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Invasive Plants
- 1. Invasive Species – The Problem and What We Can Do About It Phyllis Muska Native Plant Society of Texas – Kerrville Chapter January 8, 2013
- 2. What is an invasive species? Federal definition: An ‘invasive species’ is a species that is: – non-native (or alien) to the ecosystem under consideration – aggressive, grows outside of desired boundaries – outcompetes the natives – likely to cause harm to human health, the economy, and/or the environment Can be plants, animals, and other organisms Primary means of invasive species introduction: Human actions/activities
- 3. Invasives in Texas More than 122 non-native species, including – 10 mammals – nutria, axis deer, feral hog – 4 birds – European starling, English sparrow – 7 fishes – grass carp – 11 insects – imported fire ant, German cockroach – 11 mollusks and crustaceans – brown mussel, brown garden snail – 12 aquatic plants – hydrilla, water hyacinth – 67 terrestrial plants
- 4. Texas Invasive Plant and Pest Council (TIPPC) Unified body to address the threat of invasive species in Texas Stakeholders/participants: – State and federal agencies – Conservation organizations – Academia – Green industry – Public sector
- 5. TIPPC Focus for issues and concerns regarding exotic plants and pests Exchange of information regarding all aspects of invasive pest and plant biology, distribution, control and management Awareness and understanding regarding invasives and their control Expert advice for various interests concerned with invasive pests and plants An advisory council regarding funding, research, awareness, policy and management of invasive pests and plants
- 6. Problem invasives in other parts of US Great Lakes – zebra mussels, sea lamprey Southeast – kudzu Hawaii – Indian Mongoose Everglades National Park – Giant Burmese Python Over 2000 types of non-native creatures imported legally into the US between 2000 and 2004
- 7. Why are invasives a problem? High control costs – over $137 billion/year in US Loss of resources available to native species, degrading diversity and wildlife habitat Destruction of special habitat of imperiled species Alter hydrological patterns, soil chemistry, moisture-holding capacity, and erodibility Can change fire regimes, creating greater fire hazard Some hybridize with native plant relatives, resulting in unnatural changes to a plant's genetic makeup Can harbor plant pathogens that can affect both native and non-native plants Fauna that depend on the native species for their survival probably will not be able to adapt to the invader
- 8. How serious is the problem? “On a global basis . . . the two great destroyers of biodiversity are, first, habitat destruction and second, invasion by exotic species.” E. O. Wilson
- 9. What makes a plant potentially invasive? Well adapted to the climate and soils of an area High reproductive success Grows and spreads rapidly Favorable environmental conditions, lack of natural predators, competitors and diseases
- 10. Why do people choose invasive plants? Invasives can be pretty Easily available and inexpensive Unaware of problems they can cause
- 11. When is an ‘exotic’ not a problem? Many do not cause harm to the economy, the environment, or our health Most ‘introduced’ species do not survive Only about 15% of those that do survive go on to become a problem Well-behaved introduced species include crepe myrtle, herbs such as Russian sage, Mexican oregano, and rosemary
- 12. Some invasives may take years to become problematic
- 13. Advantages of native plants Native plant, animal and insect species work together to keep a balance Maintain diversity, avoid monocultures Well-adapted to extremes of weather, climate
- 14. Invasive Grasses
- 15. Johnsongrass Considered one of the ten most noxious weeds in the world Competes with crops
- 17. Bermudagrass
- 18. “Improved” grasses Kleingrass, Dallisgrass, rescuegrass, rattail smutgrass, and other introduced species planted for livestock pasture
- 20. Bamboo Dense stands that exclude other plants from creating an understory Monocultures like this destroy ecosystems
- 21. Alternatives to giant cane and bamboo Texas pistache is an attractive screen with good fall color
- 22. Invasive Trees and Shrubs
- 23. Ligustrum (Japanese privet) One of the top terrestrial invasives in Central Texas A top seller at plant nursery centers Toxic leaves and fruit
- 24. Alternatives to ligustrum Often chosen as an evergreen screen Alternatives include mountain laurel, evergreen sumac, yaupon holly and cenizo
- 25. Nandina (Sacred bamboo) Mistaken for a native because it is so pervasive in our natural areas Colonizes via spreading underground roots Seed dispersed by animals
- 26. Alternatives to nandina Often chosen for its reddish foliage and red berries Possible alternatives include possumhaw holly and flameleaf sumac
- 27. Vitex Very pretty purple flowers A terrible invader of ecosystems along creeks and rivers Sometimes marketed as ‘Texas lilac’ – but it’s not native!
