Plant Responses to Environmental Watering at Hattah Lakes Fact Sheet

Plant responses to environmental watering at Hattah Lakes

Native water-dependent plants benefit from environmental watering

Accordingly, environmental water deliveries are being Key points: undertaken as part of The Living Murray (TLM) • Native water-dependent plants benefited initiative, a river restoration program designed to improve the environmental health of the Murray River from environmental watering at Hattah and its floodplain. Lakes. • Native plants and plant communities differ Determining environmental watering benefits in their responses to environmental To effectively deliver environmental water in a way that watering. maintains or improves ecosystem health, we need to • Environmental watering is important for the know about the target riparian system. In addition, we survival of water-dependent plants and the need to monitor how plants and animals respond to watering events and use this information to refine future maintainance of semi-arid floodplains. watering events. Monitoring the benefits of environmental watering is particularly important in Hattah Lakes drying climates where there is insufficient rainfall to Hattah Lakes is a complex of semi-arid lake systems maintain semi-arid floodplain ecosystems. and floodplains in north-west Victoria that forms part of At Hattah Lakes a long-term monitoring program is the Hattah-Kulkyne National Park and the Murray- evaluating the effects of environmental watering on the Kulkyne Park. Hattah Lakes is one of six ‘Icon Sites’ semi-arid floodplain lake-side plant community, located along the Murray River and has significant capturing an environmental gradient from the lakebed to ecological, cultural, recreational, heritage and economic the lower and higher floodplain (Figure 1). values. The lack of connectivity between the Hattah Lakes and the Murray River, together with river regulation and water extraction, has negatively impacted the overall environmental health of the system, and habitat value for fauna has declined.

Environmental watering (managed flooding) is implemented to mitigate the effects of the reduced frequency of natural flooding and

improve ecosystem health.

Figure 1: Scientist monitoring vegetation responses to environmental watering at Hattah Lakes. (Credit C.Moxham)

delwp.vic.gov.au ari.vic.gov.au OFFICIAL

Plant responses to environmental watering at Hattah Lakes

Plant communities of Hattah Lakes Around the lakes, waterways and floodplains of the Hattah Lakes system, three main plant communities occurr in a mosaic, reflecting environmental gradients in elevation, soil moisture and flooding history (Figure 2).

Lake Bed Herbland Intermittent Swampy Woodland Riverine Chenopod Woodland < 41.71 m elevation lake bed < 43.17 m elevation lower floodplain > 43.72 m elevation higher floodplain Frequently flooded Intermittently flooded Rarely flooded

Water dependent plants Water tolerant plants Dryland plants Common species Common species Common species • Southern Liquorice (Glycyrrhiza • River Red Gum (Eucalyptus camaldulensis) • Black Box (Eucalyptus largiflorens) acanthocarpa) • Black Box (Eucalyptus largiflorens) • Ruby Saltbush (Enchylaena • Clammy Goosefoot (Dysphania • River Coobah (Acacia stenophylla) tomentose; pictured) pumilio) • Tangled Lignum (Duma florulenta) • Streaked Copperburr (Sclerolaena • Mallee Cucumber (Austrobryonia • Blue Rod (Stemodia florulenta; pictured) tricuspis) micrantha; pictured) • Common Sneezeweed (Centipeda • Flat-top Saltbush (Atriplex lindleyi) • Southern Hollyhock (Malva cunninghamii) • Hedge Saltbush (Rhagodia weinmanniana) • Spreading Nut-heads (Sphaeromorphaea spinescens) littoralis) • Nodding Saltbush (Einadia nutans) • Spring Flat-sedge (Cyperus gymnocaulos)

Figure 2: The three main plant communitites of the Hattah Lakes floodplain system and their defining characteristics.

