Invasive Plants

Invasive Species – Invasive Species – The ProblemThe Problem

and and What We Can Do About ItWhat We Can Do About It

Phyllis MuskaPhyllis Muska

Native Plant Society of Texas – Kerrville Native Plant Society of Texas – Kerrville ChapterChapter

January 8, 2013January 8, 2013

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

What is an invasive species?What is an invasive species?

Federal definition:

Invasives in TexasInvasives 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

Texas Invasive Plant and Pest Texas Invasive Plant and Pest Council (TIPPC)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

TIPPCTIPPC

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

Problem invasives in other parts Problem invasives in other parts of USof 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

Why are invasives a problem?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

How serious is the problem?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

What makes a plant potentially What makes a plant potentially invasive?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

Why do people choose invasive Why do people choose invasive plants?plants?

Invasives can be pretty Easily available and inexpensive Unaware of problems they can cause

When is an ‘exotic’ not a When is an ‘exotic’ not a problem?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

Some invasives may take Some invasives may take years to become problematicyears to become problematic

Advantages of native plantsAdvantages 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

Invasive GrassesInvasive Grasses

JohnsongrassJohnsongrass

Considered one of the ten most noxious weeds in the world

Competes with crops

King Ranch bluestemKing Ranch bluestem

BermudagrassBermudagrass

““Improved” grassesImproved” grasses

Klein grass, Dallisgrass, rescuegrass, rattail smutgrass, and other introduced species planted for livestock pasture

Giant caneGiant caneArundo donaxArundo donax

BambooBamboo

Dense stands that exclude other plants from creating an understory

Monocultures like this destroy ecosystems

Alternatives to giant cane and Alternatives to giant cane and bamboobamboo

Texas pistache is an attractive screen with good fall color

Invasive Trees and ShrubsInvasive Trees and Shrubs

Ligustrum (Japanese privet)Ligustrum (Japanese privet)

One of the top terrestrial invasives in Central Texas

A top seller at plant nursery centers

Toxic leaves and fruit

Alternatives to ligustrumAlternatives to ligustrum

Often chosen as an evergreen screen Alternatives include mountain laurel, evergreen

sumac, yaupon holly and cenizo

Nandina (Sacred bamboo)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

Alternatives to nandinaAlternatives to nandina

Often chosen for its reddish foliage and red berries

Possible alternatives include possumhaw holly and flameleaf sumac

VitexVitex

Very pretty purple flowers

A terrible invader of ecosystems along creeks and rivers

Sometimes marketed as ‘Texas lilac’ – but it’s not native!

Alternatives to vitexAlternatives to vitex

Mexican bush sage, Texas mountain laurel, redbud and Mexican buckeye are all good alternatives with showy blossoms

ChinaberryChinaberry

Produce hundreds of poisonous berries

Spread by birds Problem in

riparian areas in particular

Alternatives to ChinaberryAlternatives to Chinaberry

Western soapberry has beautiful fall color and berries very similar to Chinaberry

Chinese TallowChinese 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

Alternatives to Chinese tallowAlternatives to Chinese tallow

For good fall color, consider:– Flameleaf sumac– Texas pistache– Texas red oak

AilanthusAilanthus(Tree of Heaven) (Tree of Heaven)

Chinese pistacheChinese pistache

Mimosa (Silk tree)Mimosa (Silk tree)

Invasive VinesInvasive Vines

Japanese honeysuckleJapanese honeysuckle

Covers and smothers other plants

Chris Evans, Illinois Wildlife Action Plan, Bugwood.org

Alternatives to Japanese Alternatives to Japanese honeysucklehoneysuckle

Carolina jessamine

Coral honeysuckle

Cross vine Texas wisteria

English ivyEnglish ivy

Covers and smothers other plants

Randy Cyr, Greentree, Bugwood.org

James H. Miller, USDA Forest Service, Bugwood.org

Non-native thistlesNon-native thistles

Musk thistleMusk thistle

Bull thistleBull thistle

Photographer: Steve Dewey,Source: Utah State University, Bugwood.org

Sow thistleSow thistle

Malta starthistleMalta starthistle

Photographer: Joseph M. DiTomaso, University of California - DavisSource: Bugwood.org

New on the sceneNew on the scene

Bastard cabbageBastard 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

Brazilian vervainBrazilian vervain

Displaces native vegetation Particularly invasive in riparian areas

Christ thornChrist thorn

Native to Mediterranean and Asia

Particularly invasive in riparian areas

Forms thorny thicket

Hill Country Dirty DozenHill 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

What can you do?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

What Can You Do? cont’d.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

The goalThe 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!

ResourcesResources

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. Millerhttp://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/ /

Invaders – since 2005Invaders – 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

Want to get involved?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!

Guess who’s coming to dinner?

Texas Monthly’s list of our five tastiest invasives– Black Tiger Shrimp Penaeus monodon


Texas Monthly’s list of our five tastiest invasives– Black Tiger Shrimp Penaeus monodon– Bastard Cabbage Rapistrum rugosum


Texas Monthly’s list of our five tastiest invasives– Black Tiger Shrimp Penaeus monodon– Bastard Cabbage Rapistrum rugosum– Asian Carp (grass carp) Ctenopharyngodon

idella



idella – Nutria Myocastor coypus



idella – Nutria Myocastor coypus– Feral pig Sus scrofa


Do your part to control unwelcome populations– eat more invasive species!

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Invasive Plants