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Flora Monitoring on the Revegetation

Trial to Inform Rehabilitation Design for the Former Rum Jungle Mine Site

Prepared for: Department of Mines and Energy

Prepared by: EcOz Environmental Consultants

2 016

1. www.ecoz.com.au

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Client: Department of Mines and Energy ii Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016

Document Control Record

Document Code: EZ15131-C0301-EST-R-0001 Catalogue Number: 63397 Project Manager: Chris Brady Author(s): Chris Brady and Nicole Clark Approved by: Jeff Richardson

Approval date: 25 May 2016

DOCUMENT HISTORY

Version Issue Date Brief Description Reviewer/Approver 1.A - B 29 Mar 2016 Report preparation by authors Authors 1.C 30 Mar 2016 Internal review Jeff Richardson 1.D 31 Mar 2016 Draft sent to client Jeff Richardson 2.A 24 May 2016 Response to DME comments Jeff Richardson 3.A 25 May 2016 Final version sent to client Jeff Richardson

Recipients are responsible for eliminating all superseded documents in their possession. EcOz Pty Ltd. ABN: 81 143 989 039 Telephone: +61 8 8981 1100 Winlow House, 3rd Floor Facsimile: +61 8 8981 1102 75 Woods Street Email: [email protected] DARWIN NT 0800 Internet: www.ecoz.com.au GPO Box 381, Darwin NT 0800

Cover page: Photograph of an area of with vigorous and Eucalypt growth near sample plot RV11.

RELIANCE, USES and LIMITATIONS This report is copyright and is to be used only for its intended purpose by the intended recipient, and is not to be copied or used in any other way. The report may be relied upon for its intended purpose within the limits of the following disclaimer.

This study, report and analyses have been based on the information available to EcOz Environmental Consultants at the time of preparation. EcOz Environmental Consultants accepts responsibility for the report and its conclusions to the extent that the information was sufficient and accurate at the time of preparation. EcOz Environmental Consultants does not take responsibility for errors and omissions due to incorrect information or information not available to EcOz Environmental Consultants at the time of preparation of the study, report or analyses.

Client: Department of Mines and Energy iii Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016

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Client: Department of Mines and Energy iv Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016

Executive Summary

This report summarises the findings of monitoring of the Borrow Area 5 rehabilitation trial at the Rum Jungle former mine site. It is noted that reconstructed landscape proposed for Rum Jungle will have a variety of landscapes and that the findings here will not be applicable to all areas. The aim of the revegetation trial is to grow a woodland of local native species. The method trialled was weed control and direct seeding. Also, in an attempt to limit Gamba Grass invasion an area was seeded with Silk . This monitoring event occurred 14 months after the area was seeded. The rehabilitation is therefore at an early stage of growth somewhat limiting conclusions that can be drawn at this early stage. A diversity of tree and shrubs species seedlings are present and there was a dense ground cover, dominated by native grasses in most areas. The density of stems is within the range of a Top-End woodland. were the most common woody species with Acacia oncinocarpa the most common. Eucalypts were present, with miniata the most common. Although only recently seeded these results indicate that the area could be on a trajectory towards a woodland community dominated by local species. Two other possible trajectories are proposed: a vegetation community dominated by Gamba Grass or a vegetation community dominated by Acacia. Monitoring on an annual or every second year basis until short lived Acacias die out will provide valuable information on likely trajectory for later rehabilitation work. There was considerable variation in Gamba Grass cover between sites. Of the two Silk Sorghum sites one site had the second highest Gamba Grass cover, the other the second lowest. Thus conclusions on the effectiveness of the Silk Sorghum trial cannot be made except to note that other variables may be affecting results and further replication is required to test this. From these results Silk Sorghum did not eliminate Gamba Grass (although it may hinder its growth). Management of Gamba Grass will be an important component of rehabilitation efforts at Rum Jungle as without management of Gamba Grass and fire the area may be a Gamba Grass dominated grassland. Recommendations from this trial include: • Add more Eucalypt seeds to the seed mix for further seeding particularly Eucalyptus tetrodonta, and Ironwood. This should include Corymbia polysciada and Corymbia grandifolia as they have self-seeded and are growing in the surrounding area. • Carry out seed viability trials before any future seeding and use the results to adjust the seed mix. • Consider tailoring the seed mix to site specific conditions (e.g. adding additional seed to areas likely to be seasonally inundated).

• Investigate and if possible correct the low seed viability of many of the species in the seed mix. In the event it cannot be improved:

o Consider the use of top soil and/or inoculation with mycorrhizal fungi to increase the density and diversity of Eucalypts in rehabilitation areas. o Consider the use of tubestock to increase density and diversity. • Investigate and address the low number of some important mid storey species such as Buchanania obovata and Terminalia ferdinandiana and include some of the self-seeded mid storey species into the seed mix. • Continue Gamba Grass and Mission Grass control on a regular basis as these grassy weeds have the potential to promote hot fires that will kill desirable canopy species. • Investigate the mechanism of Gamba Grass spread at the site to facilitate management. • Investigate the range of options for managing Gamba Grass, this may include establishing a Gamba Grass buffer around the perimeter (e.g. a cleared or heavily grazed area). Monitoring of the revegetation should continue as it will provide valuable information to inform the rehabilitation methods. Important questions include the effects of competition between woody species and grasses, will Acacia dominance persist and will the lack of Eucalypt diversity effect the resilience of the

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community? To facilitate this monitoring all woody in the 11 vegetation plots have been tagged and information collected about their immediate surrounds. Adding plots in areas with vigorous growth and relatively bare areas may provide useful information for factors influencing wood plant growth. To determine specific completion criteria requires a stratification of the proposed reconstructed landform and consideration of factors that will limit revegetation in these areas. Using this information realistic goals should be set based on surrounding vegetation communities and knowledge from other mine sites. More targeted studies of surrounding communities and other rehabilitation areas may be required to inform revegetation of these specific communities. Goals should be set in conjunction with consultation with Traditional Owners. Completion criteria should remain, at this stage, broad and generic as specific completion criteria may set unrealistic expectations and erroneously be used to develop rehabilitation procedures (such as seed mix) and will limit what is considered successful rehabilitation. This conclusion is reinforced by the variability between sites: it may be that a single completion criteria may be incorrect and different edaphic (and other) profiles may be found to lead to other vegetation communities reflecting the diversity of environments and complex conditions likely at the site. A summary of the response to the project scope is given in the cross reference table below.

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Task from scope Key points Section Indicators of revegetation/ecosystem success A high level summary of the role of indicators is provided. 6.1 The rehabilitation strategy aims to be consistent with the views and interests of Traditional Owners. The setting of indicators of revegetation success must therefore reflect their aspirations and expectations. A stated objective of Traditional Owners is restoring flora and fauna species endemic to the site and its immediate surrounds (NTG 2013). This is very broad, further discussion may yield key culturally significant species. There will be a diversity of environments created during rehabilitation and the vegetation communities they can support will be variable. Indicators will be specific for each environment. Before any specific indicators are chosen the range of environments needs to be identified along with the limitations for re-vegetation considered (soil properties, slopes, water movement etc.).

The role of silk sorghum as a cover crop Silk Sorghum has not prevented the establishment of Gamba Grass, but may hinder its 5.4 growth. Woody plants species and densities in the Silk Sorghum trial area were within the range of other sites. Monitoring until Silk Sorghum dies out is required to determine if the Silk Sorghum cover crop influences growth rates and make-up of rehabilitation communities. Further replication may provide more conclusive results.

Proposed monitoring program including detailed The monitoring program that was undertaken for this report was submitted to DME (Mitchell Memo information on methodology, timing, team etc. Rider) of 1 February 2016. A suggested monitoring program for ongoing monitoring is provided in Appendix A. Appendix A

Compare species sown with what species are Given the presence of numerous woody plants the revegetation method and timing of works 4 present, considering germination testing results; can be considered appropriate to allow woody plants to establish. seeding rates; weed management; soil condition; Table 1 provides a list of all species in the seed mix, their germination rate, seedlings revegetation method; timing of works recorded during the trial and growth rates. It is noted that the seed of numerous species had low viability. The results show that Eucalypts are establishing including in areas with dense ground cover of a range of grass species. Gamba grass weed management has been sufficient to prevent a monoculture of Gamba Grass precluding the establishment of other species. However, Gamba Grass is present across the trial area and will require ongoing management.

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Propose the likely trajectory of development for this Based on this monitoring and from the literature, three trajectories are proposed: 5.2 revegetation on the basis of this early monitoring • Eucalypt dominated woodland • An Acacia dominated shrubland (in many rehabilitation areas Acacia form a dense thicket) • Gamba Grassland (in the absence of weed and fire management). Based on this monitoring there are numerous wood plants present and if they survive will form a shrubland and in time a woodland. The seedlings are predominately Acacias and it is possible they will form a dense canopy at the expense of other species. However there are sufficient Eucalypts present, such that if the majority of them survive they will form a Eucalypt woodland. Given the presence of Gamba Grass, in the absence of weed and fire management the rehabilitation could transition to a Gamba Grass dominated grassland. Propose a future monitoring program to inform a Annual monitoring of the plots surveyed here is recommended to: 5.6 longer term evaluation • investigate the growth and survival of individual species, • further assess the effectiveness of the Silk Sorghum trial and Appendix A. • determine the trajectory of the vegetation community • inform Gamba Grass control (if it takes off/over) Monitoring should continue until the trajectory can be confidently determined although monitoring may become less frequent than annual in future years (monitoring results will inform the timing). Monitoring should take place in the plots already established, using the same procedure described in the report - all woody plants have been tagged to facilitate this. Additional plots in vigorous and poorly performing areas of Borrow Area 5 should be established. Additional information should be collected in each plot such to document soil and landscape characteristics such as soil type and depth and water flow and infiltration. Additional work that should be undertaken to inform the rehabilitation program includes: i)stratifying the rehabilitated landforms, determining the environmental limitations and characteristics of them and consider what potential vegetation communities are possible; ii) developing a long term grassy weed management strategy for the site. Prepare draft completion criteria based on key We argue that, at this stage, setting completion criteria beyond broad and generis (such as 6.2 indicators stable land surface etc.) may deleteriously influence the rehabilitation program. For instance, it may lead to a seed mixture based on the completion criteria community instead of incorporating knowledge of succession. The results here show substantial differences between study plots. It is argued that there is

