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Title
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Hydromulching in Tidally Influenced Wetlands: Testing Methods to Alleviate Seed Wash-away and Revegetate Native Plant Communities
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Date
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2017
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Creator
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Denzler, Allie A
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Environmental Studies
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Hydromulching in Tidally Influenced Wetlands:
Testing methods to alleviate seed wash-away and revegetate native plant communities
by
Allie A. Denzler
A Thesis
Submitted in partial fulfillment
of the requirements for the degree
Master of Environmental Studies
The Evergreen State College
May 2017
©2017 by Allie A. Denzler. All rights reserved.
This Thesis for the Master of Environmental Studies Degree
by
Allie A. Denzler
has been approved for
The Evergreen State College
by
________________________
Kevin Francis Ph. D.
Member of the Faculty
________________________
Date
ABSTRACT
Hydromulching in Tidally Influenced Wetlands:
Testing methods to alleviate seed wash-away and revegetate native plant communities
Allie A. Denzler
Estuaries are one of the most productive, and degraded, ecosystems on earth. Functioning
estuaries provide habitat for 75% of the U.S. commercial fish catch, yet large-scale
conversion of these wetlands to agricultural uses has resulted in estuarine habitat loss of
up to 60% in some areas. With the advent of the National Estuary Program in 1987, local
programs were developed to restore lost habitat functionality. Restored or created tidal
wetland projects often include a revegetation facet to kick-start productivity and habitat
development. Direct-seeding methods of revegetation have been the most cost-efficient,
however seed wash-away has been a problem in establishing planned native plant
communities in tidally influenced wetlands. This thesis tests a direct-seeding method
augmented by the addition of a layer of hydromulch (a water and wood mulch slurry) in a
set of recently created tidal channels on the Bayshore Preserve, in Shelton, Washington,
U.S.A. We compared first season recruitment densities of one native salt-tolerant forb
and four graminoid species under five different treatment conditions—broadcast seeded,
two seeded treatments augmented by burlap or hydromulch, and two controls. The forb
species, A. patula, was found to have statistically significant (p<.0007) higher stem
densities in treatments which implemented a burlap fabric and hydromulch layer over the
broadcast seed. The four graminoid species (C. lyngbyei, C. obnupta, E. palustris, & S.
americanus) did not germinate in this experiment. While seeding A. patula into created
tidal channels using this method shows promise, further research is needed to determine
if it is feasible for other species and whether survivability in subsequent seasons
compares with other wetland revegetation methods.
Table of Contents
List of Figures…………………………………………………………………………….v
List of Tables ..................................................................................................................... v
Acknowledgements .......................................................................................................... vi
Introduction ....................................................................................................................... 1
Chapter 1: Bayshore Preserve Site History & Restoration Significance ..................... 5
1.1
Site use history................................................................................................................ 5
1.2
Capitol Land Trust Restoration Plan........................................................................... 7
1.3 Biodiversity of the Oakland Bay Area ............................................................................... 8
Chapter 2: Literature Review ........................................................................................ 11
2.1 Tidal Wetland Restoration ................................................................................................ 11
2.2 Tidal Marsh Revegetation Methods ................................................................................. 14
2.3 Hydromulching in Restoration Projects .......................................................................... 17
2.4 Species Selection ................................................................................................................. 19
2.5 Implications ........................................................................................................................ 22
Chapter 3: Methods and Materials ............................................................................... 24
3.1 Seed Preparation ................................................................................................................ 24
3.2 Experimental Plot Design & Installation ......................................................................... 26
3.3 Treatment Applications ..................................................................................................... 29
3.4 Plot Elevations .................................................................................................................... 34
3.5 Soil Sampling ...................................................................................................................... 36
3.6 Vegetation Establishment Monitoring ............................................................................. 38
3.7 Germination Testing .......................................................................................................... 39
3.7 Data Analysis ...................................................................................................................... 41
Chapter 4: Results........................................................................................................... 42
4.1 Planted Species Germination and Establishment to Maturity ...................................... 42
4.2 Naturally Occurring Diversity in Tidal Channels .......................................................... 44
4.3 Atriplex patula Treatment Responses .............................................................................. 45
4.4 Natural Recruitment in Experimental Plots and Treatment Effects ............................ 57
4.5 Soil Salinity ......................................................................................................................... 60
4.6 Germination Test Results .................................................................................................. 62
Chapter 5: Discussion ..................................................................................................... 63
5.1 Hydromulching onto Broadcast Seed—Success with Atriplex patula .......................... 63
5.2 Atriplex spp. Treatment Responses.................................................................................. 66
5.3 Recommendations .............................................................................................................. 68
Conclusion ....................................................................................................................... 70
List of Appendices ........................................................................................................... 77
iv
List of Figures
Figure 1.1 – Bayshore Preserve…………………………………………………………5
Figure 2.1 – Experimental Plot Locations.....................................................................28
Figure 3.1 – Plot Preparation………………………………………………………......29
Figure 4.1 – Plot & Treatment Layout in Tidal Channel A………………………….30
Figure 4.2 – Plot & Treatment Layout in Tidal Channel B……………………….…30
Figure 4.3 – Plot & Treatment Layout in Tidal Channel C……………………...…..31
Figure 5.1 – Hydromulching………………………………………………………...…33
Figure 5.2 – Plots with Completed Treatment Application……………………...…..33
Figure 5.3 – 24 Hours After Treatment Application……………………………..…..34
Figure 6.1 – Example of Sampling Frame…………………………………………….39
Figure 7.1 – Occurrence of Planted Species within Experimental Plots………….....43
Figure 7.2 – Occurrence of Non-Planted Species within Experimental Plots…..…..44
Figure 8.1 – Unknown Species 1…………………………………………………….…45
Figure 8.2 – Unknown Species 2…………………………………………………….…45
Figure 9.1 – Overview of Atriplex Species Densities by Treatment……………...…..47
Figure 10.1 – Live Stem Densities of Atriplex spp. on April 8, 2016…………………48
Figure 10.2 – Live Stem Densities of Atriplex spp. on May 5, 2016……………….....50
Figure 10.3 – Live Stem Densities of Atriplex patula on June 1, 2016…………….....51
Figure 10.4 – Live Stem Densities of Atriplex patula on June 21, 2016……………...53
Figure 10.5 – Live Stem Densities of Atriplex patula on July 23, 2016………………54
Figure 10.6 – Live Stem Densities of Atriplex patula on August 16, 2016…………...55
Figure 10.7 – Live Stem Densities of Atriplex patula on September 24, 2016……….56
Figure 10.8 – Live Stem Densities of Atriplex patula on October 20, 2016……….....57
Figure 11.1 – Salicornia virginiana & Spergularia canadensis Densities…………....58
Figure 12.1 – Species Richness by Elevation………………………………………….59
Figure 13.1 – Soil Salinities………………………………………………………...…..61
v
List of Tables
Table 1.1 – Salinity Tolerance Ranges of Experimental Species…………………….22
Table 2.1 – Experimental Seed Mixture………………………………………………26
Table 3.1 – Treatment Type Applied to Each Plot in Channel A…………………....30
Table 3.2 – Treatment Type Applied to Each Plot in Channel B……………………30
Table 3.3 – Treatment Type Applied to Each Plot in Channel C………………........31
v
Acknowledgements
There are so many people who supported this project, I don’t have room to thank them
all! First off, I’d like to thank my thesis reader Kevin Francis for his great help
throughout experimental design, statistics troubleshooting, writing and editing. I also
want to thank Erin Martin for the lab meetings, and her support through tough grad
school times. Without the incredibly supportive folks at Capitol Land Trust this project
wouldn’t have happened—Thanks especially to Tom Terry, Daron Williams, and Caitlin
Guthrie. My former employer Sustainability in Prisons Project deserves a big shout out
for their flexibility as I worked through this thesis. Invaluable field assistance came from
Brendan Duffy and Joshua Carter. Most of all, I could not have done this without the
support and encouragement from my best friends and family. Thank you Karen, Mandy,
Paula, and Rosalyn for always listening. Thanks Dad & Annie for all the tacos, I love
youse! Finally, my three favorite people who kept me going when I thought I couldn’t:
Grandma Lorraine, you just understand; Conrad, you knew better than I that finishing this
would make our lives easier and much more fun, I love you; and Songo, you’re the best
dog!
vi
This thesis is dedicated to my Mom, Peggy Ann Young. Without her pushing me, I
wouldn’t be writing this thesis, learning how to do science, or moving toward my
botanical dream.
vii
Introduction
Estuaries—where the river meets the sea—have historically been viewed as
wastelands, fertile ground for agricultural activities, or convenient locations for the
logging industry to store and barge logs (Sedell, Leone, & Duval, 1991). They were
essentially ignored as important habitats until the 1980s, when public awareness in the
U.S. rose and the National Estuary Program was created by Congress in 1987.
Representing the lowest altitudinal point of a watershed, estuaries provide highly
productive habitat for anadromous fish, shellfish, seabirds, and more. These ecosystems
improve water quality by storing nutrients and pollutants that would otherwise
immediately enter surface or groundwater (Wetzel, 1993). Finally, estuaries provide
ecosystem services that benefit society—fisheries maintenance, coastal protection,
erosion control, and water filtration (Barbier, et al., 2011). Estuary restoration aims to
bring functionality back to these dynamic and important ecosystems.
The Bayshore Preserve, on Oakland Bay in Shelton, Washington, is an example
of an ambitious restoration project in the midst of a region where much of the Puget
Sound shoreline is industrially and privately developed, and therefore degraded.
Bayshore, a golf course from 1930 to 2013, was purchased with grant money by Capitol
Land Trust (CLT) in 2014. CLT recognized this property’s potential for ecological
restoration, removed a dike that was installed in 1947, and restored tidal influence to a
portion of the property that hadn’t been touched by saltwater for over 60 years.
The tidal flats—considered high quality habitat—were once prime shellfishing
beds for the Squaxin Island Tribe, and are still used by people today. The shellfishing
industry produces 40% of the nation’s Manila clams in Oakland Bay (Mason
1
Conservation District, 2004). Johns Creek, which runs through the property, hosts one of
the largest summer chum salmon runs in Washington State (WDFW, 2017) and provides
habitat for chinook, coho, bull trout, steelhead, and cutthroat salmon (Mason
Conservation District, 2004). Even as a golf course, Bayshore provided excellent habitat
for salmon, oysters, and clams. CLT is leading restoration efforts to further increase
habitat quality and create a publicly open space for learning—promoting cultivation of
sense of place—and provide access to nature near the city.
Estuarine habitat restoration is commonly approached from an experimental
perspective, with many approaches being tested for viability in many types of estuarine
environments (Zedler, 2001). When it comes to habitat creation, restoration sites are
commonly evaluated on performance standards such as vegetation development and plant
community make-up. Revegetation, when performed, has been applied using methods
such as planting seedlings, cuttings, and sod plugs with high survivorship in the first
growing season (Gilbert & Anderson, 1998; Sullivan, 2001). While planting propagules
tends so result in higher initial survivorship overall (Keammerer, 2011; Mazer, Booth, &
Ewing, 2001; Sullivan, 2001; Tiner, 2013), direct seeding is the simplest and least
expensive method available to revegetate tidal marshes and wetlands (Hanslin & Eggin,
2005; Wright, 1992; Zedler, 2001).
Although direct seeding into tidal marshes is simple and inexpensive, it tends to
result in low germination and plant establishment. Developing a method that keeps
direct-sowing in tidal wetlands cost-effective and results in high rates of plant
establishment would be beneficial for organizations, maximizing project budgets and
restoration impacts.
2
While limited success has been observed from surface sowing methods (Broome,
Seneca, & Woodhouse Jr., 1988; Sullivan, 2001), significantly higher germination of
annual plants has been achieved when seeds were mixed into a mud/organic matter slurry
and applied to the marsh surface (Sullivan, 2001). While this method seems promising,
some seed is still washed away and, therefore, wasted. We think that a method of
broadcasting dry seed onto the marsh substrate, then covering it with a “cap” of
hydromulch will result in higher seed germination and plant establishment over the first
growing season by providing a stabilizing effect against seed migration caused by tidal
flow.
This thesis is focused on testing this novel method of revegetation in the created
tidal channels. Hydroseeding, or hydraulic mulch seeding, is a planting method that uses
a slurry of paper or wood mulch and seed. In this case, hydromulch will be used to
augment prior broadcast seeded native salt-tolerant forb and graminoid establishment on
the channel surfaces. Seeds will be sown onto the substrate, and a layer of hydromulch
applied onto the pre-seeded soil. Influx and outflow of tides in the created channels at
Bayshore Preserve is generally gentle and slow-moving, which should provide ample
time for the mulch mixture to set before the first tidal inundation. As this method is
monitored throughout the season for planted species’ germination and establishment
success, conclusions can be drawn about whether larger-scale applications of the method
are ecologically and financially feasible for wetland restoration projects.
