The Application of Successional Theory-Based Management to Minnesota Prairie Sites Degraded by Invasive Plant Species

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Culminating Projects in Biology Department of Biology

12-2011 The pplica ation of successional theory-based management to Minnesota prairie sites degraded by invasive plant species Jamie R. Hanson Saint Cloud State University, [email protected]

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THE APPLICATION OF SUCCESSIONAL THEORY-BASED

MANAGEMENT TO MINNESOTA PRAIRIE SITES

DEGRADED BY INVASIVE PLANT SPECIES

Jamie R. Hanson

B.S., St. Cloud State University, 2011

A Thesis

Submitted to the Graduate Faculty

St. Cloud State University

in Partial Fulfillment of the Requirements

for the Degree

Master of Science

St. Cloud, Minnesota

December, 2011

This thesis submitted by Jamie R. Hanson in partial fulfillment of the requirements for the Degree of Master of Science at St. Cloud State University is hereby approved by the final evaluation committee.

______Chairperson

______

______Dean School of Graduate Studies

THE APPLICATION OF SUCCESSIONAL THEORY-BASED MANAGEMENT TO MINNESOTA PRAIRIE SITES DEGRADED BY INVASIVE PLANT SPECIES

Jamie R. Hanson

A thesis project at Camp Ripley Army National Guard Training Site will address the effectiveness of directing succession as a means of restoring areas dominated by perennial terrestrial invasive species: Common Tansy (Tanacetum vulgare) and Spotted Knapweed, (Centaurea stoebe ssp. micranthos). The purpose of this project is to design and implement an experiment that will test different combinations of treatments that alter the three factors of site availability, species availability, and species performance, as defined by Pickett et al. (1987) and Sheley et al. (2003). Altering these three factors is done with the goal of restoring perennial invasive-species-dominated areas into a native plant community. My experimental objective is to determine if succession-based management strategies are an appropriate methodology for the restoration of Minnesota prairie ecosystems that are impacted by invasive species, as it has been shown that invasive species can severely degrade ecosystems. The research question further involves determining which practices within this framework of succession are most effective in restoring Minnesota prairie ecosystems that are degraded by the presence of these invasive plant species. This experiment took place in spring 2010 through fall 2011 and incorporated site manipulation of four seedbed preparations, two cover crop types, and two seed dispersal methods. The addition of a fourth factor involved the application of a selective herbicide, Milestone, to half of each plot. Statistical analysis determined that by the end of data collection in August 2011, all levels from the first three factors in the experimental design did not significantly reduce either invasive species. The application of the fourth factor did significantly reduce both invasive species’ mean percent cover. However, a negative consequence of this selective herbicide is reduction in species richness in plots and increase in non-native grass cover. It is

iii

recommended, due to the nature of succession, continued monitoring, data collection, and analysis occur on experimental sites.

______Month Year Approved by Research Committee:

______Jorge Arriagada Chairperson

ACKNOWLEDGMENTS

I would like to thank my advisor, Dr. Jorge Arriagada for his support and assistance through the many trials and tribulations that accompanied this thesis project. Previously known as my field assistant, and now a graduate student herself;

Kayla Malone made the execution of my experimental design possible. I cannot thank

Kayla enough for her innumerable hours spent on my project. I also thank my committee members Dr. Marco Restani, Dr. Stephen Saupe, and Dr. Michner Bender.

The members of the Environmental Office and Department of Public Works at Camp

Ripley, Linda Donnay and others in the Office of Sponsored Programs were constant supporters of this experiment, and for that I thank them immensely. Chen Zhu in the

Statistical Consulting Center and Dr. Jody Illies at Saint Cloud State University were invaluable assets to the statistical analyses contained within this thesis. Last, but not least, I thank my family and especially my friends for being with me on this two and a half year journey.

TABLE OF CONTENTS

Page

LIST OF TABLES ...... viii

LIST OF FIGURES ...... xi

Chapter

1. INTRODUCTION ...... 1

Invasive Species ...... 1

Common Tansy and Spotted Knapweed ...... 6

Ecological Succession ...... 13

Objectives ...... 19

2. METHODS ...... 22

Study Site ...... 22

Experimentation Design ...... 26

Procedures ...... 28

3. RESULTS ...... 36

Initial Data Collection—2010 ...... 36

Senescent Stand Data Collection—2011 ...... 37

Emergent Stand Data Collection—2011 ...... 40

Post-Milestone Application Data Collection—2011 ...... 42

Chapter Page

2011 Vegetation Surveys ...... 45

Statistical Analyses ...... 56

Boxplot Figures ...... 66

4. DISCUSSION ...... 73

REFERENCES ...... 77

APPENDIX ...... 89

vii

LIST OF TABLES

Table Page

1. Ups13 Southern Dry Prairie native plant community as defined by the DNR Ecological Classification System 2005 ...... 24

2. UTM GPS Point Location of Blocks at Camp Ripley, MN ...... 28

3. Timeline of events in 2010 ...... 34

4. Timeline of events in 2011 ...... 35

5. A random number generator was used to determine the number of steps walked within the block to visually estimate senescent stand invasive species percent cover in April 2010 of a meter sized area at that point with a total of 16 points per block ...... 37

6. April 2011 senescent stand mean percent cover of spotted knapweed ...... 39

7. April 2011 senescent stand mean percent cover of common tansy ...... 39

8. A block mean of visual estimates of senescent stand invasion species percent cover in April 2011 of each 10 by 20 meter plot ...... 40

9. May 2011 emergent stand mean percent cover of spotted knapweed ...... 41

10. May 2011 emergent stand mean percent cover of common tansy ...... 41

11. A block mean of visual estimates of emergent stand invasive species percent cover in May 2011 of each 10 by 20 meter plot ...... 42

12. July 2011 Post-selective-herbicide treatment mean percent cover of spotted knapweed ...... 44

13. July 2011 Post-selective-herbicide treatment mean percent cover of common tansy ...... 44

viii

Table Page

14. A block mean of visual estimates of post-selective-herbicide treatment invasive species percent cover in July 2011 of each 10 by 20 meter plot ...... 45

15. 2011 Species Richness per half-plot (# spp.) with 1m squared quadrat sampling frame randomly placed at least one meter from buffer zone ...... 47

16. Species richness per half-plot (# spp.) with 1m squared quadrat sampling frame randomly placed at least one meter from buffer zone 48

17. Forb and tree surveys in June and August 2010 ...... 49

18. Forb and tree surveys in August 2011 ...... 51

19. Grass surveys in August 2010 ...... 52

20. Grass surveys in August 2011 ...... 53

21. Cover class mean values for every treatment of the four blocks in spotted knapweed areas was determined by randomly placing a 0.2 by 0.5 m Daubenmire frames in each half-plot ...... 54

22. Cover class mean values for every treatment of the four block in common tansy areas was determined by randomly placing a 0.2 by 0.5 m Daubenmire frames in each half-plot ...... 55

23. Common tansy independent samples t-test for species richness in plot halves with and without a selective herbicide application ...... 58

24. Spotted knapweed independent samples t-test for species richness in half-plots with and without a selective herbicide application ...... 59

25. Univariate ANOVA for spotted knapweed areas with the Between- Subjects factors of seedbed preparation (SP), cover crop (CC), seeding method (SM), selective herbicide application (MS), and block ...... 59

26. Univariate ANOVA for spotted knapweed ...... 61

27. Repeated Measures ANOVA for spotted knapweed areas with the Within-Subjects Effects of time on mean percent cover ...... 62

Table Page

28. Repeated Measures ANOVA for spotted knapweed ...... 62

29. Univariate ANOVA for common tansy area with the Between-Subjects factors of seedbed preparation (SP), cover crop (CC), seeding method (MS), selective herbicide application (MS), and block ...... 63

30. Univariate ANOVA for common tansy ...... 65

31. Repeated Measures ANOVA for common tansy areas with the Within-Subjects Effects of time on mean percent cover ...... 65

32. Repeated Measures ANOVA for common tansy ...... 66

LIST OF FIGURES

Figure Page

1. Common tansy (Tanacetum vulgare) and spotted knapweed (Centaureastoebe ssp. Micranthos) distribution as of 2010 at Camp Ripley ...... 9

2. The Pine Moraines and Outwash Plains, Hardwood Hills, and Anoka Sand Plain subsections converge at Camp Ripley ...... 23

3. A randomized complete block design (2x2x4) ...... 26

4. Treatment assignments were determined by plots receiving a random number between 1-16 ...... 27

5. Spotted knapweed blocks’ mean percent cover measures for all data sets ...... 67

6. Spotted knapweed mean percent cover measures per data set ...... 68

7. Spotted knapweed mean percent cover measures for plot halves within blocks that received no selective herbicide versus those half-plots that received a selective herbicide application ...... 69

8. Common tansy mean percent cover measures per block ...... 70

9. Common tansy mean percent cover measures per data set ...... 71

10. Common tansy mean percent cover measures for plot halves within blocks that received no selective herbicide versus those half- plots that received a selective herbicide application ...... 72

Chapter 1

INTRODUCTION

Invasive Species

Invasive species are non-native species that harm economic, environmental, or human health (Executive Order 13112). These species are a threat to the ecological health of areas around the world due to their capability of changing the biotic and abiotic characteristics of their environment (Osborn, Wright, Walker, Cilimburg, &

Perkins, 2002).The term “invasive” has had many other names and definitions. Other terms that have been used to describe a non-native harmful species include: introduced, naturalized, exotic, alien, pests or weeds, and noxious. The term invasive was specifically defined by Executive Order 13112 in 1999 to eliminate ambiguity surrounding the word’s meaning. Other vocabulary previously used as synonyms of

“invasive” can still be useful. To be explicit, an introduced species is defined as any species that has been moved via humans to an area that originally was inaccessible due to some geographical barrier. An alien or exotic species are also “plant taxa in a given area whose presence there is due to intentional or accidental introduction as a result of human activity” (Richardson et al., 2000, p. 98). Alien and exotic species are generally used as synonyms of introduced. A naturalized species is a species that that can

1 2 overcome the challenges of being transported into a new area and can survive on its own. A naturalized species is not necessarily invasive, as it does not necessarily cause harm. A weed is a plant species that “grow[s] in sites where they are not wanted and which usually have detectable...effects” (Richardson et al., 2000, p. 98). “A noxious weed is an undesirable plant species that is regulated in some way by law” (Sheley &

Petroff, 1999, p. 1). It is also important to note that native species are, in a specific ecosystem, a species that historically occurred or currently occurs in that ecosystem

(Executive Order 13112, 1999, p. 6183).

Masters and Sheley describe invasive plant species as those species that

“reduce the capacity of ecosystems to provide goods and services required by society, alter ecological processes, and can displace desirable species” (2001, p. 503). Until the 20th century it was not extensively known that a non-native plant can become harmful (invasive) if said plant has certain characteristics and is introduced into certain conditions. It is now known that the spread of invasive plant species have vast financial and ecological repercussions across the globe. According to Walker and

Smith (1997), entire ecological processes, such as fire regimes, can be altered by the establishment and aggressive spread of a single non-native species. Invasive species have been introduced and spread rapidly between areas over the past century due to the exponential increase in human population and movements and the human alteration of environments. Invasive plants species have established in the United

States via accidental and intentional introduction via human vectors (Morse, Kartesz,

& Kutner, 1995). Humans have introduced non-native plants for various purposes, such as food, livestock forage, ornamental, medicinal, and erosion control.

In 1958, a manuscript concerning invasive species, and the negative impacts they incur, was published, The Ecology of Invasions by Animals & Plants. In this text,

Charles Elton dubbed the impact of invasive species as “ecological explosions”. His text described the potential dangers that non-native plants and animals pose to new environments and also used case studies to illustrate the damage that had already been done by these species (Elton, 1958). Invasion ecology has developed since Elton’s text into a field of study of its own. In 2011, when one uses Google Scholar search engine to look for articles on “invasive species,” over 64,000 items are returned. Every year, more research is being conducted and the findings are illuminating the issue of invasive species to the world. There is much work to be done, however, as the more that we know about the methods and mechanisms by which invasive species function, the better equipped we are to combat this threat.