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considerable work to be done in identifying the types of environments that will be present in the reconstructed land form and the types of vegetation that can practically be established in each environment. This work needs to be combined with discussion with Traditional Owners to identify key indicators. Given the challenges of rehabilitating this site keeping completion criteria as broad as possible will provide the rehabilitation team a range of options to achieve success. Identify improvements in revegetation techniques at Some specific recommendations and issues to investigate have been identified. 5 Rum Jungle • Low seed viability should be investigated and if possible corrected • Seed viability should be tested before any seeding and the results used to modify the seed mix • Increase the proportion of Eucalypts in the seed mix • Stratify areas based on environment conditions and tailor rehabilitation method and seed mixes to specific conditions • Explore the opportunity to use fresh top soil in revegetation • Investigate the low numbers of mid storey plant species. • Investigate the area of successful rehabilitation from the 1980’s to inform further rehabilitation efforts

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Table of Contents

1 INTRODUCTION ...... 3 1.1 Scope ...... 3 1.2 Rum Jungle ...... 3 1.2.1 History ...... 3 1.2.2 Current management and rehabilitation ...... 3 1.3 Surrounding environment ...... 4 2 REVEGETATION TRIAL ...... 6 2.1 History ...... 6 2.2 Revegetation method ...... 6 2.2.1 Cover crop trial ...... 6 2.2.2 Germination trial ...... 7 3 MONITORING METHOD ...... 9 4 RESULTS ...... 11 5 DISCUSSION ...... 16 5.1 General ...... 16 5.2 Trajectory ...... 16 5.3 Other species ...... 19 5.4 Silk Sorghum trial...... 20 5.5 Gamba Grass ...... 20 5.6 Future monitoring at Borrow Area 5 ...... 20 5.7 Research question raised from the current monitoring...... 21 5.8 Further research on revegetation at Rum Jungle ...... 21 6 INDICATORS OF SUCCESS ...... 23 6.1 Indicators of revegetation success ...... 23 6.2 Possible indicators of Rehabilitation success and completion criteria at Rum Jungle ...... 24 7 REFERENCES ...... 26

Tables Table 1. Species seeded, germination laboratory trial results, application rate and numbers of seedling and plant height range ...... 12 Table 2. Key vegetation attributes of sample sites ...... 14 Table 3. Ground cover and dominant species recorded in 1 m2 quadrats around Eucalypt seedlings ...... 15 Table 4. Cover (%) of Gamba Grass at revegetation sites (in order of increasing cover, Silk Sorghum sites shaded blue)...... 15

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Figures Figure 1. Vegetation community map, Rum Jungle (Ecological 2014a) ...... 5 Figure 2. Aerial photograph of Rum Jungle (lease boundary black outline) showing Borrow Area 5 (blue outline); source Stokes (2015) ...... 7 Figure 3. Aerial photograph showing Silk Sorghum cover crop trial area (green hatched area); source Stokes (2015)...... 8 Figure 4. Graph of wet season monthly wet season rainfall at Batchelor Aerodrome ...... 8 Figure 5. Map showing location of sample plots based around DME photo monitoring points; source Stokes (2015)...... 10 Figure 6. Photograph showing growth of Silk Sorghum taken on 11/02/2016 ...... 13 Figure 7. Hypothetical succession model of rehabilitated areas following mining ...... 17 Figure 8. Ecosystem attributes to consider when assessing rehabilitation success (SER 2015) ...... 24

Appendices APPENDIX A – PROPOSED BORROW AREA 5 MONITORING PROGRAM APPENDIX B – SURVEY SITE DESCRIPTIONS

Client: Department of Mines and Energy ii Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016

1 INTRODUCTION

This report summarises the findings of a survey of a rehabilitation trial at the Rum Jungle mine site and makes recommendations for future rehabilitation trials and monitoring and the selection of indicators and setting of completion criteria.

1.1 SCOPE

Specifically, the purpose of this project is to: • Evaluate the germination and establishment success of native vegetation seeded in rehabilitation works undertaken during late 2014 • Provide ecological advice to inform future revegetation at Rum Jungle. This will include advice on indicator species for development of terrestrial ecosystem completion criteria.

1.2 RUM JUNGLE

1.2.1 History

Rum Jungle is located near Batchelor, Northern Territory, approximately 105 km by road south of Darwin. Rum Jungle was an operational mine between 1954 and 1971 producing 3,530 t of uranium oxide and 20,000 t of copper concentrate (Davy 1975). The placement of waste rock and process tailings resulted in acid and metalliferous drainage (AMD), releasing copper, other heavy metals and acid into the surrounding environment. A rehabilitation program was undertaken between 1982 and 1986 the results are which are summarised in the ‘Former Rum Jungle Mine Site, Conceptual Rehabilitation Plan’ (NTG 2013). Revegetation focused on the establishment of introduced grasses and legumes on waste rock dump (WRD), the copper extraction area and Dyson’s backfilled pit. The old tailings areas were seeded with introduced pastures and native trees and shrubs. At completion a technical assessment determined the engineering and environmental criteria set for the rehabilitation had been met. However, the condition of the site does not meet contemporary water quality standards and the works were completed without any input from the sites Traditional Owners. An assessment of vegetation at Rum Jungle undertaken in 2014 found the majority of revegetation areas have become dominated by grassy weeds, predominantly Gamba Grass and Mission Grass (Eco Logical 2014a). A relatively small successful area of revegetation was identified in the area between the Main and Intermediate WRDs; where an open woodland dominated by Ironwood, Erythrophleum chlorostachys and Kakadu Plum, Terminalia ferdinandiana had established. This area should be further investigated to determine possible reasons for success that can be incorporated in future rehabilitation efforts.

1.2.2 Current management and rehabilitation

Under a Partnership Agreement (formed in 2009) the Northern Territory (through the Northern Territory Department of Mines and Energy (DME) and Australian Governments have been working to improve site maintenance and environmental monitoring. A rehabilitation strategy that is consistent with the views and interests of the Traditional Owners was developed in 2013 (NTG 2013). The preferred strategy is to address AMD by returning waste material to the pits and consolidating remaining waste into a single landform, located as far as practically possible from water courses (Northern Territory Government 2013). Future revegetation at Rum Jungle will need to be resilient to threatening processes such as weeds, fire and feral animals.

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Rehabilitation objectives The Northern Territory Government (2013) describes the current rehabilitation objectives as to create a landscape that: • is safe for people and wildlife • is chemically, radiologically and physically stable • has a significantly reduced contaminant load (associated with AMD) travelling beyond the boundaries of the site • supports sustainable land uses by traditional Aboriginal owners of the area with few, if any, limitations • encourages beneficial alternative post-rehabilitation land uses. For Traditional Owners the Kungarakan and Warai, rehabilitation of the physical landscape will allow spiritual healing of the country (NTG 2013). The following outcomes are required for their vision and for the healing process to be achieved: • culturally appropriate preservation of Aboriginal cultural heritage • re-establishment of the original landform as far as achieving the best outcomes allows • removing or neutralising pollution sources • removing any risk of radiological hazard • remediating polluted groundwater • stopping surface water from being polluted • restoring flora and fauna species endemic to the site and its immediate surrounds • maximising employment and business opportunities throughout the rehabilitation process. Traditional Owners would like the site to return, where practical, to its pre-mining topography and allow sustainable traditional land uses.

1.3 SURROUNDING ENVIRONMENT

The native vegetation communities of the undisturbed areas of Rum Jungle are common in the Pine Creek Bioregion (DLRM 2014). The most common communities are Eucalypt open forests dominated by Eucalyptus miniata and Eucalyptus tetrodonta and the Eucalypt woodlands dominated by a range of species including, Corymbia grandifolia, Corymbia latifolia, Corymbia confertiflora and Eucalyptus tectifica. Vegetation communities at Rum Jungle were recently surveyed and mapped by Eco Logical (2014b). They mapped a diverse range of communities including monsoon vine forests, Melaleuca open forests, Eucalypt and Acacia woodlands and grasslands (Figure 1). The most common community was open woodland dominated by Eucalyptus miniata and Eucalyptus tetrodonta. Open woodland dominated by Eucalyptus tetrodonta and Erythrophleum chlorostachys (Ironwood) is also common. Similar vegetation communities were reported from the neighbouring Browns Oxide lease (Metcalf (2002), with Eucalyptus miniata and Eucalyptus tetrodonta dominated woodland the most common. Introduced Gamba Grass (Andropogon gayanus) grassland is also very common at Rum Jungle (Figure 1); as it is around Batchelor and across the Coomalie Shire (NRETAS 2008). Gamba Grass is of particular concern as it can transform woodland to grassland (Brooks et al. 2010, Setterfield et al. 2013). Gamba Grass has the ability to colonise a wide range of habitats, from wetland margins and riparian corridors to open woodlands (Flores et al. 2005). Gamba Grass therefore poses a significant risk to attempts to re- instate Eucalypt dominated open woodland at Rum Jungle.

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Figure 1. Vegetation community map, Rum Jungle (Ecological 2014a)

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2 REVEGETATION TRIAL

DME have established a revegetation trial at Borrow Area 5; an area of 15 ha (Figure 2). The trial aims to replace the dominant Gamba Grass with native vegetation dominated by local trees and shrubs. The trial integrated weed control with direct seeding and included a cover crop trial.