The following chapters provide background on the Bayshore Preserve, the current
science and trends in estuarine restoration, and the variables present in this experiment. In
subsequent chapters, methods and materials for the experiment are outlined, results are
3
summarized and potential causal factors discussed, and conclusions and
recommendations are shared.
4
Chapter 1: Bayshore Preserve Site History & Restoration Significance
Figure 1.1 Location of Bayshore Preserve (formerly Bayshore Golf Course) northeast of Shelton,
WA.
1.1 Site use history
The Bayshore Preserve was traditionally Squaxin land until the ratification of the
Medicine Creek Treaty in 1856. Specifically, the Bayshore Peninsula was territory of the
Sa-He-Wa-Mish of Big Skookum Inlet (now Hammersly Inlet). The Treaty’s ratification
resulted in the tribes losing thousands of acres of land to the Federal government,
including this area. Coast Salish Tribal members’ lives were—and still are—oriented
toward the Puget Sound’s inlets, which provided transportation, sources of fish, shellfish,
and other marine resources. Puget Sound uplands provided plants and animals for food
and materials. Watersheds were relied upon to support flourishing salmon runs that
occurred each spring, summer, and fall. The Squaxin Tribe (People of the Water or
5
Saltwater People), depended primarily on the Puget Sound for their ways of life
(Jolivette, Huber, Van Galder, Foster, & Henry, 2014).
Oakland Bay was home to the Squaxin, and there were several occupied
longhouses present on the Bayshore Peninsula until they were demolished in 1867 (Hunn,
1993; Howard, 1949), after which time Native Americans used the area as a camp when
hiking to and from Hood Canal. Undoubtedly, the peninsula was home to productive
shellfish beds, and pre-contact shell midden was documented running 200 yards along the
edge of the peninsula (Howard, 1949).
Historically, the land of Bayshore Preserve has been used by the Squaxin Island
Tribe as a temporary living location during shellfish harvest times. It is notable that the
largest Squaxin longhouse was present on the site—near the mouth of Johns Creek—next
to one of the most productive natural oyster beds in the area. The Squaxin people are
reliant on the waters of the Puget Sound for much of their food sources, and way of life.
To American Indians, the land is not merely a resource to be used. It is a living entity
with which every person has a living relationship. The cultural importance of restoring
habitat to a high-quality state is immense—functional nearshore ecosystems provide all
people food, and opportunity for deeper understanding of reasons to hold reverence for
nature and its gifts.
The Willey family settled the land in 1866, and, with the logging of the entire
Bayshore Peninsula, opened the Willey Mill in 1871 at the mouth of John’s Creek. The
mill was powered by water channeled from a dam built on John’s Creek. By 1903 the
mill had been abandoned (Deegan, 1959) and the Willeys developed the land into a 9hole golf course and resort, completed in 1931 (Jolivette et al, 2014). The mill was
6
completely dismantled in 1947 when the new Shelton-Bayshore Golf and Country Club
was built (Sideliner, 1947a). A soil dike was built along the entire southwest border of
the property to prevent saltwater damage to the course (Sideliner, 1947b). The golf
course was closed and abandoned in 2013, then purchased in 2014 by Capitol Land Trust
(CLT) in response to the Oakland Bay Action Plan (Kenny, 2007).
Since purchasing the land, CLT has worked in partnership with the Squaxin
Island Tribe, Taylor Shellfish, and Mason Conservation District to support the restoration
and protection of these 325 acres of Oakland Bay nearshore habitat. To aid in reaching
the long-term ecological goal for the property—maintaining ecological integrity of the
shorelines, tidal wetlands, and riparian corridors of Johns Creek—CLT has removed the
tidal dike to reconnect tidal processes to the land; removed most of the golf course
infrastructure; installed a riparian buffer of native plants along Johns Creek; revegetated
portions of the uplands; and removed all invasive plant populations from the property.
Bayshore Preserve property is protected by a State of Washington deed of right to use the
property for salmon recovery and conservation purposes in perpetuity. The U.S. Fish &
Wildlife Service and Washington Department of Ecology hold a Restrictive Covenant for
the property that additionally ensures its permanent dedication to conservation (Guthrie,
2014).
1.2 Capitol Land Trust Restoration Plan
Beside the major landscape alteration of dike removal and reconnection of tidal
wetland function, CLT has focused on removing invasive species from the Bayshore
Preserve property, and planting the golf course area with native forest and prairie species.
7
To improve water quality in Johns Creek, banks and buffer areas have been planted with
native riparian tree and shrub species, and all groundwater usage from wells on the
property has ceased (Capitol Land Trust, 2014).
During initial archeological surveying, evidence of fire was observed in soil
horizons on-site. This implies that perhaps the area represents remnant prairie habitat—
Native Americans traditionally managed prairies for control of unwanted species by
burning. Because of this evidence, a 5-10 acre dry upland area of the Preserve will be
revegetated and managed as prairie habitat. Native prairie plants will be introduced with a
long-term goal of establishing viable populations of species including Quercus garryana
(Garry oak) and the state endangered Castilleja levisecta (golden paintbrush). It is worth
noting that although evidence of historical fire was detected on-site, active burning will
not take place in the future—an initial application of herbicide will be used to prepare the
area for revegetation (Capitol Land Trust, 2014).
1.3 Biodiversity of the Oakland Bay Area
Oakland Bay hosts a variety of fish, including five salmonid species: chinook
salmon and steelhead trout (both federally listed as threatened), coho salmon (federal
species of concern), chum salmon, and cutthroat trout. Hammersley Inlet hosts a stock of
chum salmon (Oncorhynchus keta) that depends on the lower reaches of Johns Creek for
its spawning grounds. Other documented fish species found in the bay include herring,
sole, starry flounder, speckled sanddab and Pacific staghorn sculpin (Jolivette, Huber,
Van Galder, Foster, & Henry, 2014).
The intertidal wetland habitat in and around the mouth of Johns Creek includes
areas of continuously diluted saltwater and emergent vegetation that provide this critical
8
habitat for juvenile anadromous fishes. Intertidal salt marshes and mudflats provide highquality habitat for salmonids, and nearby unconsolidated shorelines and sandy beaches
provide currently functional habitat for a variety of shellfish (Guthrie, 2014; Capitol Land
Trust, 2014). Beside industrially important shellfish species like manila clams, Pacific,
and Kumamoto oysters, Oakland Bay supports populations of butter clams, native
littleneck clams, horse clams, cockles, mussels, and other gastropods (Jolivette, Huber,
Van Galder, Foster, & Henry, 2014).
Marine mammals are commonly observed, including harbor seals, sea lions, and
elephant seals. The Southern Resident orca whale population occasionally visits Oakland
Bay, and the city of Shelton has designated the bay as critical habitat for the species’
recovery (Jolivette, Huber, Van Galder, Foster, & Henry, 2014). The dynamic estuary,
home to these myriad species, also provides excellent habitat for hundreds of bird
species. At least 70 species of birds use nearshore environments like Oakland Bay,
including geese and swans, ducks and mergansers, loons, grebes, petrels, cormorants and
more (Buchanan, 2006).
Oakland Bay is located within the western hemlock (Tsuga heterophylla)
vegetation zone typical of the Puget Sound Basin. This zone is characterized by dense,
tall evergreen forests with long-living trees that historically commanded shoreline
landscapes. Dominant tree species in this zone include western hemlock, western red
cedar (Thuja plicata), and Douglas’ fir (Pseudotsuga menziesii). The understory
generally consists of woody shrub species such as salal (Gaultheria shallon), Oregon
grape (Mahonia spp.), salmonberry (Rubus spectablilis), huckleberry (Vaccinium spp.),
and ferns such as sword fern and bracken fern (Pteridium spp.) (Kruckeberg, 1991).
9
Bayshore Preserve’s intact marsh communities support halophytic (salt tolerant)
plant species such as gumweed (Grindelia integrifolia), saltweed (Atriplex spp.),
pickleweed (Salicornia virginica), saltgrass (Distichlis spicata) and others (Brennan,
2007). Much of the former golf course area is primarily vegetated with exotic grass
species, with a few relic domestic fruit trees from the Willey homesteading days
(Jolivette, Huber, Van Galder, Foster, & Henry, 2014).
CLT’s restoration of the Preserve’s riparian and upland habitats aim to enhance
existing functionality with an ultimate goal of plantings becoming self-sustaining (i.e.
requiring no maintenance interventions). This thesis study focuses on revegetating
excavated tidal channels with those goals in mind. CLT did not plan to systematically
seed the channels, but did have a high marsh seed mixture they intended to sow in tidal
basins and near basin edges. This mix included the following species: meadow barley
(Hordeum brachyantherum), tufted hairgrass (Deschampsia caespitosa), saltgrass
(Distichlis spicata), slough sedge (Carex obnupta), Douglas aster (Symphyotrichum
subspicatum), Pacific silverweed (Argentina egedii ssp. egedii), and spear saltbush
(Atriplex patula). While this project included only one of these species, it provided
opportunity to compare methods for maximizing seed germination potential by
attempting to create favorable seedbed conditions. If this experiment is successful, CLT
will have a reproducible method and can continue to study efficiency of native seed
application in wetlands, ultimately saving money and time while restoring critical salmon
habitat.
10
Chapter 2: Literature Review
2.1 Tidal Wetland Restoration
Estuaries and connected tidal marshes are some of the most productive
environments in the world (Tiner, 2013). Intact marshes undertake net primary
production at rates between 2 to 4 kg above-ground dry matter per m2 every year—
vascular plants producing this matter contribute to the food web and provide energy for a
wide range of organisms (Keefe, 1972). Salt marshes provide important ecological
functions including shoreline erosion protection, wave and storm surge dampening,
trapping water-borne sediments, nutrient cycling, and acting as nutrient sinks (Matthews
& Minello, 1994). All of this contributes to health of the greater environment, and all
organisms which rely upon it. This literature review will detail the importance and
benefits of tidal saltmarsh restoration and review methods that have proved promising.
2.1.1 The Importance of Tidal Saltmarsh Restoration
Most restorations are undertaken because human intervention with the original
environment caused degradation—whether this is urban development, dredging, draining
and diking for agricultural uses, diversion of natural waterways and installation of dams
or tidal gates to prevent flooding. Other impacts to estuarine systems can stem from
pollutant discharge, agricultural run-off or accidental oil or gas spills. Effects can include
alteration to soil and water chemistry, sedimentation rates, and changes in salinity levels
(Broome, Seneca, & Woodhouse Jr., 1988). These effects combined alter the primary
production in an estuary, which affects the quality of the food web upon which wildlife
depend (NOAA, 2008).
11
The goal of estuarine restoration is to create a self-sustaining ecosystem that
mimics the original habitat’s structure and function. While it is impossible to totally
recreate what was originally lost, restoration can aim to provide conditions that allow the
site to become like the natural system through succession of flora and fauna (Broome,
1990; Gallego Fernandez & Novo, 2007) The foundation of tidal marsh restoration rests
on restoring hydrologic connectivity to the site by simply removing barriers. This step—
reintroducing natural tidal flow—allows natural flora and fauna to restore itself (Broome
& Craft, 2000; Peck, et al., 1994). Seeding or transplanting dominant vegetation types
into the restoration site can accelerate these processes (Sullivan, 2001; Zedler, 1992).
2.1.2 Estuarine Wetland Restoration and Salmon
Salmonids depend on estuarine habitats during key developmental stages of their
life cycles. Chinook (Oncorynchus tshawytsha) and chum salmon (Oncorynchus keta)
spawn in freshwater streams, depositing their eggs in gravelly eddies. Many juvenile
salmon species use brackish waters of the estuary and nearshore environments to
acclimatize to increased water salinity levels before migrating out to sea (Fresh, 2006).
The ever-changing nature of estuaries provides an environment where species evolve and
adapt to variable and extreme conditions.
Restoring estuarine wetlands is clearly beneficial for salmonid and other fish
species in the Puget Sound. Reconnecting hydrology through tidal channels promotes fish
and other marine organism usage of the wetland—increasing sediment, nutrient, and
organic matter exchange between the marsh and the larger estuary (Minello, Zimmerman,
& Medina, 1994).
12
Young restored estuaries support high numbers of juvenile salmon. Increased
primary production in early stages of recovery supports larger invertebrate populations,
and in turn support higher populations of juvenile chinook salmon (Gray et al. 2002).
Assessments at the Nisqually River Delta show newly restored habitat compares well
with undisturbed reference sites, providing juvenile chinook salmon similar foraging
opportunities and potential for growth. With maturation of the restored sites, juvenile
chinook salmon densities increased and diet composition displayed a trajectory toward
reference conditions (David, et al., 2014).