The mechanisms by which plant species can change from being non-native to being classified as invasive can be complex and multi-layered. Masters and Sheley summarized various hypotheses about the contributing factors that lead to species being invasive:

The absence of predator hypothesis states that invasive plants have an advantage because they are introduced into new environments without natural enemies from their native range. The greater reproductive potential hypothesis indicates that invasive plants are more fecund than native species. The poorly adapted native species hypothesis proposes that invasive plants exhibit a greater tolerance to resource constraints than do native species. The chemical change hypothesis suggests that invasive plants are better adapted to altered

chemical status of an invaded site. The balance of nature hypothesis is centered on the concept that species-rich communities are more resistant to invasion than species- poor communities. The empty-niche hypothesis contends that invaded communities contain unoccupied niches ready for habitation by invasive plants. The disturbance-produced gaps hypothesis suggests that some level of disturbance is necessary to allow an invading species to gain a foothold in a community. (2001, p. 504)

All or only some of these hypothetical contributions to what makes a species invasive may be useful depending on the specific situation. Invasions can also have a scale or varying measure of “success” in new environments. Rejmanek stated that invasion success is dependent on the severity and kind of disturbance and propagule pressure

(1989). Hobbs and Huenneke proposed that the amount of time between disturbances can also influence invader success (1992).

The process by which a species invades an ecosystem outside of its native range has been organized into delineated phases, A-D, by Williamson (1996). These four phases are (a) arrival and establishment, the beginning, (b) spread, the middle, and (c) equilibrium and effects, the end of the invasion process. Phase (d) resembles the implications of the invasion. In the first phase (a), a non-native species enters a new area and it either succeeds or fails in establishment of a viable, potentially permanent, group of individuals. In most cases, Williamson notes that the majority of introductions are not successful and that propagule pressure is often a determinant of success or failure. He also states that all ecosystems should be considered invasible given the right circumstance. In phase (b), the population of viable individuals begins to spread. This phase lends itself to being modeled better than the other phases. Spread can occur in various directions in various speeds. The next phase, (c), involves an

5 introduced species reaching equilibrium. At this point, the population stops spreading.

It is noted that at this phase, most invaders will not have major consequences for the ecosystem. When they do they are in the form of effects such as extinctions of native species. At this point, evolution of the invader population and the native populations can begin to be affected by the presence of the invader in the environment. The final phase (d) addresses the implications of a successful invasion. These implications are varied and often observable depending on the invaders’ impact (Williamson 1996).

The National Invasive Species Council and the Federal Interagency Committee on Management of Noxious and Exotic Weeds estimated that as of 2001, 40.5 million has of area in the United States are infested with harmful non-native plants (NISC,

2001). It was also estimated that this area will increase by 8 to 20% every year

(Westbrooks, 1998). In response to the reality that invasive plant species are both an economic and ecological threat to the United States, an executive order was issued on

February 3, 1999 by President William Clinton to address the problem at the federal level. This executive order mandates that it is imperative that each federal agency take the following actions:

…prevent the introduction of invasive species; detect and respond rapidly to and control populations of such species in a cost-effective and environmentally sound manner; monitor invasive species populations accurately and reliably; provide for restoration of native species and habitat conditions in ecosystems that have been invaded; conduct research on invasive species and develop technologies to prevent introduction and provide for environmentally sound control of invasive species; and promote public education on invasive species and the means to address them; and…not authorize, fund, or carry out actions that it believes are likely to cause or promote the introduction or spread of invasive species in the United States or elsewhere… (Executive Order 1311, p. 6184)

Common Tansy and Spotted Knapweed

The Minnesota Department of Military Affairs is one of the federal agencies that are required to be in compliance with this executive order. The Minnesota

Department of Military Affairs manages Camp Ripley Army National Guard Training

Site. Camp Ripley Army National Guard Training Site (Hereafter Camp Ripley) is located in Morrison County and is the primary study site for this thesis project.

Eighteen terrestrial invasive plant species have been identified at Camp Ripley including two species that this project will be addressing: Common tansy (Tanacetum vulgare), and spotted knapweed (Centaurea maculosa) (St. Cloud State University

[SCSU], 2008). These two species are of special concern due to their highly aggressive and opportunistic nature and large distributions at Camp Ripley.

Common tansy (Tanacetum vulgare Linnaeus) is an aggressive perennial plant present at Camp Ripley. It is a member of the Asteraceae family, native to Europe.

This plant was first introduced as an ornamental and for medicinal purposes (Colorado

Weed Management Association [CWMA], 2004; United States Department of

Agriculture [USDA], 2004). It has been classified as a Noxious or Secondary Noxious

Weed in some states due to its potential to reduce forage for livestock, wildlife habitat, and species diversity. These states include Minnesota, Colorado, Montana,

Washington, and Wyoming (USDA, 2010). Common tansy is capable of producing

50,000 seeds per plant (Royer & Dickinson, 1999; Whitson, 2000). It can also reproduce asexually, via vegetative re-growth of the rhizomes though it primarily relies on seed production for its spread (Jacobs, 2008; Prach & Wade, 1992).

The scientific taxonomy of common tansy began with Carl Linnaeus who worked for the Dutch merchant and plant enthusiast George Clifford from 1735-1737.

George Clifford founded a herbarium with an extensive collection now housed in the

Natural History Museum in London, UK. The lectotype for common tansy can be found in this collection. Linnaeus published a brief Latin species account of

Tanacetum vulgare in Species plantarum vol. 2 in 1753.

The USDA Forest Service offers an English description of the characteristics of Common Tansy:

Common tansy is a robust perennial with erect stems that may reach 7 feet (2 m) tall. Coarse stems generally branch only at the top and are somewhat woody at the base. Stems may grow singly or in clusters and are lined with alternate leaves. When crushed, leaves produce a “rank” smell. Leaves are finely dissected and toothed. They measure 2 to 12 inches (6-30 cm) long and are generally half as wide. Common tansy flower heads are comprised of daisy-like disk florets and measure up to 0.5 inch (1.2 cm) wide. Within the flower head there may be as many as 100 individual florets. Florets are perfect except for the outermost, which are pistillate. Generally florets are without ray flowers, but in some cases, reduced ray flowers are present. Flower heads are densely clustered in flat-topped terminal inflorescences. Sources report that common tansy may produce more than 8 flower heads/stem and between 20 and 200 flower heads/plant. Common tansy produces achenes that measure 1 to 1.8 mm long; the pappus, if present, is a reduced 5-toothed crown. (Gucker, 2009, p. 3)

Common tansy quickly infests disturbed sites and displaces native vegetation.

It is tolerant of most soil types and prefers areas that are exposed to full sun.

Roadsides, stream banks, pastures, and open disturbed areas are likely areas of infestation (Whitson, 2000). Tansy plants can emerge from rhizome extensions in the fall, but most stems emerge in mid-spring. Upon emergence, quick growth results in plants over a meter tall in June. Flowers form in June with seeds dropping in late

8 summer and early fall. Seeds have highest germination rates after a period of stratification (Jacobs, 2008). Common tansy is an ecological threat due to its ability to out-compete native grass species and reduce forage for wildlife and some livestock

(LeCain & Sheley, 2006). The current distribution (point locations only) of this plant at Camp Ripley can be seen in Figure 1.

Current control methods include prescribed burns combined with herbicides

(Jacobs, 2008), mechanical control by means of hand-pulling (CWMA, 2009) and mowing at appropriate times to prevent seeds from establishing (Lackschewitz, 1991), and grazing by sheep or goats (Elpel, 2009).

Spotted knapweed (Centaurea stoebe ssp. micranthos (Gugler) Hayek) is another aggressive terrestrial invader which has also posed a problem at Camp Ripley.

Historically, this plant was introduced to this country either as a contaminant of alfalfa seed from Asia, specifically Turkmenistan, or as a contaminant of alfalfa seed from

Germany. The history of the taxonomy of spotted knapweed is incredibly complex. As early as 1601, Carolus Clusius wrote about a species that may have been spotted knapweed (Ochsmann, 2001). Carl Linnaeus describes this species in 1753 in his

Species Plantarum (Linnaeus, 1753). Through molecular and ecological data, obtained and then related by Jörg Ochsmann, the final designation of Centaurea stoebe ssp. micranthos (Gugler) Hayek was accepted for spotted knapweed (2001). No type has been designated for Centaurea stoebe L. (Ochsmann, 2001).

Figure 1. Common tansy (Tanacetum vulgare) and spotted knapweed (Centaureastoebe ssp. micranthos) distribution as of 2010 at Camp Ripley. Point locations are shown in this figure, which only show a location of a population, but do not relate information about size of individual infestations, which are, in some cases, greater than a ha in area.

No halotype was designated within the herbaria used by Linnaeus. An isotype, forCentaurea stoebe ssp. micranthos (Gugler) Hayek is cited as “C. Baenitz, Herb.

Europ.Sine No. [...] (Gugler, 1907, p. 169).

In Ochsmann’s conclusion, he states the importance of correctly identifying the taxonomy of the invasive subspecies of spotted knapweed:

Even when the taxonomic view of the author is not accepted and Centaurea maculosa Lam. is used instead of C. stoebe L. for spotted knapweed, it is important to recognize that different (infraspecific) taxa of spotted knapweed exist and that only one of them (subsp. micranthos) was introduced to North America. Only with knowledge of the two subspeciesof C. stoebe it is possible to understand the biology and ecology of spotted knapweed and to improve the methods of control in North America. (2001, p. 39)

This perennial species has the capacity to produce over a thousand seeds per plant. These seeds have long-lasting viability in the soil and can produce new plants five years or more after introduction to the seedbed (Lym & Zollinger, 1992). Due to its persistence in the landscape and its allelopathic properties, this species has proven to be difficult to manage. In its mature stage spotted knapweed is unpalatable to wildlife and some livestock (Harris & Cranston, 1979).

The description of the North American Invasive variety as reviewed in

Ochsmann of Centaurea stoebe ssp. micranthos (Gugler) Hayek is as follows:

Perennial (up to 9 years), polycarpic; usually many-stemmed, erect, ca 40-150 (-200) cm high; stem paniculate branched, with relatively long branches; plants lanate; rosette leaves one- to many-times pinnatifid to pinnatisect with narrow sections, upper leaves mostly undivided; capitula single at the ends of the branches, 5-8 mm wide, narrow ovate to ovate; phyllary appendages often tinged with dark violet, sometimes ± lanate, black, triangular, acute, ciliate, with 4-7 cilia per side, each 1-2 mm long; flowers purple, ray florets present, flowering VI-IX; achenes ca 3-3.5 (-4) mm long; pappusca (0.2-) 1-2.5 mm. (2001, p. 38)

Spotted knapweed quickly establishes itself in areas that have been disturbed, and is even capable of occurring in stable plant communities if a source population is nearby (Sheley, Jacobs, & Carpinelli, 1998). This plant prefers dry soils and sunny conditions. It has been known to occur at elevations between 580 to over 3000 meters and in areas with between 200 to 2000 millimeters of precipitation (Lacey, Lacey, &

Faye, 1992). Roadsides and open disturbed areas are most susceptible to invasion by spotted knapweed (Forcella & Harvey, 1983). These plants’ seeds germinate in both fall and early spring between April and June. This early germination time is a factor that contributes toward this species’ invasiveness. Seeds are shed from mature plants between August and September (Jacobs & Sheley, 1998). It is considered an ecological threat mainly due to the arresting capacity it has on succession of native plant communities (Tyser & Key, 1988). Also, once an area has an established population, it is then a source of invasion of adjacent ecologically stable areas (Tyser

& Key, 1988). Spotted knapweed has been shown to have increased erosion on invaded sites compared to those areas that are dominated by native plants (Lacey,

Marlow, & Lane, 1989). Overall, spotted knapweed is an economic and ecological concern due to its capacity to reduce forage for livestock (Watson & Renney, 1974), reduce native plant community biodiversity (Tyser, 1990), cause a reduction in soil fertility and an increase in soil runoff (Lacey et al., 1989), and has negative effects on rare forbs and wildlife (Bedunah & Carpenter, 1989; Lesica & Stephen, 1996). The current distribution of this invasive species at Camp Ripley is shown in Figure 1.

Current control methods for spotted knapweed include prescribed fire followed by

12 herbicide treatment (Sheley,Jacobx, & Carpinelli, 1999), and other integrated weed management practices such as combining chemical, cultural, and biological controls

(Sheley et al., 1996b).

