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Invasive Plants Case Study: Cheatgrass

Invasive Plants Case Study: Cheatgrass. Taxonomy. Bromus tectorum L. = Anisantha tectorum Nevski Family – Poaceae Subfamily – Pooideae Tribe – Poeae Common names: Related invasive species: cheatgrass B. madritensis ssp. r ubens (red brome)

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Invasive Plants Case Study: Cheatgrass

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  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 Open, flexulous, drooping panicle Often dense & purple Awned lemma Mid-sized lemmas & awns Pubescent stems, sheaths, & blades 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

  5. 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

  6. Geographic range: United States plants.usda.gov

  7. Habitat Cheatgrass habitat in Turkmenistan Cheatgrass habitat in Nevada

  8. 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

  9. What makes it invasive? • Vacant niche

  10. 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

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

  12. Vacant niche • Allelopathy • Global change • Resource availability What makes it invasive?

  13. Bilbrough & Caldwell (1997) Ecology

  14. Evans et al. (2001) Ecological Applications

  15. Evans et al. (2001) Ecological Applications

  16. Evans et al. (2001) Ecological Applications

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

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

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

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

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

  22. Vacant niche • Allelopathy • Global change • Resource availability • Competition What makes it invasive? Unburned Burned Frequency Young & Evans (1978) J Range Management

  23. Vacant niche • Allelopathy • Global change • Resource availability • Competition • Microevolutionary changes What makes it invasive?

  24. Novak et al. (1993) Can J Botany

  25. Novak et al. (1993) Can J Botany

  26. 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 What makes it invasive?

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

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

  29. Anderson & Inouye (2001) Ecological Monographs

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

  31. Knapp (1998) Global Ecology & Biogeography Letters

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

  33. Humans • 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!

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

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

  36. Impacts • Ecological • Economic • Social • Rural economy & lifestyle • Wildland – urban interface

  37. Management • Assessment E. Peterson, NV Natural Heritage Program

  38. Oregon Idaho Nevada Utah Cheatgrass dominated Cheatgrass invading Cheatgrass susceptible Management • Assessment Pellant & Hall (1994) INT-GTR-313

  39. Management • Assessment • Prevention – too late!

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

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

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

  43. Assessment • Prevention • Control • Eradication Management

  44. Assessment • Prevention • Control • Eradication Management

  45. 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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