cabomba caroliniana gray in the netherlands - gt...

Cabomba caroliniana(Fanwort) in The

Netherlands

3rd International Symposium on Weeds and Invasive

Plants

Johan van Valkenburg, Rudi Roijackers & Rosalie Léonard

Cabomba caroliniana | October 2011

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The species involved

• A common component of your Goldfish plant selection


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Cabomba caroliniana or Cabomba aquatica ?

• In trade Cabomba aquatica is often misapplied to C. caroliniana plants

C. aquatica C. caroliniana

Flowers Yellow White

Submerse leaves

3-dimensional Mostly 2-dimensional

Emerse leaves

Round Elliptic


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Cabomba caroliniana distribution

2010

Published sources


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A brief history for The Netherlands

• First record 1989 Maasbracht (Meuse River) NOT invasive

• Since 2005 at Loosdrecht INVASIVE

• Spring 2006 first attempt at eradication

• Summer 2007 Oranje channel

near Orvelte expanding

• Summer 2008 suburban area at Hoogeveen & fish pond Groningen

• Summer 2010 suburban area Hardinxveld, Ridderkerk, Barendrecht

• Summer 2011 suburban area Heerenveen


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What to do ?

• Identification tools & training of field staff

• Research on habitat requirements

• Research on genetic diversity

• Research on management options


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Identification tools

• Field guide

• Info sheet


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Habitat requirementsSurvey March, July, October 2008

Visit at the 3-4 known localities

Results:

• Wide tolerance for nutrient levels

• Large range in conductivity level

• Floating plants limit growth

• Competition with Myriophyllum heterophyllum

Conclusions:

• Site conditions do not explain difference in invasive behaviour

• Can grow in any eutrophic stagnant to slow flowing water with a sediment poor to very rich in organic matter


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Genetic diversity• In collaboration with Plant

Research International and CSIRO

• Sampling of all known localities in NL

• Additional samples invasive populations in France, Germany and Australia

• Samples from import shipments SE Asia


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Management options EUPHRESCO DeCLAIM project

Funding: UK Defra and NL LNV

Partners:

• Plant Protection Service NL

• Wageningen University & Research

• CEH - Wallingford

Target species:

• Cabomba caroliniana

• Hydrocotyle ranunculoides

• Ludwigia grandiflora

• Myriophyllum aquaticum


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EUPHRESCO Cabomba trials at Loosdrecht


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Cabomba management

Field testing 4 methods at Loosdrecht

• Standard practice

• Washing out

• Covering surface

• Covering bottom

CHARISMA model to assist DSS

• Detailed measurements in time

• Predicting competition

• Timing of management actions


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Trial lay out

• Standard 3 X 100 m & enclosures

• Washing 3 X 100 m & enclosures

• Surface coverage 2 X 100 m

• Bottom coverage 10 X 10 m

• Scheduled for early April performed by May 20th (standard) and July 14th (washing)


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Location map trials Loosdrecht


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Standard practice

May

June

December

July


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Result of standard practice

• After 1 year dominance Cabomba just like it was before management (June 75-90%; August 80-90%)

Enclosures (1 x 1 m)

• On average 9(3-30) stems of Cabomba present

• Elodea nuttallii July 15-40 % coverage August 40-100%

coverage

Dominance Cabomba resulting from regrowth, inflow of fragments and competitive advantage grazing


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Washing out with hydro-venturi system


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Result of washing out

• After 1 year dominance Cabomba still reduced (June 5-10%; August 25-50%)

Enclosures (1 x 1 m)

• Just 1 cage with a few stems of Cabomba entering from the side

• Elodea nuttallii coverage August 25-100% coverage

Recovery of Cabomba resulting most likely from inflow of fragments and competitive advantage grazing


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June 2010 enclosure with Cabomba


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June 2010 outside enclosure


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August 2010 Elodea nuttallii (other enclosure)


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Coverage with black woven geotextileCoverage of sediment

• Recolonisation of Cabomba on new sedimentation on top of fabric

Does not work in a situation with siltation and large quantities of propagules in the vicinity

Coverage of surface

• No plant growth in July

• No plant growth after 1 month partial removal of fabric

August 2011

• 1st ‘removed’ stretch

2 Cabomba stems & 5 plants M. verticillatum 50% cover

• 2nd ‘removed’ stretch

No Cabomba & 7 plants M. verticillatum 50% cover

M. verticillatum and U. vulgaris on top of fabric

Non discriminant effective method


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Surface coverage experiment August 2010


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Surface coverage experiment August 2011


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CHARISMA model• Determine growth parameters

• Life-cycle knowledge

• Vulnerable stages in development

• Energy allocation

• First findings


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Charisma ‘conclusions’

Predictions on growth and competition do not match field observations

• Growth potential underestimated

• Critical role of root system

• Photosynthesis parameters to be evaluated

April 2011


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Conclusions

• Standard practice will not eradicate Fanwort in eutrophic waters

• Yearly cleaning in autumn has resulted in 100% dominance of Fanwort in ditches

• Washing out is a quite effective method to remove macrophytes rooting in the sediment (e.g. Cabomba & M. heterophyllum)

• There is no ‘best management ‘ option

• Solution has to be adapted to the actual site conditions:

Dimensions of the waterway

Conditions of the bank

Function of the waterway

cabomba caroliniana gray in the netherlands - gt...

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