- 28. Alternatives to vitex Mexican bush sage, Texas mountain laurel, redbud and Mexican buckeye are all good alternatives with showy blossoms
- 29. Chinaberry Produce hundreds of poisonous berries Spread by birds Problem in riparian areas in particular
- 30. Alternatives to Chinaberry Western soapberry has beautiful fall color and berries very similar to Chinaberry
- 31. Chinese Tallow Tops list of invasive plants in the Southeastern United States Spread by birds and water Changes grassland into tallow forests Now comprises about 40% of the Houston tree canopy Allowed to grow and reproduce because of its pretty fall color
- 32. Alternatives to Chinese tallow For good fall color, consider: – Flameleaf sumac – Texas pistache – Texas red oak
- 34. Chinese pistache
- 36. Invasive Vines
- 37. Japanese honeysuckle Covers and smothers other plants Chris Evans, Illinois Wildlife Action Plan, Bugwood.org
- 38. Alternatives to Japanese honeysuckle Carolina jessamine Coral honeysuckle Cross vine Texas wisteria
- 39. English ivy Covers and smothers other plants James H. Miller, USDA Forest Service, Bugwood.org Randy Cyr, Greentree, Bugwood.org
- 41. Musk thistle
- 42. Bull thistle Photographer: Steve Dewey, Source: Utah State University, Bugwood.org
- 43. Sow thistle
- 44. Malta starthistle Photographer: Joseph M. DiTomaso, University of California - Davis Source: Bugwood.org
- 45. New on the scene
- 46. Bastard cabbage Bastard cabbage – quickly choking out many of our spring wildflowers Forms a large rosette that prevents other forbs from germinating Pull up by roots in spring, before it flowers
- 47. Brazilian vervain Displaces native vegetation Particularly invasive in riparian areas
- 48. Christ thorn Native to Mediterranean and Asia Particularly invasive in riparian areas Forms thorny thicket
- 49. Hill Country Dirty Dozen Glossy privet – Ligustrum lucidum Chinese tallow – Triadica sebifera Tree of heaven – Ailanthus altissima Giant reed – Arundo donax Johnsongrass – Sorghum halepense King Ranch bluestem – Bothriochloa ischaemum var. sangarica Chinaberry – Melia azedarach Japanese honeysuckle – Lonicera japonica Heavenly bamboo – Nandina domestica Golden raintree – Koelreuteria paniculata Brazilian vervain – Verbena brasiliensis Bastard cabbage – Rapistrum rugosum
- 50. What can you do? Choose native plants Replace invasive plants on your property Be alert to accidental transport of invasives via shoes and clothing, boats, cars Spread the word about invasive plants Patronize nurseries specializing in natives Ask your local nursery to stock native varieties Share plants, but make sure you know what you’re giving or receiving
- 51. What Can You Do? cont’d. Check the contents on seed mixes for invasives Use ‘certified weed free’ soils and mulches Dispose of invasive plants carefully – bag or burn For potentially invasive plants that you can’t part with, harvest and dispose of fruits and seeds before they can spread Join a volunteer network to help identify and remove invasive plants from natural areas – see http://www.texasinvasives.org for details on Wildflower Center initiative
- 52. The goal Preserve and restore natural areas that support the beautiful and diverse plants and wildlife native to Central Texas Prevention: $1 dollar of prevention is worth $100,000 of the cure Control a little now or deal with a lot later!
- 53. Resources Lady Bird Johnson Wildflower Center – Texas Invasives project http://www.texasinvasives.org/ The Global Invasive Species Initiative http://www.issg.org/ Nonnative Invasive Plants of Southern Forests by James H. Miller http://www.invasive.org/eastern/srs/ Weeds Gone Wild http://www.nps.gov/plants/alien/index.htm Nature Conservancy’s Global Invasive Species Team: http://www.invasive.org/gist /
- 54. Invaders – since 2005 www.texasinvasives.org Program developed at Lady Bird Johnson Wildflower Center Over 1400 citizen scientists trained 40+ satellites across the state Over 17,000 invasive plants documented and mapped
- 55. Want to get involved? Join the ‘Texas Invaders’ Go to http://texasinvasives.org Choose ‘Citizen Science’, then ‘Become a Citizen Scientist’ Follow instructions for Voyager online training Choose ‘Hill Country’ satellite Begin reporting!
- 56. Guess who’s coming to dinner? Texas Monthly’s list of our five tastiest invasives – Black Tiger Shrimp Penaeus monodon
- 57. Guess who’s coming to dinner? Texas Monthly’s list of our five tastiest invasives – Black Tiger Shrimp Penaeus monodon – Bastard Cabbage Rapistrum rugosum
- 58. Guess who’s coming to dinner? Texas Monthly’s list of our five tastiest invasives – Black Tiger Shrimp Penaeus monodon – Bastard Cabbage Rapistrum rugosum – Asian Carp (grass carp) Ctenopharyngodon idella
- 59. Guess who’s coming to dinner? Texas Monthly’s list of our five tastiest invasives – Black Tiger Shrimp Penaeus monodon – Bastard Cabbage Rapistrum rugosum – Asian Carp (grass carp) Ctenopharyngodon idella – Nutria Myocastor coypus
- 60. Guess who’s coming to dinner? Texas Monthly’s list of our five tastiest invasives – Black Tiger Shrimp Penaeus monodon – Bastard Cabbage Rapistrum rugosum – Asian Carp (grass carp) Ctenopharyngodon idella – Nutria Myocastor coypus – Feral pig Sus scrofa
- 61. Guess who’s coming to dinner? Do your part to control unwelcome populations– eat more invasive species!
