The Relationship Of Bulbous Bluegrass (Poa bulbosa) And Big Sagebrush (Artemisia tridentata) In Utah

Sheri Hagwood @ USDA-NRCS PLANTS Database

The Relationship Of Bulbous Bluegrass (Poa bulbosa) And

Big Sagebrush (Artemisia tridentata) In Utah

Overview of Presentation

• Range Trend Project• What is Bulbous bluegrass?• What is known about it?• History of its introduction in the US• Its distribution in the US and Utah?• The relationship of bulbous bluegrass, big

sagebrush, and cheatgrass• Examples of bulbous bluegrass increase in

dominance on range trend sites

History of Range Trend Monitoring

• 1958 - Range inventory project established• 1981 - BLM and USFS partner with UDWR in range

trend program to develop Range Trend Study Guidelines

• 1982 - Permanent trend studies established using trend study guidelines with continued monitoring on 5 year rotation– Additional study sites have been established since 1982– Range trend sites are mainly found on crucial deer winter

range

Range Trend Monitoring Data Range trend study sites are monitored on a 5 year rotation

Each study site is intensively monitored

Methods• Nested frequency

‒ Measurement for abundance grass and forb species‒ 100 quadrats (1/4 m2)‒ Numerical value between 1-500 (prior to 1992 values 1-400)

• Modified Daubenmire Cover-class method‒ Measurement for % cover for grass, forb, and browse species‒ 100 quadrats (1/4 m2)‒ Ocular cover estimate

Bulbous Bluegrass (Poa bulbosa)

INFLORESCENCE •Bulblet formation or Vivipary asexual reproduction (shown in picture).•Normal seed production is rare in North America.•Each bulblet can produce a new plant.

© Gerald D. Carr

© Gerald D. Carr

© Gerald D. Carr

ROOT STRUCTURE •Consist of a bulbous base (shown in picture).•Bulbils are formed from the bulbous base reproducing asexually.•Shallow root structure.•Bulbs can withstand very dry periods time and dry to below 10% moisture content.•Sod forming

Life History

What Is known • Growth characteristics• Reproduction• Dormancy• Palatability• Life cycle• Production– Limited forage value

• Control?

What is not known• The effect it has on

ecosystems• Not much is known

about how it affects other plants

• Effect on fire regime• Effect on soil moisture• *Does it affect

sagebrush communities

Weedy Characteristics

• Similar to Cheatgrass • Short-lived perennial species• Growth occurs in early spring and re-sprouts in fall• Exists dormancy before most plants• Impacts soil moisture? • Can remain dormant for long periods of time and re-

sprout from bulbs in the soil• Sod forming ??? Does it affect other plants due to these traits ???

HISTORY OF POBU IN U.S.• Unknown - Introduction likely from

contaminated alfalfa and clover seed from Eurasia

• 1901 - First collected in Oregon.• 1906 - USDA acquired bulblets from Russia for

experimental seedings. • 1906-1930’s - USDA experimental seedings.

– Intended for use as a commercial turf grass.

• Early to mid-1900’s - used for soil erosion and to improve depleted rangelands in the intermountain west.

• Early to mid-1900’s - experimentally seeded in parts of Utah, Nevada, Idaho, and Wyoming to identify traits favorable for palatability and forage production.

• 1956 - USDA developed a POBU cultivar for seed growers but was never distributed.

• 2011 - U.S. Patent application for bulbous bluegrass hybrids for use commercially as a turf grass.

A. T. Bleak and A. Perry Plummer (1954)

1940 Seeding of bulbous bluegrass, crested wheatgrass, and beardless bluebunch wheatgrass north of Ephraim, Utah. (Picture taken between 1940 and 1954)

EDDMapS. 2013. Early Detection & Distribution Mapping System. The University of Georgia - Center for Invasive Species and Ecosystem Health. Available online at http://www.eddmaps.org/; last accessed September 30, 2013.

Distribution Map of Bulbous Bluegrass by County

Distribution Map of Bulbous Bluegrass

• Approximately 800 range trend sites.

• 128 range trend sites have sampled bulbous bluegrass

• UDWR range trend study sites are primarily located in Utah on mule deer winter range within big sagebrush habitat.