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Gnaphalium polycaulon Goodenia glauca Goodenia spp. Haloragis aspera Helichrysum luteoalbum Heliotropium europaeum Hypericum gramineum spp. agg. Hypochaeris radicata

0.020

0.4

0.015

0.008

0.010

0.02

0.0015 0.010

0.010 0.2

0.0

0.00

0.000 0.000 0.000 0.000 0.000 0.0000 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 Acacia stenophylla Ajuga australis Alternanthera denticulata s.l. AcaciaAlternanthera stenophylla sp. 1 (Plains) AsphodelusAjuga australis fistulosus AlternantheraAsteraceae denticulata spp. s.l. AlternantheraAtriplex semibaccata sp. 1 (Plains) AsphodelusAtriplex stipitata fistulosus Asteraceae spp. Atriplex semibaccata Atriplex stipitata

Lipocarpha microcephala Maireana brevifolia Medicago spp. Nicotiana glauca Nicotiana velutina Oxalis spp. Paspalidium jubiflorum Persicaria prostrata

0.012

0.20

0.012 0.06

0.10

0.006

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0.04

0.010

0.006

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0.08

0.010

0.015

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0.10 0.006

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0.008

0.015 0.004 0.10

0.03

0.006

0.04

0.00 0.00 0.00

0.000 0.000 0.000 0.000 0.000

0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 100 1020 2030 3040 40 0 010 1020 2030 30 40 40 0 0 1010 2020 3030 4040 00 1010 2020 3030 4040 0 1010 2020 3030 4040 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40

0.00 0.00 0.00 0.00

0.000 0.000 0.000 0.000 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 Atriplex suberecta Austrobryonia micrantha Austrostipa spp. AtriplexBoerhavia suberecta dominii AustrobryoniaBrassica tournefortiimicrantha AustrostipaBrassicaceae spp. spp. BoerhaviaCallitriche dominiisonderi CalostemmaBrassica purpureumtournefortii s.l. Brassicaceae spp. Callitriche sonderi Calostemma purpureum s.l.

Phyllanthus lacunellus Polycalymma stuartii Polygonum plebeium Psilocaulon granulicaule Rhagodia spinescens Rumex brownii Rumex dumosus Salsola tragus

0.30

0.4

0.12 0.08

Plant responses to environmental 0.12

0.04

0.008 0.03 0.003

0.010 0.03

0.015

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0.015

0.15

0.2

0.006

0.008 0.06

watering at Hattah0.06 Lakes

0.0020

0.04

0.06

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0.000 0.000 0.000 0.000

0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40

0.00 0.00 0.00 0.00

0 10 20 30 40 0 10 20 30 40 0.00 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40

0.000 0.000 0.0000 Short-term plant0 10 responses20 30 40 to environmental0 10 20 30 watering40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 Calotis cuneifolia Centipeda cunninghamii Centipeda nidiformis ChenopodiumCalotis cuneifolia curvispicatum CentipedaCitrullus cunninghamii colocynthis CentipedaClematis microphylla nidiformis s.l. ChenopodiumConyza bonariensis curvispicatumCucumis myriocarpusCitrullus colocynthis subsp. leptodermis Clematis microphylla s.l. Conyza bonariensis Cucumis myriocarpus subsp. leptodermis

• Plants fell into two mainSalvia groups verbenaca favouring either: Salvia(1) the verbenaca lake edge and var. lower vernalis floodplain, Sclerolaenaor (2) the higher diacantha Senecio spp. Sisymbrium erysimoides Solanum esuriale Solanum nigrum s.l. Sphaeromorphaea australis

0.04

0.030 0.04

floodplain. 0.030

0.20

0.04

0.20

0.04 0.30

• Of the 100 plants0.010 evaluated, 46 responded to environmental watering. However, plant responses did not

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0.010

0.004

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0.004

0.010 0.015

0.015 0.10

necessarily align with expected plant functional group responses (e.g. with all terrestrial plants favouring dryland 0.02

0.02

0.010 0.015

0.10

0.02

0.015

0.06 0.010

0.04 0.04

habitats). 0.008

0.15

0.02

0.00 0.00 0.00

0.000 0.000 0.000 0.000

0.000 • Lake bed/edge species generally responded positively to watering. In contrast, dryland or higher floodplain

0.00 0.00 0.00

0.000 0.000 0.000 0.000 0.000

0.00 0.00 0.00 0.00

0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30species40 may have had0 positive10 20 or negative30 40 responses.0.00 For0 example:10 20 30 40 0 10 20 30 40