2.1 HISTORY

The history of the rehabilitation trial area and description of methods is provided by Stokes (2015) and a brief summary of the report is provided here. Borrow Area 5 is known to contain buried sludge from the old water treatment plant, preventing deep ripping. The area was initially revegetated between 1984 and 1985, with batter reshaping, floor ripping, topsoiling, limited drainage works and seeding with a mixture of grasses and legumes (Ryan 1985 in Stokes 2015). Late seeding (in March 1985) left the area vulnerable to weed invasion and erosion and gave insufficient time for plants to establish before the onset of the dry season. In time Borrow Area 5 became dominated by Gamba Grass. A soil assessment was undertaken (see Eco Logical Australia 2014b) to compare soil nutrients and structure of the borrow area with the surrounding native woodland. The soil monitoring results indicated that the soils of both areas were similar, albeit with a low nutrient status. They found no reason that native plants could not establish.

2.2 REVEGETATION METHOD

The current revegetation trial began with weed eradication work, carried out over three years (2012 - 2014). The surface soil was scarified prior to seeding. Rip lines were approximately 10 – 20 cm in depth, avoiding native vegetation. Seeding commenced as soon as possible after scarification. Local native seed was collected during 2013 and 2014 by Top End Seeds (see Table 1 for species); hard coated Acacia seeds were pre-treated by scratching the seed. The seed was mixed with coarse damp sand and spread by hand at a rate of approximately 3kg/ha (9 - 11 December 2014). Approximately 200 Pandanus nuts (containing roughly 10 seeds per nut) were hand planted during March. Outback Helicopters applied 400kg/ha of superphosate fertiliser via aerial application (27 December 2014).

2.2.1 Cover crop trial

Cover crops are used on many mines for short-term erosion control, maintaining mycorrhizal populations in stockpiled soils, to build-up soil organic matter and to prevent the establishment of weeds. Cover crops are often introduced pasture species. Desirable features of cover crops include: • capacity for rapid germination and growth • ability to bind the soil surface • reasonably short lived and sterile (so fade out as desired species establish). A small scale cover crop trial of approximately 1.5 ha (Figure 3) was conducted at Borrow Area 5. The aim was to assess if a cover crop (Silk Sorghum, Sorghum x almum Parodi) is beneficial to the establishment of native vegetation, particularly if it can out-compete Gamba Grass, allowing native species time to develop. Silk Sorghum has been used as a cover crop in mine rehabilitation in northern Australia including at Gove and Hey Point (western Cape York). In the Northern Territory, Silk Sorghum has been grown successfully in the Douglas - Daly, Katherine and Tennant Creek regions (Cameron 2014). As a pioneer or weed control species, sown thickly, Silk Sorghum will overgrow most weeds and, by using available soil nitrogen, will also reduce the likelihood of a major competition from weeds in the following season (Cameron 2014). Early

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fears in Queensland of perennial sorghum becoming a weed in cropping areas, similar to Johnson grass (Sorghum halepense) have not been realised. Perennial sorghum pastures decline and eventually die when soil N is depleted. In the NT this may take only one to two years (Cameron 2014). Silk Sorghum was applied at 2kg/ha. The trial area is isolated (by road and native vegetation) from the rest of the revegetation area and, based on information from the weed contractor, gets heavily invaded by Gamba Grass; particularly at the north-west end (Bruce Delahunty, 27/1/2016). Silk Sorghum seed was spread by hand using the same method as for the native seed. There was good rainfall following the seeding of Borrow Area 5, however the two subsequent wet seasons have had below average rainfall with little rain late in the wet season (Figure 4).

2.2.2 Germination trial

A proportion of seeds were sent to Queensland Seed Technology Laboratory for a germination trial. Acacia seed had a consistently high germination rate, except Acacia hemignosta (Table 1). In general Eucalypts also had a high germination rate with the notable exception of Eucalyptus tetrodonta (36%) and Eucalyptus bigalerita (0%). Germination rates were variable among other species, with two species failing to germinate during the trial (Table 1). The seed of five species were not tested (the reason for this was not found during this investigation).

Figure 2. Aerial photograph of Rum Jungle (lease boundary black outline) showing Borrow Area 5 (blue outline); source Stokes (2015)

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Figure 3. Aerial photograph showing Silk Sorghum cover crop trial area (green hatched area); source Stokes (2015)

600

500

400

2013-2014

300 2014-2015 2015-2016 Rainfall mm Mean 200

100

0 Oct Nov Dec Jan Feb March April May

Figure 4. Graph of wet season monthly wet season rainfall at Batchelor Aerodrome

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3 MONITORING METHOD

Monitoring sites were established at 11 DME photo-monitoring points in the revegetation area, so that this study could build on existing information. The 11 sites are spread across the 15 ha (Figure 5). Two of the sites (RV7 and RV8) are within the Silk Sorghum cover crop trial area. At each site a circular plot with a radius of 10 m was centred on the picket that marks the photo monitoring point. In each plot all woody (tree and shrub) plants species were identified; in most cases to species but some small Eucalypt (hereafter includes the genus Eucalypt and Corymbia) and Acacia could only be identified to genus at this stage. The height of each plant was recorded and a photograph taken. Around each woody plant a 1 m quadrat was placed, with the woody plant in the centre. Within this quadrat all ground stratum species were identified and their percentage cover visually estimated. Each woody plant was tagged with a unique identifying number and species name. This provides an opportunity to determine survivorship and growth of these plants over time. To estimate the percentage cover of ground stratum species, and the relative cover of Gamba Grass, a 50 m long measuring tape was run from the picket (generally in a northerly direction, except in cases that this would place the transect outside the revegetation area, in which case the transect ran to the south). Every 1 m along the tape ground stratum species that intersected the tape were recorded. Data is expressed as a percentage of points (50) which the ground stratum species intersected. The monitoring was under taken on the 11 - 12 February 2016 by Tony Orr and Chris Brady both familiar with Top-End flora and the Rum Jungle area. Species that could not be identified in the field were vouchered and identified at the NT Herbarium. The identification of very young Acacia and Eucalypts is difficult as juvenile can be different to that on older plants and there are no flowers or fruits to aid in identification. A question mark was placed next to the species name on datasheets and tags in cases where there was some uncertainty with identification. Where plants could not be assigned to a species with any certainty only the genus was recorded. As each plant was individually tagged these plants can be identified to species at a later time.

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Figure 5. Map showing location of sample plots based around DME photo monitoring points; source Stokes (2015)

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4 RESULTS

The revegetation area was seeded with 34 tree and shrub species. Of these 24 species were recorded in the rehabilitation area, 21 in plots and an additional three incidentally (Table 1). Across the 11 plots 242 plants were recorded, equating to an average density of 701 plants/ha. There was considerable variation in the number of seedlings and species composition between sites (Table 2 and Appendix A). Acacias were the dominant group making up 63 % of tagged plants and recorded in all plots. Acacia oncinocarpa was the most frequently recorded plant with 41 individuals recorded across nine of the 11 plots. Acacia dimidiata and were also common (Table 1). The tallest individual Acacias were 160 cm tall (A. difficilis and Acacia latescens). There were 34 Acacias that could not be assigned to a species. Forty-five Eucalypts (including the Genera Eucalyptus and Corymbia) were recorded across the 11 plots (Table 1), equating to a density of 130 Eucalypts a hectare. Of the Eucalypts, Eucalyptus miniata was by far the most common with 26 individuals recorded across seven of the 11 plots. The tallest individual was 200 cm. There were few other Eucalypts with only the self-seeded Corymbia polysciada represented by more than one individual, although nine Eucalypts were not able to be assigned to a species. Of the species other than Eucalypts and Acacia nine of the 17 species seeded were recorded (Table 1). Calytrix exstipulata was the most common, with 12 individuals recorded across five plots. Although not in the seed mix Clerodendrum floribundum was next most common, with seedlings clustered around mature plants that were retained in the revegetation area. The tallest individual recorded was a Grevillea pteridifolia at 150 cm. Plants that were seeded but not observed were Corymbia foelscheana, Corymbia latifolia (although nine Eucalypts could not be identified to species), Callitris intratropica, Cycas armstrongii, Denhamia obscura, Grevillea decurrens, Livistona humilis, Melaleuca leucadendra, Owenia vernicosa and Pandanus spiralis. Six species, not part of the seed mix were also recorded (Acacia holosericea, Clerodendrum floribundum, Corymbia polysciada, Corymbia grandifolia, Ficus aculeata and Lophostemon lactifluus). Mature plants of all these self-seeded species were growing within or close to the revegetation area. Overall there was a high proportion of ground cover with only 9% of the 550 sample points with no vegetation. However, this varied considerably between sites with the least ground cover at RV2 with 38% bare ground (Table 2). Sites with 100% vegetation cover generally had lower numbers of seedlings, and the most seedlings and the most Eucalypt seedlings were found at the site with the lowest ground cover (Table 2). However, this relationship is not linear or clear cut with RV8 and RV9 having little bare ground and a relatively high number of seedlings (Table 2). Individual Eucalypt plants were recorded where there was up to 90% cover in the surrounding 1 m2 quadrat and with a variety of ground cover species (Table 3). Urochloa piligera was the most commonly recorded ground cover species along the transects, it was recorded at 28% of all intercept points and made up more than 50% of the ground cover at two sites (Table 2, and Appendix A). These sites have relatively high numbers of seedlings. Overall Chrysopogon fallax was next most common (18%) followed by Sorghum timorense (11%). The introduce plants Buffalo Clover, Alysicarpus vaginalis, (0.09%), Gamba Grass, Andropogon gayanus, (0.06%) and Stylo, Stylosanthes sp. (0.04%) were also relatively common (Appendix A). Gamba Grass was most common at RV2 where it was encountered at 16% of point intercepts (Table 4), but has not prevented the establishment of woody plant species at this site (Table 2). Silk Sorghum had germinated and was growing densely in the trial area (Figure 6). Silk Sorghum was recorded at 27% of intercept points at RV7 and 59% at RV8. Gamba Grass was present in the Silk Sorghum trial area. Density of Gamba Grass at RV8 was second highest of all sites (Table 4). Seedlings, including Eucalypts, were present at both Silk Sorghum trial sites and numbers were within the range of other sites (Table 2).