Editor's Notes
- Edwards Plateau – increasing invasion by exotics Causes: Growing human population – humans are primary dispersal vector Development causes habitat destruction, and many invasives thrive in disturbed areas Edwards Plateau is most prone to flash flooding of all areas in the US – most seeds are dispersed more efficiently by water than by wind
- Birds may not get the nutrients they need from non-native berries, for example. And some non-native plants such as Chinaberry can be fatal. Arundo donax, for example, causes erosion, damages bridges, alters channel morphology, increases costs for chemical and mechanical control along transportation corridors, and impedes law enforcement activities along international borders.
- Note berries in photos – nandina and ligustrum
- Fast-growing exotics can provide screening
- disperses to great distances by wind, water, agricultural activities and animals Cannot tolerate repeated close mowing
- Can be suppressed by timely mowing, burning, and herbicides
- See Miller p.46 brought from Western Asia, Northern Africa and the Mediterranean in the 1800s as an ornamental plant. widely planted throughout the warmer areas of the US as an ornamental and for erosion control in the Southwest. tall, perennial grass that may grow to over 20 feet in height. fleshy, creeping rootstocks form compact masses from which tough, fibrous roots emerge that penetrate deeply into the soil. Reproduction primarily vegetative, through tuberous rhizomes which root and sprout readily. long, fibrous, interconnecting root mats choke riversides and stream channels, crowd out native plants, interfere with flood control, increase fire potential, and reduce habitat for wildlife. Large stands of giant reed change a territory from flood dependent to fire dependent habitat. It ignites easily and can create intense fires. Few herbivores browse the plant because the plant contains many toxic chemicals. Giant reed can float miles downstream where root and stem fragments may take root and initiate new infestations. New biological control approved recently by USDA: arundo scale
- See Miller p.56
- See Miller p.22 introduced from China, Japan and Korea colonizes by root sprouts and is spread by abundant bird- and other animal-dispersed seeds Few insects feed on it because chemicals in the leaves inhibit digestion. Ligustrum is widely believed to contribute to allergies and asthma
- See Miller p.26 introduced from eastern Asia and India in the early 1800s colonizes by spreading underground root sprouts and by animal-dispersed seeds
- See Miller p.8 introduced in the mid-1800s from the Himalayas and Asia widely planted as a traditional ornamental 98% germination rate Each berry can produce four seedlings
- native to China and Japan Introduced into Georgia and S Carolina in 1700s Fallen tallow leaves release a cyanogenic compound capable of inhibiting growth of other plants Loss of grasslands: removes shelter and nesting habitat for the endangered Attwater Prairie Chicken and other species of concern Up to 100,000 seeds annually from each tree Propagates via seed and/or cuttings, stumps, roots See Miller p. 10
- See Miller p. 2
- See Miller p.4
- See Miller p.38
- Reported in Gillespie County – Schnerr Creek and Spring Creek
- Widely raised for food in Asia, black tiger shrimp can grow up to a foot long and weigh up to a pound. Late last year they were found in Texas gulf waters according to Texas A&M scientists. Tiger shrimp, which make regular appearances on menus across the globe as as “giant tiger prawns,” can be cooked like any other crustaceans. Bastard cabbage , an invasive flowering weed native to the Eurasian steppe, threatens to choke out Texas’s bluebonnets. The taller-than-waist-high flowers prompt oohs and aahs, until the admirer learns the plant is up to no good. Bastard cabbage, which grow waist-high, rob wildflowers of “sun and soil nutrients.” A member of the mustard family, bastard cabbage is classified as a “noxious weed” by both the federal and state governments. How to prepare the plant: pick the young leaves and do a really simple saute with a little garlic, sea salt and lemon. Grass carp : Marinate deboned carp pieces in the refrigerator for at least an hour. Grill over a hot fire for carp fajitas. Nutria: Louisiana created a website, www.nutria.com , to encourage turning the large, rodents into fur coats and sausages. looks like a giant rat, but tastes like rabbit. Try nutria chili. Feral hogs cause an estimated $400 million in damage to property in Texas each year, Emerging as the ultimate invasive treat. Austin’s Dai Due holds a regular “ hog school ,” in which students hunt, butcher, and eat the hairy beasts. Feral hog is called wild boar when the meat hits your plate, so it lacks the branding problem that other invasives species face. Leaner than domestic hogs, they have a slightly nutty flavor that makes their meat more interesting than regular pork. See TPWD web site for recipes – Feral Hog Guisada, schnitzel, chili, tacos.