0.000 0.000 0 10 20 30 40 0 10 20 30 40 0.000 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 ➢ Southern Liquorice0 (10Glycyrrhiza20 30 acanthocarpa40 ) is a water0 10responder20 which30 40 is dominant on0 the lake10 bed/edge20 30 . 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 Cynodon dactylon Cynodon dactylon var. pulchellus Cyperus gymnocaulos Cyperus squarrosus Dodonaea viscosa subsp. angustissima Duma florulenta Dysphania cristata Dysphania glomulifera subsp. glomulifera Cynodon dactylon Cynodon dactylon var. pulchellusModelling indicatCyperused it responded gymnocaulos positively to watering.Cyperus However ,squarrosus Plains JoyweedDodonaea (Alternanthera viscosa sp. 1), subsp.also angustissima Duma florulenta Dysphania cristata Dysphania glomulifera subsp. glomulifera

a putative water responderStemodia, hadglabella a negative s.s. response.Swainsona microphylla Teucrium racemosum s.l. Tricoryne spp. Trifolium spp. Verbena officinalis s.l. Verbena spp. Verbena supina

0.06

0.06 0.30

➢ On the higher floodplain, Dissected New Holland Daisy (Vittadinia dissecta) had a positive response, 0.06

0.06

0.30 0.06

whereas the dominant Ruby Saltbush (Enchylaena tomentosa) had a more negative response, particularly 0.030

0.10

0.02

0.015

0.10 0.06

0.03

0.10 0.03

close to the waters edge. 0.15

0.015

0.02

0.015

0.10 0.06

0.03

0.020 0.020

0.020 0.004

0.15

0.15 0.03 0.03

• Individual plant models were more useful than plant functional group models. Although the plant functional 0.015

0.00 0.00 0.00 0.00 0.00 0.00 0.00

0.000 groups illustrated overall trends, models were disproportionately influenced by several abundant taxa and did

0.00 0.00 0.00 0.00 0.00 0.00 0.00

0.000 0.00

not provide information0.00 about the many species-specific responses.

0.000 0.000 0.000 0.000 0.000 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0.000 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 0 1010 2020 3030 4040 00 1010 20 30 40 00 1010 2020 3030 4040 0 0 1010 20 20 30 30 40 40 0 0 10 1020 2030 3040 40 0 010 1020 2030 4030 40 0 10 20 30 40 0 10 20 30 40 Dysphania pumilio Eclipta platyglossa subsp. platyglossa Einadia nutans Enchylaena tomentosa var. tomentosa Eragrostis dielsii EragrostisPositive responses lacunaria EragrostisNegative responses parviflora Eragrostis spp. Dysphania pumilio Eclipta platyglossa subsp. platyglossa Einadia nutans Enchylaena tomentosa var. tomentosa Eragrostis dielsii Eragrostis lacunaria Eragrostis parviflora Eragrostis spp.

VittadiniaDissected dissectaNew Holland var. Daisy hirta WahlenbergiaRuby Saltbush fluminalis Wahlenbergia spp. Xanthium spinosum 0.8

0.06

0.20

0.8

0.06

0.04

0.20 0.008

0.04

0.06 0.004

0.020

0.4 0.03

0.0015 Favouring higher

0.10

0.02

0.06 0.004

0.015 0.020

0.4

0.02

0.03

0.0015 0.10 0.003

floodplain 0.004 0.02

0.0

0.00 0.00 0.00 0.00

0.000 0.000

0.0000

0.0

0.00 0.00 0.00 0.00

0.00

0.000 0.000

0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0.000 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0.0000 0 10 20 30 40 0 10 20 30 40 0 0 1010 2020 3030 4040 00 1010 20 30 40 00 1010 2020 3030 4040 0 0 1010 20 20 30 30 40 40 0 10 20 30 40 0 10 20 30 40 Acacia stenophylla Ajuga australis Alternanthera denticulata s.l. Alternanthera sp. 1 (Plains)------postAsphodelus watering abundance fistulosus Asteraceae spp. Atriplex semibaccata Atriplex stipitata Eucalyptus camaldulensis Eucalyptus largiflorens Eucalyptus spp. Euphorbia drummondii Glinus oppositifolius Glycyrrhiza acanthocarpa ____ pre watering abundance Abundance Plains Joyweed

Eucalyptus camaldulensis Eucalyptus largiflorens EucalyptusSouthern Liquorice spp. Euphorbia drummondii Glinus oppositifolius Glycyrrhiza acanthocarpa

