Clarks Floodplain Monitoring Report (2013-16) 1

Water for Nature Environmental Watering Site Monitoring Report

by Dr Anne Jensen

Clarks Floodplain, Lock 4 to Loxton Reach, South Australian Riverland July 2013 to June 2016

Nature Foundation SA is a not-for-profit nature charity that works to Save, Protect and Restore South Australia's natural biodiversity. Since 2008 one of our flagship programs, Water for Nature, has been delivering environmental water along the Murray River to help reduce the loss and stress to ecosystems and habitats caused by river regulation and drought. Over the last three years, our Water for Nature program has worked with 200 volunteers to deliver 4.56 gigalitres of environmental water to more than 35 wetland and floodplain sites along the Murray River. Healthy wetland and floodplain environments are important for environmental, economic, cultural and social reasons, providing an optimal environment for flora and fauna, improved water quality for human consumption and agricultural use, and opportunities for recreation and tourism. We work with private landholders, irrigators, community groups & local government on smaller sites to deliver environmental water, complementing larger government watering projects. Nature Foundation SA also works closely with the Commonwealth Environmental Water Holder to deliver environmental water.

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Water For Nature Environmental Watering Site Monitoring Report Site name Clarks Floodplain, Lock 4 to Loxton Reach, South Australian Riverland Reporting period July 2013 to June 2016

Date prepared July 2016

Location

Clarks Floodplain is on the east bank of the River Murray, downstream of Weir & Lock No 4 at Bookpurnong, approximately 11 km north of Loxton and 6.5 km south of Berri. It lies at 505-515 km river distance from the Murray Mouth, in a river reach typified by extensive meanders and sand bars. This 271 ha floodplain complex is opposite the Murray River National Park (Katarapko Island).

Contact Name NFSA Water For Nature Program Manager Natalie Stalenberg

Water Provider Commonwealth Environmental Water Holder allocation to NFSA

Partners Steve Clark & family Bookpurnong Lock 4 Environmental Association; SA Water; Loxton District Landcare

Aim of watering project

Watering at Clarks Floodplain aim to reverse the decline of black box woodlands, and to sustain extensive regeneration of river red gum, black box and lignum seedlings following the 2011 and 2012 floods. Watering aims to promote recovery of stressed mature trees, to sustain healthy bud crops and flowering on mature trees in order to promote production of high seed volumes for future regeneration.

Regional Planning Context

NFSA Loxton-Lock 4 connected floodplains e-watering projects, on opposite bank to Katfish Reach major e-watering project managed by SA Department of Environment, Water & Natural Resources Jensen A, Nichols S, Nicol J & Turner, R (2002). Clark’s Sandbar Management Strategy. For the Loxton to Bookpurnong Local Action Planning Association. Wetland Care Australia: Berri.

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Key objectives Environmental watering at this site has the following objectives: 1. encourage survival of black box seedlings which geminated in response the 2011

flood 2. promote flowering events in black box community to improve future seed production 3. sustain regeneration in major flood runners and floodplain creeks.

Site Description

Clarks Floodplain complex unusually incorporates four tight meander bends which creates a series of sandy peninsulas with good connectivity between groundwater tables and the river mainstream. At higher elevations, the clay floodplain is bisected by several flood-runners and incised channels which allow flood flows to spread across the site. Irrigation activities on adjacent highland have led to displacement of highly saline groundwater under the floodplain towards the river channel, resulting in serious decline in the health of black box and red gum woodland communities in its path. The intrusion of salt into the root zones of mature trees has been exacerbated by the lack of surface flooding, particularly in the period 1996-2010. Clarks Floodplain is now protected by a Salt Interception Scheme which lowers saline groundwater, which will reduce potential salinization effects on health and regeneration of floodplain species such as river red gum and black box.

Habitat Clarks Floodplain includes areas of tall red gum forest, unusual on the South Australian floodplain, as well as more common red gum and black box woodland. The community of red gum forest, black box woodland and lignum shrubland has suffered serious decline due to lack of flooding, drought and saline groundwater intrusion, and environmental watering can help to repair the ecosystems. Significant regeneration of red gum, black box and lignum occurred following the flood events of 2010-2012, with high survival rates of seedlings. 8 Watering sites have been identified, with 17 sub-sites covering 6 types of habitat, with 15 ecological targets. Most watering targets improving vegetation health in mature trees and sustaining extensive regeneration following the 2010-12 floods.

Watering History 2013-16

Watering at Clarks Floodplain has focussed on filling sections of flood runners and irrigating patches of elevated floodplain to deliver water to target areas. Gypsum was trialled to overcome sodic soil problems which created non-wetting, unstructured soils leading to bare, un-vegetated patches. • maintain minimum soil moisture to support growth of seedlings (river red gum,

black box, lignum) until tap roots reach subsurface water sources

• replenish freshwater lenses over saline groundwater • maintain healthy mature trees and shrubs to produce high volumes of seed.