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Table 1. Species seeded, germination laboratory trial results, application rate and numbers of seedling and plant height range

Species Germination Application Seedlings Seedlings Height rate (%) rate (kg/ha) recorded per 100 g range Acacias Acacia difficilis 0.76 0.12 21 51 10 - 160 Acacia dimidiata 0.77 0.07 26 108 10 - 120 Acacia hemignosta 0.5 0.12 4 10 15 – 48 Acacia lamprocarpa 0.88 0.12 7 17 7 – 130 Acacia latescens 0.74 0.15 7 14 45 – 160 Acacia oncinocarpa 0.8 0.15 41 79 10 - 80 Acacia umbellata 0.64 0.03 12 116 7 – 20 Eucalypts Corymbia confertiflora 0.74 0.04 1 7 Corymbia foelscheana 0.9 0.05 0 0 Corymbia latifolia 0.76 0.05 0 0 Corymbia polycarpa 0.82 0.11 inc <1 Eucalyptus bigalerita 0 0.05 0 Eucalyptus miniata 0.74 0.4 26 19 7 – 200 Eucalyptus phoenicea 0.79 0.25 1 1 45 Eucalyptus tetrodonta 0.36 0.25 1 1 38 Other Alphitonia excelsa 0.32 0.02 0 0 0.82 0.02 4 58 5 – 23 Brachychiton diversifolius 0.79 0.02 1 14 20 Buchanania obovata 0.12 0.02 inc <1 Calytrix exstipulata 0.18 0.02 12 174 4 - 47 Callitris intratropica 0.04 0.03 0 0 Cochlospermum fraseri 0.72 0.1 4 12 7 - 30 Cycas armstrongii - 375 seeds 0 - Denhamia obscura - 0.0005 0 0 Erythrophleum chlorostachys 0.51 0.18 2 3 20 - 35 Grevillea decurrens - 0.0002 0 0 Grevillea pteridifolia 0.24 0.05 3 17 8 – 150 Grevillea mimosoides 0.86 0.01 0 0 Livistona humilis 0.36 0.18 0 0 Melaleuca leucadendra 0 0.05 0 0 Melaleuca viridiflora 0 0.05 1 6 31 Owenia vernicosa - 0.05 0 0 Pandanus spiralis - 133 seeds 0 0 Petalostigma pubescens 0.78 0.08 2 7 9 - 17 Terminalia ferdinandiana 0.29 0.2 0 0

Client: Department of Mines and Energy 12 Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016

Figure 6. Photograph showing growth of Silk Sorghum taken on 11/02/2016

Client: Department of Mines and Energy 13 Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016

Table 2. Key vegetation attributes of sample sites

Site RV1 RV2 RV3 RV4 RV5 RV6 RV7 RV8 RV9 RV10 RV11 Trees and shrubs Eucalypts 4 19 0 3 0 4 4 3 5 0 2 Acacia 8 28 5 16 4 7 12 17 25 8 21

Other 2 8 6 4 2 3 0 17 3 1 0

Total # 14 55 11 23 6 14 16 37 33 9 23 Seedlings Ground stratum Cover (%) 96 62 97 69 98 98 90 95 92 91 88 Sorghum Sorghum Sorghum Urochloa Alysicarpus Silk Urochloa Urochloa Urochloa Chrysopogon Chrysopogon timorense timorense timorense pubigera vaginalis Sorghum pubigera pubigera pubigera fallax (71%) fallax (79%) Dominant (27%) (32%) (55%) (30%) (40%) (59%) (21%) (58%) (64%) species Urochloa Andropogon Urochloa Suaeda Silk Alysicarpus Passiflora Alysicarpus Suaeda Stylosanthes Stylosanthes pubigera gayanus pubigera australis Sorghum vaginalis foetida vaginalis australis sp. (12%) viscosa (12%) (21%) (20%) (25%) (11%) (27%) (11%) (8%) (16%) (8%)

Client: Department of Mines and Energy 14 Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016

Table 3. Ground cover and dominant species recorded in 1 m2 quadrats around Eucalypt seedlings

Site/Tag Eucalypt species Ground cover Dominant species of ground Dominant species (%) around cover cover (%) the seedling RV1/11 Eucalyptus sp. 90 Sorghum timorense 90 RV8/5 Eucalyptus miniata 88 Silk Sorghum 60 RV1/10 Eucalyptus sp. 80 Sorghum timorense 80 RV1/12 Eucalyptus miniata 80 Sorghum timorense 80 RV1/13 Eucalyptus miniata 75 Sorghum timorense 75 RV11/18 Eucalyptus miniata 61 Suaeda australis 60 RV7/8 Corymbia polysciada 50 Alysicarpus vaginalis 45 RV2/33 Eucalyptus miniata 50 Urochloa pubigera 30 RV4/16 Eucalyptus miniata 44 Urochloa pubigera 40 RV9/9 Eucalyptus miniata 43 Urochloa pubigera 23 RV7/4 Eucalyptus sp. 42 Alysicarpus vaginalis 30 RV6/2 Eucalyptus miniata 40 Fimbristylis littoralis 40 RV9/13 Corymbia polysciada 40 Suaeda australis 20 RV2/40 Eucalyptus miniata 40 Sorghum plumosum 40 RV2/41 Eucalyptus miniata 40 Sorghum plumosum 40 RV9/15 Eucalyptus phoenicea 37 Urochloa pubigera 20 RV2/5 Eucalyptus miniata 33 Alysicarpus vaginalis 20 RV9/1 Eucalyptus miniata 32 Urochloa pubigera 30 RV6/9 Eucalyptus miniata 31 Chrysopogon fallax 25 RV2/36 Eucalyptus miniata 30 Sorghum timorense 20 RV7/16 Eucalyptus sp. 30 Silk Sorghum 20 RV4/12 Eucalyptus miniata 28 Cynodon dactylon 20 RV2/6 Eucalyptus miniata 25 Chrysopogon fallax 20 RV2/15 Eucalyptus miniata 17 Sorghum plumosum 10 RV2/34 Eucalyptus miniata 10 Sorghum plumosum 10 RV6/3 Eucalyptus tetrodonta 10 Suaeda australis 10 RV2/54 Eucalyptus miniata 5 Sorghum timorense 5 RV2/21 Eucalyptus miniata 5 Heteropogon contortus 5 RV2/55 Eucalyptus miniata 5 Sorghum timorense 5 RV4/9 Eucalyptus miniata 1 Suaeda australis 1 RV2/26 Eucalyptus sp. 1 Sorghum plumosum 1 RV2/27 Eucalyptus sp. 0 - 0

Table 4. Cover (%) of Gamba Grass at revegetation sites (in order of increasing cover, Silk Sorghum sites shaded blue).

Site RV6 RV11 RV7 RV5 RV9 RV10 RV3 RV1 RV4 RV8 RV2 Gamba 0 0 1.43 1.79 3.33 3.57 3.85 5.88 7.55 9.26 16 Grass

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5 DISCUSSION

5.1 GENERAL

Woody tree and shrubs species have germinated and continue to grow in the rehabilitation area 14 months since seeding including the key species Eucalyptus miniata. There is a ground stratum of predominately native species that is dense in many areas. This suggests the rehabilitation method used here (weed management, ground preparation and direct seeding) and timing (seed spread at the beginning of the wet season) are appropriate methods for rehabilitation in these conditions at Rum Jungle. If a high proportion of seedlings survive to maturity the resulting area will be woodland/open forest. The current stem density of 701 stems/ha fits within the range reported for Top-End woodlands; for example, in a study of potential analogue sites for revegetation at Ranger Uranium Mine, Brennan (1996) recorded plant density of stems (>1.5 m) between 450 and 1950 stems per ha of which on average 40% were Eucalypts, 28% Acacia and 33% other. The trial area has a far lower proportion of Eucalypts (6%) and higher proportion of Acacias (63%). Numbers of seedlings, species composition and the density and composition of ground cover varies considerably between sites. This is expected given difference in topography, water flow, likely differences in soil properties and chance differences in which seed lands in favourable microclimates/edaphic conditions. This highlights that although some general inferences can be drawn from this trial all rehabilitation is subject to variation some of which can be controlled for (such as soil infiltration) and some variables can’t (such as chance events of a seed germinating). Gamba Grass was present, albeit at low density, across the rehabilitation area. Given its potential to promote hot fires that kill canopy trees (e.g. see Ferdinands et al 2006) ongoing management of this weed will be required.

5.2 TRAJECTORY

The formation of ecosystems is a complex process. Over time as our understanding of succession, ecosystem formation and restoration has improved there has been a shift away from a model of gradual change along a continuum to an understanding that includes the recognition of thresholds. A small change in environmental conditions may result in large changes in the biotic community and that there are potential numerous stable states that a community can reach rather than a single climax community (e.g. Westoby et al. 1989). Under this model revegetation areas move through several seral stages over time (Figure 7). Establishment of plants lead to changes to the environment such as soil stability, regulation of soil temperature and light, changes in soil chemistry which in turn facilitate the growth of other species. As the community develops and provides habitats for fauna the presence of herbivores, pollinators and seed dispersers may facilitate further changes in the community. Revegetation may require active management and additional inputs to transition from one stage to another. When planning and assessing a revegetation program, and the associated monitoring, it is necessary to consider these transitions. Comparing completion criteria parameters from early revegetation areas against values in a reference community may not be an appropriate way to determine if the revegetation is on the right trajectory. Somme practitioners (e.g. Doley & Audet 2013) have suggested that given the extent of environmental disturbance associated with mining there are some cases when the restoration of historical ecosystem is not practicable and novel ecosystems need to be considered. This may be the case with some areas of the Rum Jungle site.