0.04

0.012 0.06

0.20

0.8

0.6

0.4 0.04

Favouring0.06

0.8 0.6

0.10

0.4

0.006

0.04

0.010

0.015

0.06 0.004 0.02

0.4 lake edge

0.10 0.006

0.03 0.3

0.2

0.06

0.02

0.4

0.03 0.3

0.2

0.0 0.0 0.0

0.00 0.00

0.00

0.00 0.00 0.00

0.000 0.000 0.000 0.000 0.000

0.0 0.0 0.0

0.00 0.00 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 020 1030 20 40 30 40 0 100 2010 3020 4030 40 0.00 0 010 1020 2030 3040 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30Distance40 from water’s0 edge10 (m)20 30 40 0 10 20 30 40 0 10 20 30 40 Atriplex suberecta Austrobryonia micrantha Austrostipa spp. Boerhavia dominii Brassica tournefortii Brassicaceae spp. Callitriche sonderi Calostemma purpureum s.l.

0.30 0.4

0.03 0.003

0.008 Plants had a mix of responses to

0.010 0.03

0.015 0.15 environmental watering 0.2

0.0

0.00 0.00 0.00

0.000 0.000 0.000 0.000 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40

Calotis cuneifolia Centipeda cunninghamii Centipeda nidiformis Chenopodium curvispicatum Citrullus colocynthis Clematis microphylla s.l. Conyza bonariensis Cucumis myriocarpus subsp. leptodermis

0.04

0.030

0.20

0.04

0.010

0.004

0.015

0.02

0.010 0.015

0.10

0.02

0.00 0.00 0.00

0.000 0.000 0.000 0.000 0.000 OFFICIAL 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40

Cynodon dactylon Cynodon dactylon var. pulchellus Cyperus gymnocaulos Cyperus squarrosus Dodonaea viscosa subsp. angustissima Duma florulenta Dysphania cristata Dysphania glomulifera subsp. glomulifera

0.06

0.30

0.10

0.02

0.015

0.10 0.06

0.03

0.15 0.03

0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.000 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40

Dysphania pumilio Eclipta platyglossa subsp. platyglossa Einadia nutans Enchylaena tomentosa var. tomentosa Eragrostis dielsii Eragrostis lacunaria Eragrostis parviflora Eragrostis spp.

0.8

0.06

0.20

0.04

0.06 0.004

0.020

0.4

0.03

0.0015

0.10

0.02

0.0

0.00 0.00 0.00 0.00

0.000 0.000 0.0000 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40

Eucalyptus camaldulensis Eucalyptus largiflorens Eucalyptus spp. Euphorbia drummondii Glinus oppositifolius Glycyrrhiza acanthocarpa

0.04

0.06

0.8

0.6

0.4

0.06

0.02

0.4

0.03 0.3

0.2

0.0 0.0 0.0

0.00 0.00 0.00 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40 0 10 20 30 40

Plant responses to environmental watering at Hattah Lakes

How long does the effect of one enviromental watering event last? The positive response of many plants to environmental watering was short-lived: • 27 out of 67 responding plants increased in the six months after the environmental watering event; and

• 22 out of these 27 plants returned to near pre- watering levels by 18 months post watering event. It is likely that hot temperatures and the rapid loss of soil moisture in this semi-arid environment limits the duration of the response to environmental watering.

Negative plant responses to an environmental watering event can be considered a natural step to restoring water-dependent floodplain plants. For example, 20 plants declined in abundance by six months after the environmental watering event and remained low in abundance 18 months later. These dryland plants occur on the higher floodplain and are not flood tolerant. They are associated with the terrestrialisation of the floodplain vegetation in the Hattah Lakes system due to long ‘dry’ phases and the adverse response of dryland plants to prolonged inundation.

Acknowledgements Figure 3: Lake edge water-respondent plant community This project was funded by the Mallee Catchment Management immediately after environmental watering (top), 12 months Authority through The Living Murray initiative. The Living Murray is a (middle) and two years (bottom) post flooding. (Credit C. joint initiative funded by the New South Wales, Victorian, South Moxham) Australian, Australian Capital Territory and Commonwealth Further information governments, coordinated by the Murray-Darling Basin Authority. [email protected] ari.vic.gov.au

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