Evaluating the Effects of Mechanical and Manual

Home , Ammophila (plant), Ammophila arenaria, Erysimum menziesii, Poa confinis

EVALUATING THE EFFECTS OF MECHANICAL AND MANUAL

REMOVAL OF Ammophila arenaria WITHIN COASTAL

DUNES OF HUMBOLDT COUNTY

______

A Thesis

Presented

to the Faculty of

California State University, Chico

______

In Partial Fulfillment

of the Requirements for the Degree

Master of Science

Biological Sciences

______

Ayla Joy Mills

Spring 2015 EVALUATING THE EFFECTS OF MECHANICAL AND MANUAL

REMOVAL OF Ammophila arenaria WITHIN COASTAL

DUNES OF HUMBOLDT COUNTY

A Thesis

Ayla Joy Mills

Spring 2015

APPROVED BY THE DEAN OF GRADUATE STUDIES AND VICE PROVOST FOR RESEARCH:

______Eun K. Park, Ph.D.

APPROVED BY THE GRADUATE ADVISORY COMMITTEE:

______Guy Q. King, Ph.D. Kristina Schierenbeck, Ph.D., Chair

Graduate Coordinator ______Colleen Hatfield, Ph.D.

______Guy Q. King, Ph.D. Adrienne Edwards, Ph.D. ACKNOWLEDGMENTS

I would like to thank my advisor and committee chair Kristina Schierenbeck.

She has given me great advice and assistance throughout the process. I would also like to thank my knowledgeable committee members Colleen Hatfield and Adrienne Edwards. A special thanks to Amber Transou and California State Park’s North Coast Redwood

District for providing me with guidance, funding, equipment, and for making this project possible. I’d like to thank my wonderful husband Jason who helped me set up my plots and collect data, even when it was cold and raining. I couldn’t have done it without you. I would like to thank my Mom who helped me financially and emotionally make it through graduate school. I would also like to thank my best friend Krystal Godfrey for always being there to listen to me vent and also for helping collect data. Nancy Carter deserves a big thanks for helping me statistically analyze my data and for being a great teacher. The

Chico State Associated Students Sustainability Fund provided me with funding for the materials required for setting up and monitoring my experimental plots. I would also like to thank my friends, and Chico State Alumni, Tony Vertolli and Aurelia Gonzalez for helping me collect data. I would also like to thank the California Native Plant Society’s

Mt. Lassen Chapter and the Chico State Biology Department for funding trips to present my research at the Centennial Celebration of the California Botanical Society and the

CNPS Conservation Conference.

iii TABLE OF CONTENTS

PAGE

Acknowledgments ...... iii

List of Tables...... vi

List of Figures...... viii

Abstract...... x

CHAPTER

I. Introduction...... 1

II. Literature Review...... 7

The State of the Coast...... 7 California Coastal Dunes...... 8 Geology ...... 8 Climate ...... 9 Soils ...... 10 Dune Plant Adaptations...... 10 Dune Morphology ...... 11 Common Dune Mat Plant Species of Northern California...... 13 Study Species...... 15

III. Methods...... 19

Study Area...... 19 Project Plan...... 20 Removal...... 20 Monitoring...... 22 Time Comparison Monitoring...... 25 Statistical Analysis ...... 26

iv CHAPTER PAGE

IV. Results...... 28

A. arenaria before Treatment and Within the Control Sites ...... 28 Analysis of the Treatment Method of A. arenaria ...... 29 Analysis of the Monitoring Time Intervals for A. arenaria ...... 30 Analysis of the Interaction Between Treatment and Monitoring Time Interval for A. arenaria ...... 32 Analysis of the Treatment for Native Plant Recovery After A. arenaria Removal ...... 33 Analysis of the Monitoring Time Intervals for Native Plant Recovery After A. arenaria Removal...... 33 Analysis of the Interaction Between Treatment and Monitoring Time Interval for Native Plants ...... 34 Analysis of the Treatment and Time Interval for Other Non-native Plants After A. arenaria Removal...... 34 Analysis of the Interaction Between Treatment and Monitoring Time Interval for Other Non-native Plants...... 36 Analysis of the Time Comparison Sites ...... 37

V. Discussion...... 44

VI. Conclusions...... 53

Literature Cited...... 55

Appendices

A. Plant Species List for Gold Bluffs Beach...... 64 B. Plant Species List for Little River and Clam Beach...... 67

v LIST OF TABLES

TABLE PAGE

1. Dates of Initial Mechanical Removal and Manual Removal of A. arenaria at Gold Bluffs Beach ...... 22

2. Modified Braun-Blanquet Cover Scale Used to Estimate Percent Cover Values for Vegetation Within Quadrats ...... 24

3. Project Timeline Including Vegetation Monitoring Dates at Time Zero (Before Initial Removal of A. arenaria Occurred), 3 Months Post-Removal, 6 Months Post-Removal, and 12 Months Post-Removal Occurred at Gold Bluffs Beach ...... 24

4. Time frame in which monitoring and removal of A. arenaria occurred at the time comparison sites ...... 25

5. Mean Cover Class Values (± SD) for A. arenaria and Tukey Pairwise Comparisons of Treatment and Monitoring Time Interval Interactions ...... 29

6. Mean Cover Class Values (± SD) for A. arenaria and Tukey Pairwise Comparisons of Treatment Method (Mechanical, Hand, and Control) Averaged over All the Time Frames ...... 31

7. Mean Cover Class Values (± SD) for A. arenaria and Tukey Pairwise Comparisons of Monitoring Time Interval (Time Zero, 3 Months, 6 Months, and 12 Months Post-Removal) When Averaged over All the Treatments...... 32

8. Mean Cover Class Values (± SD) for Native Plants and Tukey Pairwise Comparisons of Monitoring Time Interval (Time Zero, 3 Months, 6 Months, and 12 Months Post-Removal) When Averaged over All the Treatments...... 33

9. Mean Cover Class Values (± SD) for Native Plants and Tukey Pairwise Comparisons of Treatment and Monitoring Time Interval Interactions...... 35

vi TABLE PAGE

10. Mean Cover Class Values (± SD) for Other Non-Native Plants and Tukey Pairwise Comparisons of Treatment and Monitoring Time Interval Interactions ...... 38

11. Mean Cover Class Values (± SD) and Tukey Pairwise Comparisons for A. arenaria regrowth and Native Plant Recovery at the Time Comparison Sites ...... 40

vii LIST OF FIGURES

FIGURE PAGE

1. Map of Gold Bluffs Beach Divided into Blocks 1-7 ...... 21

2. Experimental Design Used to Examine Treatment Effects ...... 23

3. Interaction Plot for A. arenaria Removal Showing Differences Between the Hand Treatment (in Red), Mechanical Treatment (in Green), and the Control Treatment (in Blue) Across Time Intervals (Time Zero, 3 Months After Removal, 6 Months After Removal, and 12 Months After Removal) at Gold Bluffs Beach...... 30

4. Interaction Between Treatments (Hand (H), Mechanical (M), and Control(C)) and Monitoring Time Interval (Time Zero, 3 Months After Removal, 6 Months After Removal, and 12 Months After Removal) of A. arenaria at Gold Bluffs Beach ...... 31

5. Interaction Plot for Native Plant Recovery After Removal of A. arenaria That Shows the Differences Between the Hand Treatment (in Red), Mechanical Treatment (in Green), and the Control Treatment (in Blue) Across Time Intervals (Time Zero, 3 Months After Removal, 6 Months After Removal, and 12 Months After Removal)...... 36

6. Interaction Between Treatments (Hand (H), Mechanical (M), and Control (C)) and Monitoring Time Interval (Time Zero, 3 Months After Removal, 6 Months After Removal, and 12 Months After Removal) for Native Plant Recovery Following A. arenaria Removal at Gold Bluffs Beach ...... 37

7. Interaction Plot for Other Non-Native Plants Pre and Post Removal of A. arenaria That Shows the Differences Between the Hand Treatment (in Red), Mechanical Treatment (in Green), and the Control Treatment (in Blue) Across the Different Time Intervals (Time Zero, 3 Months After Removal, 6 Months After Removal, and 12 Months After Removal) ...... 39

viii FIGURE PAGE

8. Interaction Between Treatments (Hand, Mechanical, and Control) and Monitoring Time Interval (Time Zero, 3 Months After Removal, 6 Months After Removal, and 12 Months After Removal) for Other Non-native Plants After A. arenaria Removal at Gold Bluffs Beach ...... 40

9. The Difference in A. arenaria regrowth Between the Three Time Comparison Sites (GBB Block 1, Little River State Beach, and Clam Beach) at the First and the Last Monitoring Time Interval ...... 41

10. The Difference in Native Plant Recovery following A. arenaria Removal at the Three Time Comparison Sites (GBB Block 1, Little River State Beach, and Clam Beach) at the First and the Last Monitoring Time Interval...... 42

11. The Difference in Other Non-native Plant Growth Following A. arenaria Removal at the Three Time Comparison Sites (GBB block 1, Little River State Beach, and Clam Beach) at the First and the Last Monitoring Time Interval...... 43

ix ABSTRACT

EVALUATING THE EFFECTS OF MECHANICAL AND MANUAL

REMOVAL OF Ammophila arenaria WITHIN COASTAL

DUNES OF HUMBOLDT COUNTY

Ayla Joy Mills

Master of Science in Biological Sciences

California State University, Chico

Spring 2015

Ammophila arenaria was introduced to North America in 1868 for sand stabilization, and since its introduction it has invaded most of the dune ecosystems of the

Pacific coast of North America. The 222 ha dune ecosystem at Gold Bluffs Beach within

Prairie Creek Redwoods State Park (Humboldt County, California) has become heavily invaded by A. arenaria , and if left unmanaged this habitat was likely to become a dense monoculture of A. arenaria. My hypothesis tests the efficacy of mechanical (excavators and dozers) and manual (hand-pulling) removal methods on plant community composition and regeneration. Vegetation was characterized and monitored before, during, and after A. arenaria removal. Six 25 m² plots running parallel to the shoreline were set up within each of the different removal sites (two mechanical, two manual, two control) for a total of 36 plots. Each plot was marked with GPS and rebar and three

x equally-spaced transects were established with five 1m² plots along each transect. Species percent cover values within the plots were established and subsequently monitored every

3 months to quantitatively evaluate A. arenaria reestablishment and native plant recovery. Mechanical removal sites had significantly lower A. arenaria regrowth than the hand removal and the control sites when averaged over all time intervals. One year post- removal, however, A. arenaria regrowth in the hand and mechanical removal sites was not significantly different. The hand removal sites had significantly more native plant cover three months post-removal than the mechanical removal sites, but this difference no longer held at one year post-removal. Mechanical removal of A. arenaria has proven to be an effective removal technique that has not impeded native plant recovery at Gold

Bluffs Beach, but as with most techniques for removing A. arenaria, properly timed follow up treatment is necessary. Documenting which removal technique is most effective at eliminating A. arenaria is imperative for the conservation management of coastal dunes and the rare species that rely on them. Ultimately, my research provides the basis to establish a conservation management protocol to effectively control one of the worst invasive plants in coastal ecosystems of the Pacific Northwest, while minimizing damage to native plant communities.