These two perennial invasive species have negatively impacted the ecological health of Camp Ripley. Their presence on this military training site threatens to serve as a source population that could eventually have economic impacts for adjacent areas in Minnesota. To be in compliance with Executive Order 13112, steps have been taken to control and manage these invasive populations on this training site. A partnership has been established between Saint Cloud State University and Camp Ripley. Multiple participants in this operation exist, including the MN Department of Military Affairs,

The Nature Conservancy, Camp Ripley Environmental Office, and the Saint Cloud

State Biology Department. Previous efforts have involved mapping distributions and predicting future spread of these species by Jill Babski in 2004, establishing herbicide control on plots within the site by Joseph Eisterhold in 2008, and evaluating chemical and fire control of one of these species, common tansy, by Joseph Carlyon in 2009.

Recommendations have been made on how to control these invasive species and prevent introductions. However, this project concerns itself on how best to restore these invasive dominated areas into an ecologically sound native plant community.

Restoring these areas back to a native plant community is difficult due to the factors that make these plants invasive. Spotted knapweed and common tansy have high seed production and these seeds are viable for years in the soil (Biesboer &

Koukkari, 1992; Davis & Fay, 1989). These plants out-compete natives and can

13 change characteristics of the soil through root system development and by changing the nutrient cycles of the area (Olson & Blicker, 2001; Harvey & Nowierski, 1989;

Marler, Zabinski, Wojtowicz, & Callaway, 1999). Ridding areas of these plants has proven to be very difficult as both exhibits some form of asexual reproduction via their rhizomes in conjunction with seed production (Raju, Steeves, & Clupland, 1963;

Sheley, Jacobs & Lucas, 2001). These plants have also thought to inhibit other species from thriving by method of allelopathy (Callaway & Aschehoug 2001). Early germination rates and fast growth early in the growing season gives these species a competitive edge versus the native plant community (Eddleman & Romo, 1988).

Ecological Succession

Methods for long-term control of these invasive species have been proposed that involve the use of the ecological principle of succession (Pickett, Collins, &

Armesto, 1987; Sheley, Mangold, & Anderson, 2006). Succession has been observed for hundreds of years by various naturalists. It was not until the late 19th century that scientists began actively exploring the concept, however. It is a difficult concept to study, as the complexity of abiotic and biotic interactions has led to many proposed patterns and mechanisms.

Pickett et al. describes succession as,

…one of the oldest of ecology’s major theories...it embodies the pervasive and fundamental idea that ecological systems are dynamic as a result of both internal and external forces... it has evolved through shifts in paradigm, growth of long-term studies, and examination of contrasting systems. (2008, p. 338)

A pattern described by one researcher, or a mechanism described by another, had not proven to be applicable as a general theory on succession until late in the 20th century.

Henry Cowles in 1899 was one of the first researchers to describe what is now referred to as primary plant succession. He studied vegetation composition and change over time on sand dunes (Cowles, 1899).

Frederic Clements in 1916 proposed a deterministic, highly predictable view on the causes, stages, and sequences of succession. He proposed the idea that succession has an orderly process with an endpoint, resulting in a climax community

(Clements, 1916). This became the traditional model of succession until the 1950s.

Henry Gleason was critical of the Clementsian model of succession. From

1917 onwards, Gleason proposed an individualistic model of succession which investigated the complex and variable interactions between environments, the species within it, and disturbances that affect it. He was a proponent for a less-predictable pattern of succession than that stated by Clements (Gleason, 1917).

Many researchers proposed further additions to the deterministic or individualistic views on succession. Frank Egler described succession, both primary and secondary stages, as a gradual process that he dubbed “Relay Floristics and Initial

Floristic Composition.” Relay floristics refers to the

...successive appearance and disappearance of groups of species. Each group of species invades the site at a certain stage of development... making conditions unsuited for themselves, but suited for invasion by the next group. And so ...predominance is relayed... from one floristic group to another, until some relatively stable end-stage is attained... The second principle is called Initial

Floristic Composition, and refers to that element which invades or has invaded at the time of abandonment. Following abandonment, there is a progressive development, with the forbs and grasses assuming predominance first, and the trees last. (Egler, 1954, p. 414)

Robert MacArthur defined r and K selection, which enhanced the understanding of biotic influences on succession. “r” species were early successional species that had properties such as elevated reproductive, higher rates of dispersal, and increased survival of severe abiotic and biotic conditions. “K” species are found in late stages of succession. These species have properties such as lower rates of reproduction, longer lifetimes, and greater environment regulation (MacArthur, 1962).

Eugene Odum explained predictable deviations between early and late succession in 1969. He stated that “early successional systems tend to have smaller plant biomass, shorter plant longevity, faster rates of soil nutrient consumption ... higher rates of net primary productivity, lower stability and lower diversity than late successional systems” (Odum, 1969).

In 1977, Joseph Connell and Ralph Slatyer summarized various models of succession (Connell & Slayter, 1977):

Connell and Slatyer propose three models, of which the first (facilitation) is the classical explanation most often invoked in the past, while the other two (tolerance and inhibition) may be equally important but have frequently been overlooked. The essential feature of facilitation succession, in contrast with either the tolerance or inhibition models, is that changes in the abiotic environment are imposed by the developing plantcommunity. Thus, the entry and growth of the later species depends on earlier species preparing the ground. The tolerance model suggests that a predictable sequence is produced because different species have different strategies for exploiting resources. Later species are able to tolerate lower resource levels due to competition and can grow to maturity in the presence of early species, eventually out competing them. The inhibition model applies when all species resist invasions of

competitors. Later species gradually accumulate by replacing early individuals when they die. (as cited in Pidwirny, 2006, p. 5)

The Resource Ratio Hypothesis was proposed by David Tilman in 1985. This hypothesis models changes in plant communities derived from the assumption that succession is determined by exchanges between competition for nutrients early on in succession, and light acquisition late in succession (Emery, 2010).

Pickett et al. proposed that Connell and Slatyer’s statements on succession were, in some cases, contradictory or empirically unobservable. Picket et al. stated that the Connell and Slatyer model of succession had testable limits. To make clear certain concepts in succession, Pickett et al. (1987) explored the causes of succession: “site availability” or disturbance, “species availability” or colonization, and “species performance”. Furthermore, Pickett et al. concretely defined several terms surrounding succession:

A successional pathway is the temporal pattern of vegetation change. It can show the change in community types with time, the series of system states, or describe the increase and decrease of particular species populations. A mechanism of succession is an interaction that contributes to successional change. A model of succession is a conceptual construct to explain successional pathways by combining various mechanisms and specifying the relationship among the mechanisms and the various “stages” of the pathway. (Pickett et al., 1987, p. 338)

Pickett et al. (1987) described succession as “a process of (1) individual replacement and (2) a change in performance of individuals” (p. 347). The three factors of site availability, species availability, and species performance can be illustrated by contributing processes as was explored by Sheley, Svejcar, & Maxwell (1996a). In the case of site availability a contributing process would be a disturbance. Species

17 availability is determined by propagule pressure and dispersal. Species performance has many contributors such as available resources, life histories, and abiotic conditions. Sheley et al. (1996a) proposed that disturbance can be designed, in that if management includes activities that create or restrict site availability, the end result can minimize continuous and costly management. Disturbances can be created or restricted with management activities such as prescribed fire, cultivation, and herbicides. White and Pickett (1985) define disturbance as “a relatively discrete event in time that disrupts ecosystem, community, or population structure and changes the resources, substrate availability, or physical environment” (p. 7). Colonization can also be managed by altering the availability or establishment of plant species in a specific area. Seed banks or propagule pools can be addressed by either introducing seed, or by restricting entry of seeds. Management of a site for optimizing germination of desirable species, while restricting the germination of undesirable species such as those that are invasive should be a main focus of any site restoration. Controlling species performance involves attempting to direct the growth and reproduction of plant species in the management area. Introducing predation that restricts the growth and reproduction of undesirable species (biological control), removing certain plant species, and planting competitive plant species are all ways of addressing species performance (Sheley et al., 1996a). According to Sheley et al. (2006), “The potential of this successional theory to guide the development and implementation of effective restoration and invasive plant management is substantial, but largely untested” (p.

366).

This project will test ecology based methods of restoration in areas dominated by spotted knapweed and common tansy. Ultimately, the goal of the project would be to restore these areas back to a pre-disturbance native plant community using the approach of successional management. The Society for Ecological Restoration defines restoration as “the intentional alteration of a site to establish a defined indigenous, historic ecosystem” (Aronson, Floret, Le Floc’h, Ovalle, & Pontanier, 1993, p. 8).

An “assisted succession” method of restoration was conducted by Cox and

Anderson (2004) in areas infested with an annual invasive grass. Assisted succession is the preliminary introduction of competitive, non-native grasses followed by a later seeding of native species (Jones, 1997). Cox and Anderson (2004) attempted to restore a native grassland through the following procedure; Seeding an introduced grass in the infested areas, performing various seedbed preparations including herbicide application, mowing, and tilling, and lastly, seeding the desired native plants. This technique of using a cover crop or bridging species in the restoration process will be implemented in this project.Cover crops are short-lived species that are seeded with the focal crop to facilitate its establishment (Hartwig & Ammon 2002). However, in this project, a native species will be used. Canada wild rye (Elymus canadensis) is a native cool-season graminoid that is found in sand prairies in Minnesota (Wanek &

Burgess, 1965). Canada Wild Rye was chosen because it is known to increase habitat stability and is adapted to a wide variety of soils (Atkins & Smith, 1967).

Sheley et al. (2006) conducted an experiment with a factorial design in 2006 that tested multiple herbicides, seeding methods, and seeding rates. Sheley et al.

19 intended to influence species performance, disturbance, and colonization by manipulating the above variables (2006). “The experimental goalwas to investigate the initial response of vegetation to various restoration strategies applied within the context of successional management on rangeland dominated by invasive weeds

[Centaurea maculosa and Potentilla recta]” (Sheley et al, 2006, p. 366). The results of

Sheley suggested that:

in most cases, integrating treatments that addressed multiple causes of succession favored a desired plant community. Thus, we accomplished our goal of using successional managementto direct plant communities toward native desired species, but the treatments used did notimprove species richness. Since naturally occurring native forbs did not respond favorably toany treatment combination, ecological restoration using successional management may best bethought of as an iterative procedure where various components and processes of the system aremethodically repaired or replaced over time. (2006, p. 365)

Other components/processes will be introduced in this project involving different seedbed preparation methods (Mowing versus mowing with herbicide application versus mowing with herbicide application with tilling) and seed dispersal methods (hand broadcasting versus drill seeding). This project began in April 2010 and data collection occurred for two consecutive growing seasons.

Objectives

The objective of this thesis project is to use a successional management method of restoring perennial invasive-species-dominated areas into a native plant community. This method incorporates various treatments including seedbed preparations, cover crop implementation, and seed dispersal methods. These

20 treatments serve as the alterations to the successional factors of site availability, species availability, and species performance. By altering these factors, I intend to direct succession so that native plant species can compete with and pervade through the arrest caused by spotted knapweed and common tansy in the current vegetation system. The implementation of Canada wild rye into sites will serve as the alteration to “species availability” and also as an alteration to “species performance”, as this cover crop can both compete with the target invasive species and serve as a bridge species for the desired native prairie plant community. I hypothesize that by introducing a competitive cover crop immediately upon intentional disturbance of these invaded areas, followed by the seeding of native grasses, a decrease in target invasive species’ percent cover measures will occur. The addition of nine native grass species via two dispersal methods, hand-broadcasting and drill-seeding, will also influence “species availability,” due to the introduction of previously absent propagules and is predicted to also impact “species performance,” due to the competitive pressure introduced once these native propagules germinate. I hypothesize that drill seeding will be the most effective means of establishing native grasses in the seedbed. Seedbed preparations of Mowing versus mowing with herbicide application versus mowing with herbicide application with tilling will act as the manipulative element in altering “site availability” as I believe that these preparations will increase the availability or openness of sites that were previously occupied by the target invasive species. I hypothesize that the most successful decrease in invasive plant

21 percent cover will occur on sites that are mowed and then sprayed with a non-selective herbicide.