Researchers have studied the effects of revegetation versus natural development
of tidal wetland sites, and how these methods affect juvenile fish populations. Grey et al.
were able to study structural and functional development of recovering marsh sites of
different ages compared to adjacent relatively undisturbed, undiked reference sites. This
gave researchers the opportunity to evaluate biotic and physical development of estuarine
wetlands at different stages of recovery (establishing a trajectory toward reference
conditions), and determine how and when dike removal timing impacts recovering
juvenile salmon habitat. They found that the ecological functioning juvenile fish rely on
does not necessarily result from the rapidly established vegetation, macrofaunal, and
sedimentary structural attributes that occur in many restorations—it can be gained from
simply allowing the restoration site to develop naturally after saltwater reintroduction.
Planting vegetation to simulate later successional stages doesn’t provide every structural
attribute that would increase juvenile fish populations in an estuary (Cornu & Sadro
2002; Moy & Levin 1991), but does provide buffer benefits that can create healthier
salmon habitat years down the road. For example, planting native vegetation in a newly
13
restored site can prevent invasion by aggressive exotic or native species that could
negatively impact habitat (Broome & Craft, 2000). While revegetation provides quickly
available habitat for fish, hydromorphic structural development and other factors impact
fish recruitment as well. Tidal wetland revegetation in a restoration context is not fully
understood, and it is worthy of deeper study from the perspective of proactively and
adaptively creating self-sustaining salmon habitat.
From a human-centered perspective, functional estuaries provide ecosystem
services beyond maintenance of fisheries. Porous soils of estuaries absorb water readily,
providing a natural buffer against floods and storm surges. Marsh grass populations on
tidal flats catch sediment and nutrients such as nitrogens from agricultural fertilizers,
filtering water as it flows to the bay. Microorganisms that live in estuarine soils digest
nutrients that enter through the greater watershed, buffering coastal waters against
eutrophication. The many unseen processes occurring in an estuary build the foundation
for a habitat that has become increasingly appreciated for its benefits to humankind.
Whether it be for birding, salmon watching, shellfishing, or pure beauty, healthy estuaries
are a lively environment to enjoy. Restoration of these dynamic ecological processes are
critical to wildlife, humans, the Puget Sound, and the environment at large.
2.2 Tidal Marsh Revegetation Methods
2.2.1 Halophytic plants
Halophytic (salt-tolerant) plants are the logical choice when revegetating tidally
influenced wetlands. Estuary soil salinities are naturally variable—salinities change
depending upon soil characteristics, precipitation and seasonal variation, and where in the
14
wetland measurements are taken. Soil salinities can range from a few parts per thousand
(ppt) to twice the concentration of seawater (35 ppt). Seeds and seedlings are generally
more intolerant to salinity than mature plants (Broome, Seneca, & Woodhouse Jr., 1988),
so plants are often grown in a greenhouse or harvested from other estuarine sites and
transplanted (Zedler J. B., 2001).
Because elevation of marsh surfaces determines tidal inundation time, it is
important to choose plant species with appropriate elevation requirements and salinity
tolerances (Broome & Craft, 2000). Revegetation can be undertaken systematically by
imitating climax plant communities of a similar reference site, or by experimentally
planting species broadly across elevation zones of the wetland (Broome, Seneca, &
Woodhouse Jr., 1988). This second method estimates species establishment ranges by
observing plantings’ survival at different elevations, and may be effective if no access to
a reference site is available and organizations are willing to undertake experimentation.
2.2.2 Transplanting
Tidal wetlands are commonly revegetated by transplanting or plugging
greenhouse grown stock in appropriate microhabitats to maximize plant community
diversity and cover. To avoid more aggressive species dominating the restoration site, it
is recommended to plant less aggressive or rarer species densely in their preferred
microhabitat and less densely in other areas throughout their full elevation range. Leaving
open spaces for natural recruitment of desirable species can be successful if the
surrounding area supports plant communities which spread propagules, and soil does not
become excessively saline (Sullivan, 2001).
15
2.2.3 Direct-seeding
Direct-seeding presents timing challenges. Many species need lowered salinity to
exhibit optimal germination rates (Boyd, 1981; Dawe & White, 1986; Disraeli & Fonda,
1979; Ewing, 1982; Hutchinson, 1982; Hutchinson, 1988; Jefferson, 1976; Karafatzides,
1987; Macdonald, 1984; Mall, 1969; Moody 1978; Palmisano, 1971; Smith, Mudd, &
Messmer, 1976; Smythe, 1987; Thom, 1981; Westley, 1962), so timing sowing after
periods of rainfall or freshwater flooding provides lower soil salinity conditions favorable
for germination (Kuhn & Zedler, 1997; Zedler, Nordby, & Kus, 1992). Seasonal lowsalinity gaps exist in some regions during early spring months with higher precipitation
rates, giving plants greater opportunity to successfully germinate and establish (Zedler,
Nordby, & Kus, 1992) since seeds are usually more salt sensitive than mature plants
(Broome, Seneca, & Woodhouse Jr., 1988).
Tidal influx and outflow present additional challenges when direct seeding a
restoration site (Sullivan, 2001), however if there is protection from wave action seeding
is more feasible (Broome & Craft, 2000). Storm-free periods are also of great help when
attempting to establish marsh plant communities from seed (Broome, Seneca, &
Woodhouse Jr., 1988). Since broadcast seeding alone often results in seed migration,
several different methods have been used in attempts to keep seeds in place.
Atriplex patula has been tested to determine if broadcast or shallowly covering
seeds with about one centimeter of soil would result in higher germination. The
researchers found that sowing seeds onto compact soil and covering with soil resulted in
the highest plant densities (Young, et al., 2011) Mulching mats have been anchored over
16
seeded areas (Zedler J. B., 2000), but details from this specific restoration are unknown.
Similar to hydroseeding, one method mixes seeds with mud and organic matter to create
a slurry which is “dropped” onto the marsh surface—this resulted in higher germination
in annual species only, but most of the seed did remain within the mixture rather than
being washed away (Sullivan, 2001). In the context of this project, the only drawback of
hydroseeding is that since seeds are evenly mixed throughout the mulch slurry, much of it
does not actually come into direct contact with the soil after application (NRCS, 2005).
2.2.4 Fertilization
Many restorations provide fertilization for new plantings—and while doing so can
provide a “boost” to young plant communities, it is short lived. Especially in nutrientpoor sites, supplementing nitrogen and sometimes phosphorus through fertilization can
determine whether restored plant communities are initially successful (Broome & Craft,
2000; Sullivan, 2001). Long-term, additions of N have not shown to increase
aboveground vascular plant growth (Boyer & Zedler, 1998), and have actually been
found to shift plant community dynamics in favor of nitrogen-competitive species (Boyer
& Zedler, 1999). Sullivan (2001) recommends applying fertilizers conservatively only
before transplanting and at the initial plant establishment period. This seems wise,
especially when considering the sensitivity of estuaries to eutrophication.
2.3 Hydromulching in Restoration Projects
Hydromulching (a.k.a. hydroseeding—the application of seed in or with a water
and mulch slurry) has been utilized in aspects of tidal wetland projects in Washington
State. As part of project plans, hydroseeding has been used as a seeding method for
17
temporary slope stabilization during construction of setback dikes and storage pond side
slopes. Grass seed mixes used in these projects were applied to provide soil stabilization
and vegetated buffer between farm fields and created tidal channels, not directly onto
restored estuary areas (Shannon & Wilson, Inc., 2014; Houghton & Ehlig, 2003).
Because projects were focused on creating or restoring estuarine habitat, it appears
hydroseeded dike and buffer areas were not monitored, therefore effects of these seeding
applications are unclear.
In another study of storm-water biofiltration swales, hydroseeding showed mixed
success in establishment of six species of Pacific Northwest native grasses, but
illuminated challenges faced when seeding in hydrologically dynamic environments. All
seeded bioswales except two served as drainage for stormwater retention ponds, and one
bioswale had a significantly steeper slope than the others. Due to storm-induced erosion,
one swale was reseeded one week after initial seeding and another was hand reseeded due
to poor establishment. These two swales showed little success in establishing native grass
cover by hydroseeding because of persistent inundation and high flows which caused
seed migration. One bioswale exhibited a strong germination response within two weeks,
and continued to support multiple grass species one year after seeding with 98% mean
vegetative cover (Mazer, Booth, & Ewing, 2001).
Hydroseeding was determined to be equally as effective, but no better than
traditional broadcast seeding of Fremont cottonwood in a Colorado River Basin test
restoration site. However, the researchers suggested hydroseeding might be preferred,
when site location makes it feasible, because it requires less seed preparation (Grabau,
Milczarek, Kapiscak, Raulston, Garnett, & Bunting, 2011).
18
The planting method has popularly been used for erosion control and bank
stabilization, and has potential for terrestrial revegetation in areas where non-native
invasive plants are a concern (e.g. wildfire sites, roadside construction). In Hawaii, where
non-native invasions are of special concern, a native sedge (Frimbristylis cymosa, or
Mau`u aki `aki) was tested in nursery beds for density and survival. Results indicated
highest success with hydroseeded and handsowing combined with hydromulch cap
methods. Researchers consequently concluded the both methods would be suitable for
large-scale establishment of the species (DeFrank & Baldos, 2007).
The Natural Resource Conservation Service has suggested that a best method for
using hydromulch in restoration projects is to apply seed first, and then perform
hydromulching over the seed in a second operation. This gives the highest seed to soil
contact ratio (NRCS, 2005). This information, however, is offered for restoration of
terrestrial environments. As of this writing, literature has not been identified that
explicitly deals with hydroseeding or hydromulching of wetland environments for the
purpose of restoration with native species.
2.4 Species Selection
Species tested in this experiment are Atriplex patula, Carex lyngbyei, Carex
obnupta, Eleocharis palustris, and Schoenoplectus americanus. The species are chosen
because they can tolerate a range of soil salinities, periodic inundation, and are known to
inhabit brackish marsh environments in the south Puget Sound region. Because soil
salinity is expected to increase as excavated tidal channels are subjected to tidal
influence, these species should be adaptable as soil salinity conditions change. See Table
19
1.1 for salinity tolerance ranges of each species. Following are descriptions of each
species:
•
Atriplex patula, commonly called spear saltbush or orache, is a fleshy, branched
and leafy annual that grows up to 100 cm tall. It is often covered with a whitish,
mealy substance which dissipates with age (Pojar & MacKinnon, 1994). A
“morphologically variable” annual, it commonly occurs in saline intertidal
marshes and less frequently in brackish marshes, occupying a wide range of
elevations, substrates, and salinity conditions (Hutchinson, 1988).
•
Carex lyngbyei, or Lyngbye’s sedge, is a singly growing to clumping sedge that
spreads by rhizomes and stolons, growing from 20-100 cm tall. It is very common
along the Washington coastline, colonizing tidal marshes and flats (Pojar &
MacKinnon, 1994), and is a dominant plant of brackish marshes (Knudson &
Woodhouse, 1982). Freshwater flushing is required to promote germination
(Hutchinson & Smythe, 1986; Smythe, 1987), and though mature plants can
tolerate a broad salinity range (Gordon, 1981) this species is absent in marshes
where persistent soil salinities above 20 ppt exist for most of the growing season
(Knudson & Woodhouse, 1982).
•
Carex obnupta, or slough sedge, is a rhizomatous sedge typically common to
freshwater marshes, swamps, bogs and stream-banks (Pojar & MacKinnon, 1994),
but has also been found in “high salt/brackish marsh” habitats (Boule, Brunner,
Malek, Weinmann, & Yoshino, n.d.). C. obnupta does not normally occur in the
same habitats as C. lyngbyei, with the occasional exception of brackish sloughs
and upper parts of tidal marshes (Pojar & MacKinnon, 1994).
20
•
Eleocharis palustris, also called common spike-rush, is a rhizomatous perennial
that grows singly or in clusters, from 10-100 cm tall. It thrives in wet ditches,
brackish tidal marsh and shoreline habitats, and can tolerate constant inundation
in shallow water (Pojar & MacKinnon, 1994). This species may have a wide
range of salt tolerances that comprise several distinct populations, due to its
taxonomical complexity (Hutchinson, 1988).
•
Schoenoplectus americanus (synonym Scirpus americanus), commonly named
three-square bulrush, is a rhizomatous perennial that grows singly or in small
groups, with strongly triangular stems and stalkless, clustered flowers. It grows in
brackish marshes and on shorelines, but prefers substrates that receive more
freshwater influence than the generally finer, more saline substrate that dominates
tidal marshes (Pojar & MacKinnon, 1994). It can be a dominant littoral species in
low elevation and low salinity brackish marshes (Hutchinson, 1988), thriving in
salinities between 5-10 ppt (Palmisano, 1971).
21
Species
Salinity tolerance range
Hutchinson (1988)
Salinity Tolerance
Rating—Max.