CHAPTER I

INTRODUCTION

The introduction and spread of invasive species has become a serious problem throughout the world (Simberloff et al. 2005). Invasive species are the second biggest threat to biodiversity after habitat loss (Lonsdale 1999; Randall 1996; Simberloff et al.

2005) and cost the US economy $137 billion US dollars every year (Pimentel et al.

2000). Government officials and land managers responsible for managing and preserving natural areas are faced with the complicated task of controlling invasive species. Invasive species control is an important and expensive part of ecosystem management and therefore needs to be done effectively and efficiently. Better policy, research, and education on invasive species are needed in order to assure that conservation efforts are being carried out using science-based decisions.

Invasive plants have the ability to completely alter ecosystems through a variety of mechanisms via competition with native plants for light, space, nutrients, pollinators, and water, and can result in changes in population dynamics, ecosystem processes, and community structure (D’Antonio and Vitousek 1992; Vitousek et al.

1996). When a plant is introduced into a habitat in which it did not evolve, it is potentially freed from its natural reproductive barriers, competitors, and natural controls.

This allows introduced species to become widespread and sometimes invasive.

1 2

Mediterranean climates, like California, make up less than 5% of the Earth’s surface and yet hold 20% of the earth’s plant species (Lambrinos 2000). The parks of

California are some of the most frequently visited in the world and have therefore been heavily impacted by humans. The susceptibility of Mediterranean landscapes is very high due to mild climates and high human population densities (D'Antonio et al. 2001). In addition, the scenic beauty of coastal California has attracted millions of people and unfortunately, the non-native species that have come with them. Invasive plants spread rapidly in the heavily visited and disturbed ecosystems of coastal California (Seabloom et al. 2006). Of the 4,844 total species in Califonia, 1,025 (17.5 %) are non-native

(Schierenbeck et al. 2007; Vitousek et al. 1996). Non-native species arrive on animals, people, packaging materials, boats, planes, and cars. They are often intentionally planted for aesthetic reasons or to serve human purposes such as wind breaks, soil stabilization, and erosion control.

Coastal dunes are a unique ecosystem. The species that live in coastal dunes are subject to fog, sea spray, strong coastal wind, intense solar radiation, and moving sand (Boyce 1954). California’s coastal dunes are home to many animals, including the threatened Western Snowy Plover. Rare and endangered plant species such as Abronia umbellata Lam. var. breviflora (Standl.) L. A. Galloway (pink sand verbena,

Nyctaginaceae), Lathyrus japonicas Willd (beach pea, Fabaceae), Erysimum menziesii

(Hook.) Wettst. ssp. eurekense R.A. Price (Humboldt Bay wallflower, Brassicaceae), and

Layia carnosa (Nutt.) Torr. and A. Gray (beach layia, Asteraceae) inhabit some of the coastal dunes of Northern California (Pickart and Sawyer 1998). The plants that depend on dune habitat have evolved special adaptations for surviving in the harsh coastal

3 conditions, including dense pubescence, foliar succulence, deep and starchy roots, and asexual reproduction (Maun 1994; Pickart 2008). Coastal dunes are being decimated at an alarming rate due to the establishment of invasive species that change community structure, dune function, and displace many native dune species.

One of the most problematic invasive dune plant species is Ammophila arenaria (L.) Link (European beachgrass, Poaceae), which was planted along the Pacific

Coast from the late 1800s to the mid-1900s for sand stabilization (DiTomaso and Healy

2007; Seabloom and Wiedemann 1994). Ammophila arenaria is a perennial and rhizomatous grass native to the sandy coastlines of northern Europe between the latitudes of 30° to 63° N (Wiedemann 1987). It has clumped, erect stems and in-rolled basal and cauline leaves (Baldwin et al. 2012). Reproducing vegetatively from rhizomes, and less often, by seed (Buell et al. 1995), A. arenaria spreads rapidly and outcompetes native dune species with its dense stands and aggressive rhizomes (Aptekar and Rejmanek 2000;

Wiedemann and Pickart 1996). The development of dense stands of A. arenaria in sand dunes has been demonstrated to reduce sand dune arthropod abundance (Slobodchikoff and Doyen 1977). This species has drastically altered dune ecology via the stabilization of otherwise naturally dynamic dune ecosystems on the Pacific North American coast from Santa Barbara to Washington (Pickart 1997). It has also become invasive in New

Zealand and Australia where it was planted for sand stabilization (Hilton et al. 2006).

Natural Pacific dunes have a mobile dune structure with open sand interspersed with hummocks of vegetation (Pickart 1997). Impenetrable stands of A. arenaria cause sand accumulation in the foredunes, thus changing dune morphology.

Dunes invaded by A. arenaria become dense monocultures characterized by steep

4 foredunes that run parallel to the shoreline (Russo et al. 1995; Wiedemann 1998) and block sand movement, a natural phenomenon upon which many species rely, directly or indirectly.

The invasion of Pacific dunes by A. arenaria has drastically altered the habitat of the threatened Western Snowy Plover, a shorebird species that relies heavily on the dunes for foraging, nesting and predator detection (Powell and Collier 2000). Western

Snowy Plover chicks use the cryptic habitat of low growing, native vegetation to escape predation (Muir and Colwell 2010; Powell 2001). In the dense stands of A. arenaria, ravens and other predators are able to sneak up and take plover eggs and young chicks

(Page et al. 1985).

The Endangered Species Act (ESA) requires a recovery plan for all federal listed endangered species (Foin et al. 1998). The Pacific Coast population of the Western

Snowy Plover was listed as threatened by the federal government in March 1993 and is considered a bird species of special concern in California (US Fish and Wildlife Service

2007). The status of the Western Snowy Plover on the IUCN’s (International Union for

Conservation of Nature) red list is ‘near threatened’. The U.S. Fish and Wildlife Service’s recovery plan for the Western Snowy Plover states that removal of A. arenaria via foredune breaching, vegetation removal, and dune grading will help restore dune processes and the natural habitat for the endangered shorebird (US Fish and Wildlife

Service 2007).

Ammophila arenaria can be manually removed by hand pulling and digging or mechanically removed using heavy equipment such as dozers and excavators (Pickart

2008). It can be chemically controlled with the use of herbicides and salt water (Pickart

1997), or burned (Hyland and Holloran, unpublished). The efficiency, effectiveness, and ecological threat of all the methods vary and some may be more appropriate than others depending on site conditions.

My primary study area is Gold Bluffs Beach within Prairie Creek Redwoods

State Park in Humboldt County, CA. This 12.9 km coastal dune habitat, surrounded by

Picea sitchensis (Bong.) Carr. (Sitka spruce) and Sequoia sempervirens (D. Don) Endl.

(redwood) forests, has been invaded by A. arenaria. The 222 hectare beach has become heavily invaded by A. arenaria, and if left unmanaged this habitat would have become a dense monoculture. The land managers of California State Park’s North Coast Redwood

District, with funding from the California Department of Parks and Recreation Natural

Heritage Stewardship Program (Proposition 84), are removing the A. arenaria using mechanical (excavators and dozers) and manual (hand-pulling) removal techniques. The absence of human developments, high cover values of A. arenaria, and bans on herbicide application are some of the reasons why mechanical removal was chosen for this site.

Manual removal was carried out for the purposes of this research and was also utilized around sensitive habitat.

Habitat restoration at Gold Bluffs Beach provides a rare opportunity because there are no human developments within close proximity of the restoration area. The removal of A. arenaria and other sand stabilizing invasive plants at other restoration sites has been limited by human developments. Coastal housing, fear of sand drifting onto roads, and the loss of storm protection are some of the reasons that A. arenaria removal projects are not feasible in some locations. Most of Gold Bluffs Beach is backed up against the Gold Bluffs which are composed of sedimentary siltstone and sandstone

6 rocks, part of the Franciscan Formation, and sand movement is not an issue (Vaughn

2006). This offers a great opportunity to restore the natural function of the moving dunes.

My goal was to evaluate the effectiveness of two A. arenaria removal methods (heavy equipment and hand-pulling), and to assess their effects by monitoring vegetation before and after A. arenaria removal. Documenting the most effective removal method will be imperative for the future management of coastal dunes and the rare species that rely on them. My research will provide a tested conservation protocol to assist land managers in reducing the negative impacts of one of the worst invasive plants in coastal ecosystems. The removal of A. arenaria on the West Coast will not only help restore endangered species habitat, but it also helps preserve one of the most beautiful and unique ecosystems in California, the coastal dunes.

CHAPTER II

LITERATURE REVIEW

The State of the Coast

The shorelines of Earth extend for more than 1.5 million km and exist in 84% of the world’s countries, but coastal dunes and sandy beaches are only found along 16% of them (World Resources Institute 2005). The aesthetic attraction of coastal areas has drawn 41% of the human population to live within 100 km of the ocean (Martinez et al.