Chapter 2

METHODS

Study Site

Camp Ripley (15000 Hwy 15, Little Falls, MN 56345, USA) is a 21,500 ha facility that is located along the forest transition zone in central Minnesota (lat. 46.2N, long. 94.3W), positioned along the divide between the Laurentian Mixed Forest province, and the Eastern Broadleaf Forest Province. Three subsections converge on

Camp Ripley: Hardwood Hills, Anoka Sand Plain, and Pine Moraines and Outwash

Plains. (Figure 2) (Minnesota DNR, 2010). The Crow Wing River and Mississippi

River border Camp Ripley to the north and east. Fifty-five percent of the installation is dryland forest habitat type and the remaining 45% is open grassland, brush land, or wetland habitat (Division of Ecological Resources Minnesota Department of Natural

Resources for the Minnesota Army National Guard, 2008). Over 600 plant species have been identified at Camp Ripley along with over 300 animal species. Spotted knapweed and common tansy are present at Camp Ripley in areas that are open grassland or oak savannah ecotypes. There are three soil type associations in grassland areas at Camp Ripley: Hubbard-Duelm-Isan, Mahtomedi-Menahga, and Cushing-

Mahtomedi-Demontreville associations.

22 23

Figure 2. The Pine Moraines and Outwash Plains, Hardwood Hills, and Anoka Sand Plain subsections converge at Camp Ripley. Subsections defined by the MN Department of Natural Resources.

All three of these soil associations are characterized by well to excessively drained, sandy, or loamy, slightly acidic soil (Almendinger, Hanson, & Jordan, 2000;

Reetz & Camp Ripley Environmental Office, 1998). The native plant community that is being restored in these areas is classified as Ups13 Upland Prairie System Southern

Dry Prairie as defined by the Field Guide to the Native Plant Communities of

Minnesota: The Eastern Broadleaf Forest Province (Minnesota Department of Natural

Resources [MN DNR], 2005). This community is defined as:

Grass-dominated herbaceous communities on level to steeply sloping sites with droughty soils. Moderate growing-season moisture deficits occur most years, and severe moisture deficits are frequent, especially during periodic regional droughts. Historically, fires probably occurred every few years. (MN DNR, 2005, p. 240)

Vegetation found in this native plant community is listed in Table 1.

Precipitation from April to August 2010 was 22.81 cm. Precipitation from

April to August 2011 was 40.46 cm. The Average rainfall from April to August over a

25 year span is 42.8 cm.

Table 1. UPs13 Southern Dry Prairie native plant community as defined by the DNR Ecological Classification System 2005

Forbs, Ferns, and Fern Allies Grasses and Sedges Shrubs and Semi-Shrubs Schizachyrium Purple prairie clover Dalea purpurea Little bluestem scoparium Leadplant Amorphacanescens Bouteloua Prairie Gray goldenrod Solidago nemoralis Side-oats grama curtipendula rose Rosa arkansana Andropogongerard Smooth Silky aster Aster sericeus Big bluestem ii sumac Rhusglabra Sporobolusheterol Symphoricarposoccid Heath aster Aster ericoldes Prairie dropseed epis Wolfberry entalis Stiff goldenrod Solidago rigida Porcupine grass Stipaspartea Long-headed Anemone Muhlenbergiacusp thimbleweed cylindrica Plains muhly idata Bearded birdfoot Sorghastrumnutan violet Viola pedatifida Indian grass s Koeleriapyramidat Rough blazing star Liatrisaspera June grass a Daisy fleabane Erigeron strigosus Hairy grama Boutelouahirsuta Scribner’s panic Panicumoligosant Pasque-flower Anemone patens grass hes Helianthus Wilcox’s panic Panicumwilcoxian Stiff sunflower pauciflorus grass um Narrow-leaved purple coneflower Echinacea pallida Blue grama Boutelouagracilis Calamovilfalongif Tall cinquefoil Potentillaarguta Sand reed-grass olia Comandraumbellat Needle-and- Bastard toad-flax a thread grass Stipacomata Pediomelumescule Prairie turnip ntum Prairie wild onion Allium stellatum Dotted blazing star Liatrispunctata

Table 1 (continued)

Forbs, Ferns, and Fern Allies Grasses and Sedges Shrubs and Semi-Shrubs Lithospermumcane Hoary puccoon scens Aromatic aster Aster oblongifolius Virginia ground cherry Physalisvirginiana Flodman's thistle Cirsium flodmanii Bird's foot coreopsis Coreopsis palmata Grooved yellow flax Linumsulcatum Ambrosia Western ragweed psilostachya Solidagocanadensi Canada goldenrod s Heart-leaved alexanders Ziziaaptera Wild bergamot Monardafistulosa Campanula Harebell rotundifolia Toothed evening Calylophusserrulat primrose us Solidagomissourie Missouri goldenrod nsis Aster Skyblue aster oolentangiensis Mock pennyroyal Hedeomahispida Prairie sagewort Artemisia frigida Hoary vervain Verbena stricta Euphorbia Flowering spurge corollata Artemisia White sage ludoviciana Asclepiasverticillat Whorled milkweed a Field blue-eyed Sisyrinchiumcamp grass estre Artemisia Tall wormwood dracunculus Hairy golden aster Chrysopsisvillosa Prairie ragwort Senecioplattensis Kuhniaeupatorioid False boneset es False gromwell Onosmodiummolle Asclepiasviridiflor Green milkweed a Narrow-leaved Lithospermumincis puccoon um Plantain-leaved Antennariaplantagi pussytoes nifolia Lithospermumcaro Hairy puccoon liniense Silky prairie clover Daleavillosa

Experimental Design

A randomized complete block design was used in this project (Figure 3).

Sixteen individual treatments were used per block in a 4 x 2 x 2 configuration. Four

blocks, or replicates, was established per each of two species: spotted knapweed and

common tansy. Each treatment consists of one of four seedbed preparations, one of

two cover crop types, one of two seed dispersal methods (Figure 4). A fourth factor,

consisting of a selective herbicide, was applied to these plots in May 2011.

Figure 3. A randomized complete block design (2x2x4). Each individual treatment will have1of 4seedbed preparation types (Mowing, Mowing/Herbicide, Mowing/Herbicide/ Tilling, No seedbed preparation), 1 of 2 cover crop types (Canadian wild rye or No cover crop), and 1 of 2 seed distribution methods for the native grass mixture (Hand broadcasting versus Drill seeding). These individual treatment types were randomly assigned their location in the block. 4 blocks total were assigned to each areas infested with common tansy, spotted knapweed. M= mowing. H= herbicide. T=tilling. NP= no preparation . C= cover crop. NC= no cover crop. HB= hand broadcasting. DS= drill seeding. Half of each plot was sprayed with Milestone, a selective herbicide, in June

2011. 27

1 M,C - 8 Hand Broadcast Native 2 M+H, C

Grass HB mix, 3 M+H+T, C NO PREP 4 NP, C

4 Canada RyeWild 4 Canada

Cover Crop, CWR Crop, Cover - 5 M, NC 1 6 M+H, NC ONLY MOW

7 M+H+T, NC

8 NP, NC

9 MOW AND

9 M, C - 16 Drill Seed Native Grass HERBICIDE 10 M+H, C 11 M+H+T, C MOW, HERBICIDE, DS mix, 12 NP, C AND TILL

Cover Crop, CWR Crop, Cover 12 Canada RyeWild 12 Canada 13 M, NC -

9 14 M+H, NC 15 M+H+T, NC 16 NP, NC

Figure 4. Treatment assignments were determined by plots receiving a random number between 1-16. Each number correlates with a specific seedbed preparation, cover crop or control, and native grass mix seed dispersal method.

This resulted in a 4 x 2 x 2 x 2 factorial design with 32 individual treatments

per block, with four replicates of each block. Each block, before the fourth factor was

applied, consisted of sixteen treatment areas 10 meters by 20 meters with three meter

mowed buffer zones between treatment areas to prevent treatments having an effect on

one another. Each block is 107 meters by forty nine meters. Blocks were delineated in

late March 2010 at field locations within Camp Ripley that are of the appropriate size

28 and have an overall invasive percent cover of 25 percent or greater. GPS coordinates of these locations were recorded. Mapping of plots was conducted pre-implementation of treatments using ArcGIS 9.3©, produced by ESRI®. The plots were delineated using rebar stakes to avoid losing boundary locations.

Procedures

Four seedbed preparations are being investigated: (1) Mowing (2) Mowing and herbicide, (3) Mowing, herbicide application, and tilling, and (4) No seedbed preparation. GPS locations of all blocks were recorded as shown in Table 2.

Table 2. UTM GPS Point Location of Blocks at Camp Ripley, MN

X Y Spotted Knapweed Block 1 Corner 1: 15N 388694 5110714 Corner 2: 15N 388750 5110713 Corner 3: 15N 388691 5110586 Corner 4: 15N 388665 5110703 Spotted Knapweed Blocks 2,3,4 (These blocks are in the same field) Corner 1: 15N 387929 5111439 Corner 2: 15N 387883 5111299 Corner 3: 15N 387743 5111298 Corner 4: 15N 387729 5111413 Common Tansy Blocks 1-4 (These blocks are in the same field) Corner 1: 15N 388482 5111222 Corner 2: 15N 388400 5110917 Corner 3: 15N 388280 5110909 Corner 4: 15N 388284 5111205

Seedbed preparations were conducted by Jamie Hanson and Kayla Malone.

Mowing of the treatment areas and buffer zones was done by Jamie Hanson and Kayla

Malone, using equipment at Camp Ripley. Herbicide was applied by Jamie Hanson and Kayla Malone with a mounted gator sprayer with a one meter boom unit.

Glyphosate (RoundUp Pro®) was used as the herbicide spray treatment at 1.5% solutionfor both invasive species. Tilling was done by Jamie Hanson and Kayla

Malone with equipment provided by the Department of Public Works at Camp Ripley.

Seedbed preparations were done from May 17 through June 11, 2010.

A cover crop and a control treatment is being investigated: (1) Canada wild rye

(Elymus canadensis), drilled at the rate of 11.2 kg per ha (10 pounds per acre), and

(2) No cover crop. The cover crop was implemented into the sites thirty days following the seedbed preparations (early June 2010). Equipment used was a Tru-ax© drill seeder. Canada wild rye was drilled into the soil at a depth of 6 cm. The cover crop was implemented into the sites June 16-June 22, 2010.

Two seed dispersal methods of the native species mix are being investigated:

Hand broadcasting and no-till seed drilling. The drill seeder used for this project will be a 2.44 meter wide (8 feet) three-point mount Tru-ax© drill seeder. Two seed dispersal methods for the native grass seed mix were used: (1) Hand broadcasting,

(2) No-till drill seeding. Sites that were drill seeded were done at a depth of 1.3 cm.

The native grass species that will be used are as follows: Big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparium), Indian grass (Sorghastrum nutans), side oats grama (Bouteloua curtipendula), switch grass (Panicum virgatum),

30 kalm’s brome (Bromus kalmii), June grass (Koeleria macrantha), and sand dropseed

(Sporobolus cryptandrus). This species mix was in the appropriate ratios as recommended by Prairie Restorations Inc. Hand broadcastingwas done at the rate of

14.6 kg per ha (3 pounds per 10000 square feet). No-till drill seeding was done at the rate of 11.2 kg per ha (10 pounds per acre), as recommended by the Prairie

Restorations Inc. catalog. The native grass mix was implemented into plots as a dormant fall seeding from October 13-14, 2010.

Once all treatments were administered to the sites, buffer maintenance and data collection was completed for the first growing season. Times of species emergence were collected. Native species identification was difficult in the first growing season.

To mitigate this difficulty, the native seed mixture was also grown in a controlled interior setting at Saint Cloud State University to assist in identification. Precipitation was observed along with any extreme weather events. Data were collected in early

July, late July, and mid-August. Prairie grasses take time to establish and therefore it is likely that the second and third growing season will have higher diversity. Grass surveys were conducted yearly to gauge seeded grass species’ emergence.

Data were analyzed using a Univariate ANOVA and Repeated Measures statistical analysis via a general linear model in the computer statistical software SPSS

17.0.

Data collected on site prior to experimental treatments included senescent stand invasive plant percent cover measures, grass surveys, and forb surveys. Data collected from April 12-14in 2010 showed that all blocks displayed an average-block

31 residual over-wintered dried stem percent cover measurements of over 25%. This indicates that during peak growth of the invasive plants, the actual coverage is much higher. Grass and forb surveys conducted throughout June and August indicate that overall diversity in these highly infested experimental blocks is lower than in healthy tallgrass prairie areas.

It was observed that spotted knapweed and common tansy germination rates may have increased post disturbance in plots that were mowed, tilled, and drill seeded.

