Managing Ludwigia peruviana (L.) Hara & Ludwigia ...

9th Ecology and Management of Alien Plant Invasions Conference, Perth, Australia 17-21 September 2007

Dr. Nimal ChandrasenaDr. Nimal ChandrasenaGHD Pty LtdGHD Pty Ltd

Managing Managing LLudwigiaudwigia peruvianaperuviana (L.) H(L.) Haraara & & LLudwigiaudwigia longifolialongifolia (DC) H(DC) Haraara infestations in NSW: infestations in NSW:

Progress and ProspectsProgress and Prospects

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OUTLINEOUTLINE

1.1. The Invaders in Sydney and NSW, Australia The Invaders in Sydney and NSW, Australia

2.2. Magnitude of infestationsMagnitude of infestations

3.3. Focus on managementFocus on management-- Case studies Case studies

4.4. Spread across NSWSpread across NSW

5.5. Conclusions Conclusions �� What we have learntWhat we have learnt


Sydney BasinSydney Basin

Hawksberry-Nepean River

Botany Wetland

Sydney Airport

Introducing the InvadersIntroducing the Invaders

Ludwigia peruvianaLudwigia peruviana (L.) Hara (Primrose Willow) (= (L.) Hara (Primrose Willow) (= JussiaeaJussiaea

peruviana, J. peruviana, J. grandifloragrandiflora, J. , J. suffruticosasuffruticosa))

Ludwigia longifoliaLudwigia longifolia (DC.) Hara ((DC.) Hara (LongLong--leaf Willow Primrose)leaf Willow Primrose)

ONAGRACEAEONAGRACEAE

Native areaNative area-- Central AmericaCentral America

PanPan--tropical, 0tropical, 0--1450 m altitude (Indonesia, Sri Lanka)1450 m altitude (Indonesia, Sri Lanka)

In the Sydney basinIn the Sydney basin-- (30(3000 South latitude)South latitude)

L. peruvianaL. peruviana-- in 1971 (escape from Botanic Gardens)in 1971 (escape from Botanic Gardens)

L. longifoliaL. longifolia-- In 1991 (escape from Nurseries ?)In 1991 (escape from Nurseries ?)


� Water supply, Sydney 1850-1866

� 59 Ha wetlands, 11 ponds + land

� 4 Km, eastern suburbs, open to the Botany bay

� Flood-mitigation system

� Largest freshwater lakes

� Water supply, Sydney 1850-1866

� 59 Ha wetlands, 11 ponds + land

� 4 Km, eastern suburbs, open to the Botany bay

� Flood-mitigation system

� Largest freshwater lakes

Botany WetlandsBotany Wetlands-- SydneySydney


Botany WetlandsBotany Wetlands-- SydneySydney

o Highly valued (native vegetation, wildlife habitats, aesthetic)

o Degraded by aquatic weeds (Ludwigia peruviana, Alligator Weed, Salvinia, Water Hyacinth) and Invasive trees (Willows, Coral trees)

1996


� Pond 3 (75% cover of L.p)

� Invasive Willows, Coral trees



P 3

P 5

Botany WetlandsBotany Wetlands-- Pond 3Pond 3


Ludwigia peruvianaLudwigia peruviana in Sydneyin Sydney

2.5 m






Botany WetlandsBotany Wetlands-- Pond 1Pond 1

P 1

P 2


� Pond 1A (90% cover of L.p)

� Invasive Willows

� Pond 1A (90% cover of L.p)

� Invasive Willows

Botany WetlandsBotany Wetlands-- Pond 1APond 1A

Willow groveWillow grove


Ludwigia peruvianaLudwigia peruviana-- potential distributionpotential distribution


Integrated Weed ManagementIntegrated Weed Management


Integrated Weed ManagementIntegrated Weed Management

RevegetationRevegetation--�� Assisted regenerationAssisted regeneration�� Purposeful planting of native speciesPurposeful planting of native species�� TansplantingTansplanting macrophytesmacrophytes�� Bush regenerationBush regeneration�� Habitat creationHabitat creation-- logs, snagslogs, snags


Before (up to 1996) Before (up to 1996) After (2006)After (2006)

� Serious noxious weeds

� Poor water quality, murky water

� Stagnant water due to choking

� Toxic algal blooms annually,

� Feral fish (European Carp)

� Poor diversity of native plants

� Less noxious weeds, invasive trees

� better water quality, water clarity (>3.0 m)

� Vastly improved flow

� No algal blooms, reduced feral fish

� Native plants- greater diversity

Botany Wetlands, SydneyBotany Wetlands, Sydney


Pond 1A

Before (up to 1996) Before (up to 1996)

Botany Wetlands, Botany Wetlands, SydneySydney

After (2006) After (2006)


� 1 frog species; 99 bird species (1991)

� 6 frog species; 164 bird species (2004)