2013). Twenty-one of the world’s megacities (> 10 million inhabitants) are situated along the coast which substantially increases the potential for coastal habitat degradation

(Martinez et al. 2007). The abiotic and biotic alterations of coastal dunes by humans are numerous. Examples of abiotic processes being altered are landform changes due to construction, urbanization, and altering topography; changes in sediment transport; and quantity and quality of water via alterations of biological and geomorphological processes. The biotic processes of coastal dunes being altered by human actions are plant community abundance and composition as well as community and ecosystem dynamics.

Some of the human actions that are altering coastal dune biology are grazing, harvesting, introduction of non-native species to stabilize sand, eutrophication, habitat fragmentation, and dune reconstruction (Martinez et al. 2013). The growing human population and constant coastal tourism will only intensify impacts to the coastal dunes and beaches of

7 8 our planet, thus what is left of these ecosystems needs to be carefully managed and conserved (Lithgow et al. 2014).

California Coastal Dunes

Only three percent or approximately 12,103 square km of the California coast is composed of coastal dunes and most of this relatively small area has been drastically modified by humans (Pickart and Sawyer 1998). Native Americans were the first humans to utilize the vast resources of the coastal dunes in California. They used them as migration corridors, and there were many aboriginal settlements along bays and estuaries near the coastline (Wiedemann 1984). In the early 19th century the first Europeans colonized the coast and established farms and towns. Agriculture and sand mining were the first human impacts to affect the coastal dunes in California. Starting in the mid-20th century, coastal dunes became a major recreation destination and real-estate commodity.

Commercial development, water resource exploitation, sand stabilization projects, tree planting, and off-road vehicle use have continued to alter the ecosystems of coastal dunes in California (Wiedemann 1984). Although humans have had a major influence on the coast of California, the natural processes that shaped the coastal dunes before humans arrived produced many of the unique ecological phenomena in this rare habitat.

Geology

Around 7 million years ago (mya), toward the end of the Miocene, the uplift that formed the Coast Range began (Wiedemann 1984). During the Pliocene (7-2 mya) when the uplift of the Coast Range reached its highest point, peneplanation started which caused erosional lowering and leveling to occur. The sedimentary beds quickly and easily

9 eroded forming the low lying Coast Ranges and the wave-shaped terraces where most of the coastal dunes of California have developed. Tectonic, eustatic, and glaciation activity causing cyclic resubmergence of the coastline permitted sand dune formation where topography permitted. The sand that composes coastal dunes is a mixture of colluvium eroded from the surrounding bluffs and alluvium from creeks, rivers, and beach deposits

(Wiedemann 1984). The colluvium derived from the Mesozoic Franciscan Complex most likely contains a mixture of easily eroding materials such as marine shale and sandstone and more durable igneous and metamorphic rocks such as granite, basalt, and greenstone

(Aalto 1989).

Climate

The California coast has wet winters, dry summers, and cool, foggy conditions throughout most of the year. The climate of coastal California is Mediterranean with 90% of the rainfall occurring between the months of October and April (Barbour et al. 1973).

The average annual temperature along the northern California coast is between 5.6-

17.2ºC (42-63ºF) (Western U.S. Climate Historical Summaries). Rainfall patterns on the coast are the result of seasonal changes in offshore atmospheric pressure systems. The

Aleutian Low, a semi-permanent low pressure center that passes over the northern Pacific

Ocean, governs the weather patterns during the winter and brings intense southwesterly winds and rain that dominant the coast during the winter months. During the summer months, the North Pacific High, a semi-permanent subtropical anticyclone, brings northwesterly winds and dry weather (Holton et al. 1991; Wiedemann 1984).

Soils

Coastal sand dunes are often low in macronutrients such as potassium, phosphorous and especially nitrogen. In general, sand dunes have poor water holding capacity because of their low organic matter content which leads to excessive nutrient leaching. Some nutrients are made available via fog, sea-spray, wave-deposited organic debris, and nitrogen fixation (Holton et al. 1991). Concentrations of micronutrients such as Ca, Na, Mg, and Cl supplied from fog and salt spray can be in large enough quantities to meet plant requirements in coastal sand dunes or even be detrimental to their health; however most dune plants have adaptations that alleviate stress from excess micronutrients (Barbour et al. 1995).

Dune Plant Adaptations

Coastal dune plants are subjected to a variety of environmental extremes such as high temperatures, drought, salt spray, moving substrate, wind, low nutrient levels, and wave disturbance. Sand temperatures on coastal dunes during the summer can reach over

65.6º C (150º F). Sand in the dunes is constantly moving and strong coastal winds can expose the root systems of dune plants, or even cover the plants completely with sand.

Foliage in the dunes is subjected to salt spray and fast moving sand (Munz et al. 2003).

Many dune species share physiological and morphological adaptations in order to deal with their constantly changing environment and are classified as psammophytes

(Martinez et al. 2013). Alternatively, coastal dune species are classified as xerophytes which are either facultative halophytes or salt tolerant glycophytes (Breckon and Barbour

1974). Special adaptations for dealing with their harsh environment include hypertrophy,

11 or succulence which protects dune species from desiccation via evapotranspiration.

Pubescence, a well-developed cuticle, and sunken or furrowed stomata help prevent water loss from wind and intense solar radiation. Dune plants are usually prostrate with creeping stems or stolons with growing roots produced along their length. Other vegetative strategies which help deal with moving substrate include swollen root systems that store water and help in reestablishment if moved by the wind. Many dune plants also have seed dispersal and dormancy strategies that help with survival in a highly unpredictable environment (Munz et al. 2003, personal observations).

Dune Morphology

Dune morphology and geological processes are the main factors that contribute to the pattern of vegetation on Pacific coastal dunes (Peinado et al. 2011).

Dune morphology is influenced by a variety of aspects such as wind, sand, water and plant community composition (Wiedemann 1984). Distance from the shoreline also shapes species composition and richness within coastal dunes (Barbour 1978). Coastal dune forms vary from mobile (with little to no plant cover), semi-mobile, to stabilized

(completely covered with vegetation) depending on plant cover (Martinez et al. 2013).

The primary foredune is the first dune which runs parallel to the ocean and occurs after the mean high tide line (Pickart and Sawyer 1998, Wiedemann 1984). The original shape of California coastal foredunes, before the introduction of A. arenaria, was a series of semi-closely spaced dune hummocks (mounds) dominated by Elymus mollis

Trin.ssp. mollis (American dune grass) (Cooper 1967, Peinado et al. 2011, Wiedemann

1984). Foredune plant species such as E. mollis trap sand around their base and impede

12 sand movement which allows accumulation to occur and dune formation takes place.

Although E. mollis traps sand, its low density, lateral tiller growth allows sand to move freely to other parts of the dunes (Zarnetske et al. 2012). Out of all of the native dune species in California, E. mollis had been shown to be the most salt tolerant, which is not surprising given its tendency to occur in foredunes (Barbour 1978). Unfortunately, A. arenaria has displaced many of the native plants and therefore decreased species diversity in most of California’s coastal dunes (Barbour et al. 1976; Boyd 1992; Breckon

& Barbour 1974). Now the dunes are dominated by A. arenaria which has led to increased sand accumulation in the foredune because of its tall, densely packed shoots

(Aptekar and Rejmanek 2000). The size of some of the foredune ridges along the Pacific

Northwest have reached heights of up to 10 m largely because of A. arenaria establishment (Wiedemann 1984). This prevents sand from moving to other parts of the dunes and changes natural dune morphology (Zarnetske et al. 2012).

Foredune ridges sometimes occur after the primary dune within the foredune complex (primary dune and foredune ridges) (Pickart and Sawyer 1998). Foredune ridges are often oriented parallel to the prevailing winds, however blowouts in the primary foredune can create breaks or gaps that allow high velocity winds to move sand through the dune system. Sometimes parabolic dune formations occur, essentially U-shaped retention ridges formed when wind-blown sand encounters a barrier (vegetation, etc.), resulting in a long moderate windward slope and a steep leeward slope. When marginal ridges form on either side of the retention ridge and form a trough in between them it is then referred to as a parabolic dune (Wiedemann 1984). The marginal ridges of parabolic dunes either become colonized by plants or merge and form large sand sheets which are

13 often devoid of vegetation. Sand sheets along with the parabolic dunes make up the moving dunes which are usually backed up against some type of forested barrier.

Transverse dunes, within the moving dunes, are often perpendicular to the prevailing winds and highly mobile. Deflation plains form in some areas of the moving dunes where the water table is close to the sand surface which results in wet sand that is resistant to additional erosion. These wet areas then become stable which causes seasonal flooding and development of hydrophytic vegetation that make up dune hollows (Pickart and

Sawyer 1998; Wiedemann 1984).

Dune hummocks form throughout the foredune complex and the moving dunes. These hummocks or mounds are formed by the colonization of dune mat species.

These plants are resistant to sand burial and as sand gets trapped in and around them, they form various sized hummocks. These hummocks can reach five meters in height, but are constantly fluctuating as wind-blown sand moves in and out of the mounds (Wiedemann

1984).

Common Dune Mat Plant Species of Northern California

Abronia latifolia Eschsch. (yellow sand verbena, Nyctaginaceae) is a common dune mat species in northern California that has a mounding, prostrate form usually < 2 meters in height. It has fleshy leaves with fine glandular-hairy trichomes. They flower between May and October (Baldwin et al. 2012; Munz et al. 2003). Abronia latifolia has a large, thick tap root anchored deep in the sand, which is edible. Native American’s gathered their sweet roots in the fall and ate them raw (Gunther 1973).

Another dune mat species, Calystegia soldnella (L.) R. Br. (beach morning glory, Convolvulaceae) is a decumbent, perennial rhizomatous plant usually < 0.6 m in length. It has glabrous and sometimes fleshy leaves and blooms between April and

August. It occurs along the Pacific coast from San Diego to Washington and also in

South America and Europe (Baldwin et al. 2012; Munz et al. 2003).

Camissoniopsis cheiranthifolia (Spreng.) W.L. Wagner & Hoch ssp. cheiranthifolia (beach evening-primrose, Onagraceae), another common coastal dune plant, is a perennial, short-lived species with the typical prostrate form of the dune mat community, usually only growing to 60 cm in length. It grows in rosettes and has grayish-hairy leaves. Its four yellow petals open during the day and turn red with age

(Munz et al. 2003), blooming between April and August. It is found growing from Coos

County, Oregon to Santa Barbara.