Salinity in Field
A. patula
1-30 ppt (Boyd, 1981; Dawe & White, 1986;
Hutchinson, 1982; Mall, 1969; Smith, Mudd, &
Messmer, 1976; Westley, 1962; Hutchinson,
1988)
Very Tolerant—0-45
ppt
C. lyngbyei
0-27 ppt (Boyd, 1981; Dawe & White, 1982;
Dawe & White, 1986; Disraeli & Fonda, 1979;
Ewing, 1982; Hutchinson, 1982; Jefferson, 1976;
Macdonald, 1984; Smith et al., 1976; Smythe,
1987; Thom, 1981; Westley, 1962)
Tolerant—0-20 ppt
C. obnupta
4-13 ppt (Macdonald, 1984)
Sensitive (estimate)—
N/A
E. palustris
0-12 ppt (Dawe & White, 1982; Disraeli &
Fonda, 1979; Ewing, 1982; Macdonald, 1984)
Moderately
Tolerant—0-12 ppt
S.
americanus
0-17 ppt (Boyd, 1981; Disraeli & Fonda, 1979;
Hutchinson, 1982; Karafatzides, 1987;
Macdonald, 1984; Moody 1978; Smith et al.,
1976; Westley, 1962)
Moderately
Tolerant—0-15 ppt
Table 1.1 Salinity (in parts per thousand) tolerance ranges of species chosen for this experiment.
2.5 Implications
Section 2.1 illustrates the importance of estuarine marsh restoration in the Puget
Sound and how revegetation can act as a catalyst to providing new and available
productive fish habitat. When revegetation is desired by restoration organizations, simple
direct seeding has largely been abandoned in favor of planting plugs of halophytic
species. While survivability is better when already established plugs are transplanted, this
method is labor and cost-intensive. Additionally, often replanting of plugs is necessary to
meet vegetation performance standards. Broadcast seeding and hydromulching as the
initial seeding regime for an estuarine wetland may provide a cost-effective method to
22
revegetating a site, and can be augmented by planting plugs when needed. This study
examines the viability of this seeding-hydromulch method using five halophytic plant
species that naturally occur in tidal wetland environments.
23
Chapter 3: Methods and Materials
To prepare any site for restoration requires clear planning. Because every site is
different, methods can be adapted to the site locality while adhering to the general
principles of ecological restoration. In this experiment, we used recommended methods
to calculate seed planting densities, prepare the seeding areas, measure elevations, collect
and analyze soil samples, and test seeds for viability. We were not aware of an existing
methodology for application of hydromulch in a wetland or estuarine environment at the
time of this experiment’s planning, so we used creative freedom and tested our own
method of sowing.
This section will go over methods of seed preparation and experimental design,
followed by sampling methods. Methods for a germination test that was performed to test
seed viability are explained. Finally, the types of data analysis performed are introduced
before results are reported.
3.1 Seed Preparation
Species for revegetation were chosen based on tolerance to saline conditions,
inundation, and their classification as wetland plants. Calculations were made to
determine a sowing rate of seeds per square foot, for each species, based on the
literature’s recommended rates of seeding densities per acre (Bishop & Bunter, 1999).
We encountered variables such as unknown percentages of pure live seed (PLS),
unknown chaff volume present with seed (purity), and unknown amount of tidal washaway that would occur. Because of this, recommended seeding rates were inflated to
24
compensate for any losses these variables could potentiate. Additionally, we simply had
enough seed to apply at higher rates than recommended by the literature.
Total area to be seeded was 387.5 ft2 (36 m2). Eighteen plots were to be seeded,
each measuring approximately 21.53 ft2 (2 m2). To find the amount of seed needed for
each individual plot, the total allocated weight of seed per species was divided by 18.
Grams of seed needed per plot for each species were combined to make a seed mixture
for each plot. Each identical seed mixture was pre-mixed with a 12oz scoop of sand
before broadcast seeding. Table 2.1 shows seed weights allocated and sowing rates.
Weight ratios of each species within the seed mixture were determined based on
what was known about each species performance in a brackish wetland environment, and
the size of seeds. For example, S. americanus has large seeds and makes up over 40% of
the seed mixture by weight, but the sowing rate is lower for this species.
25
Species
Avg. seeds
per gram
Total
grams
allocated
Grams
per plot
Seeds per
ft2 sowing
rate
% of seed
mixture by
weight
Atriplex patula
339
(Bishop &
Bunter,
1999)
31.11
1.72
27.25
11.4
Carex lyngbyei
1,814
(Buenning,
2011)
60.76
3.37
311.45
22.3
Carex obnupta
1,203
(AOSA,
2007)
30.48
1.69
142.76
11.2
Eleocharis
palustris
1,986
(Bishop &
Bunter,
1999)
31.45
1.74
97.64
11.6
118.1
6.55
109.51
43.4
Schoenoplectus 476
americanus
(Harwell,
2014)
Table 2.1 Experimental seed mixture species makeup and sowing rates per species. Note seed
mixture percentage does not add up to 100.0% due to rounding.
3.2 Experimental Plot Design & Installation
Six sets of five side-by-side plots, measuring one meter high by two meters wide,
were installed in three different tidal channels—two sets in each channel. The two sets
were positioned as directly across from each other as possible, one on each side of the
channel. Sets of plots were placed so each plot in a set was situated along an elevation
gradient on the channel’s side wall, with no part of any plot on the channel floor. The
tops of plots were positioned at the visible average high tide line (based on deposited
debris).
26
A one by two (1x2) meter PVC frame was built to act as a guide when installing
plots. The inside edges to corners of the frame measured one meter high by two meters
wide. Holes were drilled one half meter in from both corners of the long (2 m) section of
PVC—this served as a location to run twine through, which easily delineated the sample
plot for monitoring.
For each set of plots, a piece of rebar was sunk into the ground at the location of
the upper left corner of the plots, at the observed average high tide line. A meter tape was
run ten meters from this corner, parallel to the high tide line, and rebar was sunk into the
upper right corner of the plots. Making sure the meter tape was taut, rebar was sunk every
two meters between the outer corners to mark the upper corners of each plot. The PVC
frame was then laid over the top-edge corners and rebar was sunk into the lower corners
to complete installation of each plot.. This installation method was used to create six sets
of five side-by-side 1x2 meter plots—one set on each side of three separate channels.
27
Figure 2.1 Aerial photo of Bayshore Preserve showing channels and
locations for each set of experimental plots.
3.2.1 Plot Preparation
To prepare for seeding treatments, each plot in every block was scarified to a
depth of three inches using a bow-style metal garden rake. Any tidal deposited detritus in
plots was measured for depth and area, and removed before treatments were applied.
Nursery staples were used to secure polyethylene sheeting over control plots and plots
adjacent to active treatment plots, to avoid contamination during seeding.
28
Figure 3.1 Affixing polyethylene sheeting to plots during seeding preparation.
3.3 Treatment Applications
Five different sowing treatments were applied:
•
Unseeded control: no treatment
•
Hydromulch only control: no seed
•
Broadcast seeded + hydromulch (hereafter referred to as “seed +
hydromulch”)
•
Broadcast seeded with burlap cover
•
Broadcast seeded only
Figures 4.1 through 4.3 show layout of experimental plots in each channel, and
Tables 3.1 to 3.3 show associated treatments. Plots 1.1 and 2.1 were positioned across
from each other in every channel, closest to the channel terminus. Plots 1.5 and 2.5 are
closest to the bay in every channel.
29
Plot
A1.1
A1.2
A1.3
A1.4
A1.5
A2.1
A2.2
A2.3
A2.4
A2.5
Figure 4.1 Plot layout in Channel A.
Seed only
Seed +
hydromulch
Hydromulch
only control
Unseeded
control
Burlap
Table 3.1 Treatments
applied to each plot in
Channel A.
Plot
B1.1
B1.2
B1.3
B1.4
B1.5
B2.1
B2.2
B2.3
B2.4
B2.5
Figure 4.2 Plot layout in Channel B.
Treatment
Hydromulch
only control
Seed +
hydromulch
Burlap
Seed only
Unseeded
control
Treatment
Seed +
hydromulch
Burlap
Hydromulch
only control
Seed only
Unseeded
control
Seed +
hydromulch
Hydromulch
only control
Seed only
Unseeded
control
Burlap
Table 3.2 Treatments
applied to each plot in
Channel B.
30
Plot
C1.1
C1.2
C1.3
C1.4
C1.5
C2.1
C2.2
C2.3
C2.4
C2.5
Figure 4.3 Plot layout in Channel C.
Treatment
Burlap
Hydromulch
only control
Seed only
Seed +
hydromulch
Unseeded
control
Burlap
Unseeded
control
Hydromulch
only control
Seed only
Seed +
hydromulch
Table 3.3 Treatments
applied to each plot in
Channel C.
3.3.1 Unseeded control treatment
There was one unseeded control plot in each set of plots. This control treatment
was covered with polyethylene sheeting during the treatment application process.
3.3.2 Hydromulch only control treatment
One plot in each set received a hydromulch only control treatment. Adjacent plots
to this treatment were covered securely by polyethylene sheeting to avoid contamination.
Hydromulch was applied, by a contractor (Hoyt’s Hydroseeding, Tahuya, WA), two
inches deep to each hydromulch only treatment plot. The hydromulch product used was
Rainier Fiber™ Premium Wood Fiber Mulch For Hydroseeding and Erosion Control. See
Appendix A for details on hydromulch specifications and mixing instructions.
31
3.3.3 Broadcast seed plus hydromulch treatment
One plot in each set received a broadcast seeding plus hydromulch cap treatment.
Plots adjacent to the area to be treated were covered using polyethylene sheeting and
nursery staples. The treated plot was broadcast seeded using the prepared seed mixture,
then covered by two inches (2”) of hydromulch by the contractor.
3.3.4 Broadcast seed plus burlap cover treatment
One plot in each set received a broadcast seeding plus burlap cover treatment.
Adjacent plots were covered to avoid contamination. Prepared seed mixture was
broadcast onto the treatment plot, and a 1x2 meter piece of burlap was tacked overtop the
plot.
3.3.5 Broadcast seed only treatment
One plot in each set received a broadcast seeding treatment. Again, adjacent plots
were covered to avoid contamination. Prepared seed mixture was broadcast onto the plot.
No covering or mulch of any kind was used to secure seeds in this treatment, nor were
seeds raked into the soil after application.
After all five treatments were applied, remaining polyethylene sheeting was
removed, and treatments were checked 24 hours later.
32
Figure 5.1 Hydromulching in progress on March 9, 2016.
Figure 5.2 Examples of finished sets of seeded plots, showing all treatments applied on March 9, 2016.
33
Figure 5.3 Plots 24 hours after seeding on March 10, 2016. Note migration of hydromulch, especially
in plot at left. Hand broadcast sowing and hydromulching was performed on March 9, with hydromulch
applied between 9:00am and 10:00am (seed was applied prior, the same morning). Low tide occurred at
1:11pm at 2.58 feet (MLLW), and the next high tide occurred 6:22pm at 14.35 feet.
3.4 Plot Elevations
Elevations were measured at the midpoints of the top and bottom edges of each
plot using the standard method of differential leveling. To prepare, several benchmark
points near experimental channel edges were located using Google Maps and coordinates
were recorded. These benchmark point coordinates were input into the USGS Elevation
Point Query Service (NAD83) to retrieve point elevations in meters. A horizontal laser
level on a tripod was used to measure vertical differences in elevation of each plot’s top
and bottom edge, relative to the elevation of the benchmark point used.
The laser level was affixed to the tripod and set up so its height was just above
eye level, in a location where the line of sight allowed me to see the backsight and the
foresights. The instrument was leveled, making sure the bubble was within the circle on
34
the tripod, and that the bubble was between the two lines on the laser level. The
instrument was moved 90 degrees to both sides to check leveling.
Using a handheld GPS device with benchmark coordinates input, we navigated to
and marked the benchmark elevation point. A reading was taken at the benchmark point
to determine elevation difference between the height of the instrument and the known
elevation—this is known as the backsight. The backsight rod reading value (BS) was
added to the known elevation value at the benchmark point—this gave us the height of
the instrument (HI) relative to the benchmark’s known elevation. From this point, we
took rod readings at the midpoint of each top and bottom edge of each plot—these were
the foresights (FS). To calculate elevation of each point, we subtracted the foresight
reading from the height of the instrument (i.e. HI-FS=elev). To end the survey, we
returned to the same benchmark point and took another reading to confirm the instrument
height had not deviated outside an acceptable margin of error (0.03m) (University of
Colorado Boulder, n.d.).
3.4.1 Calculating tidal inundation
To calculate how many tides completely inundated all experimental plots,
converting elevations from the horizontal datum (NAD83), in which original data was
collected using the USGS elevation benchmark points, into a vertical datum (NAVD88)
was required. Vertical datums are used to measure heights of various points relative to a
set zero elevation, and tides are often measured using Mean Lower Low Water (MLLW).