The map is based on range trend study sites

Bulbous Bluegrass Correlation Study• Observed decreases of sagebrush and increases of bulbous bluegrass• Decreases in sagebrush is a concern for wildlife• Designed a study to determine if there was a relation between sagebrush

and bulbous bluegrass

Bulbous Bluegrass Correlation Study• Used the log Response Ratio

– Compared the Daubenmire % cover of POBU, ARTR, and BRTE• log (POBU % cover/ARTR % cover)• log (POBU % cover/BRTE % cover)• log (BRTE % cover/ARTR % cover)

– Standardizes the relationship across sample sites and years

• Criteria for site selection– Both big sagebrush and bulbous bluegrass sampled on the site– No disturbance on the site following the establishment of the study

site

• Tested for three relationships– POBU:ARTR– POBU:BRTE– BRTE:ARTR

Bulbous Bluegrass and Big SagebrushLS Means Plot

R2 = 0.68

Probƒ = <0.0001

Time Period LS Mean Std Err

1992-1997 (1) C -2.900290 0.32

1998-2002 (2) B -1.420144 0.30

2003-2007 (3) A B -0.582367 0.29

2008-2012 (4) A 0.136140 0.31

Bulbous Bluegrass and Big SagebrushLS Means Differences Tukey HSD

• The more negative the LS Mean score the higher sagebrush cover is in relation to bulbous bluegrass

• The more positive the LS Mean score the higher bulbous bluegrass cover is in relation to sagebrush

Bulbous Bluegrass and CheatgrassLS Means Plot

R2 = 0.68

Probƒ = <0.0001


1992-1997 (1) B -0.117533 0.27

1998-2002 (2) A 2.427069 0.25

2003-2007 (3) A 2.569744 0.24

2008-2012 (4) A 3.591432 0.26

Bulbous Bluegrass and CheatgrassLS Means Differences Tukey HSD

R2 = 0.86

Probƒ = <0.0001

• The more negative the LS Mean score the higher cheatgrass cover is in relation to bulbous bluegrass

• The more positive the LS Mean score the higher bulbous bluegrass cover is in relation to cheatgrass

Cheatgrass and Big SagebrushLS Means Plot


1992-1997 (1) A -2.580578 0.38

1998-2002 (2) B -3.791087 0.35

2003-2007 (3) A B -3.080804 0.34

2008-2012 (4) A B -3.446897 0.37

Cheatgrass and Big SagebrushLS Means Differences Tukey HSD

R2 = 0.89

Probƒ = <0.0001

• The more negative the LS Mean score the higher sagebrush cover is in relation to cheatgrass

• The more positive the LS Mean score the higher cheatgrass cover is in relation to sagebrush

Old Pinery

1983

Old Pinery

1989

Old Pinery

1997

Old Pinery

2002

Old Pinery

2007

Old Pinery

2012

1997 2002

2007 2012

N. Frequency (Max of 500) or Density Cover

1997 2002 2007 2012 1997 2002 2007 2012

Bulbous bluegrass 64 246 346 320 1% 15% 29% 35%

Cheatgrass 259 259 317 170 2% 3% 9% 2%

Crested Wheatgrass 110 107 87 10 5% 6% 1% < 1%

Mountain Big Sagebrush(% Young)

2040 plants/acre(69%)




6% 10% 13% 16%

Old Pinery Summary

• Sagebrush has increased in cover over the sample years, but has decreased in density since 2002

• Recruitment of young sagebrush plants has decreased over the sample years• Cheatgrass fluctuated in cover and frequency over the sample years• Crested Wheatgrass decreased substantially in cover and frequency• Bulbous bluegrass increased in cover and frequency over the sample years

North Wallsburg

1989

North Wallsburg

1996

North Wallsburg

2002

North Wallsburg

2007

North Wallsburg

2012

1996 2002

2007 2012


1996 2002 2007 2012 1996 2002 2007 2012


Cheatgrass 370 232 358 293 16% 5% 9% 7%






9% 14% 11% 11%

North Wallsburg Summary

• Sagebrush has decreased in density and cover since 2002• Recruitment of young sagebrush plants has decreased over the sample years• Cheatgrass has fluctuated over the sample years• Bulbous bluegrass increased in cover and frequency over the sample years