Another common dune species found growing from Northern California to

Alaska is Glehnia littoralis (A. Gray) Miq. ssp. leiocarpa (Mathias) Hult-n (American glehnia, Apiaceae), a prostrate, fleshy perennial with ternate-pinnate hairy leaves. It has compound umbels that bloom from May through June (Baldwin et al. 2012; Munz et al.

2003).

Elymus mollis ssp. mollis (American dune grass, Poaceae) grows in northern

California coastal dunes. It has a well-developed rhizome and grows up to 1.7 m tall. It has a 3-15 mm wide leaf blade with a scabrous upper surface (Baldwin et al. 2012). It is a primary successional plant in coastal dunes (Imbert and Houle 2000) and grows along the coast from Central California to Alaska (Baldwin et al. 2012).

Study Species

Unfortunately, most of the native species listed above are being replaced by the invasive grass Ammophila arenaria (European beachgrass) (Breckon & Barbour

1974, Barbour et al. 1976, Boyd 1992). It is a perennial member of the Poaceae with long, thick rhizomes that can grow over 2 meters laterally in six months (Aptekar 1999).

Rhizomes have been found growing to depths of 1-2 meters and sometimes more

(Schmalzer and Hinkle 1987). In Oregon A. arenaria roots grew deep enough to reach the water table (Pavlik 1985). The stems grow from 5-12 dm high and its rolled leaf blades are 2-5 mm wide (Baldwin et al. 2012). It reproduces vegetatively by rhizomes but sometimes by seedling establishment (Buell et al. 1995, Pickart and Sawyer 1998); seed can persist in the seed bank and establish new seedlings nine years after a flowering population is removed (Konlechner and Hilton 2010).

Ammophila arenaria grows best in mobile to semi-stable dunes with sandy, well-drained substrates (Buell et al. 1995; Huiskes 1979). It grows most vigorously with the accumulation of fresh sand and can withstand burial by sand of up to one meter per year (Huiskes 1979; Wiedemann 1984). Research has shown that A. arenaria produces more new shoots from vertical rhizomes when buried by sand (Gemmell et al. 1953).

Ammophila arenaria can tolerate a wide range of soil nutrient spectrums and mycorrhizal and nitrogen fixing microbes have been found in association with their root systems

(Abdel Wahab 1975; Nicolson and Johnston 1979; Schmalzer and Hinkle 1987). There has been no documentation of A. arenaria being affected by plant disease (Schmalzer and

Hinkle 1987). All of these characteristics make it a great competitor with the ability to rapidly colonize coastal dune ecosystems.

Ammophila arenaria was first planted along the west coast in 1869 to stabilize the sand dunes around Golden Gate Park in San Francisco (Cooper 1967; Lamb 1898;

Lamson-Scribner 1895, Wiedemann 1984). It was also used to stabilize sand dunes in

Humboldt County starting in 1901 (Buell et al. 1995). Seed collected from Golden Gate

Park was dispersed over several acres at the North Spit in the town of Samoa in

Humboldt County (Buell et al. 1995). Stabilizing vegetation was also planted along the

Oregon Coast, beginning in 1910, to protect private properties, roads, rivers, railroads, and military infrastructure from sand encroachment (McLaughlin and Brown 1942). In the first half of the twentieth century thousands of acres of Pacific coastal dunes, mostly along the Oregon coast, were stabilized by planting A. arenaria (Reckendorf et al. 1987).

As a result of these sand stabilization projects, Northern California, Oregon, and

Washington beaches and foredunes are now dominated by A. arenaria (Barbour et al.

1976, Barbour and Johnson 1977, Wiedemann 1984).

Attempts to restore dune habitat and remove A. arenaria are being carried out in many ways including manual removal, herbicide application, prescribed burning, salt water application, and mechanical removal (Hesp and Hilton 2013; Hyland and Holloran

2005; Peterson 2004, Pickart and Sawyer 1998; Van Hook 1983). Research on hand removal of A. arenaria has been carried out in Humboldt County at the Lanphere and

Ma-le’l Dunes in the Humboldt Bay National Wildlife Refuge (Pickart and Sawyer 1998,

Pickart 2013). Both restoration projects took place over a 5 to 6 year period. After 2 years of treatment, the A. arenaria at the Lanphere site was largely dead but a third year of resprout retreatment followed by annual “sweeps” to remove Ammophila have been necessary to maintain the restored state. It took five years at the Ma-le’l site to get the A.

17 arenaria reduced to less than 1%. Another two year study was conducted at the

Lanphere-Christensen Dune preserve to test burning, digging, mowing, sand removal, solarization, and herbicide and salt water application as potential removal methods for controlling A. arenaria (Pickart and Sawyer 1998). Control measures were first tested on

1m² plots followed by treatment of entire stands of beachgrass. The most effective control measure was found to be repeated digging of aerial shoots below the sand which depletes the stored nutrients in the rhizomes. This can also be accomplished by frequent, repetitive treatments of cutting and burning followed by removal of left over rhizomes by sifting them out of the sand.

In February of 2004, 1.6 hectares of A. arenaria was mechanically removed from Abbott’s Lagoon in Point Reyes National Seashore (Marin County, CA) (Peterson

2004). The A. arenaria was mechanically removed using excavators and was buried in a pit which was usually about 4m x 5m x 3m deep. The removed vegetation was buried in the excavated hole and covered with clean sand that was removed from underneath the

Ammophila vegetation and rhizomes. The burial depth varied from 0.5 to 1.5 meters because of poor communication with heavy equipment operators. Six months after the removal occurred they found that the A. arenaria buried under 0.5-1 m of sand had a mean density of 10.5 Ammophila stems/m2 whereas the A. arenaria that was buried under

1-1.5 meters of sand had a mean density of 0.7 Ammophila stems/m2. Hand removal was also evaluated and after six months there was a mean density of 31.5 Ammophila stems/m2.

Herbicide application has been the primary method used to control A. arenaria in New Zealand and is generally accepted as the most effective treatment option

18 there (Hesp and Hilton 2013). The Department of Conservation and the New Zealand

Forest Service have been using helicopter and backpack sprayers to apply Gallant (a grass specific systemic herbicide) to A. arenaria on Stewart Island. In February of 1999,

7 ha of A. arenaria were sprayed with Gallant by helicopter and 4 months after the application total necrosis of the vegetation was observed. However, by late spring of the same year, large areas had regrown from surviving rhizomes. Helicopters and ARGO vehicles were used again in 2000-2001 to respray the regrowth. From 2004-present spraying and hand-pulling have been necessary to retreat regrowth which they believe is the result of the persistence of the A. arenaria seed bank (Hesp and Hilton 2013).

The effectiveness and potential risks of these methods need to be evaluated in order to assure the best conservation and protection of remaining native coastal dune flora and fauna. Several researchers have already evaluated some of the removal techniques but to date no one has comprehensively compared mechanical and manual removal of A. arenaria to see which removal method is most effective and has the least impact on existing native vegetation. The goal of this research is to evaluate which removal technique (manual versus mechanical) is most effective at eliminating A. arenaria while having the least impact on existing native vegetation.

CHAPTER III

METHODS

Study Area

The primary study area, Gold Bluffs Beach, is located in Orick, CA, within

Humboldt County, CA, and is part of Prairie Creek Redwood State Park. Gold Bluffs

Beach is 12.9 km long and 640 m wide at its widest point. The entire area of the beach and dune ecosystem is 222 ha. Gold Bluffs Beach is at the end of a ridge of low mountains called West Ridge, part of the Pacific Coast Range. A series of bluffs, from 30 to 120 meters in height, called the Gold Bluffs are at the end of the West Ridge

Mountains where they meet the beach. Five creeks that seasonally flow into the ocean on

Gold Bluffs Beach are Home, Boat, Butler, Ossagon, and Johnson. There are several wetlands at the back of the beach near the bluffs (Gizinki, unpublished). The average annual precipitation in Prairie Creek Redwood State Park is 67.1 inches and the average annual temperature is between 5.7-16.3ºC (Western U.S. Climate Historical Summaries).

Primary foredunes, nearshore dune hummocks, deflation plains, dune hollows and further stabilized back dunes make up the project area. The primary foredune is the first dune which runs parallel to the ocean and occurs after the mean high tide line.

Nearshore dune hummocks and deflation plains occur after the primary foredune.

Seasonal wetlands and dune hollows have formed in some areas within the nearshore dune complex (primary foredunes, nearshore dune hummocks and deflation plains). The

19 20 backdunes, which are the most stable, occur after the nearshore dune complex. My study plots are located within the foredunes and nearshore dune hummocks (Transou 2012).

Project Plan

The California State Park land managers of Gold Bluffs Beach have divided the 12.9 km 222 hectare beach into seven ~40 ha blocks (Figure 1) with the goal of removing A. arenaria in stages over the next 10 years. Some of the A. arenaria in block one was removed using mechanical and manual removal starting in 2005. I monitored the removal of A. arenaria within blocks two, three and five which were chosen based on their proximity to intact native plant stands which would facilitate recolonization of the removed areas.

Removal

The removal of A. arenaria on Gold Bluffs Beach was done in two ways, mechanically using excavators and bulldozers, and manually via hand pulling. The mechanical removal took place between 10/16/2013 and 11/22/2013. A total area of

29.57 ha was mechanically treated within block 2 and part of block 5. Bulldozer operators scraped away the A. arenaria and the “dirty” sand (contaminated with A. arenaria plant parts), buried it at least 2 m deep, and covered it with clean sand. The manual removal took place between 10/01/2012 and 2/01/2013. A total area of 4.67 ha was manually treated within areas of blocks 3 and 5. The hand pulling was carried out by

California Conservation Corps crews and prison inmates using hand tools. The A. arenaria from the hand removal was staged in piles and then burned. After the initial

Figure 1. Map of Gold Bluffs Beach divided into blocks 1-7.

22 treatment (mechanical and manual) there was follow up manual removal of A. arenaria around every 3 months to remove resprouts in each of the treatment areas (Table 1).