Water Source NFSA allocation from Commonwealth environmental water 2013-2016: delivered by NFSA Water for Nature Regional Community Coordinator Craig Ferber, NFSA volunteers Peter & Tom Forward, landholder Steve Clark

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Event details 2013-14 In 2013 the Clarks Floodplain project utilised sprinkler irrigation and managed flooding to deliver water; sandbags and an AquaDam (inflatable water dam) were used to retain water in the target areas (the aquadam flood-runner was initially filled from mid-February 2013). A total of 35.8 ML was delivered to 7 sub-sites within Habitat Sites 6, 7 & 8 2014-15 In 2014 water was delivered by the West End Community Fund ‘Big Red’ Pump, Flexiflume, flood irrigation and sprinkler irrigation. 329 ML was delivered to 14 sub-sites within Habitat Sites 1, 2, 3, 4, 6, 7 & 8, including the aquadam flood-runner, northern flood-runner, Georges Creek, and main red gum flood-runner, chenopod shrubland and tall dense black box & red gum woodland 2015-16 105.5 ML was delivered to 10 sub-sites within Habitat Sites 4, 5, 6, 7 & 8, including red gum woodland and seedlings in incised creek Georges Creek, lignum wetlands in the shallow creeks Pegs Creek, Rubys Creek and tall dense black box & red gum woodland on the elevated floodplain

Maximum area inundated (ha) Estimated area 78 ha (see Figures 1 & 2) Duration of the environmental watering project (2013-16) Watering commenced in February 2013 at the aquadam site, and has continued over 42 months. Watering is spread over 8 habitat types, with 15 sub-sites being watered and 2 control sites kept dry.

Figure 1 Watered areas at Clarks Floodplain, main red gum flood-runner (Area I, coloured blue), open black box woodland and seedlings on elevated floodplain (Areas B &C, coloured orange), lignum wetland and fringing black box (minor flood-runner, coloured pink), narrow incised creek with fringing red gum and black box woodland on aquadam flood-runner (Area A, coloured blue), stressed tall closed black box woodland (Areas F & G, coloured green)

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Annual Observations against key objectives (including species of conservation significance (state or Commonwealth listed threatened species, or listed migratory species) observed at the site, any breeding of frogs, birds or other prominent species observed at the site and details of any observable responses in vegetation, such as improved vigour or significant new growth)

2013-14 (report by NFSA staff) • 95% of watered black box seedlings survived • germination and healthy growth of native ground cover • initial epicormic recovery on mature black box trees, now switching to healthy tip

growth • lignum growth and flowering • emergence of new black box seedlings in response to watering 2014-15 (observations by Anne Jensen) Vegetation condition continued to improve in mature red gum and black box trees, with epicormic growth converting to normal growth from branch tips. No further epicormic growth was recorded, even on very stressed trees. Healthy bud and fruit crops were recorded on healthier trees. Survival rates of seedlings were very high, >95%,at both watered and non-watered sites. The primary response to watering was in increased growth rates in eucalypts and lignum. Non-watered lignum remained dormant. 2015-16 (observations by Anne Jensen) Initial findings from monitoring since March 2015 indicate continued very high survival rates of seedlings at both watered and non-watered sites, with negligible deaths recorded to June 2016. The primary response to watering was in increased growth rates and crop volumes of buds, flowers and fruit in the eucalypts. The primary response in lignum was growth of vertical branches, with only limited production of leaves and flowers. Non-watered lignum remained mostly dormant. Flowering was observed in many trees, with data initially confirming summer as the key season for seed production in red gum and black box, with some variation from November to January in individual trees. However, contrary to the previously observed pattern, intense flowering occurred in many mature black box trees in June 2016. Further monitoring is required to assess whether this was a response to watering, and/or recovery from drought and a return to longer term natural cycles.

Future Watering Watering plan prepared for forward years, across 8 habitat sites and 15 watering sub-sites, taking into account environmental water needs, antecedent watering regime and current river and climatic conditions

Figure 2 Watered sites in floodplain creeks on Clarks Floodplain (coloured blue), showing lignum wetlands in shallow creeks (Rubys Creek (left) & Pegs Creek (centre) and fringing red gum woodland on incised creek Georges Creek (right).

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Figure 3 Site in main flood runner on Clarks Floodplain in February Figure 2 Site in main flood runner on Clarks Floodplain in September 2013,

Figure 3 Site in main flood runner on Clarks Floodplain in April 2014 Figure 4 Site in main flood runner on Clarks Floodplain in May 2014 red gum

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Figure 5 Site in main flood runner on Clarks Floodplain in May 2015, Figure 6 Site in main flood runner on Clarks Floodplain in June 2016 (staff is 3 m

Figure 5 Watering black box seedlings at Clarks Floodplain (Area 6), April 2014 compared with June 2016