Invasive Species - The Problem and What We Can Do About It by Phyllis Muska

Invasive Species –

The Problem

and

What We Can Do About It

Phyllis Muska

Native Plant Society of Texas – Kerrville Chapter

January 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?

Federal definition:

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

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

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

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

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?

“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 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 plants?

Invasives can be pretty

Easily available and inexpensive

Unaware of problems they can cause

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

Some invasives may take years to

become problematic

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

Invasive Grasses

Johnsongrass

Considered one of the ten most

noxious weeds in the world

Competes with crops

King Ranch bluestem

Bermudagrass

“Improved” grasses

Klein grass, Dallisgrass, rescuegrass, rattail

smutgrass, and other introduced species

planted for livestock pasture

Giant cane

Arundo donax

Bamboo

Dense stands

that exclude

other plants

from creating an

understory

Monocultures

like this destroy

ecosystems

Alternatives to giant cane and bamboo

Texas

pistache is an

attractive

screen with

good fall

color

Invasive Trees and Shrubs

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 ligustrum

Often chosen as an evergreen screen

Alternatives include mountain laurel, evergreen sumac,

yaupon holly and cenizo

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 nandina

Often chosen for

its reddish

foliage and red

berries

Possible

alternatives

include

possumhaw

holly and

flameleaf sumac

Vitex

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 vitex

Mexican bush

sage, Texas

mountain laurel,

redbud and

Mexican buckeye

are all good

alternatives with

showy blossoms

Chinaberry

Produce hundreds of

poisonous berries

Spread by birds

Problem in riparian

areas in particular

Alternatives to Chinaberry

Western soapberry has beautiful

fall color and berries very

similar to Chinaberry

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

Alternatives to Chinese tallow

For good fall color, consider:

– Flameleaf sumac

– Texas pistache

– Texas red oak

Ailanthus

(Tree of Heaven)

Chinese pistache

Mimosa (Silk tree)

Invasive Vines

Japanese honeysuckle

Covers and smothers

other plants

Chris Evans, Illinois Wildlife Action Plan, Bugwood.org

Alternatives to Japanese honeysuckle

Carolina

jessamine

Coral

honeysuckle

Cross vine

Texas wisteria

English ivy

Covers and smothers

other plants

Randy Cyr, Greentree, Bugwood.org

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

Non-native thistles

Musk thistle

Bull thistle

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

http://texasinvasives.org/plant_database/detail.php?symbol=CIVU

Sow thistle

Malta starthistle

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

New on the scene

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

Brazilian vervain

Displaces native vegetation

Particularly invasive in riparian areas

Christ thorn

Native to

Mediterranean and Asia

Particularly invasive in

riparian areas

Forms thorny thicket

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

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.

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 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!

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/

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

http://www.texasinvasives.org/

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!

http://texasinvasives.org/

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






– Nutria Myocastor coypus

– Feral pig Sus scrofa


Do your part to control

unwelcome populations–

eat more invasive species!

Environment

Invasive Species - The Problem and What We Can Do About It by Phyllis Muska