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Theme 3: Human Impacts on Catchments
Topic: Exotic Plants
What is an Exotic plant?
An exotic plant is one that originates from outside the local area. The plant may have come from overseas or it may even have come from another part of Australia. Exotic plants are often referred to as environmental weeds. There are over 2,500 exotic plants in Australia.
Why are exotic plants a problem?
Exotic plants cause a threat to the health of the local native environment in a variety of ways including:
- competition with native plants for light, space, soil moisture, pollinators and nutrients. Some weeds can form a dense cover and prevent the emergence and regeneration of native seedlings
- change of habitat and ecology through creating extra shade and altering the soil chemistry
- provision of only limited food resources or habitat to a small number of indigenous species, while taking resources from the indigenous plants that provide food and habitat for native species, and
- promoting the spread of pest animal species, such as foxes and starlings that feed on their fruits.
Student Activity Ideas
- Visit your local natural area for a weed identification lesson. Your Catchment Water Management Board may be able to provide you with a weed identification chart.
- Students to record whether the weeds are flowering or not.
- Students to examine the weed (bark, leaves, fruit) for evidence of the weed being used by insects or birds. For example, the comparison between they way that Olive leaves have been eaten, compared to Eucalyptus leaves. Students will easily be able to see which plant is an important food and habitat source to local wildlife.
- One group of students to study an exotic tree and another group to watch an indigenous tree and record which birds use these them. Compare results and discuss the differences.
- Groups of students to research a weed found and answer the following. Which country did the weed originally come from? What has the plant been used for in Australia, why is or was it important to us? What time of year does the weed flower? Does the plant provide food or habitat to any native or introduced species? Does it provide food or shelter to humans? Why is the weed a problem in natural areas? Is the plant sold in the local nursery? Name a specific location where they have seen this plant growing? What steps can we take to prevent this weed from spreading.
- Draw a picture or take a photo of the weed, and even collect a cutting. Students to present their results to the class.
- Show deciduous tree clippings to the class and discuss where the tree species came from, how it spreads and why it is a problem. Explain that many people really love these types of trees and don't like them to be cut down.
- Students to pretend they work for the council. The council knows that some Willow trees in the local creek, which run straight into a reservoir, are bad weeds and they are threatening biodiversity and water quality. The Willows need to be removed. Students to write a letter to the residents living near the creek, and who like the willows. Students need to explain clearly to the residents why they are chopping down the trees and how they intend to restore the area after the trees are gone.
- Start a media file of articles appearing in the newspaper concerning weed management issues in your local area. Discuss the articles pertaining to exotic trees and write down the benefits and the problems of exotic trees. Students to determine how exotic trees and community attitudes to them can be managed.
- Participate in the Weedbusters program offered by your local Animal and Plant Control Board.
- Organise a structured debate whereby groups of students are issued portfolios from various community group interests. Students to explore the issues involved and each group to prepare a case and present it to the council/land management body. Teachers to play the role of the council or other managing body and pass judgment, based on the strength of the arguments provided by students.
Enquiry Learning
- How has the introduction of plants from other parts of Australia and from around the world impacted on your local landscape?
- Why can some plants that are from other parts of Australia or from overseas, do so well in some environments despite the fact that they are not native to the area?
- Why and how do plants get transported from one area to another?
- How can we minimize the spread of exotic plants? What can you do around your own home?
Internet Resources
Type Description Resources Covering the Topic Easy
- Good overview of key trends in invasive species in South Australia.
SA Department of Environment and Heritage
www.environment.sa.gov.au/reporting/
biodiversity/introduced.html
- Weed invasion.
- Landcare summary of the main issues concerning weeds.
Landcare Victoria
www.netc.net.au/enviro/fguide/
weed.html
- Marine pests.
- Succinct site with a link to types of pests found in Victorian coastal waters.
VIC EPA
www.epa.vic.gov.au/Water/Threats/
invasive_species.aspMore Comprehensive
- Environmental weeds in Australia.
- What they are, how they spread and flourish, effects on natural environments and more.
Environment Australia - Biodiversity
www.deh.gov.au/biodiversity/
invasive/publications/weeds-potential/review.html
- Weeds.
- Brief description of issues with a list of nationally significant weeds.
Community Biodiversity Network
nccnsw.org.au/member/cbn/projects/
EducationCentre/Edu_Weeds.html
- Background to threats to biodiversity around the world.
Species Survival Commission
www.iucn.org/themes/ssc/pubs/policy/
invasivesEng.htm#BACKGROUNDMore Complex
- Weed Management Society of South Australia.
- Web links to a whole range of organisations concerned with weeds in SA.
Weed Management Society of South Australia
www.wmssa.org.au
- The threat of non-indigenous species across the US.
- Thorough and comprehensive examination of the processes of invasion.
US Geological Survey
biology.usgs.gov/s+t/SNT/noframe/
ns112.htmActivities
Band Activity Contact Early and Middle Years
- Weed Warriors.
- Mt Lofty Ranges only, but links to other weed related sites.
www.mlrapcb.net/
weedwarriors.html
- Weed removal with students.
- Resource sheet.
- PDF download.
Onkaparinga Catchment Water Management Board
www.onkaparinga.net/education/
downloads/folder_4/
6_17_1.pdfWho Can Help?
Organisation Who Can Help? Metropolitan Catchment Water Management Boards Catchment Care - North Adelaide and Barossa Catchment Water Management Board (CWMB)
State-wide program Weed Warriors