Table 1. Dates of initial mechanical removal and manual removal of A. arenaria at Gold Bluffs Beach. Dates when the treatment areas were retreated by hand-pulling (manual removal) to remove A. arenaria resprouts following the initial treatment.

Treatment Phase Treatment Window Hand Initial 10/01/2012-02/01/2013 Hand Retreat 1 09/11/2013-10/04/2013 Hand Retreat 2 02/20/2014-03/14/2014 Hand Retreat 3 07/09/2014-07/13/2014 Hand Retreat 4 10/08/2014-10/13/2014 Mechanical Initial 10/16/2013-11/22/2013 Mechanical Retreat 1 03/12/2014-05/07/2014 Mechanical Retreat 2 07/09/2014-07/16/2014 Mechanical Retreat 3 10/09/2014-10/29/2014

Monitoring

A centric systematic sampling design was used to monitor vegetation within the study areas (Elzinga et al. 1998). Six 25m² plots running perpendicular to the ocean were set up within each of the different removal areas (2 mechanical, 2 manual and 2 control) for a total of 36 plots. At first plots were randomly selected using ArcGis, but in order to assure comparable amounts of invasion between treatment types/areas a few plots were selectively placed. Within each plot three equally spaced transects were placed perpendicular to the ocean along the 25 m line (parallel to the ocean) at intervals of 6.25 m, 12.5 m, and 18.75 m (Figure 2). Along each of the three transects, five 1m² quadrats were placed at 4.6 m, 9.1 m, 13.7 m, 18.3 m, and 22.9 m. A Juno GPS unit was used to identify the latitude and longitude of the northwest corner of each of the plots and marked with buried rebar (Figure 2). Vegetation was monitored within the quadrats before and

Figure 2. Experimental design used to examine treatment effects. The 3 transects (perpendicular to ocean) along the 25 m line (that runs parallel to the ocean) occurred at 6.25 m, 12.5 m, and 18.75 m. Along each of the transects there were five 1m² quadrats at 4.6 m, 9.1 m, 13.7 m, 18.3 m, and 22.9 m.

after removal in all of the study areas using percent cover of each species via a modified

Braun-Blanquet (1932, 1965) cover scale (Table 2). After the removal was complete, the plots were monitored every three months to quantitatively evaluate A. arenaria resprout rate and native plant recovery. The time frame in which the monitoring and removal of A. arenaria occurred at Gold Bluffs Beach is listed in Table 3.

Table 2. Modified Braun-Blanquet cover scale used to estimate percent cover values for vegetation within quadrats.

Cover Class Range of Cover 1 >0% - < 1% 2 1% - <5% 3 5% - <10% 4 10% - <25% 5 25% - <50% 6 50% - <76% 7 75% - 100%

Table 3. Project timeline including vegetation monitoring dates at time zero (before initial removal of A. arenaria occurred), 3 months post-removal, 6 months post-removal, and 12 months post-removal occurred at Gold Bluffs Beach. The initial removal dates (hand /manual or mechanical) are also included.

Treatment Area Monitoring Phase Time Frame Hand Plots Time 0 (before removal) 7/24/2012-10/6/2012 Hand Plots Initial removal occurred 10/01/2012-02/01/2013 Hand Plots ~3 months after removal 4/27/2013-4/28/2013 Hand Plots ~6 months after removal 8/6/2013-8/7/2013 Hand Plots ~12 months after removal 2/6/2014-2/8/2014 Mechanical Plots Time 0 (before removal) 7/24/2012-10/6/2012 Mechanical Plots Initial removal occurred 10/16/2013-11/22/2013 Mechanical Plots ~3 months after removal 2/7/2014 Mechanical Plots ~6 months after removal 5/3/2014 Mechanical Plots ~12 months after removal 10/11/2014 Control Plots Time 0 7/25/2012-1/25/2013 Control Plots ~3 months 4/27/2013-4/28/2013 Control Plots ~6 months 8/6/2013-8/7/2013 Control Plots ~12 months 2/6/2014-2/8/2014

Time Comparison Monitoring

Plots were also established at sites (block 1 of Gold Bluffs Beach, Little River

State Beach, and Clam Beach) where A. arenaria had either been mechanically or manually removed in the past in order to analyze the treatment effects over time. Six

25m² plots (as described above) were set up in block one at Gold Bluffs Beach, where A. arenaria was mechanically removed between 2005-2008. Six additional 25m² plots (as described above) were set up at Little River State Beach, located 48.28 km south of Gold

Bluffs Beach, where 16 hectares of A. arenaria were mechanically removed in 2009.

Clam Beach, located 5.95 km south of Little River State Beach, which had 19.4 hectares of A. arenaria manually removed from 2006 until present was also set up with six 25m² plots. All of the time comparison sites have had follow up treatments by hand to remove

A. arenaria resprouts. These plots were monitored in the same manner as described in the monitoring section and the data was used to analyze the effectiveness of the removal techniques over time. The time frame in which the monitoring and removal of A. arenaria occurred at the time comparison sites is listed below in Table 4.

Table 4. Time frame in which monitoring and removal of A. arenaria occurred at the time comparison sites (Block 1 Gold Bluffs Beach, Little River State Beach, and Clam Beach).

Site and Treatment Project Phase Time Frame Block 1 Gold Bluffs Beach (Mechanical) Initial Mechanical Removal 2005-2008 Block 1 Gold Bluffs Beach (Mechanical) Time Comparison Monitoring 7/24/2012-5/3/2014 Little River State Beach (Mechanical) Initial Mechanical Removal 2009 Little River State Beach (Mechanical) Time Comparison Monitoring 9/23/2012-5/2/2014 Clam Beach (Hand) Initial Hand Removal 2006 Clam Beach (Hand) Time Comparison Monitoring 9/22/2012-5/5/2014

Statistical Analysis

A repeated measures ANOVA using treatment method and monitoring time interval as factors was conducted in order to analyze the vegetation percent cover values and Tukey pairwise comparisons were carried out when a significant value was found

(Minitab 17, Minitab Inc.). The Tukey pairwise comparison analyzed differences in treatment, time, and treatment x time. Significance levels for all analyses was α = 0.05.

Percent cover class value for A. arenaria from all the quadrats within each plot were averaged, which provided a single cover class value for each plot within each treatment at time zero, 3 months, 6 months, and 12 months post removal; time 0 being the initial percent cover class value of the A. arenaria before it was removed. Treatments

(manual, mechanical, and control) and time since removal (0, 3, 6, and 12 months) were compared for significant differences with an additional comparison for the interaction between treatment and time. Once the ANOVA revealed a significant difference between any of the treatments and time since removal, Tukey pairwise comparisons were used to determine which treatment and time interval had the greatest effect on the A. arenaria.

To analyze native plant recovery following the A. arenaria removal I calculated a total mean cover class value for all the native plants within each quadrat. To do so, the midpoint value for the cover class that was documented for each native plant species within the quadrats were summed to get a total for all natives within each quadrat and then averaged for each plot. The same procedure for the repeated measures analysis were followed to determine which treatment and time interval had the least impact on native plant recovery. Percent cover values collected for other non-native plant species within plots were analyzed utilizing the same method used for evaluating native plant

27 recovery. The latter will help determine whether there is a potential for secondary invasion after A. arenaria removal.

For the time comparison sites I also performed a repeated measures ANOVA.

I did not have time zero (before A. arenaria removal) data because the A. arenaria at these sites was removed before I started my research. Therefore, I analyzed the percent cover values that I collected at the beginning of my research (first) and at the end of my research (last). This allowed me to evaluate whether there is a significant difference in the amount of A. arenaria, native plants, and other non-native plants currently growing at the three time comparison sites.

CHAPTER IV

RESULTS

A. arenaria before Treatment and Within the Control Sites

Mean cover class for all of the treatment areas (hand, mechanical, and control) at time zero (before A. arenaria removal) were not significantly different (Table 5).

There were no significant differences among the control sites over time which indicates that A. arenaria growth in mature stands does not change much over the course of a year

(Figure 4). There was a slight increase in A. arenaria in the control plots over time; the

12 month time interval had the highest mean cover class value for A. arenaria, but again none of these values were significantly different (Table 5, Figure 3, Figure 4).

Analysis of the Treatment Method of A. arenaria

The ANOVA showed that the mean cover class value was not the same for all three treatments (hand, mechanical, control) (F = 7.95, P = 0.002). The Tukey pairwise comparisons (α = 0.05) found the mean cover class value for A. arenaria regrowth was lowest in the mechanical removal sites, followed by the hand removal sites, and the control sites had the largest mean cover class value when averaged over all the time frames (Table 6).

28 29

e not significantly different. rval that share a letter ar and Tukey pairwise comparisons of treatment and monitoring and Tukey pairwise A. arenaria Mean cover class values (± SD) for Mean cover class Table 5. time inte within each Treatments interactions. time interval

Figure 3. Interaction plot for A. arenaria removal showing differences between the hand treatment (in red), mechanical treatment (in green), and the control treatment (in blue) across time intervals (time zero, 3 months after removal, 6 months after removal, and 12 months after removal) at Gold Bluffs Beach.

Analysis of the Monitoring Time Intervals for A. arenaria

The ANOVA showed that the mean cover class value was not the same for all four monitoring time intervals (time zero, 3 months after removal, 6 months after removal, and 12 months after removal) when averaged over all treatments (F = 31.55, P

<0.001). The Tukey pairwise comparison found the time zero mean cover class value for

A. arenaria was significantly higher than all of the other time intervals with no significant difference among the other three time intervals (Table 7).

Figure 4. Interaction between treatments (hand (H), mechanical (M), and control(C)) and monitoring time interval (time zero, 3 months after removal, 6 months after removal, and 12 months after removal) of A. arenaria at Gold Bluffs Beach. The treatment intervals that are underlined together are not significantly different. Values are means ± SE.

Table 6. Mean cover class values (± SD) for A. arenaria and Tukey pairwise comparisons of treatment method (mechanical, hand, and control) averaged over all the time frames. Treatments with the same letter are not significantly different.