This result is not unexpected, as certain disturbances may invigorate the seed bank present in the soil. A benefit of inducing germination is that emerging invasive plants can be controlled post-germination and pre-flowering, therefore eliminating the seeds and future plants that result from a dormant seed bank. To do this, while still being able to analyze the effectiveness of combinations, it was decided that a selective herbicide would have to be applied over all combinations except for areas that were had no site preparation (those plots that were not mowed, herbicided, or tilled).

Milestone, as the selective herbicide of choice, was planned to be applied at the appropriate maximum recommended label rate of 511.54 ml/hato half of every plot using an ATV-mounted 3-point fan nozzle skid sprayer. The herbicide was applied on

May 25 and May 26 of 2011. Some variation occurred in spray application. Spotted knapweed Block 1 was sprayed at the rate of 520.31 ml/ha, with total milestone application of 105.28 ml in 75.71 liters H20. Spotted knapweed Block 2 was initially oversprayed on the western side. The spray rate was corrected resulting in an overall rate of 700.09 ml/ha, with total milestone application of 141.66 ml in 75.71 liters H20.

Spotted knapweed Block 3 was sprayed at the rate of 548.08 ml/ha, with total milestone application of 110.61 ml in 79.49 liters H20. Spotted knapweed Block 4 was sprayed at the rate of 548.08 ml/ha, with total milestone application of 110.61 ml in

79.49 liters H20. Common Tansy Block 1 was sprayed at the rate of 460.39 ml/ha, with total milestone application of 93.15 ml in 79.49 liters H20. Common Tansy

Block 2 was sprayed at the rate of 482.31 ml/ha, with total milestone application of

97.59 mlin 83.28 liters H20. Common Tansy Block 3 was sprayed at the rate of

460.39 ml/ha, with total milestone application of 93.15 ml in 79.49 liters H20.

Common Tansy Block 4 was sprayed at the rate of 460.39 ml/ha, with total milestone application of 93.16 ml in 79.49 liters H20.

2011 data collection involved multiple methods. Senescent stand percent cover estimates were taken using two 1-m2 quadrats placed in the northwest and southeast portions of each plot and an overall visual estimate of senescent target invasive percent cover per plot. This was done April 18-25, 2011. Emergent stand percent cover estimates were also taken using two 1-m2 quadrats placed in the northwest and southeast portions of each plot and an overall visual estimate of senescent target invasive percent cover per plot. This was done May 19-23, 2011. Post-Milestone selective herbicide application, data was collected for invasive percent cover in the same manner as previously stated during July 6-8, 2011. Species Richness data was collected per plot between August 3-8, 2011. A 1-m2quadrat was randomly placed in each half of plots, both on the half that received the selective herbicide, and also on the untreated half. Total number of vascular plant species were counted, identified,

33 and recorded. During August 15-25, 2011 a cover class survey was conducted using a daubenmire frame. The 20cm by 50cm frame was randomly placed in each half of each plot. 6 cover class percent ranges were established: 1:1-5%, 2:6-25%, 3:26-50%,

4:51-75%, 5:76-95%, 6:96-100% and various classes were recognized including the target invasive species of spotted knapweed, the target invasive species of common tansy, non-native grasses such as smooth brome and quack grass, native grasses, non- native forbs such as common mullein, native forbs, and bare ground. Tables 3 and 4 show the timeline of all procedures done to the study sites.

Table 3. Timeline of events in 2010

April May June July August October 2nd, 7th: Marking 3rd: No-prep 1st-3rd : 6th: 27th: Re- 13th: Drill seed corners of blocks markers Herbicide Observation mow of all and HB of natives finished in all applied to all of Rye buffers in Knapweed plots appropriate plots plots: Approx 7.85 PLS kg/ha 12th, 14th : 12th: Soil 4th, 7th: Mow 22nd: Data 14th: Drill seed Percent cover sterilization, and Herbicide collection and HB of natives invasive data grow room Blue rebar tilled area in Tansy plots: collected started 161 markers were that were Approx 10+ kg grams seed mix placed on drill seeded PLS/ha appropriate plots 19th-26th: Post- 17th-18th: 9th-11th: 26th: Tilled 18th-22nd: Mow pounding: approx. Mowing of Tilling areas that and Herbicide 130 t-stakes and Spotted were not drill and Till Green cyber stake caps Knapweed seeded were rebar markers Block 1, Tansy observed were placed on Blocks 1,2,3,4 appropriate plots. 26th-30th: No- 19th-20th: 16th: Drill 30th: Grass prep markers Mowing of seeding Canada survey of all (rebar) were Knapweed Wild Rye in no-prep plots placed on Plots 2,3,4 Tansy 1-4, appropriate plots Knapweed 2-3 except no-prep plots, 24th-26th: 22nd: Drill Mow-only pink seeding markers (rebar) Knapweed 4 and were placed on 1 and appropriate appropriate no- plots prep plots. Approx. 6.73 to8.97 PLS kg/ha 28th: 23rd-26th: Forb Herbicide surveys in all applied to all yellow no prep appropriate zones plots 29th: Re-mow of buffer zones and pink mow- only plots.

Table 4. Timeline of events in 2011

April May June July August 8th-25th: 19th: Emergent 27th: Mowed 6th: Milestone % 3, 5, 8th: Species Senescent stand stand data SK 2 and 3 cover invasive Richness data data collection. collection data collection and collected Spotted soil survey Knapweed. Common Tansy 1- 4 and plot photographs 23rd: Emergent 29th: Mowed 8th: Milestone % 15-25th: stand data SK 4 cover invasive Daubenmeier collection data collection and Cover Class Data Common Tansy soil survey collected Spotted Knapweed 1-4 and plot photographs 25th: Spray 11th: Sprayed Milestone on edges with wand Spotted off gator. Sprayed Knapweed plot 10 and 14 in Blocks 2-4 Block 4 SK.

26th: Spray Milestone on Spotted Knapweed Block 1 and Tansy Blocks 1-4

Chapter 3

RESULTS

Initial Data Collection—2010

Spotted knapweed blocks and common tansy blocks were initially surveyed for senescent visual estimation of percent cover of invasive plant percent cover in April

2010 using sixteen randomly obtained 1-m2 areas. Table 5 includes the mean percent cover obtained for each block of the target invasive plant species in areas that were infested with either spotted knapweed or common tansy.

All blocks contained over 25% senescent stand percent cover. Seedbed preparations prevented the determination of emergent percent cover in 2010. The emergent percent cover is projected to have been higher as can be observed by the comparison of senescent versus emergent percent cover data obtained from control plots in 2011. The mean initial percent cover in spotted knapweed blocks of spotted knapweed was 43.7%. The mean initial percent cover in common tansy blocks of common tansy was 30.9%.

Also in summer 2010, forb, tree, and grass surveys were conducted in control plots in all blocks from June to August (Table 17, p. 49 and Table 19, p. 52). These surveys involved the complete inventory of all identifiable grasses, tree species, and forbs that existed within plots that received no seedbed preparations (plots numbered

36 37

4, 8, 12, and 16) in all blocks. Forb surveys were conducted June 21-26, 2010. Grass surveys were conducted in the same manner from July 28-30, 2010. In spotted knapweed and common tansy blocks, 42 forb and tree species were identified and recorded. In spotted knapweed blocks, 17 grass species were identified and recorded.

In common tansy blocks, 13 grass species were identified and recorded.

Table 5. A random number generator was used to determine the number of steps walked within the block to visually estimate senescent stand invasive species percent cover in April 2010 of a meter sized area at that point with a total of 16 points per block.

Spotted Knapweed Block Mean Percent Cover (%) 1 39.7 2 45.9 3 49.1 4 40 Overall Mean 43.7 Common Tansy Block Mean Percent Cover (%) 1 27.8 2 27.5 3 35.6 4 32.5 Overall Mean 30.9

Senescent Stand Data Collection—2011

Year 2011 mean overall estimates of percent cover of the four replicates of each of the 16 plot treatment combinations for spotted knapweed and common tansy blocks during senescence are shown in Tables 6 and 7. These mean percent covers display the immediate impact of the previous summer’s treatments. As one could

38 predict, seedbed preparations can decrease the presence of senescent stands of the target invasive species. However, this does not necessarily mean that this will result in a subsequent decrease in emergence of invasive species post-germination. The overall mean percent covers per blocks 1-4 of spotted knapweed and common tansy areas are displayed in Table 8. Table 8 contains two mean percent covers per block. The first mean percent cover is an overall visual estimate. Two 1-m2 random samples per plot were also assessed for percent cover. The mean sample percent covers and mean overall estimates were different for this particular data set, due to the sparse habit of both invasive species and impact on other species’ presence during senescence. Larger areas have a higher visual impact and resulting estimate. Table 8, when compared to

Table 5, reveals that post-treatment percent covers of senescent stands of the two invasive species were reduced. Over all blocks, the mean percent cover was 10.9-

21.2% in spotted knapweed areas versus the initial mean of 43.7%. Over all blocks, the mean percent cover was 9.2-15.6% in common tansy areas versus the initial mean of 30.9%.

Table 6. April 2011 senescent Table 7. April 2011 senescent stand stand mean percent cover of mean percent cover of common spotted knapweed. tansy.

Treatment Treatment Combination Mean Percent Combination Mean Percent (Four Cover (%) (Four Cover (%) replicates) replicates) 1 18.8 1 14.0 2 21.3 2 30.0 3 4.0 3 2.8 4 35.0 4 25.0 5 32.5 5 13.8 6 18.8 6 17.5 7 3.0 7 5.3 8 38.8 8 56.3 9 28.8 9 10.3 10 15.0 10 6.3 11 3.0 11 1.5 12 45.0 12 12.5 13 27.5 13 7.8 14 15.0 14 19.0 15 3.8 15 2.8 16 28.8 16 25.0

Table 8. A block mean of visual estimates of senescent stand invasive species percent cover in April 2011 of each 10 by 20 meter plot. A block mean of two one meter samples of senescent stand invasive species percent cover in April 2011 of each 10 by 20 meter plot.

Spotted Knapweed Mean Visual Estimate of Plot Mean Sample Percent Cover Block Percent Cover (%) (%) 1 16.9 8.7 2 24.3 12.8 3 24.4 12.3 4 19.2 9.8 Overall Mean 21.2 10.9 Common Mean Visual Estimate of Plot Mean Sample Percent Cover Tansy Block Percent Cover (%) (%) 1 14.4 4.9 2 9.6 5.8 3 21.1 14.7 4 17.25 11.6 Overall Mean 15.6 9.2

Emergent Stand Data Collection—2011

Once vegetation began to emerge, it was observed that spotted knapweed and common tansy were still very present in many plots that had shown a reduction in percent cover when the senescent survey was done. Tables 9 and 10 contain the emergent percent cover means for all treatment combinations applied to plots in spotted knapweed areas and common tansy areas. Within Table 11, one can see the mean percent cover measures per block for both species. The mean percent cover measures in spotted knapweed areas per plot were at times higher post treatment, than in 2010. This was also true, albeit to a lesser degree, in areas infested with common

41 tansy. Table 11, when compared to Table 5, reveals that post-treatment percent covers of emergent stands of the two invasive species were not meaningfully reduced. Over all blocks, the mean percent cover was 43.8-44.3% in spotted knapweed areas versus the initial mean of 43.7%. Over all blocks, the mean percent cover was 20.8-25.6% in common tansy areas versus the initial mean of 30.9%.

Table 9. May 2011 emergent Table 10. May 2011 emergent stand mean percent cover of stand mean percent cover of spotted knapweed. common tansy.

Treatment Treatment Combination Mean Percent Combination Mean Percent (Four Cover (%) (Four Cover (%) replicates) replicates) 1 33.8 1 30.0 2 43.8 2 46.3 3 47.5 3 12.5 4 26.3 4 17.5 5 40.0 5 35.0 6 51.3 6 28.8 7 68.8 7 16.3 8 32.5 8 46.3 9 47.5 9 23.8 10 42.5 10 32.5 11 51.3 11 15.0 12 47.5 12 10.0 13 47.5 13 17.5 14 35.0 14 41.3 15 66.3 15 15.0 16 27.5 16 22.5

Table 11. A block mean of visual estimates of emergent stand invasive species percent cover in May 2011 of each 10 by 20 meter plot. A block mean of two one meter samples of emergent stand invasive species percent cover in May 2011 of each 10 by 20 meter plot.