MLLW is the average elevation of the daily lower low tide over a 19-year recording
35
period (also known as the National Tidal Datum Epoch), relative to a primary benchmark
at the tidal station (NOAA, 2017).
Tide information was calculated based on the MLLW datum predictions for
Barron Point, Little Skookum Inlet Entrance (NOAA Subordinate Station ID 9446742)
located in Shelton, WA. Little Skookum station is referenced to Seattle (Station ID
9447130), so plot elevations were adjusted using NAVD88 referred to MLLW at this
Seattle location to calculate the total number of high tides that submerged the plots
between soil sample collection dates. See appendix Table A1 for a chart showing original
elevations collected in NAD83 and converted elevations to relative datums.
3.5 Soil Sampling
3.5.1 Collection
Soil samples were collected on March 4, 2016 from each plot to test for soil
salinity. In each plot, five six-inch deep scoops were collected from random locations and
mixed together in a clean bucket to create a composite sample. This composite sample
was screened through a large screen into a new clean bucket to remove rocks and debris.
The rocks and debris were discarded back into the tidal channel, below and not in the plot
the sample was taken from. Approximately one quarter pound of this soil was reserved
and placed into a new, labeled 1-quart ziplock bag. Any remaining soil was returned to
the sample holes in the plot. Before moving on to the next plot, buckets and the sieve
were wiped with a towel until clean, rinsed with distilled water, and dried with a separate
clean towel.
36
A second round of soil samples was collected on February 13-14, 2017 to
measure salinity changes across control plots’ elevation gradients. Composite samples
were collected from three locations along the elevation gradient in the unseeded control
plot in each block, 0.1, 0.5, and 0.9 meters from the top of each control plot. Three sixinch deep scoops were collected from each elevation within the plot, mixed together, and
processed as above.
3.5.2 Drying
All first-round samples were air dried at room temperature by leaving ziplock
bags open and periodically shaking the samples to redistribute the soil until completely
dry. Second-round soil samples were dried in a drying oven, stirring periodically, at 90F
for 24-48 hours (or until completely dry) in paper bags.
3.5.3 Electrical conductivity testing for salinity
Each sample was subjected to soil electrical conductivity testing for soluble salts,
using a Hanna HI 9813-6 Portable pH/EC/TDS/C Meter. The meter was calibrated
before each testing session and after every tenth sample to a known electrical
conductivity standard using Hanna aqueous electrolyte calibration solution (HI 70031;
1413 S/cm) and temperature. Before testing began, each sample was sieved again
through a 2mm (U.S. #10) soil sieve and mixed well. A 1:5 extraction method was
used—20 grams of soil were measured and mixed with 100mL of distilled water in a
glass beaker. The solution was mixed well with a stainless steel lab spoon spatula for 30
seconds every five minutes, for 30 minutes. After the 30-minute mixing period, the
solution was allowed to rest for 30 minutes so fine sediment could settle. This solution
was strained through VWR Scientific 28213 Grade 617 (Fast) Qualitative filter paper into
37
a separate clean, dry beaker. The electrical conductivity in mS/cm (millisiemens per
centimeter) of this filtrate was read with the Hanna meter and recorded. Each sample was
retested in duplicate to determine sample variability.
3.6 Vegetation Establishment Monitoring
Experimental plots were monitored for vegetative germination and plant
establishment at low tide, once per month beginning one month after seeding. Monitoring
was conducted on the following dates: April 8, May 5, June 1, June 21, July 23, August
16, September 20-24, and October 20, 2016.
Qualitative observations were made at each visit regarding changes, patterns and
effects of tide on each type of plot; thickness of new litter and debris deposits; estimated
percent of hydromulch washed away; and development of plant communities in greater
tidal channel areas. Quantitative measurements taken included first germination dates of
observed species, density of each planted and naturally occurring species, and total
vegetative cover in each plot.
3.6.1 Sampling for density & percent cover
Using the PVC frame constructed for plot installation, 1 m2 sample areas were
delineated by running twine through pre-drilled holes and laying the frame over the rebar
plot corners. Species densities were measured by counting each live stem that occurred
within the 1m2 sample area—as a rule, stems were counted if they fell underneath the top
edge of the frame or right-side twine, and omitted if they fell underneath the bottom edge
of the frame or left-side twine. When estimating percent total vegetative cover, any and
38
all vegetative plant parts that fell within the sample area were counted, even if a plant’s
stem was itself outside of the sample area.
Figure 6.1 PVC frame and twine delineating 1m2 sample area. Top: Plot A2.5 Bottom: Plot A2.1.
3.7 Germination Testing
Germination testing was performed on Atriplex patula to determine viability of
seed. A first germination test failed due to equipment malfunction, so a second test was
39
performed to gain usable results. Due to time constraints, testing of A. patula seed was
prioritized based on occurrence of two Atriplex species in the experimental plots (see
Chapters 4 & 5).
Testing was performed in a controlled environment, under non-saline conditions.
Fresh (deionized) water was used to maximize the likelihood of germination—based on
measurements of environmental conditions on-site at the time of sowing, field conditions
in which sowing took place revealed close to freshwater soil salinity concentrations.
Before germination testing occurred, A. patula seeds underwent a period of coldmoist stratification for 30 days (Baskin & Baskin, 2001). 100 seeds of A. patula were
wrapped in cotton gauze, moistened with distilled water, and wrapped in a paper towel
moistened with distilled water. This seed packet was put into a plastic bag and twist-tied
shut. Seeds were stratified in a dedicated refrigerator at a temperature of 38F.
Once the stratification period was complete, 100 A. patula seeds were separated
into five sterilized petri dishes (20 seeds per dish) lined with one piece of filter paper
(Double Rings 90mm) and 3mL of distilled water was added. Petri dishes were placed
into the germination chamber (SG30 Controlled Environment Chamber), and started on
the 12-hour dark cycle. Although Baskin & Baskin (2002) tested A. patula at a 5/25 °C
alternating temperature cycle, this test used a 5/20 °C setting with 12 hours of dark at 5°C
and 12 hours of grow lights (40 μmol photons m-2 s-1 PPFD) at 20°C. The decision to
lower the upper temperature resulted from a desire to test multiple species at once in the
interest of time.
40
During the germination testing period, each set of seeds was monitored for
germination (emergence of a radicle—the embryonic root). As seeds sprouted, successful
germinants were recorded for the day, and removed from the petri dish before returning
samples to the germination chamber. Seeds were monitored every other day for a period
of 35 days.
3.7 Data Analysis
Data was analyzed using JMP software. A one-way analysis of variance
(ANOVA) was performed on vegetative recruitment data to compare treatment effects on
planted species against two controls (unseeded control and unseeded hydromulch only
control). A two-tailed t-test was run to compare the treatment means to each other in
significant datasets.
Linear regression analysis was performed to reveal correlations between elevation
and species recruitment and richness on select dates. Continuous variables were plotted
against each other, and appropriateness of fit was checked by plotting residuals.
41
Chapter 4: Results
This chapter contains the vegetative survey analysis results, along with results of
soil salinity and germination testing. First, section 4.1 introduces Atriplex patula as the
sole successful species in this experiment and addresses reasons for plant identification
confusion that occurred in this experiment. Section 4.2 highlights overall species
occurrence in the tidal channels and discusses natural vegetative recruitment. In section
4.3, results showing A. patula recruiting with higher success in burlap and hydromulch
treatments are explained in detail by delving into results from each monitoring date.
Section 4.4 shows that naturally recruiting species did not show significant density
differences between treatment types, but did show an unusual relationship between
species richness and elevation. Increasing soil salinity and tidal inundation time are then
discussed in section 4.5. Finally, section 4.6 reveals germination test results showed that
four species tested were indeed viable, indicating their potential for germination in the
field.
Graphs in this section reflect results analyzed from six replicates of each
treatment. Oneway ANOVA graphs are set up as follows: x-axes are labeled with
manipulative treatment types, and y-axes represent the mean live stem densities recorded
for each treatment type. Linear regression graphs show species richness plotted against
elevation per plot in which data was collected on the date of highest richness.
4.1 Planted Species Germination and Establishment to Maturity
Of five planted species, one was positively identified to have reached maturity
within the experimental plots: Atriplex patula (Figure 7.1). This species was not
42
positively identified until June 2016—at the first two monitoring visits it was confused
with a naturally occurring species, Atriplex prostrata. Both species were counted
together—they were thought to be the same—and this is reflected in the data for the April
through May 2016 monitoring period. By June, distinctive differences in leaf shape
between the observed specimens prompted an in-depth identification effort, revealing that
two species were present in the experimental plots. Beginning in June, both distinct
Atriplex species are reflected in the data.1
Figure 7.1 Recorded observations of each of five planted species within experimental plots.
1
Since completion of the experiment, a potential misidentification of the naturally occurring species
Atriplex prostrata has come to light. Based upon observations by Capitol Land Trust (CLT) ecologists, the
plant referred to in this study may in fact be Chenopodium album—which is difficult to distinguish from A.
prostrata to the naked eye. The plant in question was keyed to species A. prostrata in summer 2016,
however specimens were beginning to senesce and few intact flowers remained. This presents a problem of
ambiguous identification. Therefore, in the following sections, all mentions of A. prostrata could
potentially be referring to C. album—final identification of which species is present on-site will be
determined by CLT in 2017 when flowering specimens are present. This potential misidentification in no
way affects the data analysis or results, as only the planted Atriplex patula was analyzed for treatment
effects.
43
Figure 7.2 Recorded observations of naturally recruited (non-planted) species within experimental
plots.
4.2 Naturally Occurring Diversity in Tidal Channels
Several naturally recruited native species colonized the experimental plots (Figure
7.2) and the tidal channel areas that were not part of the experimental plots. All tidal
channel floors were abundantly vegetated by Salicornia virginica and Spergularia
canadensis, while Atriplex prostrata was commonly observed. In tidal Channel A,
Jaumea carnosa was less commonly observed, and Atriplex patula was rarely observed
on the channel floor in addition to species mentioned above. All tidal channel walls
supported A. prostrata (commonly observed), A. patula (common to less common), S.
virginica and Spergularia canadensis (both common to less common).
Channel A also supported the greatest species diversity on channel walls, with
common observations of A. prostrata, less common occurrences of A. patula (becoming
more common approaching experimental plots), Grindelia integrifolia, S. virginica
44
(generally present on lower channel walls), and Spergularia canadensis, and rare
occurrence of J. carnosa. Two unidentified species occurred on tidal channel walls. One
appeared to be in the Cyperaceae or Poaceae families (species in these families exhibit
very similar structure at young growth stages), and occupied upper elevation areas in
some experimental plots (hereafter referred to as UNKN1; Figure 8.1). The other
(UNKN2; Figure 8.2) occurred near channel edges (one specimen each in Channel A &
B), having thick, fleshy leaves to eight inches long.
Figure 8.1 (Left) Species UNKN1 occurred in experimental plots. Figure 8.2 (Right) Species
UNKN2 occurred outside of experimental plots on the edge of tidal channel.
4.3 Atriplex patula Treatment Responses
Results seem to indicate a pattern showing higher A. patula stem densities in
treatments that were manipulated by adding seed. Beginning on June 1, 2016, we clearly
see higher recruitment rates in the seed + hydromulch and burlap treatment groups than
the control treatments. Plots which were dry broadcast seeded also exhibit a pattern of
higher plant establishment than controls, but less so than more intensely manipulated
plots.
45
Overall, the pattern seems to indicate that hydromulching or otherwise providing
a stabilizing fabric over this species after broadcast seeding onto the soil results in higher
rates of plant establishment. Higher numbers of planted A. patula in the first season after
saltwater reintroduction adds value by providing more aboveground biomass to the
system, increasing the ability of the channels to trap sediment, and a faster rate of habitat
development benefitting benthic macroinvertebrates and other species.
Figure 9.1 shows an overview of mean live stem densities of A. patula on each
sampling date for each treatment type. Results from each individual monitoring date are
discussed in more detail below.
46
Figure 9.1 Mean Atriplex species densities shown for each monitoring date. Graphs in red show data
gathered before A. patula was differentiated from A. prostrata, and therefore simply reflect mean
densities of Atriplex spp. Note that over time, stem densities are clearly higher in plots that received
the hydromulch-over-seed and burlap treatments.
4.3.1 April 8, 2016
On April 8, germinants of Atriplex spp. were observed in each treatment plot.
Because germinants were so young—most had cotyledons, some had developed one set
of true leaves—it was impossible to identify to species. Significant differences (p=.0045)
in germination were observed between treatment groups on this date.