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source Grant 2006 Figure 7. Hypothetical succession model of rehabilitated areas following mining

Predicting the trajectory of a rehabilitation community is difficult as they are subjected to a variable environment with potential events such as droughts, floods, fires, cyclones, disease out breaks, weed and pests impacting of species survival. However, species that grow in similar conditions in the surrounding area could be expected to be resilient to the common disturbances that affect the area. The presence of important ecological processes such as nutrient cycling, fungal associations and the presence of pollinators and seed dispersers is also necessary for a community to be on a trajectory to develop into a self-sustaining and resilient ecosystem. At Gove mine-site Reddell et. al. (1993) identified three distinct phases in the rehabilitation: the initial 3 – 4 years when biomass was dominated by grasses; the subsequent 4 – 10 years in which Acacias dominated; and between 10 – 16 years, when the growth rates of Acacias slowed and they began to die and Eucalypts developed an emerging canopy. Borrow area 5 is currently dominated by grasses, there are numerous seedling beginning to emerge the majority of which are Acacias, thus, in comparison to Reddell et al. (1993) one could infer that the community has the current species assemblage to transition.

Competition with grasses Although no grasses, except the Silk Sorghum trial area, were part of the seed mix for the area grasses and other ground strata species were present across the entire area and they were very dense in some spots with Urochloa piligera, Chrysopogon fallax and Sorghum timorense forming dense stands. In some instances, perennial grass or legume monocultures have resisted successional change (Luken 1990). In an experiment aimed at quantifying the effect of grass competition on the establishment of native species at Weipa, Foster and Dahl (1990) detailed an inverse relationship whereby reducing native grass competition was found to dramatically increase native seedling survival. At Pine Creek (Fawcett 1995) found where couch grass had established from the topsoil seed bank, native seedling mortality was 100%. An assessment of the success of ERA’s revegetation of the Jabiru East area Lane (1996), found the dense cover of introduced grasses and legumes, which comprised the original seed mix, suppressed the establishment of the preferred native woody and herbaceous species.

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However, during this study at least some Eucalypts were growing in densely grassed areas and along with each of the common grass species, whilst one of the more open sites (RV10) had no Eucalypts. Individual tagged plants will allow the survival of these individuals to be compared with those growing with less competition to be compared over time. Given that numerous seedlings are present and appear healthy and assuming that climatic conditions stay favourable, it seems likely they will emerge from the ground strata in the next few years.

Acacia dominance A high proportion of Acacia seedlings are common for rehabilitation and other disturbed areas. Acacias can have a positive impact in early rehabilitation, through nitrogen fixing, protection soil from erosion, contributing litter to support nutrient cycling and breaking up the soil. There is some contention and a range of experience with the dominance of Acacia in early rehabilitation; as structural or competitive dominance in a community can prevent the ascendancy of later seral species (e.g. Connell & Slatyer 1977). On disturbed sites in the Kakadu National Park the dominance of early seral species such as Acacias has been observed to effectively stagnate successional development, with recruitment of eucalypts and other species to these systems being poor (Setterfield et al. 1993). At a Pine Creek Gold mine early rehabilitation resulted in an Acacia dominated community whilst later when seeding without Acacia seed (although they were present in the topsoil) resulted in the establishment of eucalypt dominated communities (Fawcett 1995). In contrast at Alcan Gove, Hinz (1992) found recruitment of Eucalypts and other genera was more successful after the establishment of pioneering Acacias. The seed mix used in this trial is weighted to Eucalypts (Eucalypts 8: Acacias 5: Others 7 – by weight), however this is a higher proportion of Acacia than used at some rehabilitation programs in the Top-End. A seed mix trial at Ranger resulted in Cramb et al (1997) recommending that Acacias be limited to less than 16% by weight (compared to 25% in this trial). At Gove a mixture of about 20 native species the Eucalypt to Acacia ratio equates to Eucalyptus 8: Acacia 3.2 (Hinz 1992).

Eucalypts Of the Eucalypts present in the trial area only Eucalyptus miniata is common (it was also the most common seed pre weight in the seed mix). Given the variability in topography and drainage in the trial area (and the site more generally) for long term stability it is desirable that other Eucalypts are present. Consideration should be given to increasing weight of other Eucalypts seed or improving the quality of seed. As Corymbia polysciada and Corymbia grandifolia have self-seeded they and are growing in the surrounding area they could be added to the seed mix. The very low density of the key species Eucalyptus tetrodonta is of particular concern. This species had a relatively low germination rate from the laboratory trial (36%) so was effectively seeded at 30% of the rate of Eucalyptus miniata. The low germination rate should be investigated and if possible addressed or compensated for by increasing the weight of Eucalyptus tetrodonta seed. Although E. tetrodonta was effectively seeded at lower rate than E. miniata it was recorded in plots far less often (just one E .tetrodonta seedling compared to 25 E. miniata). As E. tetrodonta is such an important component of Top-End woodlands methods to increase its presence in rehabilitation at Rum Jungle should be investigated. Hinz (1997) believes the growth of E. tetrodonta in rehabilitation is dependent on an effective association with mycorrhizal fungi (Nothocastoreum cretaceum) and Reddell and Milnes (1992) reported that mycorrhizal fungi (and nitrogen-fixing rhizobia) were ubiquitous components of the soil biota in undisturbed soils of Kakadu National Park. The importance of re-establishing indigenous symbiotic microorganisms in mined soils in the tropics is widely accepted (e.g. Malajczuk et al. 1994, Ragupathy et al. 1997). Inoculation or the strategic use of fresh topsoil may increase numbers of this species. Given a low volume of topsoil compared to the area to be rehabilitated across Rum Jungle careful consideration should be given to its best use. Bell (1993) suggests that on WRD soil showing no major physical or chemical limitations to growth – such as alkalinity, sodicity or acidity – a layer of topsoil as thin as 50 mm will help vegetation to establish.

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Introduction of tube-stock is an alternative option to attempt to increase numbers of other Eucalypts. However, rehabilitation experience at Nabarlek mine indicates that the performance of direct seeded revegetation is superior to that of tubestock planted areas (Hinz 1990). In addition to the lower cost and the ability to cover large areas in a short space of time, plants grown from seed were generally more healthy and robust. Similarly, at a Pine Creek mine direct seeded plants displayed superior growth rates compared with tubestock (Fawcett 1995). Both Fawcett (1995) and Queensland Mines Ltd (1990) reported a ‘stagnation’ of tubestock shoot growth after planting. At Gove bauxite mine, Hinz (1992) found direct seeded plants developed a stronger root system than tubestock and the plants adapted to local conditions more rapidly and subsequently proved more sustainable. In contrast, Reddell and Hopkins (1995) found that tubestock revegetation trials at Ranger mine had consistently outperformed direct seeded trials. This again highlights the site specific nature of rehabilitation. Ironwood, Erythrophleum chlorostachys, is an important component of the canopy in surrounding vegetation and has been identified as a key species in successful rehabilitation at the Rum Jungle site (Eco Logical 2014a). As such consideration should be given to increase the weight of its seed in future rehabilitation.

Summary - possible trajectory Based on the information gathered during this monitoring three scenarios appear most likely. A woodland dominated by Eucalypts, a shrubland dominated by Acacia or a grassland dominated by Gamba Grass. At the current time it appears there are sufficient woody plants to transition the community from a grassland to a community dominated by trees and shrubs. On-going monitoring is required to determine if the current high proportion of Acacia seedlings will result in the Acacias out competing of other species, or if Eucalypts are able to persist and eventually dominate the community. Given the density of Gamba Grass in the surrounding landscape and the impact of the hot fires it promotes (e.g. Ferdinands et al 2006) without active management of Gamba Grass and fire it is likely that the area would become a Gamba Grass dominated grassland.

5.3 OTHER SPECIES

Twelve tree or shrub species other than Eucalypt or Acacia were recorded in the trial area, nine of which seeded. Of the seeded species that were not recorded Cycad armstrongii and Pandanus spiralis were hand planted in relatively low numbers so may not have been recorded due to the location of sample sites. Some other species had very low weight of seed (Denhamia obscura, Grevillea decurrens), whilst others had very low germination rate (Buchanania obovata, Callitris intratropica, Terminalia ferdinandiana and Melaleuca spp.). The low germination rates (and possible absence) of the fruiting trees Buchanania obovata and Terminalia ferdinandiana should be addressed as these species are important for many fauna species and have traditional uses for Traditional Owners. Better seed quality and increasing quantity may be the simplest way to increase numbers of these species. Terminalia ferdinandiana was identified by Eco Logical (2014a) as a species which is a key component of a small area of successful rehabilitation at Rum Jungle. Clerodendrum floribundum, Ficus aculeata and Lophostemon lactifluus have self-seeded and should be considered for incorporation it in future seed mixes. Only one Melaleuca plant was recorded during the survey, although two survey sites (RV5 and RV6) appear to be suitable habitat as they are low lying and were waterlogged during an inspection of the area in January 2016. The low density of Melaleuca appears to be related to poor seed, as seed did not germinate in the laboratory trial. In future rehabilitation consideration should be given to tailoring the seed mix to site specific condition; i.e. adding Melaleuca seed to areas likely to be seasonally inundated. Several disturbed areas that have regrown with Melaleuca spp. are present at Rum Jungle (C. Brady personal observation).

