Monitoring of Die-Back in River Red Gum (Eucalyptus Camaldulensis)

Die Back and Lack of Regeneration in River Red Gum (Eucalyptus camaldulensis) Communities in the Northern & Yorke Region 2008-2016 Willochra Creek Mambray Coast Broughton River Wakefield River Adelaide Base map: Rural Water Maps http://adl.brs.gov.au/water2010/mapserv/ Initial Survey 2008 • investigation into die-back in River Red Gum populations in August 2008, prompted by Booleroo Whim die-back • four target catchments Broughton, Mambray Coast, Wakefield and Willochra, 131 sites • found significant decline in condition of rural trees across region, particularly canopy die-back • river red gums in serious decline, showing visible signs of stress and death • concluded primary cause of river red gum die-back was reduced water availability, particularly reduced surface flows and reduced recharge of shallow groundwater • secondary impacts like corellas & mistletoe locally but not regionally significant • <10% of sites had healthy intact riparian vegetation • <5% of sites had intact understorey communities Monitoring Program for NY NRM region (2009 – 2016) • 66 monitoring sites from 131 initial assessment sites • 20 representative sites, 5 per catchment, 5 trees at each site • 4 catchment monitoring manuals developed Monitoring program: • photopoints at all sites • site observations at all sites • rapid health assessments at all sites • tree observations at representative sites • phenology scores at representative sites • additional sites for Four Catchments Program since 2013 Mar 2009, Jun 2010, Nov 2010, Sep 2011, Sep 2012, Oct 2013, Sep 2014, Sep 2015, Sep 2016 Red Gum Monitoring Results 2008-2016 • major stress and die-back continues across region • 7 years, >60 sites, 1200 km route but no mass seedlings regenerating at any site • seed being produced but not germinating or seedlings not surviving • continued critical recruitment failure, aging population not replacing itself • similar lack noted in South East of SA • mass recruitment on SA River Murray floodplain following 2010-2012 floods Red Gum Monitoring Results 2008-2016 • partial recovery since 2009 but severe insect attack in 2012 and 2013 • river flows in 2014, 2015, 2016 • BUT canopy condition of river red gums variable & declined across region compared to 2008 • level of stress still high • seed being produced but only few isolated seedlings • >60% sites at high-medium risk of decline • <10% sites high chance of recovery • NEED ACTION: could lose red gum communities in 30-50 years Seed Production & Germination depends on Water Banrock 2005 Banrock 2008 Banrock 2009 healthy, 9,000 seeds m-2 dry, stressed, 900 seeds m-2 watered, recovering, buds Mass germination & survival of red gum needs: water + healthy trees + bare soil + seeds + no weeds + no grazing for 2 years Competition from Weeds • winter and spring rains produce dense grassy weeds under red gums, competing for moisture and space with red gum seedlings • few/no seedlings found at these sites Competition from Reeds • local observations suggest earlier cease-to- flow dates for regional rivers, which means earlier annual growth of dense reed beds, that out-compete red gum seedlings germinating at the same time Dense reedbed at junction of Wakefield River and Pine Creek at Undalya Wakefield River near Rhynie, October 2015 Insect Attack and Grazing • stressed gums produce more nutrients in sap which attracts insect attack (lerp) • single trees exposed more to climate stress and insect attack • loss of shrubs means loss of birds which eat insects • changed flow regime favours insects • grazing by stock and rabbits removes or stunts seedlings Recovery Potential 2008 2014 2016 if stressors removed . River flows reduced, lack of flow data Flows in Broughton River at Lower Broughton Road, September 2014 Flows in Rocky River downstream of Laura, September 2016 Community Action to promote and protect Red Gum Regeneration Actions which could be taken include: • fencing and bare soil preparation for seed fall in riparian zones, weed control • direct seeding or broadcasting seed at appropriate sites • fencing off new natural regenerated seedlings and saplings from grazing • adopt a reach, record local river flows, levels, duration and timing, protect seedlings • community ‘save the red gums’ campaign • landholder champions Hutt River valley <3% native vegetation, no riparian cover, no migration corridors A Landscape Solution – 20:80 Vision • save river red gums within wider landscapes • ‘20:80 Vision for Sustainable Landscapes’ proposes restoring 20% of native vegetation to the general landscape • mix of 20% native vegetation corridors, buffer zones and habitat patches across landscape with 80% agricultural use • red gums would be key part of watercourse vegetation • critical to re-introduce bushes and groundcovers for sustainable habitat and full range of environmental services, especially control of insects 20:80 Vision for Sustainable Landscapes Work to target of 20% native vegetation in landscapes in 10 years: • use water reserves, road reserves, public reserves, rocky hilltops • one side of 5-chain roads (allow width for machinery to pass) • riparian zones along watercourses • fencelines & driveways • can be bushes only, or trees and bushes • develop ‘golden corridors’ of acacias and sennas • community, local government, landholders Acknowledgements These investigations are part of the Australian Government funded 2012-17 Four Catchments (Willochra, Broughton, Wakefield, and Light) project in the Northern and Yorke Natural Resources Region .

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