47
A two-tailed t-test showed that Atriplex spp. germinated in significantly greater
numbers in the seed + HM plot. The seed + HM group had a sample mean (x̄) of 7.33
germinants, significantly higher (p=.0019) than the unseeded control (x̄=.873). The
hydromulch only control group (hereafter referred to as “HM”) exhibited a sample mean
of 4.33 germinants per plot. The burlap and seed only treatment groups had much lower
germinant counts, and were both significantly lower (p=.0030 and .0012, respectively)
than the seed + HM group on this date. The burlap treatment resulted in x̄=1.67
germinants. The seed only treatment resulted in x̄=.50 germinants. No significant
differences were observed between the unseeded control and either the burlap (p=.8604)
or the seed only (p=.8604) treatment groups.
Figure 10.1 4/8/16 Establishment of Atriplex spp. in seed +
hydromulch, burlap, and seed only treatment plots—compared with
unseeded control and unseeded hydromulched control treatments.
48
4.3.2 May 5, 2016
By this date, highly significant differences (p<.0001) are seen between treatment
groups for Atriplex spp. At this point, Atriplex spp. were at a young stage of maturation,
with most plants showing several sets of true leaves and no flowers. While noticeable
differences in leaf shapes of Atriplex plants were observed, they weren’t distinct enough
to prompt investigation into the possible presence of two “varieties.” Therefore, at this
date, all Atriplex spp. were again counted and analyzed together.
When performing a two-tailed t-test, the sample means of all seeded treatments
reflected significantly greater numbers of Atriplex spp. germination and establishment
compared with the two controls. The sample mean of the burlap treatment (x̄=15.00) is
significantly higher than the unseeded (p=.0001, x̄=5.17) and HM (p=.0002, x̄=5.67)
control groups. The seed + HM treatment also exhibited significantly higher germination
and establishment of Atriplex spp. (x̄=14.00) compared with the unseeded (p=.0004) and
HM (p=.0007) controls. The seed only treatment exhibited a sample mean (x̄=10.83)
significantly higher than the unseeded (p=.0143) and HM (p=.0241) controls. There were
no significant differences detected between the seed only and burlap (p=.0641) or seed +
HM (p=.1534) groups. No significant differences were observed between the unseeded
and HM control groups (p=.8181).
49
Figure 10.2 5/5/16 Establishment of A. patula in seed + hydromulch,
burlap, and seed only treatment plots—compared with unseeded control
and unseeded hydromulched control treatments.
4.3.3 June 1, 2016
This is the first date in which data reflects positive identification of Atriplex
patula and Atriplex prostrata as two separate species, both occurring in the experimental
plots. For the first two data collection dates, this distinction was not confirmed and all
Atriplex species within the sample area were counted together. On this date, a oneway
analysis of variance (ANOVA) showed significant differences (p<.0001) in A. patula live
stem densities between treatment groups.
A two-tailed t-test showed significantly higher live stem counts in all seeded
treatments. The seed + HM group had a significantly higher number of established plants
50
(x̄=11.67) than the unseeded (p=.0003, x̄=2.83) and HM (p<.0001, x̄=1.00) controls. The
burlap treatment was also significantly more successful (x̄=11.83) than unseeded
(p=.0002) and HM (p<.0001) controls. Additionally, both the seed + HM (p=.0114) and
burlap (p=.0095) treatments supported significantly higher densities of live stems than
the seed only (x̄=6.00) treatment. The seed only treatment had significantly higher stem
densities compared to the HM control (p=.0237)—there was no observed difference when
compared with the unseeded control (p=.1396).
Identical analysis of A. prostrata was performed to determine if any patterns
between treatment groups existed, and because this species was unintentionally counted
on the first two monitoring dates. Oneway analysis (p=.8938, R2=.04) and a two-tailed ttest (p-values between .3337 and .9137) of A. prostrata data revealed no significant
differences between any of the treatment groups.
Figure 10.3 6/1/16 Establishment of A. patula in seed + hydromulch,
burlap, and seed only treatment plots—compared with unseeded control
and unseeded hydromulched control treatments.
51
4.3.4 June 21, 2016
Oneway analysis revealed significant differences (p<.0001) between stem
densities of A. patula across treatment groups. Two-tailed t-tests showed significant
differences between the seed + HM treatment (x̄=11.67) compared with unseeded
(p=.0003, x̄=2.83) and HM (p<.0001, x̄=1.00) controls. The burlap treatment recruited
significantly higher live stem densities (x̄=12.33) than unseeded (p=.0001) and HM
(p<.0001) controls. The seed only treatment group exhibited higher stem densities
(x̄=6.67) than only the HM (p=.0133) control group—when compared with unseeded
controls no significant difference was detected (p=.0834). The seed only treatment
densities were additionally significantly lower than seed + HM (p=.0268) and burlap
(p=.0133) treatments.
A. prostrata showed no significant differences between treatment groups
(p=.8490, R2=.05).
52
Figure 10.4 6/21/16 Establishment of A. patula in seed + hydromulch,
burlap, and seed only treatment plots—compared with unseeded control
and unseeded hydromulched control treatments.
4.3.5 July 23 and August 16, 2016
On July 23 and August 16, 2016 monitoring dates, A. patula continues to show
significant differences between treatments (p<.0001). On respective dates, the seed + HM
treatments show significantly higher stem densities (x̄=10.67 on both dates) than
unseeded (p=.0002 on 7/23/16, p=.0017 on 8/16/16) and HM (p=.0002 on 7/23/16,
p=.0002 on 8/16/16) controls. Burlap treatments show significantly higher stem densities
(x̄=12.33 on 7/23/16, x̄=12.83 on 8/16/16) than unseeded (p=.0002 on 7/23/16, p=.0001
on 8/16/16) and HM (p<.0001 on both dates) controls. Seed only treatment densities
53
(x̄=6.50 on both dates) continue to only be significantly higher than HM controls
(p=.0185 on 7/23/16, p=.0205 on 8/16/16).
A. prostrata continues to show no significant differences between treatment
groups (p=.8761, R2=.05 on 7/23/16 and p=.8591, R2=.05 on 8/16/16).
Figure 10.5 7/23/16 Establishment of A. patula in seed + hydromulch,
burlap, and seed only treatment plots—compared with unseeded control
and unseeded hydromulched control treatments.
54
Figure 10.6 8/16/16 Establishment of A. patula in seed + hydromulch,
burlap, and seed only treatment plots—compared with unseeded control
and unseeded hydromulched control treatments.
4.3.6 September 24, 2016
Again, ANOVA reveals significant differences in live stem densities of A. patula
(p=.0001) between treatment groups. Two-tailed t-tests show greater seed + HM
treatment stem densities (x̄=12.67) than unseeded (p=.0017, x̄=3.00) and HM (p=.0003,
x̄=1.00) controls. Burlap treatments also achieved significantly higher stem densities
(x̄=14.50) than unseeded (p=.0003) and HM (p<.0001) controls. Seed only plots continue
to show lower stem densities (x̄=6.83) than the previous two treatments (p=.0437 and
.0099, respectively). Seed only treatments again are only higher than HM controls
(p=.0437).
55
ANOVA reveals no significant differences in A. prostrata stem densities between
treatments (p=.8832, R2=.04).
Figure 10.7 9/24/16 Establishment of A. patula in seed +
hydromulch, burlap, and seed only treatment plots—compared with
unseeded control and unseeded hydromulched control treatments.
4.3.7 October 20, 2016
On this date most plants were almost fully senesced (dying, or entering
dormancy). Plants were counted if they exhibited signs of life—dry, dead specimens were
ignored. ANOVA showed significant differences between treatments (p=.0007). The
burlap treatment contained significantly higher live stem densities (x̄=5.33) than all other
treatment types on this date. Two-tailed t-tests confirmed this when compared with
unseeded controls (p=.0003, x̄=.83), HM controls (p<.0001, x̄=.33), seed + HM (p=.0187,
x̄=2.67), and seed only (p=.0131, x̄=2.50) treatments. The seed + HM treatment still
56
exhibited higher live stem densities than HM controls (p=.0372), but was not
significantly different from the unseeded controls (p=.0962) on this date.
A. prostrata again shows no significant differences between treatments (p=.7359,
R2=.07).
Figure 10.8 10/20/16 Establishment of A. patula in seed + hydromulch,
burlap, and seed only treatment plots—compared with unseeded control and
unseeded hydromulched control treatments. Lower densities reflect end of
season plant senescence and die-off.
4.4 Natural Recruitment in Experimental Plots and Treatment Effects
4.4.1 Stem densities across treatments
Naturally recruited species colonized the experimental plots, and live stem counts
were performed during data collection. Two species (Salicornia virginica and
57
Spergularia canadensis) occurred most commonly in the experimental plot area. A
oneway ANOVA was performed to determine if stem densities were affected by the
manipulative treatments. No significant differences were found between treatment groups
for either species (Figure 11.1). In this experiment, it appears that applying hydromulch
or burlap over the soil substrate did not affect natural recruitment of these two halophyte
species. Potentially, this indicates that these treatments, when applied as part of a salt
marsh restoration project, may not hinder natural recruitment of vascular plant species.
Figure 11.1 9/24/16 Establishment of the two most commonly occurring naturally
recruited species: S. virginica (Rsquare=0.08) and S. canadensis (Rsquare=0.07) in
each treatment group. Neither species appeared to have a relationship with any of the
applied treatments.
4.4.2 Species richness and elevation
Species richness (i.e. how many different species occurred) data were collected
for each treatment. Analysis was performed for data collected on September 24, 2016—
species richness was highest on this date. A oneway ANOVA showed no significant
58
differences between number of species occurring in different treatment groups (p=.9069,
R2=.03). We can reason that species richness was not affected by the manipulative
treatments in this experiment.
A regression analysis of species richness on the same date showed negative
correlation with elevation (Figure 12.1)—higher richness occurred in plots with lower
elevations. Naturally recruiting halophytic species could be occurring more commonly at
lower elevations where higher soil salinities occur. Because this restoration site is in early
stages of development, soil salinities will take some time to stabilize. Once that condition
is reached, it will be interesting to examine how this relationship has changed.
Figure 12.1 Species richness increased as elevation decreased (R2=0.44, p<.0001),
an unusual result. Significance was determined based on p < 0.05.
59
4.5 Soil Salinity
Soil salinity in all experimental plots was sampled on March 4, 2016 and fell
within the freshwater range, below 0.5 ppt. In fact, all soil samples except for one—plot
C1.3—tested below 0.1 ppt. A second sample was taken on February 14, 2017. These
results showed an increase in soil salinity in the unseeded control plots—all samples fell
between 0.5 and 0.75 ppt. See chart below (Figure 13.1) comparing soil salinity levels on
the two sample dates.
Salt content is expressed in parts per thousand (ppt).
o 0.0 to 0.5 ppt = fresh water
o 0.6 to 30 ppt = brackish water
o >30 to 50 ppt = saline
o Seawater = 35 ppt
o Drinking water supply generally restricted to <0.5 ppt.
o Irrigation water must be less than 2 ppt or it will kill most crop plants.
60
Figure 13.1 Soil salinity levels measured by electrical conductivity in
parts per thousand (ppt). Samples in green were collected from the
unseeded control plots.
4.5.1 Elevation and tidal inundation
After conversion to the Mean Lower Low Water (MLLW) datum, all plots fell
between 8.48 and 12.12 feet in elevation. Using NOAA Tide Predictions charts from
2016 and 2017, each high tide above 12.1 feet was counted for Barron Point, Little
Skookum Inlet Entrance tide station (Station ID 9446742) between the dates of 3/9/2016
and 2/14/2017. Between these two dates it was estimated that 530 high tide events
completely submerged all experimental plots. As the new tidal channels were exposed to
these tides, allowing seawater to absorb into the substrate, soil salinities rose (Figure
13.1). Soil salinities should be expected to continue rising over time until they stabilize.
As soil becomes more saline, plant community compositions should shift toward
vegetation types reflected in mature salt marshes.
61
4.6 Germination Test Results
A germination test of A. patula resulted in 83% of the seeds germinating quite
rapidly—at 20°C germination began within 24 hours, peaked at four days, and ceased
altogether after 11 days in the chamber. After 11 days, the temperature was raised to
25°C because A. patula germination was assumed to be nearly complete. At the
conclusion of the germination test on 5/17/17, Carex lyngbyei and Carex obnupta showed
low germination rates in freshwater conditions (3% and 8%, respectively), while
Schoenoplectus americanus germinated at 41%.
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Chapter 5: Discussion
5.1 Hydromulching onto Broadcast Seed—Success with Atriplex patula
Data from this experiment show a pattern potentially indicating a relationship
between Atriplex patula plant establishment and the hydromulch treatment applied over
broadcast seed. The oneway ANOVA for this species showed statistically significant
differences of means between the six hydromulched samples and six unseeded control
samples, for all monitoring dates. This may be promising for future restorations of tidal
wetlands in which direct seeding of this species is desired. This species could be
broadcast seeded mechanically or by hand during an ebb tide, and hydromulch applied
directly after. The other four species did not yield results in this study. This could be due
to several factors, which will be discussed in subsequent sections.