Cedar Hollow

1984

Cedar Hollow

1990

Cedar Hollow

1996

Cedar Hollow

2001

Cedar Hollow

2006

Cedar Hollow

2011

1996 2001

2006 2011


1996 2001 2006 2011 1996 2001 2006 2011


Cheatgrass 1 0 4 0 0% 0% 0% 0%




940 plants/acre(2%)

980 plants/acre(8%)

8% 8% 6% 6%

Cedar Hollow Summary

• Sagebrush has decreased in density and cover over the sample year• Recruitment of young sagebrush was minimal• Cheatgrass was minimal on the site• Bulbous bluegrass increased in cover and frequency over the sample years

Echo Canyon

1984

Echo Canyon

1990

Echo Canyon

1996

Echo Canyon

2001

Echo Canyon

2006

Echo Canyon

2011

1996 2001

2006 2011

*N. Frequency (Max of 500) or Density Cover

1996 2001 2006 2011 1996 2001 2006 2011


Cheatgrass 330 169 179 128 14% 4% 5% 5%






14% 15% 10% 4%

Echo Canyon Summary

• Sagebrush decreased in density and cover over the sample years• Recruitment of young sagebrush plants has decrease over the sample years• Cheatgrass decreased in cover and frequency over the sample years• Bulbous bluegrass increased in cover and frequency over the sample years

Bulbous Bluegrass and Big SagebrushLS Means Plot

Bulbous Bluegrass and Big SagebrushLS Means Differences Tukey HSD

Bulbous Bluegrass and Cheatgrass LS Means Plot

Cheatgrass and Big SagebrushLS Means Plot

Bulbous Bluegrass and CheatgrassLS Means Differences Tukey HSD

Cheatgrass and Big SagebrushLS Means Differences Tukey HSD


1992-1997 (1) A -2.580578 0.38

1998-2002 (2) B -3.791087 0.35

2003-2007 (3) A B -3.080804 0.34

2008-2012 (4) A B -3.446897 0.37


1992-1997 (1) B -0.117533 0.27

1998-2002 (2) A 2.427069 0.25

2003-2007 (3) A 2.569744 0.24

2008-2012 (4) A 3.591432 0.26


1992-1997 (1) C -2.900290 0.32

1998-2002 (2) B -1.420144 0.30

2003-2007 (3) A B -0.582367 0.29

2008-2012 (4) A 0.136140 0.31

Conclusions• There is a relationship between bulbous bluegrass and sagebrush

– Decreases of sagebrush correspond to the increases of bulbous bluegrass.

– The study shows an increase of bulbous bluegrass abundance and distribution since 1982, as well as an increase in co ver of bulbous bluegrass in relation to sagebrush and cheatgrass since 1992.

• The study does not determine mechanisms of change.– Is the decrease of sagebrush due to increase of bulbous bluegrass?– Is the increase of bulbous bluegrass due to decrease in sagebrush?

• Need for further research to identify if bulbous bluegrass has an impact on sagebrush and other plant species.– Is bulbous bluegrass a problem?– If so how do we address this problem?– Is bulbous bluegrass a primary factor or a compounding factor to the

decrease of sagebrush?

Discussion• Hypotheses– Cheatgrass may be the disturbance in the plant

community allowing bulbous bluegrass to invade• The plant community may be more susceptible to

invasion by bulbous bluegrass when cheatgrass is present on the site

– Bulbous bluegrass may inhibit recruitment of young sagebrush plants

– Early growth characteristics may give bulbous bluegrass a competitive advantage,

– May limit soil moisture for other plant species

• I’d like to thank the UDWR in funding and supplying the data used for analysis of the bulbous bluegrass, sagebrush, and cheatgrass.

• I like to thank UDWR personnel K. Gunnell, J. Lane, D. Summers and J. Vernon for their help and input to this study.

• I like to thank T. Monaco and D. Turner who helped with the statistics and analysis for this project.

• I also would like to thank the members of my graduate committee F. Howe, J. Kurtzman, and N. Mesner for their critiques and direction for this project

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The Relationship Of Bulbous Bluegrass (Poa bulbosa) And Big Sagebrush (Artemisia tridentata) In Utah