Spotted Knapweed Mean Visual Estimate of Plot Percent Block Cover (%) Mean Sample Percent Cover (%) 1 61.9 62.5 2 49.7 50.8 3 37.5 38.0 4 28.1 23.9 Overall Mean 44.3 43.8

Common Tansy Mean Visual Estimate of Plot Percent Block Cover (%) Mean Sample Percent Cover (%) 1 20.0 15.6 2 18.8 15.0 3 33.8 28.3 4 30.0 24.4 Overall Mean 25.6 20.8

Post-Milestone Application Data Collection—2011

It was decided that the increase in percent cover that was observed in May warranted an addition of another method of treatment. Since a reduction in percent cover using the first three factors was not being observed it was decided that the addition of a selective herbicide would be a valuable addition as a fourth factor in the factorial design. Previous research and recommendation had shown that Milestone is a reliable selective herbicide for the control of these two species (Beck, 2008) (M.

Halstvedt, personal communication, July 22, 2010).

To preserve the integrity of the factorial design, especially for the continued monitoring of the effects of the first three factors in combination, this selective herbicide was applied only on half of each 10 by 20 meter plot, thus producing a 4 by

2 by 2 by 2 design with 32 individual combinations. Five weeks after the application of this selective herbicide to each half-plot, percent cover data was obtained per plot for every block. Tables 12 and 13 show that during this data collection, there was far less percent cover of either of the invasive species than that which can be seen in

Tables 9 and 10, which contain the emergent percent cover means for all treatment combinations applied to plots in spotted knapweed areas and common tansy areas.

Spotted knapweed areas had lower percent cover measures for each treatment combination that received the selective herbicide than the percent cover measures taken on the common tansy plots with the same treatments. Table 14 also shows that per block on all half-plots that received the selective herbicide, the percent cover was reduced as compared to the emergent percent cover data obtained in May. Table 14, when compared to Table 5, reveals that percent cover measures of post-milestone application standswere reduced. Over all blocks, the mean percent cover was 1.3-

1.9% in spotted knapweed areas versus the initial mean of 43.7%. Over all blocks, the mean percent cover was 8.9-9.3% in common tansy areas versus the initial mean of

30.9%.

Table 12. July 2011 Post- Table 13. July 2011 Post- selective-herbicide treatment selective-herbicide treatment mean percent cover of mean percent cover of spotted knapweed. common tansy.

Treatment Treatment Mean Mean Combination Combination Percent Percent (Four (Four Cover (%) Cover (%) replicates) replicates) 1 0.0 1 7.8

2 11.0 2 17.5

3 0.3 3 4.8

4 0.3 4 3.5

5 2.0 5 3.5

6 0.5 6 17.8

7 2.5 7 11.3

8 0.3 8 6.8

9 1.0 9 5.3

10 3.3 10 14.5

11 1.5 11 9.3

12 1.0 12 2.0

13 1.0 13 4.0

14 2.0 14 21.5

15 4.5 15 9.0

16 0.3 16 4.0

Table 14. A block mean of visual estimates of post-selective-herbicide treatment invasive species percent cover in July 2011 of each 10 by 20 meter plot. A block mean of two one meter samples of post-selective-herbicide treatment invasive species percent cover in 2011 of each 10 by 20 meter plot.

Spotted Knapweed Mean Visual Estimate of Plot Mean Sample Percent Cover Block Percent Cover (%) (%) 1 0.0 0.0 2 1.9 2.3 3 5.1 2.4 4 0.6 0.4 Overall Mean 1.9 1.3

Common Tansy Mean Visual Estimate of Plot Mean Sample Percent Cover Block Percent Cover (%) (%) 1 6.4 5.1 2 2.8 3.9 3 15.4 15.9 4 10.9 12.2 Overall Mean 8.9 9.3

2011 Vegetation Surveys

A selective herbicide such as Milestone can also reduce other broadleaf species within plots along with the targeted broadleaf invasive species. To measure the impact that the herbicide had to species richness per plot, number of species were surveyed in each half plot in August 2011. The selective herbicide did significantly reduce the number of species within half-plots as compared to half-plots without the herbicide, as shown in Tables 15 and 16.

During August 2011 the cover class survey that was conducted on half plots with and without a Milestone application yielded the measures shown in Tables 21 and

22. The results of this cover class survey show that in spotted knapweed plot halves with Milestone, spotted knapweed was reduced. However in these same plot halves, undesirable non-native grass species proliferated. In common tansy plot halves with

Milestone, common tansy was reduced. In these same plot halves, undesirable non- native grass species also thrived. It is also interesting to note that spotted knapweed took over increasingly in common tansy areas, post all treatments.

Also in August 2011, forb, tree, and grass surveys were conducted in in all blocks (Table 18 and 20). These surveys involved the complete inventory of all identifiable grasses, tree species, and forbs that existed within all half-plotsin all blocks. In spotted knapweed blocks 23 forb and tree species were identified and recorded. In common tansy blocks, 29 forb and tree species were identified and recorded. In spotted knapweed blocks, 11 grass species were identified and recorded.

In common tansy blocks, 11 grass species were identified and recorded. Number of species was lower in all surveys conducted in 2011 versus those surveys in 2010. In

2010 84 forb and tree species, and 30 grass species were identified total in both invasive species areas. In 2011, only 52 forb and tree species were identified, and only

22 grass species were identified total.

Table 15. 2011 Species Richness per half-plot (# spp.) with 1m squared quadrat sampling frame randomly placed at least one meter from buffer zone (nm= half-plot without selective herbicide, m= half-plot with selective herbicide applied).

Common Tansy Block 1 August 5 Common Tansy Block 2 August3 1 nm 8 1 m 4 1 nm 7 1 m 4 2 nm 8 2 m 8 2 nm 10 2 m 5 3 nm 9 3 m 8 3 nm 10 3 m 6 4 nm 9 4 m 5 4 nm 6 4 m 4 5 nm 9 5 m 5 5 nm 5 5 m 4 6 nm 9 6 m 6 6 nm 6 6 m 5 7 nm 4 7 m 7 7 nm 10 7 m 4 8 nm 4 8 m 3 8 nm 6 8 m 3 9 nm 10 9 m 6 9 nm 10 9 m 4 10 nm 8 10 m 4 10 nm 9 10 m 5 11 nm 9 11 m 7 11 nm 7 11 m 3 12 nm 6 12 m 6 12 nm 4 12 m 6 13 nm 7 13 m 4 13 nm 10 13 m 6 14 nm 10 14 m 4 14 nm 8 14 m 6 15 nm 10 15 m 8 15 nm 9 15 m 5 16 nm 5 16 m 4 16 nm 4 16 m 4 Mean 7.8 5.6 Mean 7.6 4.6

Common Tansy Block 3 August3 Common Tansy Block 4 August 3 1 nm 5 1 m 4 1 nm 5 1 m 5 2 nm 10 2 m 6 2 nm 10 2 m 5 3 nm 10 3 m 9 3 nm 10 3 m 7 4 nm 9 4 m 6 4 nm 12 4 m 6 5 nm 5 5 m 5 5 nm 8 5 m 3 6 nm 7 6 m 6 6 nm 9 6 m 5 7 nm 12 7 m 3 7 nm 10 7 m 7 8 nm 8 8 m 6 8 nm 6 8 m 3 9 nm 4 9 m 4 9 nm 7 9 m 4 10 nm 10 10 m 9 10 nm 8 10 m 5 11 nm 12 11 m 6 11 nm 9 11 m 9 12 nm 10 12 m 5 12 nm 8 12 m 5 13 nm 9 13 m 4 13 nm 10 13 m 5 14 nm 7 14 m 6 14 nm 5 14 m 9 15 nm 10 15 m 8 15 nm 14 15 m 3 16 nm 8 16 m 6 16 nm 7 16 m 5 Mean 8.5 5.8 Mean 8.6 5.4

Table 16. Species richness per half-plot (# spp.) with 1m squared quadrat sampling frame randomly placed at least one meter from buffer zone (nm= half-plot without selective herbicide, m= half-plot with selective herbicide applied).

Spotted Knapweed Block 1 August 8 Spotted Knapweed Block 2 August 5 1 nm 5 1 m 5 1 nm 11 1 m 9 2 nm 5 2 m 6 2 nm 9 2 m 6 3 nm 5 3 m 3 3 nm 10 3 m 6 4 nm 4 4 m 2 4 nm 6 4 m 5 5 nm 4 5 m 3 5 nm 8 5 m 7 6 nm 5 6 m 3 6 nm 7 6 m 7 7 nm 4 7 m 2 7 nm 7 7 m 7 8 nm 7 8 m 4 8 nm 9 8 m 5 9 nm 4 9 m 3 9 nm 9 9 m 8 10 nm 7 10 m 6 10 nm 6 10 m 12 11 nm 3 11 m 3 11 nm 6 11 m 8 12 nm 5 12 m 4 12 nm 6 12 m 6 13 nm 7 13 m 3 13 nm 9 13 m 6 14 nm 4 14 m 4 14 nm 7 14 m 6 15 nm 7 15 m 5 15 nm 6 15 m 7 16 nm 6 16 m 2 16 nm 9 16 m 8 Mean 5.125 3.625 Mean 7.8125 7.0625

Spotted Knapweed Block 3 August 8 Spotted Knapweed Block 4 August 8 1 nm 7 1 m 6 1 nm 13 1 m 7 2 nm 7 2 m 7 2 nm 10 2 m 10 3 nm 10 3 m 10 3 nm 17 3 m 10 4 nm 10 4 m 8 4 nm 12 4 m 8 5 nm 11 5 m 8 5 nm 9 5 m 5 6 nm 14 6 m 7 6 nm 11 6 m 3 7 nm 4 7 m 6 7 nm 16 7 m 9 8 nm 9 8 m 7 8 nm 8 8 m 4 9 nm 11 9 m 6 9 nm 6 9 m 9 10 nm 5 10 m 5 10 nm 15 10 m 8 11 nm 14 11 m 8 11 nm 19 11 m 8 12 nm 9 12 m 6 12 nm 11 12 m 4 13 nm 11 13 m 9 13 nm 16 13 m 9 14 nm 7 14 m 5 14 nm 13 14 m 8 15 nm 11 15 m 7 15 nm 18 15 m 9 16 nm 11 16 m 6 16 nm 15 16 m 8 Mean 9.4375 6.9375 Mean 13.0625 7.4375

Table 17. Forb and tree surveys in June and August 2010.

Forb and TreeSpecies Survey in Spotted Forb and Tree Species Survey in Knapweed Blocks in June and August Common Tansy Blocks in June and 2010 August 2010

Common Name Scientific Name Common Name Scientific Name Absinthium Artemisia absinthium Absinthium Artemisia absinthium Aslike Clover Trifoliumhybridum Aslike Clover Trifoliumhybridum Aspen Spp. Populus Birch Spp. Betula Bedstraw Spp. Galium Black Eyed Susan Rudbeckia hirta Birch Spp. Betula Bladder Campion Silene nivea Black Eyed Susan Rudbeckia hirta Butter & Eggs Linariavulgaris Common Blackberry Spp. Rubus Potentilla simplex Cinquefoil Bull Thistle Cirsiumvulgare Common Mullein Verbascum thapsus Common Chickweed Stellaria media Common Sorrel Rumex acetosa Common Mullein Verbascum thapsus Common Yarrow Achillea millefolium Common Sorrel Rumex acetosa Cow Vetch Vicia cracca Common Yarrow Achillea millefolium Deptford Pink Dianthus armeria Apocynum Apocynum Dogbane Dogbane cannabinum cannabinum Fleabane Spp. Erigeron Evening Lychnis Lychnis alba Goat's Beard, Tragopogon dubius Fleabane Spp. Erigeron Western Salsify Goldenrod Spp. Solidago Goldenrod Spp. Solidago Grass leaved golden Chrysopsisgraminifol Hoary Alyssum Berteroaincana aster i Horseweed Conyzacanadensis Hairy Rock Cress Arabishirsuta Indian Paintbrush Castillejacoccinea Hoary Alyssum Berteroaincana Milkweed Spp. Asclepias Hop Clover Trifolium aureum Mustard Spp. Brassica Horseweed Conyzacanadensis

Night-flowering Silene noctiflora Milkweed Spp. Asclepias Lychnis

Oak Spp. Quercus Mustard Spp. Brassica Toxicodendronradica Night-flowering Poison Ivy Silenoctiflora ns Catchfly Prairie Cinquefoil Potentilla Nightshade Spp. Solanum

pensylvanica Table 17 (continued)

Forb and TreeSpecies Survey in Spotted Forb and Tree Species Survey in Knapweed Blocks in June and August Common Tansy Blocks in June and 2010 August 2010

Common Name Scientific Name Common Name Scientific Name Symphyotrichumlanc Prairie Rose Rosa arkansana Panicled Aster eolatum Purple Clover Trifolium purpureum Plantain Spp. Plantago Toxicodendronradica Purple Vetch Vicia americana Poison Ivy ns Potentilla Quaking Aspen Populus tremuloides Prairie Cinquefoil pensylvanica Rabbit's foot Clover Trifolium arvense Prairie Rose Rosa arkansana Artemisia Red Clover Trifolium pratense Prairie Sage ludoviciana Sandbar Willow Salix Purple Vetch Vicia americana Spp. Silvery Cinquefoil Potentillaargentea Red Clover Trifolium pratense Slender Leaved Rough Fruited Aster tenuifolius Potentilla recta Aster Cinquefoil Smooth Sumac Rhusglabra Silvery Cinquefoil Potentillaargentea Hypericumperforatu Slender Leaved St. John's Wort Aster tenuifolius m Aster Tall Cinquifoil Potentillaarguta Smooth rock cress Arabiscanadensis Centaurea stoebe ssp. Vetchling Spp. Lathyrus Spotted Knapweed micranthos Parthenocissusquinq Virginia Creeper Vetchling Spp. Lathyrus uefolia Wild Strawberry Fragariavirginiana White Campion Silene latifolia Willow Spp. Salix White Sweet Clover Melilotus alba Yellow Sweet Melilotusindicus Wild Strawberry Fragariavirginiana Clover

Table 18. Forb and tree surveys in August 2011.