5.1.1 Identification difficulties of Cyperaceae species
The four species for which no data was collected were all in the Cyperaceae
family. Species in this family are quite challenging to identify when very young, and can
easily be confused with germinating grasses (Poaceae family). When graminoids present
as germinants, it is very difficult to distinguish between key vegetative identification
features such as stem shape and whether leaf sheaths are open or closed (Chase, Clark, &
Pohl, 1996; Carex Working Group, 2014)—and of course floral features are lacking.
Germinants were observed on several monitoring dates that may have been species
belonging to either the Cyperaceae or Poaceae families. Because of their young age,
identification to family was not determined.
63
While these plants in question appear on the first two monitoring dates, they had
disappeared by June 2016, and did not reappear in experimental plots until August. It is
speculated that unusually hot weather could have caused spring die-off of these
germinants, drying and heating the soil beyond what the tender seedlings could handle.
Perhaps a second, late emergence of germinants occurred that would account for the
period with no observations. Temperatures reached the mid to high-eighties (°F) during a
four-day period in mid-April, and in the first week of May temperatures rose to a record
high of 97°F by 5/5/16. Germinants were noted on that date, but subsequently were
absent until observed again starting on 8/16/16. Temperatures between May and August
ranged generally between 60°F and 89°F, with three temperature events above 90°F for
two or more days in a row during this time. Historical weather observations are based on
readings from Sanderson Field in Shelton, WA (Weather History for KSHN, 2016).
5.1.2 Seed limitations
Quality of seeds and sourcing locations are critically important in restoration.
Ideally, seed should be sourced as closely as geographically possible to the restoration
site. This maintains local genetic diversity and is critical in avoiding propagation of
genetic bottlenecks across the region. Seeds for this experiment were sourced from Inside
Passage Seeds, a specialty native seed company focused on providing seeds from the
Salish Sea bioregion and coastal areas ranging north and south. A. patula, C. lyngbyei,
and C. obnupta were all collected within Jefferson County, Washington. Eleocharis
palustris and Schoenoplectus americanus were collected in Benton and Lane Counties,
Oregon, respectively.
64
Beyond seed quality, age and storage conditions can affect viability. Seed for this
experiment were used within a month of receipt from Inside Passage Seeds, however seed
used for the germination test had been stored for a year in cool, dark and dry conditions.
Many species lose the ability to germinate as time passes or if exposed to high
temperatures, but not all. Because four out of the five planted species were not observed
during the first growing season at Bayshore Preserve, seeds were tested for viability in a
germination chamber under controlled conditions. E. palustris was excluded from testing
because it required temperatures above 27°C (Bartow, 2007) to germinate in a reasonable
amount of time. A. patula seeds tested were from a more recently collected (2016) lot
than seed used in the hydromulching experiment (collected 2015), and both lots were
collected from the same location (Shomer, 2016).
5.1.3 Controlled versus natural environments and seed germination
While germination testing can show whether seeds are viable or not, it is
important to note that the controlled environment of a germination chamber eliminates
several factors present in natural environments. During this test, seeds received
consistently adequate moisture throughout their germination phase and a non-variable
light and temperature regime. Seeds were not subject to potential stressors like pests,
pathogens, variable temperature and moisture inputs, tidal movement, or soil salinity
fluctuations. All of these factors can impede germination in the field, and this test merely
shows whether seeds of each species had the potential to germinate in the tidal channels.
The high rate (83%) of germination achieved for A. patula in controlled
conditions reflects results in which Baskin & Baskin achieved rapid germination of the
65
species (2001). The seed lot used in our germination test was collected in 2016. The
remaining lots of other species were collected in 2015. S. americanus achieved a 41%
germination rate, while C. lyngbyei germinated at 3% and C. obnupta germinated at 8%.
Because these three species were stored one year longer than A. patula, their viability
could have been reduced. Additionally, factors such as heat exposure during transport
may have reduced viability. Germination tests were conducted 12 months after the field
experiment was installed, introducing a potential decrease in viability over this time.
While seed viability is generally expected to decrease over time, these seeds
showed at least low levels of germination. These seeds were exposed to salinity stress—
even though within their expected tolerance ranges—and other environmental factors
immediately upon planting. As discussed, natural conditions make successful
germination a gamble, and it seems the conditions on-site were less than perfect for all
but A. patula seeds.
5.2 Atriplex spp. Treatment Responses
Though A. patula and A. prostrata were recorded as one species in early data
collection2, this mishap does begin to illuminate some interesting trends. The first
monitoring date shows two plots supporting high numbers of Atriplex germinants: seed +
hydromulch and the hydromulch only control groups. All the other treatments show very
little germination on the first date (4/8/16). The second monitoring date (5/5/16) shows
the hydromulch only control group supporting about the same amount of Atriplex spp.
plants, but the numbers rise significantly for all the other treatments. On 6/1/16, when A.
patula was positively identified and recorded separately from A. prostrata, we see the A.
2
See footnote 1, section 4.1 for information regarding ambiguous identification of A. prostrata.
66
patula density in the seed + hydromulch and burlap treatments decrease somewhat, along
with a notable decrease in the two control and seed only treatments. This general pattern
persists throughout the data collection period for A. patula. Since we see the density
numbers drop so drastically after A. prostrata was omitted, one could assume that the
hydromulch only control plot supported more of this naturally recruiting species at the
beginning of the season. Perhaps the hydromulch offered a more hospitable environment
for seeds already present in the seed bank to germinate—potentially by retaining soil
moisture during low tides (NRCS, 2003).
The A. patula density pattern reflected across the monitoring period shows the
highest recruitment in the burlap rather than the seed + hydromulch treatment. Although
the burlap treatment group did not show much germination at all on the first monitoring
date, from May on it supported a higher density of plants than any other treatment. It is
possible that the burlap itself may have slowed germination of Atriplex, blocking out
light. It is likely, however, that small germinants were simply not observed in April
because they were still underneath the fabric, and had emerged through by May. Overall,
there was not a significant difference in the densities of A. patula that were supported
between the burlap and seed + hydromulch treatments. Either way, both of the treatments
did a good job of increasing the ability of Atriplex patula to establish, compared with the
seed only treatments in the tidal channels. The USDA Natural Resource Conservation
Service recommends mulch usage when seeding for most types of restoration projects,
stating that they “reduce seed movement, mortality and predation, retain soil moisture
and fertilizers, and reduce erosion (2003).” From the results attained in this experiment, it
seems both types of “mulch” did a good job and it would be worth repeating the
67
experiment with other species, while calculating costs per square foot to determine the
most cost-effective method.
5.3 Recommendations
Repeating this experiment with A. patula and other species is recommended. At
Bayshore Preserve, second season (and beyond) data collection should determine
survivability of A. patula past the first growing season to determine if this planting
method augments longer-term development of the tidal wetland restoration—data should
be compared with reference plots in areas of the tidal channels that did not receive these
experimental treatments. An additional recommendation is identification of nursery
grown stock of Inside Passage’s A. patula seed to positively ensure that data collected
was indeed from planted seed (specimens are being grown at the time of this writing). In
the future, if possible, it may be desirable to grow seed stock to maturation prior to
experimentation to ensure positive species identification.
With future research of this method, it will be interesting to more closely study
influential factors (precipitation, extreme tides, elevation, aspect, etc.) on hydromulch
treatments more closely. For example, stratifying samples at different micro-elevations
could provide finer resolution data regarding species recruitment and secondary effects of
the hydromulch treatment on the soil substrate. It also seems wise to analyze chemical
and physical effects of hydromulch on seawater to determine any potentially detrimental
changes to water quality caused by this method. Monitoring soil development, benthic
invertebrates, and performing fish counts in treated areas compared to reference sites
would provide additional information related to functional development of revegetated
68
tidal wetlands, and aid in determining whether the methods are cost-effective into the
future of the restoration site.
69
Conclusion
Estuaries are an essential part of earth’s biosphere, providing unique habitat that
once sustained fisheries, ecosystem services for humans such as flood mitigation, and
critical habitat for wildlife. Estuary restoration efforts have increased since the
establishment of the National Estuary Program, authorized by the Clean Water Act in
1987. The science of estuary restoration has evolved over the years, with many
techniques developed and adaptively managed as scientists learn more about this
dynamic ecosystem.
Revegetation techniques such as direct seeding have often produced less than
ideal results, and producing plugs in a nursery and planting out can be costly. This thesis
researched a novel method to amend direct seeding techniques—hydromulching on top of
seeded areas to provide stabilization and buffer seed migration from tidal influence, with
hopes to gain higher revegetation establishment than with direct seeding alone. Our
hypothesis that hydromulch “seed anchoring” would increase germination and
establishment for five native saltmarsh species was not fully substantiated. Only one of
the planted species, Atriplex patula, was observed to have significantly greater
establishment in this experiment. None of the planted Cyperaceae family species were
positively identified as germinants or established plants during the course of this
experiment.
Natural recruitment of several native saltmarsh species did occur in the first year
post-dike removal time period in which this experiment took place. Prior estuary
restoration researchers have often recommended allowing natural vegetation regeneration
to occur instead of manipulating restoration sites, and long-term studies have shown
70
return of healthy ecosystem functioning without extra effort. However, if restoration
biologists or organizations desire specific plant communities and have the resources to do
some experimentation, this method could be worthy of continued research study. If found
to be successful with certain plant species, hydromulching could provide a quick and easy
revegetation method and allow organizations to stretch their project dollars to be as
effective as possible.