Treatment Analysis: A. arenaria Treatment Average MCCV Grouping Mechanical 1.59 (± 1.75) A Hand 2.27 (± 1.23) B Control 3.52 (± 1.62) C

Table 7. Mean cover class values (± SD) for A. arenaria and Tukey pairwise comparisons of monitoring time interval (time zero, 3 months, 6 months, and 12 months post-removal) when averaged over all the treatments. Time intervals with the same letter are not significantly different.

Time Analysis: A. arenaria Monitoring Time Average MCCV Grouping 0 (before removal) 3.43 (± 1.79) A 3 months 1.99 (± 1.83) B 6 months 2.23 (± 1.51) B 12 months 2.18 (± 1.50) B

Analysis of the Interaction Between Treatment and Monitoring Time Interval for A. arenaria

The ANOVA showed there is a significant interaction between treatment and monitoring time interval on mean cover class values of A. arenaria (F = 19.83 and P

<0.001). Figure 4 shows the relationship among the 12 mean cover class values for the treatments and time interactions and whether or not they are significantly different. The

Tukey pairwise comparison confirmed the mechanical treatment at all three monitoring time intervals had the lowest mean cover class values for A. arenaria, but not all of these values were significantly different than the hand monitoring time intervals. The control sites had the highest mean cover class values of A. arenaria which shows that mechanical and hand removal are significantly more effective than doing nothing at all. There was no significant difference among the treatments at time zero (Figure 4), however at three months post removal the mean cover class value for A. arenaria within the mechanical removal sites was significantly lower than the mean cover class value for A. arenaria in the hand removal sites which was significantly less than in the control sites (Table 5). At six months post removal the exact same relationship as described for the 3 months post

33 removal was present. However, at 12 months post removal the mechanical and hand removal sites were no longer significantly different from one another but still significantly lower than the control treatment sites. (Table 5, Figure 3, Figure 4).

Analysis of the Treatment for Native Plant Recovery After A. arenaria Removal

The ANOVA showed that the mean cover class value for native plants was not significantly different between the three treatments (hand, mechanical, control) when averaged over all the time intervals (F = 1.95, P= 0.159).

Analysis of the Monitoring Time Intervals for Native Plant Recovery After A. arenaria Removal

The ANOVA showed that the mean cover class value for native plants was not the same for all four monitoring time intervals (time zero, 3 months after removal, 6 months after removal, and 12 months after removal) (F = 13.65, P< 0.001). The Tukey pairwise comparison indicates that the time zero mean cover class value for native plants was significantly higher than all of the other time intervals. It also showed that the other three time intervals were not significantly different (Table 8).

Table 8. Mean cover class values (± SD) for native plants and Tukey pairwise comparisons of monitoring time interval (time zero, 3 months, 6 months, and 12 months post-removal) when averaged over all the treatments. Time intervals with the same letter are not significantly different.

Time Analysis: Native Plants Monitoring Time Average MCCV Grouping 0 (before removal) 1.42 (± 0.79) A 3 months 0.94 (± 0.77) B 6 months 1.03 (± 0.88) B 12 months 1.00 (± 0.85) B

Analysis of the Interaction Between Treatment and Monitoring Time Interval for Native Plants

The ANOVA found a significant interaction between treatment and monitoring time interval on mean cover class values for native plants (F = 11.61 and

P < 0.001). The mechanical removal sites at time zero had significantly more native plants than the hand removal sites, but the control removal sites at time zero were not significantly different than the hand or mechanical sites at time zero (Table 9, Figure 6).

However, at three months post removal of A. arenaria the mechanical removal sites had a significantly lower mean cover class value for native plants than the hand and control sites which were not significantly different from each other. At six months post removal the mechanical sites had a significantly lower mean cover class value for natives than the control sites but it was not significantly different than the hand removal sites. However, the mean cover class values for native plants within the hand and control sites at six months post removal were not significantly different. At 12 months post removal the mean cover class value for natives in the hand and mechanical sites were not significantly different but both were significantly lower than the control site (Table 9, Figure 5, Figure

6).

Analysis of the Treatment and Time Interval for Other Non-Native Plants After A. arenaria Removal

The ANOVA showed the mean cover class value for other non-native plants were not significantly different between the three treatments (hand, mechanical, control) when averaged over all time intervals (F = 0.55, P = 0.582).The ANOVA also showed

35 ukey pairwise comparisons of treatment and monitoring time share a letter are not significantly different. share a letter are not significantly different. in each time interval that Mean cover class values (± SD) for native plants and T interval interactions. Treatments with interval interactions. Treatments Table 9.

Figure 5. Interaction plot for native plant recovery after removal of A. arenaria that shows the differences between the hand treatment (in red), mechanical treatment (in green), and the control treatment (in blue) across time intervals (time zero, 3 months after removal, 6 months after removal, and 12 months after removal).

that the mean cover class value for other non-native plants was not significantly different between the four monitoring time intervals (time zero, 3 months after removal, 6 months after removal, and 12 months after removal) when averaged over all treatments (F = 1.47,

P = 0.227).

Analysis of the Interaction Between Treatment and Monitoring Time Interval for Other Non-native Plants

The ANOVA found a significant interaction between treatment and monitoring time interval on mean cover class values for other non-native plants after A. arenaria removal (F = 3.24, P = 0.006). However, the Tukey pairwise comparison

Figure 6. Interaction between treatments (hand (H), mechanical (M), and control (C)) and monitoring time interval (time zero, 3 months after removal, 6 months after removal, and 12 months after removal) for native plant recovery following A. arenaria removal at Gold Bluffs Beach. The treatment intervals that are underlined together are not significantly different. Values are means ± SE.

showed the only significant difference was that the mechanical treatment at 3 months post removal had a lower mean cover class value for other non-native plants than the mechanical treatment at time zero and a lower mean cover class compared to the control treatment time intervals (Table 10, Figure 7, Figure 8).

Analysis of the Time Comparison Sites

The ANOVA showed that the mean cover class value for A. arenaria was significantly different between the three time comparison sites (GBB block 1, Little River

State Beach, and Clam Beach) (F = 135.99, P <0.001). The Tukey pairwise comparison found that Clam Beach (2006 hand removal) had the highest mean cover class value for

38 wise comparisons of treatment and share a letter are not significantly a letter are not significantly share other non-native plants and Tukey pair eatments within each time interval that time interval eatments within each Mean cover class values (± SD) for

monitoring time interval interactions. Tr interactions. time interval monitoring different. Table 10.

Interaction Plot for cover class Data Means

0.9 trt c 0.8 h m 0.7

0.6

0.5 Mean

0.4

0.3

0.2

0.1 0 3 6 12 time

Figure 7. Interaction plot for other non-native plants pre and post removal of A. arenaria that shows the differences between the hand treatment (in red), mechanical treatment (in green), and the control treatment (in blue) across the different time intervals (time zero, 3 months after removal, 6 months after removal, and 12 months after removal).

A. arenaria followed by Little River State Beach (2009 mechanical removal), with block

1 at Gold Bluffs Beach (2005-2008 mechanical removal) having the lowest mean cover class value for A. arenaria regrowth, but the difference between Little River State Beach and block 1 at Gold Bluffs Beach was not significant (Table 11, Figure 9).

The analysis of native plant recovery following A. arenaria removal for the time comparison sites found a significant difference between the mean cover class values

(F = 28.85, P < 0.001). Gold Bluffs Beach has a higher mean cover class value for native plants followed by Little River State Beach with Clam Beach having the lowest mean cover class value for native plants (Table 11, Figure 10). In summarizing the results of

Figure 8. Interaction between treatments (hand, mechanical, and control) and monitoring time interval (time zero, 3 months after removal, 6 months after removal, and 12 months after removal) for other non-native plants after A. arenaria removal at Gold Bluffs Beach. The treatment intervals that are underlined together are not significantly different. Values are means ± SE.

Table 11. Mean cover class values (± SD) and Tukey pairwise comparisons for A. arenaria regrowth and native plant recovery at the time comparison sites. Mean cover class values that share the same letter are not significantly different.

Time Comparison: Mean Cover Class Values Site A. arenaria Grouping Natives Grouping GBB B1 0.05 (± 0.12) A 3.27 (± 0.87) A LRSB 0.22 (± 0.22) A 0.71 (± 1.08) B Clam Beach 2.22 (± 0.55) B 0.20 (± 0.20) B

B B

A A A A

Figure 9. The difference in A. arenaria regrowth between the three time comparison sites (GBB block 1, Little River State Beach, and Clam Beach) at the first and the last monitoring time interval. The letter under each site and monitoring time interval indicates the initial A. arenaria treatment for that site (M = mechanical and H = hand/manual). Sites that share the same letter (A or B) are not significantly different.

the Tukey pairwise comparison, the mean cover class value for native plants in block 1 at

Gold Bluffs Beach was significantly higher than Little River State Beach and Clam

Beach but the difference between Little River State Beach and Clam beach are not significant (Table 11).The last analysis which compared the mean cover class for other non-native plants at the time comparison sites showed that there was no significant difference between the three sites (F = 2.16, P = 0.150) (Figure 11).

A A

B BBB

Figure 10. The difference in native plant recovery following A. arenaria removal at the three time comparison sites (GBB block 1, Little River State Beach, and Clam Beach) at the first and the last monitoring time interval. The letter under each site and monitoring time interval indicates the initial A. arenaria treatment for that site (M = mechanical and H = hand/manual). Sites that share the same letter (A or B) are not significantly different.

A A A A A

Figure 11. The difference in other non-native plant growth following A. arenaria removal at the three time comparison sites (GBB block 1, Little River State Beach, and Clam Beach) at the first and the last monitoring time interval. The letter under each site and monitoring time interval indicates the initial A. arenaria treatment for that site (M = mechanical and H = hand/manual). Sites that share the same letter (A or B) are not significantly different.