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5.4 SILK SORGHUM TRIAL

The Silk Sorghum cover crop has grown densely, but has not excluded Gamba Grass. However, it is noted that the area chosen for the trial is particularly susceptible to Gamba Grass according to the weed contractor. The density of Gamba in the trial area was in the range of other sites, with one site at the lower end of Gamba Grass density at the other at the high end. Without greater replication and investigation of other factors it is not possible to determine if the Silk Sorghum is hindering the growth of Gamba Grass. The cover crop does not appear to be hindering the establishment of native trees and shrubs, with seedling numbers within the range of other sites and Eucalypts present in the two trial plots. Monitoring of these plots over the next couple of years will tell if the Silk Sorghum dies out and has influenced the growth and composition of the vegetation. The use of cover crops has had mixed success in the Top-End. At Gove mine-sites where Rhodes Grass was used as a cover crop it has been considered a success and shown to fade out of the system after approximately five years due to competition by recolonising native flora and reduced nutrient availability after cessation of fertiliser application (Hinz 1981). In contrast cover crops are no longer incorporated into seed mixes at Pine Creek after Fawcett (1995), found that they out-competed tree seedlings for moisture and resulted in an increased fire fuel load.

5.5 GAMBA GRASS

The control of Gamba Grass will be an ongoing challenge at Rum Jungle. The current control program is having considerable success as Gamba Grass is not dominating any area of Borrow Pit 5. Management of Gamba Grass will require follow up control annually, although the effort required may diminish with time, as mature seed bearing plants are eliminated. As Gamba Grass is prevalent in the area around Rum Jungle seed is likely to continue to enter the site from neighbouring properties. Control of water-flow onto the site may assist with management of where seed enters the site and germinates and so can be controlled. A buffer around the boundary may reduce re- infestation. This could take the form of an easy access area where chemical control is used on a regular basis or a fenced strip that is heavily grazed with stock where Gamba Grass can grow but is prevented from seeding. There are grazed paddocks in close vicinity to the Rum Jungle site where heavy grazing prevents seeding (C. Brady, personal observation); the Northern Territory Government recommends a stocking rate of at least 4 head/hectare in the wet season to keep Gamba Grass in check (Lemcke & Cameron 2006). However, such a strategy would involve providing alternate pasture or de-stocking in the dry season. Given the extent of Gamba Grass in the Comalie Shire, Gamba Grass may need to be considered to be an inevitable component of revegetation communities. A focus is required on control in early rehabilitation to allow woody species to establish. In the long term management of Gamba Grass at Rum Jungle should be consistent with management in the broader region.

5.6 FUTURE MONITORING AT BORROW AREA 5

All seedlings within the 11 plots have been tagged with a unique code, had their species, height and information recorded about their immediate surroundings. This will allow a long term study on their survival and growth rates. This will give information about the survival and growth of individual species that can be used to inform the seed mix. Additional plots in areas with vigorous growth and with limited or no growth may provide useful information on localised factors that contribute to or detract from rehabilitation success. Plots should be monitored (initially on annual basis) until it can be determined if there is a trend towards a Eucalypt dominated community or an alternate state such as Gamba Grass dominated grassland or Acacia dominated Shrubland (estimated 5 to 10 years). This information will be important to determine the ratio of Eucalypt to Acacia in the seed mix.

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The focus of this research following the fate of these plots and the marked trees within them over a longer period of time include:

• Competition with grasses: What is the long term impact of competition with ground cover plants? • Acacia dominance: Will the relatively high density of Acacia prevent or facilitate the establishment of a Eucalypt dominated community?

The two plots in the Silk Sorghum trial area should be followed annually until the Silk Sorghum dies out. Comparison of growth of Eucalypts, species composition and the density of Gamba Grass at this point will be important in assessing the value of the cover crop.

Over time additional information should be collected in each plot to allow a better understanding of the impact of the localised environment. This would include soil depth and compactness, water holding capacity and water flows.

5.7 RESEARCH QUESTION RAISED FROM THE CURRENT MONITORING

There is low seed viability for numerous species including some key Eucalypts and . This needs to be investigated and in lei of being able to correct it other strategies for increasing the number of Eucalypts should be considered. This could include the use of top soil and/or inoculation with mycorrhizal fungi and the use of tubestock. The low number of some important mid storey species such as Buchanania obovata and Terminalia ferdinandiana should be further investigated. This could include investigating the low germination rate and trialling of spreading additional seed in the rehabilitation areas. The effect of fine scale variation in environmental conditions and its impact on establishment of vegetation should be further considered. This could involve investigating variation and its cause in Borrow area 5 and trialling specific seed mixes for specific areas, such as low lying poorly drained sites. The management of Gamba Grass will be an essential component of revegetation at Rum Jungle. The mechanism of Gamba Grass spread at the site should be investigated to facilitate management. Potential options for long term management should assessed. This should include considering grazing as a management tool.

5.8 FURTHER RESEARCH ON REVEGETATION AT RUM JUNGLE

An area of what is considered successful rehabilitation from the 1980’s was identified by during a vegetation survey of the site Ecological (2014a). Investigations should be conducted in this area to identify as much historic information as possible and record the species present and environmental conditions. The rehabilitation plan proposed for Rum Jungle involves creation of a highly modified and varied environment. This presents a significant challenge for re-vegetating the site. To inform further research the site needs to be stratified based upon the conceptual model and consideration given to soil and rock type. The aim would be to identify the range of physical environments that need to be rehabilitated. This will include a consideration of factors including substrate and landscape position (e.g. soil types and depth, sub soil material, water flow and drainage, aspect, and elevation). This information can then be used to determine what vegetation communities could potentially be established given a specific set of conditions. This may involve considering what vegetation is found growing in similar conditions in the surrounding landscape or in the case of highly modified environments what has

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been successful at similar mine sites. In consultation with Traditional Owners a particular vegetation community could be set as a goal for each set of conditions. At this point individual rehabilitation strategies, success indicators and completion criteria can be considered and knowledge gaps identified. Given the challenges that legacy issues pose at this site rehabilitation proponents are best served by broad completion criteria that allow a range of possible communities to be considered successful.

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6 INDICATORS OF SUCCESS

6.1 INDICATORS OF REVEGETATION SUCCESS

Rehabilitation programs require measures of success to compare different rehabilitation methodologies and to determine if rehabilitation goals are being met. A restoration project will have greater transparency, manageability and improved chances of success if the restoration targets and goals are clearly defined and translated to measurable objectives (Society for Ecological Restoration 2015). In the case of Rum Jungle the rehabilitation strategy is to be consistent with the views and interests of Traditional Owners it is important that these views are discussed and documented. To determine success criteria and indicators involves several stages (Bellairs 1998): • identify what is required to be achieved for the rehabilitation to be considered successful • determine what structural, compositional, and functional processes are required to achieve the set criteria • determine how to assess whether those processes are occurring or going to be achieved. Suitable completion criteria depend upon the aim of the revegetation program. In the case of Rum Jungle many of the aims of rehabilitation are focused on creating a safe and stable environment and reducing offsite impacts. Traditional Owners desire the site is returned, where practical, to its pre-mining topography and allow sustainable traditional land uses and supports flora and fauna species endemic to the site and its immediate surrounds. The vegetation endemic to the site and immediate surrounds is dominated by Eucalypts and Ironwood. These surrounding communities could be used as a reference for the target of the restoration project. The Society for Ecological Restoration (2015) propose that important ecosystem attributes to consider include an absence of threats, physical conditions, species composition, community structure, ecosystem function and external exchanges (Figure 8).

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Figure 8. Ecosystem attributes to consider when assessing rehabilitation success (SER 2015)

Ecosystem indicators need to be easy to measure, scientifically credible, and rigorously defined (Kearns & Barnett 1998).

6.2 POSSIBLE INDICATORS OF REHABILITATION SUCCESS AND COMPLETION CRITERIA AT RUM JUNGLE

The rehabilitation at Rum Jungle will involve the creation of a range of a range of environments (e.g. realigned river channel, waste rock dump, borrow pits, roads, remains of former waste rock area). Given the history of disturbance and the nature of the substrate many of these environments will pose significant challenges for rehabilitation. Setting of specific indicators requires defining these environments and consideration of their limitations. Given the challenges that legacy issues pose at this site rehabilitation proponents are best served by broad completion criteria that allow a range of possible communities to be considered successful. Some broad indicators that would be applicable to Rum Jungle are:

Client: Department of Mines and Energy 24 Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016

Absence of threats • Gamba Grass and other weeds do not threaten the stability of communities • Feral animals are not transforming communities.

Physical conditions • No erosion • Water can infiltrate soil.

Species composition • Canopy is dominated by local long lived trees • Mid strata is dominated by local shrub species • Ground strata is dominated by local species • Local fauna species are present • Culturally significant species are present.

Community structure • Trees at a density within the range of surrounding woodland/open forest

• Shrubs are at a density within the range of surrounding woodland/open forest.

Ecosystem function • Communities resilient to fire

• Macrorhizal fungi and nitrogen-fixing rhizobia present

• Nutrient is cycling • Seed dispersers present

• Plants are producing viable seed

Ecosystem exchanges • Native species other than those in the seed mix establishing

• Fauna species are colonising rehabilitation areas.

