WapatoWetland restoration and reintroduction of Sagittaria latifolia on the Tulalip Reservation

Authors and Affiliations: Sarah Verlinde, University of Washington Student; Darla Boyer, Tulalip Tribes Wetland Biologist, and Dr. Jeff Jensen, University of Washington Adviser.

Objective In the field In the Greenhouse

Conclusion

Background

Waterfowl and Wapato are thought to have co-evolved. Ducks and geese grub for corms, separating the plant allowing plant fragments to transplant and grow away from the parent plant. Waterfowl also fertilize the plant communities with excrement, resulting in increased nitrogen levels and increased productivity2.

Wapato populations succeed when there are waterfowl or a gardener separating and harvesting the plant. The decline of native tribal populations dependent on this food staple has also coincided with the decline of Wapato stands in Washington State2.

Explore the viability of expanding Wapato, Sagittaria latifolia, into additional wetland habitat types on the Tulalip Reservation.

Salinity Experiment: USDA plant specs supports that Wapato is a freshwater plant1 but tribal records and horticulturalists state it may be able to tolerate brackish water. I hypothesized that Wapato should be able to tolerate low levels of salinity and establish in brackish environments which would help open up habitat areas to restore. To test, I compared test plots of a non-saline, a 2ppt saline, and a 4ppt saline treatment with corms and allowed to grow. Results showed that corms were able to grow in 2ppt saline, but did not establish well in the 4ppt saline environment. This supports my hypothesis that they could tolerate low levels of saline. The 2ppt had less robust growth than the control indicating that they are more fit for freshwater environments.

Seed Germination Experiment: Wapato grows from Canada to Colombia1, which includes areas without cold winters. USDA and seed companies state that these seeds need to be cold-stratified for two months prior to planting1. Since these plants grow in areas not conducive to cold, I hypothesized that another seed treatment would be suitable to break up the seed coat. To test this, I created five treatments: 1. no treatment, 2. acid treatment, 3. water soak, 4. boiling water soak, and 5. scarification. Out of 392 seeds planted, only one from the acid soak germinated within 6 weeks. My hypothesis was refuted and the cold-stratification treatment is supported as the most effective germination strategy.

October 5, 2015

Wapato is an emergent wetland plant distributed in North America1 and utilized by Pacific Northwest tribes2. Tulalip Cultural Staff report that women harvested it from Quilceda Creek, part of the Snohomish River,3 and written records from the early 1900s indicate that it was an important food source and commodity that could be easily grown and transplanted on the Tulalip Reservation2.

Sagittaria latifolia grows well in full-sun and in partially flooded areas of ponds, rivers, and lakes4. It has a broad leaf shaped like an arrow4. The flowers are white4, and ducks eat the seeds of the plant2. The root has a starchy bulb (called a corm) which are eaten by ducks, beavers, muskrats, geese, and humans2. Lewis and Clark documented that this tuber tastes similar to the Irish potato and was an important food for the Washington State Tribes2.

This plant does well in freshwater areas4, although some green-thumb-culture and verbal stories claim it makes a great estuary plant with low salinity. To date, there is a gap in knowledge and studies surrounding salinity. Wapato is noted for its ability to withstand eutrophic conditions and is often used with cattails for created wetland systems for water treatment5.

The Tulalip Natural Resources Department initiated reintroduction of Wapato to the reservation in 2013 to support the Hibulb Rediscovery Program’s emphasis on native food education.

In test plots the previous year, Darla noticed that Wapato was not establishing which could be a result of grazing animals. To prevent herbivory and allow the plants to establish, we chose to do animal-exclusion fencing to see if it helped increase plant establishment.

Findings indicate that exclusion fencing had a positive effect on plant establishment where active browsing was observed. In the controlled greenhouse plots, plants leafed out and grew in low saline treatments but were less successful when salinity levels increased. Germination using alternative seed treatments to break dormancy was unsuccessful and further studies are recommended.

These results provide the Tulalip Tribes with helpful germination, salinity tolerance, and browse protection information upon which to base expansion of Wapato plots.

Hypothesis: By preventing animal access to the plants with fencing, more plants will establish because of prevented herbivory or trampling.

Method: We introduced Wapato corms to three wetlands with both fenced and non-fenced areas planted with 15 tubers each. We checked the plots weekly to ensure fences were up and no animals were trapped.

About the sites:Sturgeon Creek

Freshwater tidal creek

White RockBeaver created wetland with

excellent water quality

ELA Wetland1-year old enhanced wetland,

full sun with high levels of nutrients.

Results:

1. Stevens, Michelle. 03 Jun 2003. NRCS USDA: Broadleaf Arrowhead Saggitaria latifolia Willd. Available from: https://plants.usda.gov/plantguide/pdf/cs_sala2.pdf 2. Deur, D and N Turner. 2005. Keeping it living. Project Muse. Seattle (WA) University of Washington Press. 3. Personal Communication: Hibulb Cultural Center, Tulalip, WA, 2015. 4. Pojar, J and MacKinnon, A. 2004. Plants of the Pacific Northwest Coast: Washington, Oregon, British Columbia and Alaska. Vancouver (BC): Lone Pine Publishing. 5. Kearney MA, W Zhu. 2012. Growth of three wetland plant species under single and multi-pollutant wastewater conditions, Ecological Engineering (47):214-220. 6. Personal Communication: Dale Kolbe, Habitat Steward, Snohomish County Parks and Recreation, 2015. 7. Crandell, C. 2001. Effect of Grazing by Canada Geese on the Fitness of Carex lyngbyei at a Restored Wetland in the Duwamish River Estuary. M.S. Thesis. University of Washington, Seattle. 8. Wapato picture: Norton Naturals [Internet]. c2015 [cited 2015 Sep 29.} Available from: http://www.nortonnaturals.com/product-p/sl.htm

Wapato Leaf

Plots at ELA Wetland

Fencing Gear Planting Tubers

Control Plot, 0ppt saline

Tuber plants in Greenhouse Seed Plot

Leaf nibbled on by grazers at White Rock, present at week five and gone by week six.

2 ppt saline 4 ppt saline

Student Scholarship, SWS

HistoryWapato plant with leaf, roots, and corm Plate of Wapato corms8

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Fenced Not fenced

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Plant establishment for fenced/non-fenced plots.

Further Considerations: Our fencing was up for only two months while tubers grew into plants about a foot tall. Some exclusion fencing studies show that plant establishment preventing geese from grazing takes up to three years to become effective7. In areas with high herbivory, one should consider long-term exclusion fencing in these more vulnerable locations.

We received mixed results for fenced and non-fenced areas in plant establishment. White Rock had clear signs of waterfowl grazing in which fencing was most effective. The ELA site was very successful for both plots, but no grazing was present. The Tidal influence may have negatively influenced plant establishment at Sturgeon Creek, where the fenced plot was flooded more often.