CHAPTER V

DISCUSSION

Restoring natural ecosystems is a complex task due to the multifaceted interactions occurring within them. Although restoration efforts aim to assist degraded areas in recovery, many projects fail to do so because science-based decision making and follow-up monitoring are lacking. Habitat restorations that include biological research as part of the process enables land managers to modify and adapt their methods as necessary. The restoration research at Gold Bluffs Beach was initiated by land managers of California State Parks (CSP) to ensure that large scale restoration of California coastal dunes is being carried out effectively and efficiently. The research I have presented here is the beginning of a comprehensive analysis of the effects of mechanical and manual removal of A. arenaria in California coastal dunes; continued monitoring at Gold Bluffs

Beach will help solidify and clarify the initial findings of this research.

My hypothesis was that there would be a significant difference in the efficacy of the manual and mechanical removal of A. arenaria and the data support these differences. At Gold Bluffs Beach the mechanical removal sites initially had significantly less A. arenaria than the hand removal and control treatments; however, after one year there was no significant difference in the amount of A. arenaria between the hand and mechanical removal sites at Gold Bluffs Beach. These findings show that although the mechanical treatment was very successful at first, A. arenaria was able to reestablish

44 45 after one year. It is important to note that the mechanical sites received one less resprout retreatment than the hand removal sites, which could influence the results. Other factors that could have led to the regrowth in the mechanical sites are reestablishment from left over rhizomes that were not buried deep enough, sand contaminated with A. arenaria seed, or rhizomes being blown into the removed areas from the surrounding stands of A. arenaria.

The burial depth of A. arenaria during the mechanical removal at Abbott’s

Lagoon in Point Reyes National Seashore influenced the rate of regrowth. They found A. arenaria that was buried under 0.5-1 m of sand had an average regrowth rate of 10.5

Ammophila stems/m² whereas the A. arenaria that was buried under 1-1.5 meters of sand had an average regrowth rate of 0.7 Ammophila stems/m² at 6 months post removal.

Differences in burial depth in this case reportedly were caused by poor communication with the heavy equipment operators; this scenario offers an important caveat for the establishment of clear communication. Previous suggestions for improving mechanical removal of A. arenaria were 1) to bury removed plants as deep as possible or at least 1.5 m deep, 2) to bury removed plants on windward slopes deeper than 1.5 m, and 3) to pull the resprouts as soon as possible to avoid the establishment of well-developed root systems (Peterson 2004).

The findings of my research in conjunction with the results of Peterson’s study (2004) indicate that mechanical removal of A. arenaria is an effective removal technique, but only when the beachgrass is buried deep enough and re-treated in a timely manner. Clear communication and supervision of heavy equipment operators seems to be a crucial part of successful mechanical removal of A. arenaria. Both studies have found

46 that A. arenaria regrowth at 6 months post-mechanical removal is significantly less than in hand removal areas, however, in my study I found that at 12 months post-removal there was not a significant difference between the hand and mechanical removal. These findings indicate that it is important to aggressively re-treat A. arenaria resprouts within the first 6 months after removal.

At 3 months post-removal the hand removal sites had a mean cover class value for A. arenaria of 2.10 whereas the mechanical sites had a mean cover class value of 0.26. The regrowth of A. arenaria within the hand removal sites was most likely due to the complication of removing deep rhizomes in moving sand. Grass species are adapted to grazing by animals and therefore readily regrow from underground parts after the top vegetation has been removed (Stromberg et al. 2007). My personal observations after watching the Conservation Corps crews manually remove A. arenaria is that crews often remove the top vegetation and some of the roots, but fail to dig deep enough to remove the entire root system. This is understandable because the crew members are often working long days in harsh weather conditions and digging into a substrate that is constantly moving. If workers dig to remove deep rhizomes the sand refills the hole, and rhizomes often break off in the process. The other issue with hand removal is getting rid of the plant material after it is removed. Many coastal dune ecosystems occur at the bottom of steep bluffs or in remote areas. Pulled A. arenaria is staged in piles and often burned because hauling the vegetation is often unfeasible. Burning the piles requires permitting and ideal weather conditions which are uncommon on the Northern California coast. Days without wind, permit requirements, and crew scheduling can lead to the A.

47 arenaria piles having to stay on the dunes for weeks at a time. If the removed piles sit at the removal sites for long enough, inevitably rhizomes are dispersed by winds.

Native plant recovery following mechanical and manual removal of A. arenaria was also evaluated at Gold Bluffs Beach. The mechanical removal areas started out with the most native plants but three months post-removal these sites had the fewest native plants, whereas the hand removal sites had more native plants than at time zero.

Interestingly, after one year there was no difference in native plant abundance between mechanical removal sites and hand removal sites, and both treatment areas had fewer native plants than the control plots. It appears that after mechanical removal of A. arenaria, native plants take at least a year to start to reestablish. In the hand removal sites native plants appear to more easily rebound initially but overtime decline. One possible explanation for these findings is that during hand removal of A. arenaria native plant root systems are not completely uprooted as during mechanical removal. Therefore, native plants reestablish themselves more quickly after hand removal but because the rhizomes of A. arenaria are still intact, they may be competing with A. arenaria for space and resources.

It is important to note that most perennial dune mat species in California are dormant and completely die back during the winter months. Therefore, low cover values during this time are to be expected. Unfortunately, the mechanical removal that occurred at Gold Bluffs Beach was delayed a year and therefore my monitoring time intervals for the hand and mechanical removal sites are slightly different (Table 3). Consequently, continued monitoring of native plant regeneration at these sites is needed to fully understand how these treatment methods affect native plant recovery.

The time comparison analysis of block 1 at Gold Bluffs Beach, Little River

State Beach (LRSB) and Clam Beach shows that currently the mechanical removal sites

(GBB block 1 and LRSB) have significantly less beach grass then the manual removal site (Clam Beach). The manual removal of A. arenaria at Clam Beach started in 2006 whereas the mechanical removal in block 1 at GBB occurred between 2005-2008 and at

LRSB in 2009. Analyses show that the plots at Clam Beach have significantly fewer native plants compared to the plots within block 1 at Gold Bluffs Beach. Clam Beach also had fewer native plants than LRSB, but the differences were not significant. Native plant recovery at LRSB has already surpassed Clam Beach despite the fact that the A. arenaria removal occurred at LRSB 3 years after the removal at Clam Beach. The differences in native plant recovery following A. arenaria removal at the time comparison sites suggests again that native plants recover better after mechanical removal.

In analyses to determine whether other non-native plants would become an issue (or a secondary-invader) following A. arenaria removal, there was no significant difference between the treatments or time intervals at Gold Bluffs Beach. The only significant differences found at Gold Bluffs Beach were that mechanical sites at three months post removal had significantly less non-native plants than the mechanical sites at time zero and the control sites. Other non-native plant growth within the time comparison sites revealed that both of the mechanical sites (GBB block 1 and LRSB) had fewer non- native plants than the manual removal site (Clam Beach), but the difference between

LRSB and Clam Beach were not significant.

Cakile maritima Scop. (sea rocket) is the other non-native plant species encountered most frequently in the study plots. An annual succulent of the mustard

49 family (Brassicaceae), native to the coasts of Europe, the fruits of this species can float long distances in the ocean (Davy et al. 2006). Cakile maritima can tolerate salt water inundation and spray and has been shown to utilize nitrogen enrichment associated with organic detritus that is washed onto beaches by waves. It also tolerates sand burial and contains glucosinolates that help deter pathogen attack (Davy et al. 2006). Cakile seedlings are almost always located within a 2 meter radius of the parent plant and once established, can maintain itself for long periods of time (Barbour 1970c, 1972b). Cakile maritima also utilizes amphicarpy (cross pollinating and self-pollinating flowers) and hydrochory (dispersal by water) as reproductive strategies which allow them to have both restricted and extensive dispersal of diaspores. Although its reproductive strategies are effective, the California Invasive Plant Council classifies its ability to alter native ecosystems as limited. It also blooms throughout the year and appears to be a good pollinator resource.

The total area initially treated by hand at Gold Bluffs Beach was 4.67 ha and a total of 2262.25 person hours (ph) (484.42 ph/ha) were needed to carry out the removal.

The combined cost for the initial hand removal at Gold Bluffs Beach was $8,235/ha for a total of $38,458 (doesn’t include travel costs). The total area treated mechanically at Gold

Bluffs Beach was 29.57 ha and a total of 370 ph (12.81 ph/ha) were needed to carry out the removal. The combined cost for the mechanical removal at Gold Bluffs Beach was

$5,492.99/ ha for a total of $162,427.74 (including travel costs).

It is clear that larger areas of A. arenaria initially can be removed using heavy equipment when compared to hand removal and at lower cost, but after the initial mechanical removal, follow up treatments for these large areas are required. California

State Park’s North Coast Redwood District utilizes California Conservation Corps crews and prison inmates for the follow up hand removal. California Conservation Corps crews are in high demand and costly to procure. Therefore it is important when treating A. arenaria mechanically that work be conducted in stages, which is not only key for effective re-treatment, but also for native plant reestablishment. If endangered plants or large areas of intact native vegetation occur at a site it is probably wise to treat the A. arenaria by hand. Erysimum menziesii ssp. eurekensii (Humboldt Bay wallflower) and

Layia carnosa (beach layia) are two federal listed endangered plants that occur at the

Lanphere and Ma-le’l Dunes in the Humboldt Bay National Wildlife Refuge. The presence of these endangered plants, as well as large areas of intact native vegetation, caused the Nature Conservancy to utilize manual techniques to remove A. arenaria within these sites.

Ammomphila arenaria at the Lanphere-Christensen Dunes Preserve

(Humboldt Co.) was manually removed between 1992-1998 within an 11 ha area of the foredune-blowout-parabolic dune complex. Hand removal was carried out by California

Conservation Corps Crews and volunteers. An average of eight treatments was required in the first season of removal and seven in the second year. Plants were staged in piles after removal and burned once they had dried for a month or more. The labor needs for the first three years of the project totaled 7,379 person hours/ha (2,951 ph/ac) which equated to $87,703/ha. Transporting crews to the site, hiking to the site, and treatment are all included in this figure. The costs for this project were recalculated using only the area in which A. arenaria occurred instead of the area of the total site, which changed the labor needs to 4,631 ph/ha which equaled a combined cost of $54,590/ha for manual

51 removal at the Lanphere-Christensen Dunes Preserve. Two years after the hand removal at the Lanphere-Christensen Dunes Preserve the A. arenaria was mostly dead. In the third year after removal sparse resprouts required re-treatment. After the third year, annual

“sweeps” were required to pull resprouts or new occurrences within the restoration site.