71
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List of Appendices
Table A 1: Differential leveling plot elevation data ......................................................... 78
Table A 2: Soil salinity electrical conductivity data for samples collected 3/4/16 ........... 79
Table A 3: Soil salinity electrical conductivity data for samples collected 2/14/17. ........ 80
Table A 4: Comparison of soil salinities in unseeded control plots on two dates. ........... 81
Figure A 1: Graphical comparison of soil salinities……………………………………..81
Appendix A: Burlap fabric & hydromulch specifications……………………………….82
Appendix B: Organization Contact Information………………………………………....83
77
Backsight Height of Foresight
(BS)
Instrument (FS)
Elevation Elev in
Station (STA)
meters
(HI) meters meters in meters feet
Remarks
USGS BM CHA2
A
0.22
2.06
6.76 begin
2.28
2.28
2.28
2.28
2.28
2.28
2.28
2.28
2.28
2.28
2.28
2.28
2.28
2.28
2.28
2.28
2.28
2.28
2.28
2.28
2.28
0.39
0.8
0.48
0.9
0.55
0.94
0.57
0.97
0.52
0.98
0.35
0.83
0.45
0.84
0.36
0.82
0.39
0.81
0.36
0.85
0.25
B
2.03
0.11
2.7
2.81
2.81
2.81
2.81
2.81
2.81
2.81
2.81
2.81
2.81
2.81
2.81
2.81
2.81
2.81
2.81
2.81
2.81
2.81
2.81
2.81
C
1.89
1.48
1.8
1.38
1.73
1.34
1.71
1.31
1.76
1.3
1.93
1.45
1.83
1.44
1.92
1.46
1.89
1.47
1.92
1.43
6.20
4.86
5.91
4.53
5.68
4.40
5.61
4.30
5.77
4.27
6.33
4.76
6.00
4.72
6.30
4.79
6.20
4.82
6.30
4.69
A1.1 TOP
A1.1 BOTTOM
A1.2 T
A1.2 B
A1.3 T
A1.3 B
A1.4 T
A1.4 B
A1.5 T
A1.5 B
A2.1 TOP
A2.1 BOTTOM
A2.2 T
A2.2 B
A2.3 T
A2.3 B
A2.4 T
A2.4 B
A2.5 T
A2.5 B
USGS BM CHA2
6.66 end
2.64
0.17
2.62
USGS BM CHC1 47.24774, N47.24774,
8.60 begin
-123.03905 W123.03905
2.07
1.76
1.84
1.55
1.75
1.54
1.9
1.6
1.96
1.63
2.2
1.83
2.26
1.84
2.28
1.84
2.41
1.98
2.29
1.93
6.79
5.77
6.04
5.09
5.74
5.05
6.23
5.25
6.43
5.35
7.22
6.00
7.41
6.04
7.48
6.04
7.91
6.50
7.51
6.33
0.16
2.63
Adjusted
BM
elevation in
NAVD88 (ft) Difference
13.31
47.24774,
-123.03905
Adjusted
elev NAVD88
(ft)
Adjusted
elev in
MLLW
(ft)
A1.1 TOP
A1.1 BOTTOM
A1.2 T
A1.2 B
A1.3 T
A1.3 B
A1.4 T
A1.4 B
A1.5 T
A1.5 B
A2.1 TOP
A2.1 BOTTOM
A2.2 T
A2.2 B
A2.3 T
A2.3 B
A2.4 T
A2.4 B
A2.5 T
A2.5 B
12.75
11.41
12.46
11.08
12.23
10.95
12.16
10.85
12.33
10.82
12.88
11.31
12.56
11.28
12.85
11.34
12.75
11.37
12.85
11.24
10.41
9.07
10.12
8.74
9.89
8.61
9.82
8.51
9.99
8.48
10.54
8.97
10.22
8.94
10.51
9.00
10.41
9.03
10.51
8.90
B1.1 TOP
B1.1 BOTTOM
B1.2 T
B1.2 B
B1.3 T
B1.3 B
B1.4 T
B1.4 B
B1.5 T
B1.5 B
B2.1 TOP
B2.1 BOTTOM
B2.2 T
B2.2 B
B2.3 T
B2.3 B
B2.4 T
B2.4 B
B2.5 T
B2.5 B
13.47
11.70
13.28
11.90
13.31
12.00
13.47
12.03
13.38
12.03
14.20
12.56
13.87
12.42
13.93
12.46
14.13
12.75
14.16
12.69
11.13
9.36
10.94
9.56
10.97
9.66
11.13
9.69
11.04
9.69
11.86
10.22
11.53
10.08
11.59
10.12
11.79
10.41
11.82
10.35
C1.1 TOP
C1.1 BOTTOM
C1.2 TOP
C1.2 B
C1.3 T
C1.3 B
C1.4 T
C1.4 B
C1.5 T
C1.5 B
C2.1 TOP
C2.1 BOTTOM
C2.2 T
C2.2 B
C2.3 T
C2.3 B
C2.4 T
C2.4 B
C2.5 T
C2.5 B
13.34
12.33
12.59
11.64
12.29
11.60
12.79
11.80
12.98
11.90
13.77
12.56
13.97
12.59
14.03
12.59
14.46
13.05
14.06
12.88
11.00
9.99
10.25
9.30
9.95
9.26
10.45
9.46
10.64
9.56
11.43
10.22
11.63
10.25
11.69
10.25
12.12
10.71
11.72
10.54
6.5514696
USGS BM CHB2 47.24687, N47.24687,
8.86 begin
-123.03963 W123.03963
0.17
0.72
1.03
0.95
1.24
1.04
1.25
0.89
1.19
0.83
1.16
0.59
0.96
0.53
0.95
0.51
0.95
0.38
0.81
0.5
0.86
2.11
1.57
2.05
1.63
2.06
1.66
2.11
1.67
2.08
1.67
2.33
1.83
2.23
1.79
2.25
1.8
2.31
1.89
2.32
1.87
USGS National
Map - Elevation
BM long, lat Point Query
used in GPS Service coords
N47.24473,
W123.04085
1/3 arc-second
dataset
B1.1 TOP
B1.1 BOTTOM
B1.2 T
B1.2 B
B1.3 T
B1.3 B
B1.4 T
B1.4 B
B1.5 T
B1.5 B
B2.1 TOP
B2.1 BOTTOM
B2.2 T
B2.2 B
B2.3 T
B2.3 B
B2.4 T
B2.4 B
B2.5 T
B2.5 B
USGS BM CHB2
8.66 end
2.79
2.79
2.79
2.79
2.79
2.79
2.79
2.79
2.79
2.79
2.79
2.79
2.79
2.79
2.79
2.79
2.79
2.79
2.79
2.79
2.79
0.7
1.24
0.76
1.18
0.75
1.15
0.7
1.14
0.73
1.14
0.48
0.98
0.58
1.02
0.56
1.01
0.5
0.92
0.49
0.94
Benchmark
(BM) long,
lat used in
GPS
47.24473,
-123.04085
6.92
5.15
6.73
5.35
6.76
5.45
6.92
5.48
6.82
5.48
7.64
6.00
7.32
5.87
7.38
5.91
7.58
6.20
7.61
6.14
C1.1 TOP
C1.1 BOTTOM
C1.2 TOP
C1.2 B
C1.3 T
C1.3 B
C1.4 T
C1.4 B
C1.5 T
C1.5 B
C2.1 TOP
C2.1 BOTTOM
C2.2 T
C2.2 B
C2.3 T
C2.3 B
C2.4 T
C2.4 B
C2.5 T
C2.5 B
USGS BM CHC1
8.63 end
Table A 1: Differential leveling plot elevation data. Adjusted elevations to local tidal datum (MLLW) in
right-most column.
78
Soil Samples collected by Allie Denzler, Josh Carter, Brendan Duffy on March 4 2016.
Plot
A1.1
A1.2
A1.3
A1.4
A1.5
A2.1
A2.2
A2.3
A2.4
A2.5
B1.1
B1.2
B1.3
B1.4
B1.5
B2.1
B2.2
B2.3
B2.4
B2.5
C1.1
C1.2
C1.3
C1.4
C1.5
C2.1
C2.2
C2.3
C2.4
C2.5
mS/Cm Adjusted
g/100ml Factor Reading value
ppm
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
ppt
1
1
1
1
1
0.05
0.09
0.07
0.04
0.05
0.050
0.090
0.070
0.040
0.050
32
57.6
44.8
25.6
32
0.0320
0.0576
0.0448
0.0256
0.0320
1
1
1
1
1
0.045
0.04
0.04
0.04
0.04
0.045
0.040
0.040
0.040
0.040
28.8
25.6
25.6
25.6
25.6
0.0288
0.0256
0.0256
0.0256
0.0256
1
1
1
1
1
0.07
0.09
0.07
0.05
0.1
0.070
0.090
0.070
0.050
0.100
44.8
57.6
44.8
32
64
0.0448
0.0576
0.0448
0.0320
0.0640
1
1
1
1
1
0.04
0.04
0.045
0.09
0.045
0.040
0.040
0.045
0.090
0.045
25.6
25.6
28.8
57.6
28.8
0.0256
0.0256
0.0288
0.0576
0.0288
1
1
1
1
1
0.14
0.07
0.26
0.12
0.13
0.140
0.070
0.260
0.120
0.130
89.6
44.8
166.4
76.8
83.2
0.0896
0.0448
0.1664
0.0768
0.0832
1
1
1
1
1
0.08
0.06
0.06
0.07
0.06
0.080
0.060
0.060
0.070
0.060
51.2
38.4
38.4
44.8
38.4
0.0512
0.0384
0.0384
0.0448
0.0384
20
20
20
1
1
1
1
1
0.05
0.09
0.07
0.05
0.05
0.050
0.090
0.070
0.050
0.050
32
57.6
44.8
32
32
0.0320
0.0576
0.0448
0.0320
0.0320
Mean soil
salinity
(ppt)
0.032
0.058
0.045
0.029
0.032
20
20
20
1
1
1
1
1
0.05
0.04
0.035
0.04
0.04
0.050
0.040
0.035
0.040
0.040
32
25.6
22.4
25.6
25.6
0.0320
0.0256
0.0224
0.0256
0.0256
0.030
0.026
0.024
0.026
0.026
20
20
20
1
1
1
1
1
0.065
0.07
0.07
0.06
0.1
0.065
0.070
0.070
0.060
0.100
41.6
44.8
44.8
38.4
64
0.0416
0.0448
0.0448
0.0384
0.0640
0.043
0.051
0.045
0.035
0.064
20
20
20
1
1
1
1
1
0.03
0.04
0.04
0.09
0.05
0.030
0.040
0.040
0.090
0.050
19.2
25.6
25.6
57.6
32
0.0192
0.0256
0.0256
0.0576
0.0320
0.022
0.026
0.027
0.058
0.030
20
20
20
1
1
1
1
1
0.14
0.07
0.245
0.11
0.12
0.140
0.070
0.245
0.110
0.120
89.6
44.8
156.8
70.4
76.8
0.0896
0.0448
0.1568
0.0704
0.0768
0.090
0.045
0.162
0.074
0.080
20
20
20
1
1
1
1
1
0.08
0.05
0.04
0.06
0.05
0.080
0.050
0.040
0.060
0.050
51.2
32
25.6
38.4
32
0.0512
0.0320
0.0256
0.0384
0.0320
0.051
0.035
0.032
0.042
0.035
mS/Cm Adjusted
g/100ml Factor Reading value
ppm
20
20
20
20
20
20
20
20
20
20
20
20
ppt
Table A 2: Soil salinity electrical conductivity data for samples collected 3/4/16, run in duplicate.
79
Samples collected by Allie and Conrad on Feb 13-14, 2017
mS/Cm Adjusted
Avg ppt for
entire plot
Plot
g/100ml Factor Reading value
A1.5 U
20 1
0.75
0.750
A1.5 M
20 1
0.97
0.970
A1.5 L
20 1
0.9
0.900
ppm
480
620.8
576
0.4800
0.6208
0.5760
0.5589
A2.4 U
A2.4 M
A2.4 L
20
20
20
B1.5 U
B1.5 M
B1.5 L
B2.4 U
B2.4 M
B2.4 L
20
20
20
20
20
20
ppt
1
1
1
1.24
1.35
0.7
1.240
1.350
0.700
793.6
864
448
0.7936
0.8640
0.4480
0.7019
1
1
1
0.77
1.25
1.32
0.770
1.250
1.320
492.8
800
844.8
0.4928
0.8000
0.8448
0.7125
1
1
1
0.88
0.82
0.94
0.880
0.820
0.940
563.2
524.8
601.6
0.5632
0.5248
0.6016
0.5632
C1.5 U
C1.5 M
C1.5 L
20
20
20
1
1
1
1.31
1.16
0.98
1.310
1.160
0.980
838.4
742.4
627.2
0.8384
0.7424
0.6272
0.7360
C2.2 U
C2.2 M
C2.2 L
20
1
1
1
0.89
1.06
1.04
0.890
1.060
1.040
569.6
678.4
665.6
0.5696
0.6784
0.6656
0.6379
20
20
Table A 3: Soil salinity electrical conductivity data for samples collected 2/14/17.
80
Mean soil Mean soil
salinity ppt - salinity ppt Control Plot 03/04/2016 02/14/2017
A1.4
0.03
0.56
A2.4
0.03
0.70
B1.5
0.06
0.71
B2.4
0.06
0.56
C1.5
0.08
0.74
C2.2
0.04
0.64
Table A 4: Comparison of soil salinities in unseeded control plots on two dates.
0.80
0.70
0.60
0.50
0.40
0.30
0.20
0.10
0.00
Mean soil salinity
ppt - 03/04/2016
Mean soil salinity
ppt - 02/14/2017
A1.4 A2.4 B1.5 B2.4 C1.5 C2.2
Figure A 1: Graphical comparison of soil salinities in unseeded control plots on two dates.
81
Appendix A
Materials
Easy Gardener brand 100% natural burlap fabric. Address: easy gardener products,
inc., p.o. box 21025, Waco, tx 76702-1025
Rainier Fiber™ Premium Wood Fiber Mulch For Hydroseeding and Erosion Control.
Net Wt. 50 lbs/22.7 kg. Manufactured by: Rainier Veneer Inc. P.O. Bos 1250 Graham,
Wash. 98338. 253-846-0242. Date stamp on bag: 07/21-15 15:37.
SPECIFICATION
TEST METHOD TEST RESULTS
Moisture content
ASTM D 644
12% ± 3%
Organic matter (minimum)
ASTM D 586
98%
Ash content (maximum)
ASTM D 586
2%
Water holding capacity (minimum) ASTM D 7367
1300%
pH @ 3% fiber concentration
SW846 9045
4.5 ± 0.5
Color
Observed
Green
Mixing instructions
All Rainier products are smooth loading wood fiber mulches with load rates up to 25
bags per 3000 gallons of water or 50 lbs per 120 gallons of water. Loading rates may vary
depending on the type of machine and its working capability.
Mixing instructions:
1) Mechanically agitated hydroseeders:
A.
B.
C.
D.
Fill tank with water to bottom of agitator shaft.
Start agitation
Keep water running while adding fiber until proper amount is reached.
Mix slurry approximately 5 minutes for Rainier Fiber. Mix for minimum of 8
minutes for +Tac, BFM, SMM and Supreme to fully activate the additives.
2) Before spraying:
Slow agitator speed down to approximately ¼ speed—just fast enough to keep the
slurry in an active rolling mix. Do not run agitators fast or they will bear air in the
slurry. Slowing down the agitators will help avoid cavitation problems.
82
Appendix B
Contact Information
•
Bayshore Preserve
3800 WA-3
Shelton, WA 98584
•
Capitol Land Trust
4405 7th Ave SE, Suite 306
Lacey, WA 98503
(360) 943-3012
info@capitollandtrust.org
•
Inside Passage Seeds
P.O. Box 639
Port Townsend, WA 98368
1-800-361-9657
(360) 385-6114
forest@insidepassageseeds.com
•
Hoyt’s Hydroseeding
Tahuya, WA
360-204-3053
steve@hoytshydroseeding.com
•
Mason Conservation District
450 W. Business Park Rd.
Shelton, WA 98584
(360) 427-9436
https://www.masoncd.org/
83
