectus pungens — — X — X — X X — Schoenoplectus tabernaemontani — — — — — X X X — Typha spp. (T. x glauca, T. angustifolia) — — — — — X X X — - Table 4.
The plant composition of restored shorelands by life forms (guilds). Approximately one-third of observed species had been planted or seeded; one-fifth of all species were widespread (i.e., occurring on 7–9 sites). Less than 15% of all species (i.e., planted and unplanted) had spread to have more than 5% cover in a zone (littoral, wet meadow, upland prairie/savanna) on any site.
Life Form No. observed %, (no.) observed species-planted % widespread % spread Perennial forbs 147 47.0 (69) 23.0 (34) 6.1 (9) Woody plants 57 10.5 (6) 17.5 (10) 7.0 (4) Annuals/Biennials 49 2.0 (1) 18.4 (9) 4.1 (2) Perennial graminoids 44 56.8 (25) 18.2 (8) 6.8 (3) Emergent macrophytes 11 72.7 (8) 27.3 (3) 36.6 (4) Aquatic & Floating 5 0.0 20.0 (1) 20.0 (1) ALL 320 109 20.3 (65) 6.9 (22) - Table 5.
Species planted and colonized that were observed on shoreland restoration sites. Colonized species are those that were observed in 2021 vegetation site surveys but had not been planted. Species with more than 1% cover are those that had spread to this extent over at least one zone (littoral, wet meadow, upland prairie/savanna) of a site.
Numbers of Species Sites A B C D E F G H I Total observed 108 173 191 138 112 142 149 165 148 Total planted 42 93 112 87 82 104 121 97 105 Planted species observed 25 72 88 63 55 69 81 72 69 Native species colonized observed 65 70 74 61 44 55 47 62 71 Native species >1% cover 10 12 14 21 27 14 14 13 14 Introduced species colonized observed 18 31 29 14 13 18 21 21 18 Introduced species >1% cover 2 1 0 0 2 5 1 2 1
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