Botany Wetlands, SydneyBotany Wetlands, Sydney


Vegetation Changes- Botany Wetlands

0

10

20

30

40

50

60

70

80

1996 1998 2000 2002 2005

% A

rea

Ludw igia

Undesirable Vegetation

Native Vegetation

Open Water� L. peruviana- negligible

� Native vegetation (Typha orientalis, three Baumea sp., Phragmites australis, Juncussp., Cyperus sp., Schoenoplectus sp., Elaeocharissp. + many others)

Botany WetlandsBotany Wetlands-- Annual costs of implementing IWM and Annual costs of implementing IWM and monitoring Ecological Healthmonitoring Ecological Health

Annual Monitoring- WQ, Macroinvertebrates, Frogs, Reptiles, AusrivasSIGNAL Index, Vegetation

Birds- once in 5 years

Annual Costs of Implementing IWM- Botany Wetlands

0

50

100

150

200

250

300

350

400

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Au

s $

'000

Total costs

IWM- on ground costs

Management costs


Monitoring Review

New POM

Ludwigia longifoliaLudwigia longifolia-- north of Sydney (Newcastle)north of Sydney (Newcastle)

� Location of Mambo Wetlands (175 ha), Salamander Bay, Port Stephens,

� Largest infestations of L. longifolia- first found

� Note closeness to the port city Newcastle, north of Sydney.

� Other infestations, thus far are small and sporadic in occurrence.


Ludwigia longifoliaLudwigia longifolia

L. l found in Botany Wetlands in 1991, 2002, L. l found in Botany Wetlands in 1991, 2002, 2005; Just upstream of drain is a nursery2005; Just upstream of drain is a nursery

Controlled with herbicides + manual removalControlled with herbicides + manual removal

Persistent seedsPersistent seeds


L. peruvianaL. peruviana has has spread widely over spread widely over the past 12 years, the past 12 years, despite despite implementation of implementation of Regional WMPRegional WMP

L. longifolia has L. longifolia has appeared in a few appeared in a few locations, sporadic locations, sporadic patchespatches

Lessons learntLessons learnt-- Focus of managementFocus of managementUnderstand biological attributes of the invader, which make themUnderstand biological attributes of the invader, which make theminvasives (seed production, vegetative reproduction etc.); invasives (seed production, vegetative reproduction etc.); Understand why such species have invadedUnderstand why such species have invaded

Coordinated management captured by one NSW DPI Regional Coordinated management captured by one NSW DPI Regional WMP for both species; WMP for both species; Plan for the entire catchment (watershed) Plan for the entire catchment (watershed) and regionand region

Eradication vs containment ? Relatively easy to treat (if there Eradication vs containment ? Relatively easy to treat (if there is is Commitment)Commitment)

Integrated Weed Management (Early detection, prevention of Integrated Weed Management (Early detection, prevention of spread, herbicides, mechanical removal, burning, cultural controspread, herbicides, mechanical removal, burning, cultural control) l)

no biono bio--control agent yet; not an option in early 1990s because of control agent yet; not an option in early 1990s because of limited resources and need for more urgent actionlimited resources and need for more urgent action


Eradication strategy is workable, so long has the invader has noEradication strategy is workable, so long has the invader has not t spread too muchspread too much

Improved reporting and sharing of informationImproved reporting and sharing of information

Improved Contract specs & contract management; Improved Contract specs & contract management; Training (weed Training (weed contractors)contractors)

Improved project implementation can bring about successImproved project implementation can bring about success--

oo Eradication should be a goal with these two speciesEradication should be a goal with these two species

oo Learning from successful projects Learning from successful projects

oo Set performance targets (i.e. reduce local infestations by 50% iSet performance targets (i.e. reduce local infestations by 50% in n next 12 monthsnext 12 months��.).)

oo Monitor costs, achievement, reportMonitor costs, achievement, report

Lessons learntLessons learnt-- Focus on managementFocus on management


ConclusionsConclusions

Some invasive species are moving with human disturbancesSome invasive species are moving with human disturbances

These species are only doing what they are meant to doThese species are only doing what they are meant to do-- i.e. exploit i.e. exploit vacant vacant ��nichesniches�� created by disturbances, maintain fecundity (rcreated by disturbances, maintain fecundity (r--strategists)strategists)

Spread caused by and sustained by Spread caused by and sustained by urbanisationurbanisation impactsimpacts

Aggressive Aggressive ��maintenance controlmaintenance control�� until comprehensive until comprehensive WMPsWMPs for for areas, regions are producedareas, regions are produced

Stronger insistence on interStronger insistence on inter--agency cooperation & information agency cooperation & information sharingsharing

Keep a watch on other Ludwigias (Keep a watch on other Ludwigias (L. L. hyssopifoliahyssopifolia, L. , L. decurrensdecurrens, L. , L. octovalvisoctovalvis) )

Immigrants to Invaders !!Immigrants to Invaders !!


Thank youThank you

Managing Ludwigia peruviana (L.) Hara & Ludwigia ...

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