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7 REFERENCES

Bellairs, SM 1998, Determining ecological indicators for native vegetation and wildlife habitat rehabilitation success at the Blair Athol and Tarong mines, in Asher, CJ & Bell, LC (Ed.) Indicators of ecosystem rehabilitation success, Workshop proceedings, Australian Centre for Mining Environmental Research, Kenmore, Qld. Bell LC 1993, Biological aspects of the rehabilitation of waste rock dumps, In Riley, SJ, Waggitt, PW & McQuade, C (Ed.) Proceedings of the symposium on the management and rehabilitation of waste rock dumps, 7–8 October 1993, Darwin, Supervising Scientist for the Alligator Rivers Region, Canberra. Brennan, K 1996, Flowering and fruiting phenology of native plants in the Alligator Rivers Region with particular reference to the Ranger uranium mine lease area, Supervising Scientist Report 107, Supervising Scientist for the Alligator Rivers Region, Canberra. Brooks, KJ, Setterfield, SA & Douglas, MM 2010, Exotic grass invasions: applying a conceptual framework to the dynamics of degradation and restoration in Australia's tropical savannas, Restoration Ecology 18, 188– 197. Cameron, CJ 2014, Perennial Sorghum Agnote NO: E67, Northern Territory Government, Darwin. Connell, JH & Slatyer, RO 1977, Mechanisms of succession in natural communities and their role in community stability and organization, American Naturalist 111, 1119–1144. Cramb, G, Nisbet, H, Reddell, P & Hopkins, M 1997, Large scale planting on the low-grade stockpiles and waste rock dumps at Ranger, Draft report to ERA Ranger Mine by ERA Environmental Services, Darwin. Davy, DR 1975, Rum Jungle Environmental Studies, Report to the Australian Atomic Energy Commission. Department of Land Resource Management (DLRM) 2014, Pine Creek – bioregional description, http://lrm.nt.gov.au/plants-and-animals/herbarium/nature/bioregional/pinecreek, Accessed 19 Aug 2014. Department of Natural Resources, Environment, the Arts and Sport (NRETAS) 2008, Gamba Grass in the NT: a summary of current knowledge, http://www.lrm.nt.gov.au/__data/assets/pdf_file/0008/18926/gamba_summaryknowledge.pdf, (accessed 19 Aug 2014). Doley, D, &Audet, P, 2013, Adapting novel ecosystems as suitable rehabilitation alternatives for former mine sites, Ecological Processes, 2013, 2:22. Eco Logical Australia 2014a, Flora and Fauna Surveys of the former Rum Jungle Mine Site and proposed cover material extraction areas, Prepared for the NT Department of Mines and Energy. Eco Logical Australia 2014b. Soil investigations of borrow area 5, Rum Jungle mine site, Prepared for the NT Department of Mines and Energy.

Fawcett, MNR 1995, Evolution of revegetation techniques at Pine Creek Gold Mine, In Managing environmental impacts – policy and practice, 20th Annual Environmental Workshop 1995: Proceedings, Darwin NT, 2–6 October 1995, Minerals Council of Australia, Canberra, Australia. Ferdinands, K, Setterfield, S, Douglas, M, & Barratt, J, 2006, Africanising the tropical woodlands: canopy loss and tree death following gamba grass Andropogon gayanus invasion, in Preston, C, Watts, JH & Crossman, ND (eds), Proceedings of the 15th Australian Weeds Conference, Adelaide, South Australia. Flores, TA, Setterfield, SA & Douglas, MM 2005, Seedling recruitment of the exotic grass, Andropogon gayanus, () in northern Australia, Australian Journal of Botany, 53, 243–249.

Client: Department of Mines and Energy 26 Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016

Foster, B & Dahl, N 1990, Advances in direct seeding in tropical Australia, in Sowing the seeds, direct seeding and natural regeneration conference, Adelaide, May 1990, Greening Australia. Hinz, DA 1981, Returning land to Eucalyptus forest after bauxite mining at Gove, NT, in Proceedings of the North Australian Mine Rehabilitation Workshop, Gove NT, 1–4 June 1979, Nabalco, Nhulunbuy. Hinz, DA 1992, Bauxite mining and Walyamirri: The return of the living environment. Paper two. The rehabilitation programme, In Seventeenth Annual Environmental Workshop 1992, Papers, Yeppoon Qld, 5–9 October 1992, Australian Mining Industry Council, Canberra. Hinz, DA 1997, The return of the Gadayka tree after bauxite mining. Minerals Council of Australia. Hinz, R 1990, Direct seeding in the Top End. In Sowing the seeds: Direct seeding and natural regeneration conference. Adelaide, May 1990, Greening Australia. Kearns, A & Barnett, G 1998, Use of ecosystem function analysis in the mining industry, In Asher, C & Bell, L (Ed.), Indicators of Rehabilitation Success; Workshop Proceedings, ACMER, Kenmore. Lane, A 1996, Experimental reconstruction of woodland ecosystems under irrigation on the waste rock dumps at Ranger, Report on monitoring of trials, Report to ERA Ranger Mine by ERA Environmental Services Pty Ltd, Darwin. Lemcke, BG, & Cameron, AG, 2006, Agnote – Management of Kent Gamba Grass, Northern territory Government, Darwin. Luken, JO 1990, Directing ecological succession, Chapman & Hall, London. Malajczuk, N, Reddell, P & Brundrett, M 1994, Role of ectomycorrhizal fungi in minesite reclamation, in Pfleger, FL & Linderman, RG (Ed.), Mycorrhizae and plant health, American Phytopathology Society Symposium Series, St Paul, Minnesota. Metcalf, K 2002, Flora assessment study for environmental impact statement – Browns polymetallic project, Batchelor, NT, Report prepared for Compass Resources NL and NSP Environmental Consultants Pty Ltd. Northern Territory Government (NTG) 2013, Former Rum Jungle Mine Site, Conceptual Rehabilitation Plan, Department of Mines and Energy, Darwin. Queensland Mines Limited 1990, Surface preparation and revegetation techniques project, QML internal report. Ragupathy, S, Ashwath, N & Mahadevan, A 1997, Acacias and mine rehabilitation: The need for inoculating Acacias with mycorrhizal fungi, In Recent developments in Acacia planting, Proceedings of the international workshop held in Hanoi, Vietnam, October 1997, ACIAR Proceedings No 82. Reddell, P & Milnes, AR 1992, Mycorrhizas and other specialised nutrient-aquition strategies: Their occurrence in woodland plants from Kakadu and their role in rehabilitation of waste rock dumps at a local uranium mine, Australian Journal of Botany 40, 223–42. Reddell, P, Spain, AV, Milnes, AR, Hopkins, M, Hignett, CT, Joyce S & Playfair LA 1993. Indicators of ecosystem recovery in rehabilitated areas of the open strip bauxite mine, Gove, NT, Final report for Nabalco Pty Ltd, CSIRO Minesite Rehabilitation research Program, Adelaide. Ryan, P 1985, Review of Revegetation Operations and Monitoring – Rum Jungle Rehabilitation Project October 1984 – August 1985, Rum Jungle Project CCNT, Darwin. Setterfield, S, Cook, G & Williams, D 1993, Rehabilitation of borrow pits in Kakadu National Park, CSIRO Division of Wildlife and Ecology, second progress report to ANPWS, Darwin. Setterfield, SA, Rossiter-Rachor, NA., Douglas, MM, Wainger, L, Petty, AM, Barrow, P, Shepherd, IJ & Ferdinands KB 2013, Adding fuel to the fire: the impacts of non-native Grass invasion on fire management at a regional scale, PLoS ONE 8: e59144. doi:10.1371/journal.pone.0059144

Client: Department of Mines and Energy 27 Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016

Society for Ecological Restoration (SER) 2015, National Standards for the practice of ecological restoration in Australia (Draft), Society for Ecological Restoration, Australia. Stokes, C, 2015, Weed eradication and revegetation trial – what was done, Department of Mines and Energy, Darwin. Westoby, M, Walker, B, & Noy-Meir, I 1989, Range management on the basis of a model which does not seek to establish equilibrium, Journal Arid Environments 17, 235-239.

Client: Department of Mines and Energy 28 Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016

Appendix A – Proposed Borrow Area 5 monitoring program

Purpose: On going monitoring of Borrow Area will provide valuable information on the growth and survival of individual species, the trajectory of the community and the value of Silk Sorghum as a cover crop. Timing: Annual monitoring of plots is recommended until the trajectory of the rehabilitation can be determined or analysis of the data provides evidence that bi- or tri- annual monitoring will provide sufficient information. Monitoring should be conducted in the early wet season so plants are actively growing, but before grass growth makes finding plants difficult. Methods: Survey sites Monitoring should use the same plots established at 11 DME photo-monitoring points in the revegetation area, so that this study could build on existing information. All seedlings within the 11 plots have been tagged with a unique code to facilitate ongoing monitoring and information should be collected on the growth and survival of each individual. Additional plots should be placed in areas with vigorous growth and with limited or no growth to provide information on localised factors that contribute to or detract from rehabilitation success. Survey methods At each site a circular plot with a radius of 10 m should be centred on the picket that marks the photo monitoring point. In each plot all tagged woody (tree and shrub) plants species should have the tag number recorded, height measured and DBH measured (once there has been sufficient growth). Around each woody plant a 1 m quadrat should be placed, with the woody plant in the centre and all ground stratum species identified and their percentage cover visually estimated. To estimate the percentage cover of ground stratum species, and the relative cover of Gamba Grass, a 50 m long measuring tape should be run from the picket (generally in a northerly direction, except in cases that this would place the transect outside the revegetation area, in which case run the transect to the south). Every 1 m along the tape ground stratum species that intersected the tape were recorded. Data is expressed as a percentage of points (50) which the ground stratum species intersected. Information on soil and landscape characteristic should be collected to provide context for variation in the vegetation. This should include: soil type, soil depth, rock cover, water infiltration, water flow (flow on flow off, pooling).

Analysis of results Results should focus on the survivorship of individual species, the impact of interspecies interaction (e.g. impact of competition with ground cover species, do Acacia out compete or facilitate the growth of Eucalypts), the trajectory and the impact of Silk Sorghum.

