Fig 1.
Location of Elkhorn Slough and restoration sites.
The locations of the restoration sites at Hester and Whistlestop Marsh at Elkhorn Slough are shown, as well as the locations of the acoustic experiment. Image created using 10 m Digital Elevation Models from the USGS National Elevation Dataset.
Fig 2.
Landscape setting of study sites.
(A) Whistlestop Marsh restoration planting in high marsh where tall exotic forbs (black arrow) are immediately landward of marsh; (B) Coyote Marsh experimental plantings for acoustic experiment in area similarly adjacent to exotic forbs (black arrow); (C) Whistlestop Marsh restoration planting in high marsh where high forbs have been mowed (white arrow) adjacent to marsh; (D) Hester Marsh restoration planting with freshly seeded grassland restoration immediately adjacent, with mostly bare cover (white arrow).
Table 1.
Overview of the four study components.
Fig 3.
High marsh species used for restoration experiments.
All five species were used in the Hester Marsh restoration experiment; other experiments used a subset of these species (see text for details).
Fig 4.
Locations of restoration with caging and mowing.
The location of the caging experiments and the mowing experiment (lettered sites) at Whistlestop Marsh are shown. This photo is from USDA’s National Agriculture Imagery Program in 2018, the year following the experiments, when more extensive mowing was implemented in the caging experiment area and in areas A-D than during the period of the experiments. Salt marsh habitat appears as a narrow green “bathtub ring” adjacent to the water in this wetland that had been diked, with the majority of the historic marsh plain subsided too low to sustain marsh when tidal exchange was restored.
Fig 5.
Final survival in the Spring 2017 and Fall 2017 experimental restoration.
Survival by caging treatment (the only significant predictor) is shown in (A) for Frankenia and (B) for Jaumea in the Spring 2017 experiment; bars show survival for both tidal elevations combined. Survival by caging treatment and tidal elevation (both significant predictors of survival) is shown in (C) for Distichlis, (D) for Extriplex, (E) for Frankenia, and (F) for Jaumea in the Fall 2017 experiment. By the final survey date for each experiment, very few uncaged plants remained alive, while most caged plants remained alive.
Table 2.
Numbers of plants surviving in Spring and Fall 2017 restoration.
Table 3.
GLM results for caging effects on survival and stem length in restoration plantings.
Fig 6.
Final stem length by caging treatment in restoration plantings.
Maximum stem lengths from the final survey are shown (A) for Frankenia and (B) for Jaumea in the Spring 2017 experiment, and (C) for Distichlis, (D) Extriplex, (E) Frankenia, and (F) Jaumea in the Fall 2018 Experiment. There was no significant difference in plant size by treatment on planting day for either experiment. The figure includes plants that were dropped prior to statistical analysis (those with a final stem length of zero).
Fig 7.
Herbivores on marsh plants at Whistlestop in Elkhorn Slough.
Frankenia outplants in (A) the caging experiment, and (B) the acoustic experiment at Whistlestop (seedlings indicated by arrows). The top row shows the plantings by day; the lower rows show herbivores photographed at the same locations by night (mostly brush rabbits, but a woodrat was also observed eating a restoration planting—see the lower left photo).
Fig 8.
Herbivory rates in restoration plants in areas with different mowing intensity.
Block lettering at the top of panels corresponds to the locations in Fig 4. Frankenia salina plants were transplanted to Whistlestop in December 2017 and assessed for herbivory in January 2018. Numbers above bars indicate the number of plants in each block and treatment. Only uncaged individuals were planted in blocks E-L.
Fig 9.
Relationship between rabbit detections and restoration plantings.
Rabbit detections were summed over the month-long experiment. Maximum stem length at the end of the experiment was subtracted from that at the beginning of the experiment, and averaged across the ten plants per location. The 12 locations (two per site, Fig 1) were used as replicates for a simple regression analysis.
Fig 10.
Stem length of restoration plantings by site and playback treatment.
Length of the longest stem per plant at the final assessment was used as the response variable. See Fig 1 for site locations.