In 2011, mean total cover values and species richness for dune-mat species within the hand removal areas at the Lanphere restoration site were compared to intact dune-mat vegetation and there was no significant difference between them (P= 0.59) (Pickart and

Sawyer 1998, Pickart 2013).

A similar manual removal restoration project occurred at the Ma-lel’l Dunes

(Humboldt Co.) between 2005-2010, but at this site A. arenaria was treated fewer times per year over the course of three years and revegetation was added in the third year.

Elymus mollis ssp. mollis culms with attached budding rhizomes were harvested from nearby established stands and out-planted during the winter months within the removal areas. After a year, 61% of the planted Elymus mollis ssp. mollis had survived. In 2011,

100% of the Elymus planting areas contained live plants but there was a lot of variation in density and cover. Ammophila eradication took longer at this site because the initial treatments were less intensive, but by the fifth year cover was less than 1%. Six years after the start of the restoration project (or one year post-completion) the restored area exhibited native plant cover values that were not significantly different than sites with intact vegetation (P = 0.20) (Pickart 2013).

The success of Elymus mollis ssp. mollis transplanting at the Ma-le’l Dunes restoration project indicates that native plant revegetation following removal is worthwhile. There are many large stands of Elymus at Gold Bluffs Beach which could be

52 utilized for rhizome transplants. Another possibility would be to grow Elymus and other native plants and outplant them after removal is complete. There are several rare plants at

Gold Bluffs Beach including Abronia umbellata var. breviflora (pink sand verbena) and

Lathyrus japonicas (beach pea). Seed collection and propagation of both of these species in areas that are scheduled for mechanical removal would help protect these populations from further decline. The unassisted native plant recovery of block 1 at Gold Bluffs

Beach shows that native plant re-vegetation is not essential for restoring the dunes but native plant re-vegetation could help speed up the process. Native plant re-vegetation might not be necessary at sites, such as Gold Bluffs Beach, where there are intact native plant stands. However, in areas where native plant populations are scarce, utilizing this technique could be beneficial.

My research, the findings of other A. arenaria restoration studies, and the cost differences of the removal techniques indicates that mechanical removal is an effective strategy for treating A. arenaria. The decision of whether to utilize mechanical or hand removal techniques for removing A. arenaria depends on site conditions and funding availability. Hand removal of A. arenaria is important when working in sensitive habitat areas and mechanical removal is a good option in sites where dense monocultures of A. arenaria have formed. Both techniques have their place in the restoration field, but I suggest using mechanical removal at sites that are heavily infested with A. arenaria and have low native plant abundances. Coastal dunes have a naturally high disturbance regime and therefore heavy equipment can be utilized, however research on sand compaction, animal disturbances, and dune morphological changes caused by heavy equipment use are needed to assure the safety/success of this restoration technique.

CHAPTER VI

CONCLUSIONS

Humans have altered natural ecosystems to such an extent that it is no longer possible to preserve biodiversity by just protecting critical habitat areas. Science-based, ecological restoration will be crucial to ensure the health of our planet. Fully understanding the habitat in which one is working to restore is necessary to regain ecosystem function. Land agencies and managers should steward natural areas with a whole ecosystem approach. Biotic (microbes, fungi, insects, plants, and animals) and abiotic (geology, nutrients, structure, disturbance) factors should be considered when determining how habitats should be restored. A cost-benefit analysis should also be a key part of decision making. For example, one method of restoration might eliminate an invasive plant but in the process it could wipe out a rare species or alter soil biota.

Biological research before and after ecological restoration will help ensure that these processes are being analyzed.

My research has helped further the understanding of the effects of mechanical and manual removal of A. arenaria within California coastal dunes. A long term study is needed in order to fully understand how these techniques have “restored” the habitat and ecosystem function given the persistent onslaught of invasive species. It is my hope that

California State Parks will continue this research so the initial findings can be strengthened. California coastal dune ecosystems are in need of conservation and would

53 54 benefit from further research. This unique habitat is threatened by human development, recreation, and invasive species. The sound of waves, the smell of the ocean, and the warmth of sand beneath your feet will always beckon you to the coast; but the call of shorebirds, the site of a seal in the surf, and the glow of flowers on the dunes are really what make this habitat unique. I hope conservation efforts will give future generations a chance to experience it.

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APPENDIX A

Plant Species List for Gold Bluffs Beach Scientific Name Common Name Native? Family CNPS RANK Abronia latifolia yellow sand verbena Y Nyctaginaceae Abronia umbellata var. breviflora pink sand verbena Y Nyctaginaceae RARE-1B.1 Achillea millefolium yarrow Y Asteraceae Acmispon glaber deerweed Y Fabaceae Aira caryophyllea silver hair grass N Poaceae Alnus rubra red alder Y Betulaceae Ambrosia chamissonis beach bur Y Asteraceae Ammophila arenaria European beachgrass N Poaceae INVASIVE-HIGH Anagallis arvensis scarlet pimpernel N Myrsinaceae Anaphalis margaritacea pearly everlasting Y Asteraceae Angelica hendersonii coast angelica Y Apiaceae Anthoxanthum odoratum sweet vernal grass N Poaceae INVASIVE-MODERATE Baccharis pilularis coyote bush Y Asteraceae Bellis perennis English daisy N Asteraceae Brassica rapa common mustard N Brassicaceae INVASIVE-LIMITED Cakile maritima sea rocket N Brassicaceae INVASIVE-LIMITED Camissoniopsis cheiranthifolia beach primrose Y Onagraceae Cardamine oligosperma bitter-cress Y Brassicaceae Cardionema ramosissimum sand mat Y Caryophyllaceae Carex obnupta slough sedge Y Cyperaceae Calystegia soldanella beach morningglory Y Convolvulaceae Cerastium glomeratum mouseear chickweed N Caryophyllaceae Cirsium vulgare bull thistle N Asteraceae INVASIVE-MODERATE Claytonia perfoliata miner's lettuce Y Montiaceae Cortaderia selloana pampas grass N Poaceae INVASIVE-HIGH Cotula coronopifolia brass buttons N Asteraceae INVASIVE-LIMITED Cytisus scoparius scotch broom N Fabaceae INVASIVE-HIGH Dipsacus fullonum teasel N Dipsacaceae INVASIVE-MODERATE Distichlis spicata salt grass Y Poaceae Dudleya farinosa bluff lettuce Y Crassulaceae Dysphania ambrosioides Mexican Tea N Chenopodiaceae Elymus mollis ssp. mollis American dune grass Y Poaceae Erigeron canadensis horseweed Y Asteraceae Erigeron glaucus seaside daisy Y Asteraceae Festuca microstachys annual fescue Y Poaceae Fragaria chiloensis beach strawberry Y Rosaceae Galium aparine common bedstraw Y Rubiaceae Gamochaeta ustulata purple cudweed Y Asteraceae Glehnia littoralis ssp. leiocarpa glehnia Y Apiaceae RARE-4.2 Holcus lanatus velvet grass N Poaceae INVASIVE-MODERATE Hypericum perforatum St. John's Wort N Hypericaceae INVASIVE-MODERATE Hypochaeris radicata rough cat's ear N Asteraceae INVASIVE-MODERATE Isatis tinctoria dyer's woad N Brassicaceae INVASIVE-MODERATE Juncus falcatus sickleleaved rush Y Juncaceae Kickxia elatine sharpleaf cancerwort N Plantaginaceae Lathyrus japonicus sea pea Y Fabaceae RARE-2.1 Lathyrus littoralis beach pea Y Fabaceae Linaria dalmatica ssp. dalmatica Dalmatian toadflax N Plantaginaceae INVASIVE-MODERATE Linum bienne flax N Linaceae Lupinus arboreus bush lupine Y Fabaceae NATIVE-INVASIVE Lythrum hyssopifolia loosestrife N Lythraceae INVASIVE-LIMITED

65 Melilotus albus white sweetclover N Fabaceae Mentha pulegium pennyroyal N Lamiaceae INVASIVE-MODERATE Morella californica wax myrtle Y Myricaceae Picea sitchensis Sitka spruce Y Pinaceae INVASIVE-LIMITED Plantago lanceolata English plantain N Plantaginaceae Plantago major common plantain N Plantaginaceae Poa annua annunal blue grass N Poaceae Poa confinis beach blue grass Y Poaceae Poa douglasii sand dune blue grass Y Poaceae Poa macrantha seashore bluegrass Y Poaceae Poa pratensis Kentucky blue grass N Poaceae INVASIVE-LIMITED Polycarpon tetraphyllum Four-leaved polycarp N Caryophyllaceae Polygonum aviculare common knotweed N Polygonaceae

Plant Species List for Gold Bluffs Beach Scientific Name Common Name Native? Family CNPS RANK Polygonum paronychia dune knotweed Y Polygonaceae Polypodium scouleri coast polypody Y Polypodiaceae Potentilla anserina ssp. pacifica Pacific potentilla Y Rosaceae Pseudognaphalium californicum ladies tobacco Y Asteraceae Pseudognaphalium stramineum cottonbatting plant Y Asteraceae Rumex acetosella sheep sorrel N Polygonaceae INVASIVE-MODERATE Rumex conglomeratus clustered dock N Polygonaceae Rumex crispus curly dock N Polygonaceae INVASIVE-LIMITED Rumex crassus willow leaved dock Y Polygonaceae Sanicula crassicaulis Pacific sanicle Y Apiaceae Senecio glomeratus cutleaf burnweed N Asteraceae INVASIVE-MODERATE Senecio minimus coastal burnweed N Asteraceae INVASIVE-MODERATE Silene gallica wind-mill pink N Caryophyllaceae Sonchus oleraceus sow thistle N Asteraceae Symphyotrichum chilense aster Y Asteraceae Trifolium wormskioldii cow clover Y Fabaceae Vaccinium ovatum huckleberrry Y Ericaceae Vicia gigantea giant vetch Y Fabaceae

APPENDIX B