Client: Department of Mines and Energy 29 Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016

Appendix B – Survey site descriptions

Site RV1 Zone 52; 719193 E 8563831 N

Height Tree and shrub Number range species (cm) All species 14 14 Acacia difficilis 3 50-160 Acacia oncinocarpa 3 40-80 Eucalyptus miniata 2 140- 200 Eucalyptus sp. 2 35-45 Acacia lamprocarpa 1 0-30 Acacia latescens 1 0-160 Photograph taken January 2015 Erythrophleum 1 0-35 chlorostachys Grevillea pteridifolia 1 0-150 Acacias 8 30-160 Eucalyptus 4 35-200 Other 2 0-150 Ground cover species Cover (%)

Total vegetation 96 Sorghum timorense 27 Photograph taken June 2015

Urochloa pubigera 21

Chrysopogon fallax 15

Paspalum plicatulum 13 Cyperus iria 8 Andropogon gayanus 6 Sorghum timorense 2

Ludwig sp 2

Bare ground 4 Photograph taken March 2016

Client: Department of Mines and Energy 30 Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016

Site RV2 Zone 52 719172 E; 8563897 N

Number Height Tree and shrub range species (cm) Eucalyptus miniata 14 7-90 Acacia oncinocarpa 10 10-75 Acacia sp 7 6-100 Calytrix exstipulata 4 4-42 Acacia lamprocarpa 4 7-45 Eucalyptus sp 4 15-18

Acacia dimidiata 3 36-50 Acacia umbellata 3 7-13 Photograph taken January 2015 Cochlospermum 2 7-21 fraseri Acacia difficilis 1 0-20 Brachychiton 1 0-5 megaphyllus Corymbia polysciada 1 0-50 Grevillea pteridifolia 1 0-8 Acacias 28 4-100 Eucalyptus 19 7-90 Other 8 7-21 Photograph taken June 2015 Ground cover Cover (%) species Total Vegetation 62

Sorghum timorense 32

Andropogon gayanus 20 Chrysopogon fallax 4 Paspalum plicatulum 4 Ipomoea quamoclit 2 Bare ground 38

Photograph taken March 2016

Client: Department of Mines and Energy 31 Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016

Site RV3 Zone 52 719206 E; 8563986 N

Number Height Tree and shrub range species (cm) Clerodendrum 4 12-50 floribundum Acacia umbellata 2 35-38 Brachychiton 2 12-23 megaphyllus Acacia dimidiata 1 0-1 Acacia oncinocarpa 1 0-80 Photograph taken January 2015 Acacia sp 1 0-30 Acacias 5 1-80 Eucalyptus 0 0 Other 6 12-50 Ground cover (% cover) species Total Vegetation 97 Sorghum timorense 55 Urochloa pubigera 25 Paspalum plicatulum 3 Photograph taken June 2015

Heteropogon 3 contortus

Andropogon 3 gayanus

Alysicarpus vaginalis 2 Crotalaria novae- 2 hollandiae Flemingia 2 trifoliastrum Ludwig sp 2 Photograph taken March 2016

Client: Department of Mines and Energy 32 Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016

Site RV4 Zone 52; 719054 E; 8564086 N

Number Height Tree and shrub range species (cm) Acacia 4 12-40 oncinocarpa Eucalyptus miniata 3 60-80 Calytrix exstipulata 3 5-47 Acacia sp 3 9-12 Acacia difficilis 3 30-40 Acacia 2 20-130 lamprocarpa Photograph taken January 2015 Acacia dimidiata 2 0-110 Acacia umbellata 1 0-18 Acacia hemignosta 1 0-45 Cochlospermum 1 0-7 fraseri Acacias 16 7-130 Eucalyptus 3 60-80 Other 4 5-47 Ground cover (% cover) species

Total Vegetation 69 Photograph taken June 2015 Urochloa pubigera 30 Suaeda australis 11 Andropogon 9 gayanus Crotalaria novae- 7 hollandiae Melinis repens 3 Euphorbia hirta 3 Eucalyptus Sp. 2 Seedling Acacia sp seedling 2 Photograph taken March 2016 Phyllanthus sp 2

Client: Department of Mines and Energy 33 Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016

Site RV5 Zone 52; 719163 E;8564141 N

Number Height Tree and shrub range species (cm) Acacia sp 2 0-17 Acacia difficilis 1 0-40 Acacia hemignosta 1 0-48 Melaleuca viridiflora 1 0-31 Petalostigma 1 0-9 pubescens

Acacias 4 17- 48 Photograph taken January 2015 Eucalyptus 0 0 Other 2 9-31 Ground cover Cover (%) species Total Vegetation 98 Chrysopogon fallax 71 Stylosanthes sp 12 Ipomoea quamoclit 9 Paspalum plicatulum 5 Photograph taken June 2015 Andropogon gayanus 1

Photograph taken March 2016

Client: Department of Mines and Energy 34 Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016

Site RV6 Zone 52; 719131 E;8564196 N

Number Height Tree and shrub range species (cm) Acacia dimidiata 3 12-45 Acacia oncinocarpa 2 20-50 Acacia sp 2 9-30 Eucalyptus miniata 2 32-50 Photograph taken January 2015 Melaleuca sp 2 9-18 Calytrix exstipulata 1 0-6 Corymbia grandiflora 1 0-45 Eucalyptus tetrodonta 1 0-38 Acacias 7 9-50 Eucalyptus 4 32-50

Other 3 6-18 Photograph taken June 2015 Ground cover Cover (%) species Total Vegetation 98 Chrysopogon fallax 79

Stylosanthes viscosa 11

Paspalum plicatulum 5 Sorghum timorense 3 Photograph taken March 2016

Client: Department of Mines and Energy 35 Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016

Site RV7 Zone 52; 719022 E; 8564065 N

Tree and shrub Number Height species range (cm) Acacia sp 9 18-85 Acacia difficilis 2 38-40 Corymbia polysciada 2 30-100 Eucalyptus sp 2 17-25

Acacia umbellata 1 0-40 Acacias 12 18-85 Photograph taken January 2015 Eucalyptus 4 17-100 Other 0 0 Ground cover Cover (%) species Total Vegetation 98 Alysicarpus vaginalis 40 Sorghum timorense 27 Urochloa pubigera 15 Stylosanthes viscosa 5 Photograph taken June 2015 Andropogon gayanus 1 Bare ground 10

Photograph taken March 2016

Client: Department of Mines and Energy 36 Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016

Site V8 Zone 52; 718968 E 8564087 N

Tree and shrub Number Height species (number of range individuals) (cm) Clerodendrum 8 13-150 floribundum Acacia difficilis 7 10-50 Acacia oncinocarpa 5 10-40 Acacia dimidiata 3 25-50 Calytrix exstipulata 2 12-13 Eucalyptus miniata 2 0-45 Ficus aculeata 2 20-25 Acacia sp 1 0-55 Acacia umbellata 1 0-20 Photograph taken January 2015 Brachychiton 1 0-20 diversifolius Brachychiton 4 0-10 megaphyllus Buchanania obovata 4 0-270 Erythrophleum 1 0-20 chlorostachys Eucalyptus sp 1 0 Grevillea pteridifolia 1 0-40 Acacias 17 10-55 Eucalyptus 3 0-45 Other 17 13-150 Photograph taken April 2015 Ground cover Cover (%) species Total Vegetation 96 Sorghum timorense 59 Alysicarpus vaginalis 11 Andropogon 9 gayanus Suaeda australis 5 Urochloa pubigera 5 Paspalum plicatulum 1 Crotalaria novae- 1 hollandiae

Bare ground 5 Photograph taken March 2016

Client: Department of Mines and Energy 37 Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016

SiteRV9 Zone 52; 718784 E 8564188 N

Tree and shrub Number Height species range (cm) Acacia oncinocarpa 7 30-60 Acacia dimidiata 6 10-45 Acacia sp 6 10-30 Acacia dunnii 2 20-120 Acacia latescens 2 45-50 Calytrix exstipulata 2 12-35 Corymbia polysciada 2 30-35 Eucalyptus miniata 2 45-50 Acacia difficilis 1 0-140 Acacia hemignosta 1 0-20

Eucalyptus phoenicea 1 0-45 Photograph taken January 2015 Petalostigma 1 0-17 pubescens Acacias 25 10-60 Eucalyptus 5 30-50 Other 3 12-35 Ground cover Cover (%) species Total Vegetation 85 Urochloa pubigera 60 Passiflora foetida 8 Andropogon gayanus 3 Fimbristylis schultzii 3 Heteropogon 1 contortus Photograph taken June 2015 Chrysopogon fallax 1 Cyperus iria 1 Bare ground 8

Photograph taken March 2016

Client: Department of Mines and Energy 38 Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016

Site RV10 Zone 52; 718632 E 8564178 N

Tree and shrub Number Height species range (cm) Acacia umbellata 3 25-50 Acacia oncinocarpa 3 20-55 Acacia dimidiata 2 15-35 Acacia latescens 1 0-85 Ficus aculeata 1 0-90 Acacias 8 15-85 Eucalyptus 0 0

Other 1 0-90 Photograph taken January 2015 Ground cover Cover (%) species Total Vegetation Urochloa pubigera 58 Alysicarpus vaginalis 16 Andropogon 5 gayanus Stylosanthes viscosa 5 Melinis repens 3 Eucalyptus sp 1 seedling Photograph taken June 2015 Bare ground 9

Photograph taken March 2016

Client: Department of Mines and Energy 39 Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016

Site RV11 Zone 52; 718642 E 8564123 N

Tree and shrub Number Height species range (cm) Acacia oncinocarpa 6 15-75 Acacia dimidiata 4 18-60 Acacia difficilis 3 12-30 Acacia latescens 3 45-65 Acacia sp 3 5-15 Acacia hemignosta 1 0-15 Acacia umbellata 1 0-30 Corymbia polysciada 1 0-25 Eucalyptus miniata 1 0-70 Acacias 21 5-75 Photograph taken April 2015 Eucalyptus 2 25-75 Other 0 0 Dominant ground Cover (%) cover species Total Vegetation 86 Urochloa pubigera 64 Suaeda australis 8 Sida acuta 8 Alysicarpus vaginalis 2 Crotalaria novae- 2 hollandiae Corchorus aestuans 2

Bare ground 12 Photograph taken June 2015

Photograph taken March 2016

Client: Department of Mines and Energy 40 Doc Title: Rum Jungle Rehabilitation Trial – Monitoring 2016