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Invasive Plants Case Study: Cheatgrass. Taxonomy Bromus tectorum L. = Anisantha tectorum Nevski Family – Poaceae Subfamily – Pooideae Tribe – Poeae Common.

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Presentation on theme: "Invasive Plants Case Study: Cheatgrass. Taxonomy Bromus tectorum L. = Anisantha tectorum Nevski Family – Poaceae Subfamily – Pooideae Tribe – Poeae Common."— Presentation transcript:

1 Invasive Plants Case Study: Cheatgrass

2 Taxonomy Bromus tectorum L. = Anisantha tectorum Nevski Family – Poaceae Subfamily – Pooideae Tribe – Poeae Common names:Related invasive species: cheatgrass B. madritensis ssp. rubens (red brome) downy brome B. diandrus (rip-gut brome) downy chess B. inermis (smooth brome) broncograss www.itis.usda.gov

3 Description Awned lemma Mid-sized lemmas & awns Pubescent stems, sheaths, & blades Open, flexulous, drooping panicle Often dense & purple Cronquist et al. (1977) Intermountain Flora

4 Geographic range: Native Native to: Plains of central Asia; common in Middle East & Arabian Peninsula Western edge of distribution: Balkan peninsula with utlying populations in Spain Northern edge: Moscow Likely sources for North American invaders: Lower Volga, northern Caucasus, Ukraine, Balkan Peninsula Kostivkovsky & Young (2000) Rangelands

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6 Geographic range: Worldwide Today is found in: Most of Europe Most of North America Japan South Africa Australia & New Zealand Iceland & Greenland Carpenter & Murray (2001) TNC Stewardship Abstract

7 Geographic range: United States plants.usda.gov

8 Habitat Cheatgrass habitat in Nevada Cheatgrass habitat in Turkmenistan

9 How did it get here? (Knapp 1994) Accidental introduction – packing material, crop seed and ballast soil Intentional introduction at expt farm in Pullman: forage (‘100-day grass’) Intro to Eastern US (first record 1859) and PNW in 1889 By 1916 was widespread in west By 1930 was dominant & reached current extent Dispersed along rail lines, in animal bedding, packing material, and feed; also by grazing animals

10 What makes it invasive? Vacant niche

11 What makes it invasive? Vacant niche Allelopathy Hogal & Sandford (2004): Root exudates from cheatgrass reduced growth of Hilaria jamesii by ~60% Kulmatski & Beard (2006) Restoration Ecol: Activated charcoal reduced cheatgrass growth and increased native grass growth in field

12 What makes it invasive? Vacant niche Allelopathy Global change Smith et al. (1987) Functional Ecology Smith et al. (2000) Nature

13 What makes it invasive? Vacant niche Allelopathy Global change Resource availability

14 Bilbrough & Caldwell (1997) Ecology

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17 Evans et al. (2001) Ecological Applications

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20 What makes it invasive? Vacant niche Allelopathy Global change Resource availability Competition Melgoza et al. (1990) Oecologia

21 What makes it invasive? Vacant niche Allelopathy Global change Resource availability Competition Melgoza et al. (1990) Oecologia

22 What makes it invasive? Vacant niche Allelopathy Global change Resource availability Competition Melgoza et al. (1990) Oecologia

23 What makes it invasive? Vacant niche Allelopathy Global change Resource availability Competition Harris (1967) Ecological Monographs

24 What makes it invasive? Vacant niche Allelopathy Global change Resource availability Competition Melgoza & Nowak (1991) J Range Management

25 What makes it invasive? Vacant niche Allelopathy Global change Resource availability Competition BurnedUnburned Frequency Young & Evans (1978) J Range Management

26 What makes it invasive? Vacant niche Allelopathy Global change Resource availability Competition Microevolutionary changes

27 Novak et al. (1993) Can J Botany

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29 What makes it invasive? Vacant niche Allelopathy Global change Resource availability Competition Microevolutionary changes Novak & Mack: Founder effects, but high intra- population diversity from multiple introductions and novel genotypes Longland & Ashley (2007): evidence for local adaptation

30 What makes it invasive? Vacant niche Allelopathy Global change Resource availability Competition Microevolutionary changes Escape from biotic constraints

31 What makes it invasive? Vacant niche Allelopathy Global change Resource availability Competition Microevolutionary changes Escape from biotic constraints Biodiversity

32 Anderson & Inouye (2001) Ecological Monographs

33 What makes it invasive? Vacant niche Allelopathy Global change Resource availability Competition Microevolutionary changes Escape from biotic constraints Biodiversity Disturbance / land use

34 Knapp (1998) Global Ecology & Biogeography Letters

35 What makes it invasive? Vacant niche Allelopathy Global change Resource availability Competition Microevolutionary changes Escape from biotic constraints Biodiversity Disturbance / land use Humans

36 Introduction corresponded with dramatic overgrazing across the Great Basin Spread through introduced range due to humans Excessive grazing reduces perennial vegetation AND disseminates cheatgrass seed (awns adhere to animal coats and hooves) Plant is native in the ‘cradle of human civilization’ – long history with humans!

37 Impacts Ecological o Increased fire frequency o Conversion of native perennial plant community to cheatgrass monoculture o Change in N cycle: lower C:N ratios, faster N cycling, more available N o Effects on wildlife: reduced ground squirrels, reduced preditors

38 Impacts Ecological Economic o Fire fighting: estimated at $10 million per year o Fire rehabilitation costs o Some early spring value, but generally forage losses (perennials have 2-12X greater production & is more consistent among years; injury from awns o Erosion o TES o Reduced carbon sequestration

39 Impacts Ecological Economic Social o Rural economy & lifestyle o Wildland – urban interface

40 Management Assessment E. Peterson, NV Natural Heritage Program

41 Management Assessment OregonIdaho Nevada Utah Cheatgrass dominated Cheatgrass invading Cheatgrass susceptible Pellant & Hall (1994) INT-GTR-313

42 Management Assessment Prevention – too late!

43 Management Assessment Prevention Control o Chemicals: variety of herbicides effective Roundup (glyphosate) in early-mid spring Plateau (imazapic) in fall

44 Management Assessment Prevention Control o Chemicals: variety of herbicides effective, but herbicides can damage natives Carpenter & Murray (2001) TNC Stewardship Abstract

45 Management Assessment Prevention Control o Chemicals: variety of herbicides effective, but herbicides can damage natives o Burning timed to reduce seed production, but don’t burn partially infested sites o Continuous grazing timed to ↓seed production but don’t over-graze partially infested sites o Repeated mowing (every 3 weeks), otherwise plants generate new culms & seeds Carpenter & Murray (2001) TNC Stewardship Abstract

46 Management Assessment Prevention Control Eradication

47 Management Assessment Prevention Control Eradication

48 Summary Key biological characteristics – uses every tool in the book. But strongest characters include: Competitiveness Prolific seed production Control strategies Grazing/fire to reduce seed production Restore with competitive natives Soil N manipulations Herbicide treatments


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