Forb and Tree Species Survey in Spotted Forb and Tree Species Survey in Common Tansy Knapweed Blocks in August 2011 Blocks in August 2011

Common Name Scientific Name Common Name Scientific Name Blackberry Rubus Absinthium Artemisia absinthium Black Eyed Susan Rudbeckia hirta Black Eyed Susan Rudbeckia hirta Campion Spp. Silene Bull Thistle Cirsiumvulgare Cinquefoil Spp. Potentilla Butter & Eggs Linariavulgaris Clover Spp. Trifolium Campion Spp. Silene Common Yarrow Achillea millefolium Canada Thistle Cirsium arvense Field Bindweed Convolvulus Cinquifoil Spp. Potentilla Fleabane Spp. Erigeron Bedstraw Spp. Galium Goldenrod Spp. Solidago Clover Spp. Trifolium Hoary Alyssum Berteroaincana Common Mullein Verbascum thapsus Common Mullein Verbascum thapsus Common Yarrow Achillea millefolium Plantain Spp. Plantago Dogbane Apocynum cannabinum Poison Ivy Toxicodendronradicans Fleabane Spp. Erigeron Rabbit's Foot Goat's Beard, Trifolium arvense Tragopogon dubius Clover Western Salsify Rough Cinquefoil Potentillanorvegica Goldenrod Spp. Solidago Smartweed Spp. Polygonum Hawkweed Hieraciumlachenalii Smooth Sumac Rhusglabra Hoary Alyssum Berteroaincana Vetchling Spp. Lathyrus Milkweed Spp. Asclepias Parthenocissusquinquef Virginia Creeper Poison Ivy Toxicodendronradicans olia White Sweet Melilotus alba Prairie Dock Silphiumterebinthinaceum Clover Wild Strawberry Fragariavirginiana Prairie Rose Rosa arkansana Willow Spp. Salix Primrose Primula vulgaris Yellow Wood Oxalis stricta Smartweed Spp. Polygonum Sorrel Centaurea stoebe ssp. Spotted Knapweed micranthos St. John's Wort Hypericumperforatum Vetchling Spp. Lathyrus Wild Strawberry Fragariavirginiana Willow spp. Salix Yellow Wood Sorrel Oxalis stricta

Table 19. Grass surveys in August 2010.

Grass Species Survey in Spotted Grass Species Survey in Common Knapweed Blocks in August 2010 Tansy Blocks in August 2010 Common Name Scientific Name Common Name Scientific Name Big Bluestem Awlfruit Sedge CarexStipata Grass Andropogngerardii Calamagrostiscanade Big Bluestem Andropogngerardii Blue Joint Grass nsis Deer Tongue Green Foxtail Setariaviridis Grass Panicumclandestinum Green Foxtail Horsetail Equisetum arvense Grass Setariaviridis June Grass Koeleriamacrantha Horsetail Equisetum arvense Kentucky Blue Grass Poapratensis June Grass Koeleriamacrantha Schizachyrium Kentucky Blue Little Bluestem scoparium Grass Poapratensis Love Grass Spp. Eragrostis Love Grass Spp. Eragrostis Panic Grass Spp. Panicum Panic Grass Spp. Panicum Purple Love Grass Eragrostisspectabilis Quack Grass Elymus repens Quack Grass Elymus repens Redtop Grass Agrostisgigantea Smooth Redtop Grass Agrostisgigantea Bromegrass Bromusinermis Bouteloua Side-oats Grama curtipendula Timothy Grass Phleumpratense Smooth Bromegrass Bromusinermis Switch Grass Panicumvirgatum Bouteloua Tall Grama Grass curtipendula Timothy Grass Phleumpratense

Table 20. Grass surveys in August 2011.

Grass Species Survey in Spotted Grass Species Survey in Common Tansy Knapweed Blocks in August 2011 Blocks in August 2011 Common Name Scientific Name Common Name Scientific Name Bottlebrush Sedge Carex comosa Bottlebrush Sedge Carex comosa Canada Wild Rye Elymus Canadensis Canada Wild Rye Elymus Canadensis Panicumclandestinu Panicumclandestinu Deer Tongue Grass m Deer Tongue Grass m Indian Grass Sorghastrum nutans Horsetail Equisetum arvense June Grass Koeleriamacrantha June Grass Koeleriamacrantha Kentucky Blue Kentucky Blue Grass Poapratensis Grass Poapratensis Love Grass Spp. Eragrostis Panic Grass Spp. Panicum Panic Grass Spp. Panicum Quack Grass Elymus repens Sedge Spp. Carex Redtop Grass Agrostisgigantea Smooth Brome Smooth Brome Grass Bromusinermis Grass Bromusinermis Timothy Grass Phleumpratense Timothy Grass Phleumpratense

Table 21. Cover class mean values for every treatment of the four blocks in spotted knapweed areas was determined by randomly placing a 0.2 by 0.5 m Daubenmire frames in each half-plot. Values correspond to a scale of percentage ranges: 1-5%=1, 6-25%=2, 26-50%=3, 51-75%=4, 76-95%=5, 96-100%=6.

Non- Spotted Common native Native Native Non-native Bare Knapweed Tansy forbs forbs grass spp. grass spp. Ground 1 nm 3.0 1.3 1.8 2.0 2.0 2 nm 4.5 1.0 1.0 1.0 2.3 3 nm 2.8 1.8 1.5 2.0 2.0 4 nm 3.0 1.0 1.0 3.0 3.5 5 nm 3.0 1.7 2.3 1.3 1.0 6 nm 3.0 1.3 1.0 1.7 2.5 7 nm 4.3 1.0 1.5 2.3 8 nm 3.5 1.0 1.3 2.0 1.5 9 nm 3.3 1.5 1.5 1.7 2.0 10 nm 3.3 1.3 1.0 2.0 3.3 11 nm 3.5 1.5 1.5 1.5 2.3 12 nm 3.8 1.7 1.5 2.0 1.3 13 nm 4.5 1.5 1.3 1.3 1.7 14 nm 2.8 2.3 2.0 1.7 1.8 15 nm 3.0 1.3 2.0 1.3 3.3 16 nm 2.5 1.5 2.0 2.3 2.5 Mean 3.3 1.5 1.5 1.8 2.2 1 m 2.0 5.7 2.5 2 m 1.0 2.0 4.5 2.0 3 m 1.0 3.5 2.7 2.0 4 m 1.0 2.0 5.3 3.0 5 m 1.0 2.5 4.0 2.0 6 m 2.0 5.0 2.0 7 m 2.5 2.7 3.0 8 m 1.0 2.3 4.3 3.0 9 m 1.0 2.0 4.7 2.7 10 m 1.7 3.5 4.7 2.0 11 m 2.0 3.0 3.3 2.0 12 m 1.0 2.5 4.3 2.3 13 m 3.0 2.5 3.3 2.7 14 m 1.7 2.3 4.0 2.0 15 m 1.7 2.5 3.5 2.8 16 m 1.0 2.3 5.0 1.3 Mean 0 1.4 2.5 4.1 2.3

Table 22. Cover class mean values for every treatment of the four block in common tansy areas was determined by randomly placing a 0.2 by 0.5 m Daubenmire frames in each half-plot. Values correspond to a scale of percentage ranges: 1-5%=1, 6-25%=2, 26-50%=3, 51-75%=4, 76-95%=5, 96-100%=6.

Non- Native Spotted Common native Native grass Non-native Bare Knapweed Tansy forbs forbs spp. grass spp. Ground 1 nm 4.3 1.0 2.0 1.0 2.7 2 nm 3.0 2.3 2.0 2.3 1.0 2.0 1.0 3 nm 4.5 3.0 2.0 2.3 2.0 1.0 1.0 4 nm 3.3 1.7 1.0 2.8 1.0 5 nm 4.0 3.0 1.0 1.7 1.0 2.3 6 nm 3.7 2.0 2.0 2.5 1.0 7 nm 4.5 3.0 2.0 2.7 1.0 1.0 1.0 8 nm 1.0 3.5 2.0 2.0 1.5 2.7 9 nm 4.0 3.0 2.0 2.0 1.0 3.5 1.0 10 nm 1.5 5.0 2.0 1.5 1.0 1.0 1.7 11 nm 2.7 1.7 3.0 1.3 12 nm 4.0 3.5 2.0 1.0 2.5 13 nm 4.0 3.0 1.3 1.0 2.8 2.0 14 nm 3.7 1.7 2.0 2.0 1.3 15 nm 3.0 1.5 3.3 2.0 1.0 1.0 1.0 16 nm 3.0 2.3 2.0 2.5 3.8 Mean 3.3 3.2 1.9 2.1 1.1 2.2 1.2 1 m 3.5 2.0 1.0 4.7 4.0 2 m 1.5 2.0 2.0 3.0 2.8 1.0 3 m 2.0 1.7 3.8 1.7 2.0 4 m 1.5 1.0 5.5 5 m 1.3 1.0 5.0 1.5 6 m 3.0 1.0 2.3 3.5 2.0 7 m 2.0 1.5 1.3 2.0 3.0 2.3 8 m 3.0 1.5 2.0 5.7 1.0 9 m 1.0 1.0 1.7 5.0 1.0 10 m 3.0 2.0 1.3 2.0 2.3 1.5 11 m 3.0 1.7 1.3 3.5 1.7 12 m 1.7 2.0 4.8 13 m 1.0 1.3 5.0 1.0 14 m 2.0 2.5 1.5 1.7 3.3 2.0 15 m 2.0 2.7 1.5 3.5 2.0 1.0 16 m 2.0 1.7 2.0 4.8 Mean 0 2.3 2.0 1.5 2.1 3.8 1.7

Statistical Analyses

Year 2011 mean overall estimates of percent cover of the four replicates of each of the 16 plot treatment combinations of invasive species during emergence pre- milestone are also compared using SPSS 17.0. A Univariate ANOVA was conducted to determine which, if any, of the treatments affected invasive plant mean percent cover to a statistically significant degree. Table 25 shows that in the case of areas infested with spotted knapweed, the only statistically significant variable that affected the dependent variable, mean percent cover, was the application of a selective herbicide, Milestone, F (1,124) = 56.258, p < .05. All other treatments had no statistically significant, or at this time, biologically significant effect on invasive plant percent cover of plots. Table 29 shows that in the case of areas infested with common tansy, the only statistically significant variable that affected the dependent variable, mean percent cover, was the application of a selective herbicide, Milestone, F (1,124)

= 11.465, p < .05. All other treatments had no statistically significant effect on invasive plant percent cover of plots.

A repeated measures ANOVA was also used in this experiment because all data collected are measured over different times. The measurement of the dependent variable, percent cover, is repeated. This analysis detects if time affected mean percent cover of vegetation. When time is incorporated as an independent variable, what is really being determined is if the four data sets collected at four different times, have statistically significant difference between mean percent cover. The four times of data collection reflect 2010 initial mean percent cover, 2011 senescent stand mean percent

57 cover, 2011 emergent stand percent cover, and 2011 post-milestone stand percent cover. Tables 27 and 31 show that in both the case of spotted knapweed and common tansy, time was a significant within-subjects effect. Mean percent cover was significantly different between the four times of data collection (F (3,183) = 64.597, p < .05, F (3,189) = 18.56, p < .05).

Using the repeated measures ANOVA, Individual spotted knapweed blocks were not significantly different in measures of percent cover from each other. This suggests that placement and treatment application were successfully done to the blocks so that they act as effective replicates. Individual common tansy blocks were significantly different in measures of percent cover over time from each other

(F (3, 60) = 2.957, p < .05). This suggests that placement and/or treatments increased variability in blocks. Environmental variability and consistent execution of large-scale treatments can have an effect on the establishment of replicates in large-scale studies of vegetation.

The milestone treatment did reduce the overall invasive plant presence, but to evaluate the effect of the selective herbicide on other species, a t-test of the species richness of 4 replicates of each of the 16 plot halves with and without milestone application were conducted for both spotted knapweed and common tansy areas.

Tables 23 and 24 shows that differences between mean number of species in plot halves with milestone and without the selective herbicide were statistically significant for both common tansy and spotted knapweed areas (t (126) = 7.98, p < .05, t (126) =

4.65, p < .05).There was less overall species richness in plot halves that had a selective herbicide applied.

Table 23. Common tansy independent samples t-test for species richness in plot halves with and without a selective herbicide application. Means differed significantly. T (126) = 7.98, p < .05.

Levene's Test for Equality of Variances t-test for Equality of Means

95% Confidence Interval of the Sig. Difference (2- Mean Std. Error F Sig. t df tailed) Difference Difference Lower Upper

Equal variances 7.210 .008 7.983 126 .000 2.781 .348 2.092 3.471

assumed

7.983 114.304 .000 2.781 .348 2.092 3.471 Equal variances not assumed

Table 24. Spotted knapweed independent samples t-test for species richness in half- plots with and without a selective herbicide application. t (126) = 4.65, p < .05.

Levene's Test for Equality of Variances t-test for Equality of Means

95% Confidence Interval of the Sig. Difference (2- Mean Std. Error F Sig. t df tailed) Difference Difference Lower Upper

Equal variances 14.330 .000 4.654 126 .000 2.594 .557 1.491 3.697

assumed

4.654 102.266 .000 2.594 .557 1.488 3.699 Equal variances not assumed

Table 25. Univariate ANOVA for spotted knapweed areas with the Between-Subjects factors of seedbed preparation (SP), cover crop (CC), seeding method (SM), selective herbicide application (MS), and block. The only statistically significant factor was the application of the selective herbicide, Milestone. F (1,124) = 56.258, p < .05.

Tests of Between-Subjects Effects

Dependent Variable:Percent Cover

Type III Sum Source of Squares df Mean Square F Sig.

Corrected Model 81961.495a 129 635.360 .879 .765

Intercept 65240.041 1 65240.041 90.272 .000

SP 80.908 3 26.969 .037 .990

CC 14.560 1 14.560 .020 .887

SM 1785.208 2 892.604 1.235 .294

MS 40658.183 1 40658.183 56.258 .000

Table 25 (continued)

Type III Sum

Source of Squares df Mean Square F Sig.

Block 1475.848 3 491.949 .681 .565

SP * CC 625.412 3 208.471 .288 .834

SP *SM 719.483 3 239.828 .332 .802

SP * MS 252.058 3 84.019 .116 .950

SP * Block 612.407 9 68.045 .094 1.000

CC * SM 152.427 1 152.427 .211 .647

CC * MS 42.052 1 42.052 .058 .810

CC * Block 867.235 3 289.078 .400 .753

SM * MS 133.477 1 133.477 .185 .668

SM * Block 560.505 6 93.418 .129 .992

MS * Block 1352.674 3 450.891 .624 .601

SP * CC * SM 333.133 3 111.044 .154 .927

SP * CC * MS 249.193 3 83.064 .115 .951

SP * CC * Block 1120.638 9 124.515 .172 .996

SP * SM * MS 108.494 3 36.165 .050 .985

SP * SM * Block 1661.722 9 184.636 .255 .985

SP * MS * Block 1099.417 9 122.157 .169 .997

CC * SM * MS 451.560 1 451.560 .625 .431

CC * SM * Block 111.853 3 37.284 .052 .984

CC * MS * Block 629.949 3 209.983 .291 .832

SM * MS * Block 580.275 3 193.425 .268 .849

SP * CC * SM * MS 166.309 3 55.436 .077 .972

SP * CC * SM * Block 876.240 9 97.360 .135 .999

SP * CC * MS * Block 982.288 9 109.143 .151 .998

SP * SM * MS * Block 151.440 8 18.930 .026 1.000

CC * SM * MS * Block 47.938 3 15.979 .022 .996

Table 25 (continued)

Source Type III Sum df Mean Square F Sig.

of Squares

SP * CC * SM* MS 291.958 8 36.495 .050 1.000 *Block

Error 89615.313 124 722.704

Total 370321.000 254

Corrected Total 171576.807 253 a. R Squared = .478 (Adjusted R Squared = -.066)

Table 26. Univariate ANOVA for spotted knapweed. Means reported and descriptive statistics.

Second Year Milestone

Dependent Variable:Percent Cover

95% Confidence Interval SecondYear Milestone Mean Std. Error Lower Bound Upper Bound

No MS 36.380 1.548 33.331 39.429

MS 1.935 2.724 -3.430 7.301

Table 27. Repeated Measures ANOVA for spotted knapweed areas with the Within- Subjects Effects of time on mean percent cover. Time was a statistically significant factor. F (3,183) = 64.597, p < .05.

Tests of Within-Subjects Effects

Type III Sum of Source Squares df Mean Square F Sig.

Time Sphericity Assumed 78722.077 3 26240.692 64.597 .000

Greenhouse-Geisser 78722.077 2.182 36073.563 64.597 .000

Huynh-Feldt 78722.077 2.266 34735.477 64.597 .000

Lower-bound 78722.077 1.000 78722.077 64.597 .000

Error(time) Sphericity Assumed 74338.173 183 406.220

Greenhouse-Geisser 74338.173 133.118 558.437

Huynh-Feldt 74338.173 138.246 537.723

Lower-bound 74338.173 61.000 1218.659

Table 28. Repeated Measures ANOVA for spotted knapweed. Means reported and descriptive statistics.

Time

95% Confidence Interval

Time Mean Std. Error Lower Bound Upper Bound

1 43.710 3.495 36.721 50.698

2 21.613 2.087 17.440 25.786

3 45.403 2.640 40.124 50.683

4 1.935 .687 .562 3.309

Table 29. Univariate ANOVA for common tansy areas with the Between-Subjects factors of seedbed preparation (SP), cover crop (CC), seeding method (SM), selective herbicide application (MS), and block.The only statistically significant factor was the application of the selective herbicide, Milestone. F (1,124) =11.465, p<.05. Seedbed preparation is significant due to replicates being significantly different in mean overall percent cover.

Tests of Between-Subjects Effects

Dependent Variable:Percent Cover

Type III Sum of

Source Squares df Mean Square F Sig.

Corrected Model 61349.797a 131 468.319 .916 .689

Intercept 40651.792 1 40651.792 79.544 .000

SP 4612.917 3 1537.639 3.009 .033

CC 472.594 1 472.594 .925 .338

SM 1392.828 2 696.414 1.363 .260

MS 5859.375 1 5859.375 11.465 .001

Block 3935.564 3 1311.855 2.567 .058

SP * CC 1157.615 3 385.872 .755 .521

SP * SM 649.375 3 216.458 .424 .736

SP * MS 2786.375 3 928.792 1.817 .147

SP * Block 3363.937 9 373.771 .731 .679

CC * SM .094 1 .094 .000 .989

CC * MS 119.260 1 119.260 .233 .630

CC * Block 81.469 3 27.156 .053 .984

SM * MS 682.667 1 682.667 1.336 .250

SM * Block 1698.505 6 283.084 .554 .766

MS * Block 21.271 3 7.090 .014 .998

SP * CC * SM 1004.865 3 334.955 .655 .581

SP * CC * MS 906.281 3 302.094 .591 .622

SP * CC * Block 1334.073 9 148.230 .290 .976

Table 29 (continued)

Type III Sum of

Source Squares df Mean Square F Sig.

SP * SM * MS 311.750 3 103.917 .203 .894

SP * SM * Block 1738.271 9 193.141 .378 .944

SP * MS * Block 566.063 9 62.896 .123 .999

CC * SM * MS 1.260 1 1.260 .002 .960

CC * SM * Block 565.010 3 188.337 .369 .776

CC * MS * Block 588.385 3 196.128 .384 .765

SM * MS * Block 369.021 3 123.007 .241 .868

SP * CC * SM * MS 490.865 3 163.622 .320 .811

SP * CC * SM * Block 3415.115 9 379.457 .742 .669

SP * CC * MS * Block 1283.156 9 142.573 .279 .979

SP * SM * MS * Block 330.313 9 36.701 .072 1.000

CC * SM * MS * Block 419.260 3 139.753 .273 .844

SP * CC * SM * MS* 1343.031 9 149.226 .292 .976

Block

Error 63371.188 124 511.058

Total 229616.000 256

Corrected Total 124720.984 255 a. R Squared = .492 (Adjusted R Squared = -.045)

Table 30. Univariate ANOVA for common tansy. Means reported and descriptive statistics.

Second Year Milestone

Dependent Variable:Percent Cover

95% Confidence Interval Second Year Milestone Mean Std. Error Lower Bound Upper Bound

No MS 24.026 1.527 21.019 27.033

MS 8.891 2.645 3.682 14.099

Table 31. Repeated Measures ANOVA for common tansy areas with the Within- Subjects Effects of time on mean percent cover. F (3,189) = 18.56, p < .05.

Tests of Within-Subjects Effects

Type III Sum of Source Squares df Mean Square F Sig.

Time Sphericity Assumed 18698.578 3 6232.859 18.565 .000

Greenhouse-Geisser 18698.578 1.760 10626.497 18.565 .000

Huynh-Feldt 18698.578 1.806 10352.142 18.565 .000

Lower-bound 18698.578 1.000 18698.578 18.565 .000

Error(time) Sphericity Assumed 63453.422 189 335.732

Greenhouse-Geisser 63453.422 110.856 572.395

Huynh-Feldt 63453.422 113.794 557.617

Lower-bound 63453.422 63.000 1007.197

Table 32. Repeated Measures ANOVA for common tansy. Means reported and descriptive statistics.

Time

95% Confidence Interval

Time Mean Std. Error Lower Bound Upper Bound

1 30.859 3.616 23.633 38.086

2 15.594 2.330 10.937 20.251

3 25.625 2.464 20.702 30.548

4 8.891 1.310 6.272 11.509

Boxplot Figures

SPSS Boxplots consist of box length, which reflects sample variability. The median value of the sample is displayed as a horizontal line within the box. Box plots which reflect a normally distributed sample will have tails as long as the box. If one tail is longer, than the means are skewed in a certain direction. The bottom of the box represents the first quartile of the sample; the top of the box shows the third quartile.

Outliers are also shown, asterisks being more extreme outliers. The labels next to outliers are the data labels from the original data sheet.

Using SPSS 17.0, Boxplot graphs were produced to visually depict relationships between experimental blocks and invasive mean percent cover, data sets and invasive mean percent cover, and the effect of Milestone on plot halves’ invasive mean percent cover. Figure 5 (spotted knapweed) and Figure 8 (common tansy) compare boxplots of individual blocks’ ranges of invasive mean percent cover.

Figure 6 (spotted knapweed) and Figure 9 (common tansy) compare boxplots of ranges of invasive mean percent cover between data sets (time). Figure 7 (spotted knapweed) and Figure 10 (common tansy) compare boxplots of ranges of invasive mean percent cover between plot halves that were treated with Milestone, and plot halves that had no selective herbicide applied.