PART 3 - Technical overview
Part 3 provides an update on recent field observations and research learning in invasive biology and management. Information on how control activities can align with other landscape management targets and approaches in a whole of system approach.
INVASIVE BIOLOGY
History of introduction 37 Flowering and seed production 37 Germination and dormancy 38 Growth and establishment 40 Dispersal 41 CONTROL OVERVIEW Control overview 42 Herbicide 43 Mechanical 46 Grazing 47 Fire 48 REAHBILITATION Revegetation and regeneration strategies 49
Beneficial native species 50
Aligning with other management programs 52 Mapping , monitoring and data collection 54
Technical overview History of introduction Flowering and seed production
Introduced into Australia in 1970 Hymenachne commences and approved for release by DPIF in flowering when day length drops below 1988, hymenachne was promoted and 12 hrs (Weeds CRC, 2003). Initial distributed widely as a ponded pasture results from the CSIRO Defeating the species, particularly in the dry tropics. Weeds Menace project suggest peak Concerns about its invasive nature in flowering occurs for 1-2 weeks during the wet tropics, were realised in the April-May across all populations. 1990’s when the species began to (Wearne et al. 2008). Another flowering naturalise in natural and agricultural event appears to occur in the lead up to waterways. the wet season from late November to January. Reports from land managers Hymenachne was Declared a indicate that in some instances, Weed of National Significance (WoNS) flowering will occur year round (pers. in 1999 and a Class 2 Pest under the comm. Matt Buckman). Land Protection Pest and Stock Route Management Act 2002 in the State of Seed production occurs in the Queensland several years later. months from May to June peaking in July. Up to 4,000 seeds per stem are Several key publications deal produced at densities of up to 200 with the identification, habitat stems per square metre. Seeds are requirements and invasive biology of small at around 1-2 mm in size. hymenachne in Australia (see Csurhes, Research by Biosecurity Queensland 1999, Charleston 2006 and Kinnear et (DPI&F) is currently underway to al. 2008). This strategy document does establish general seed characteristics, not cover this information in any detail the initial results are discussed in the beyond that required for planning a following pages. The large number of strategic management approach seed produced develops the seedbank across the region. Attention has been that is characteristic of this species. given to highlighting gaps in biological Because the seedbank is and technical knowledge of the species accumulative, established infestations that have been addressed since the can be expected to have more time of those publications. extensive reserves of dormant seed than new introductions. An extensive report on the social and environmental impacts of hymenachne management within the Fitzroy Basin are available in Kinnear et al. 2008. Many of the examples and outcomes from the study are applicable and relevant to the strategy area. (WetlandCare Australia 2008) provides an extensive overview and list of resources for planning and implementing wetland rehabilitation.
Flowering peaks during April-May but also occurs pre wet season in November-December Invasive biology 39 Technical overview
Germination and dormancy
Learning what we can about • Enforced dormancy could occur for seed characteristics can go some way both H. amplexicaulis and H. in determining how to manage an acutigluma because of the invasive species. Knowing the optimum seasonally inundated habitats in conditions for germination and which they grow. Having a layer of establishment can guide managers to water on top of the soil may cause select control options that best suit the anaerobic conditions and/or prevent situation at hand with the resources high or fluctuating temperatures available. Knowing the longevity and necessary for germination to occur. the dormancy behaviour of a seedbank assists to determine the timescales and This information is important parameters which programs of when considering the timing of management need to operate within. herbicide application and follow up. As ‘activities that create more favourable In a study investigating the conditions for germination may help germination of H. amplexicaulis and H. deplete seed banks faster’ (Campbell acutigluma (Campbell et al. in press) et al. in press). After initial treatments suggest that fresh seeds of both that target the immediate visible species exhibit similar germination vegetative infestation, management requirements. The characteristics they needs to shift its focus to alternating identified are summarised below: between treating or suppressing the dormant seedbank dependant on • Optimum conditions for germination management approach adopted. occurred under a combination of alternating temperature, the presence of light (either constant or alternating) and the addition of (nitrogen) KNO3.
• Across all seed lots the earliest that germination commenced following exposure to moisture was four and a half days, with peak germination generally occurring over the following 36 hours.
These results suggest the following:
• conditions that buffer seeds from light and/or temperature fluctuations could reduce germination and possibly extend the life of seed banks of both H. amplexicaulis and H. acutigluma.
Factors that ‘enforce’ dormancy of seed are removed or manipulated following chemical control
Invasive biology 40 Technical overview
Germination and dormancy
CASE STUDY coincided with a natural control event Recent works funded by the strategy provided by flooding. applied herbicide as close as possible The chart below (Setter to the onset of the wet season. Works unpublished data) identifies the were conducted in mid to late longevity of hymenachne seeds in a November through to late December. controlled environment. From a starting Conditions for access were at their average of 95.4 % the average viability optimum, with seasonally dry areas recorded for hymenachne seeds was accessible for herbicide application on approximately 12% at 8 years. A 50 % foot or via ARGO. Recent rains in the decrease in average viability was storm season had reinvigorated plants, reached somewhere between 1 and 2 allowing effective herbicide application years and the next major drop in but flower development had only just viability occurred between 4 and 6 begun. Dormant seeds from under years when close to the minimum areas treated by non selective viability was recorded. The chart herbicide had the opportunity to supports field observations (pers. germinate in the disturbed conditions comm. Matt Buckman, Damon Sydes, just prior to being inundated by rising Ken English) that after three to four flood waters in mid January. (non selective) herbicide treatments over the period of 1-2 years, the vigour of the seedbank has declined significantly. Ensuring resources to Hymenachne is considered to manage the initial seed response after go from seed to maturation in control is critical particularly in the first approximately 7-8 months (pers. year of treatment. The challenge after comm. Lynise Wearne) It has been this point is to suppress re- observed that freshly germinated establishment of mature plants in the seedlings cannot elongate enough to treatment area by focused control of rise above flood levels as effectively as germinating seedlings. mature plants can. The timing of the control works in the case study
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months Average viability of hymenachne seed over time, (Setter , unpublished data) Invasive biology 41 Technical overview
Growth and establishment
A frontal pattern of A management program needs establishment has been observed in to be informed by seedbank response developing hymenachne infestations. while reacting to the prevailing climatic More vigorous growth and flowering conditions. The targeting of control has been observed at progressing (or establishment and maintenance of fronts and declining in vigour towards beneficial competition) in areas most the centre of an established clump susceptible to high germination rates (pers. comm. Lynise Wearne, Mike may be a useful tactic for management. Nicholas). This suggests that a In a similar way, infestations in deeper management approach targeting the water may take longer to establish, and approaching front might be effective at the effect from control may last longer reducing seed production, particularly if because invasion may be more it can limit the germination and vegetative than seed. maturation of the exposed seedbank in follow up. Hymenachne germinates in Current studies from CSIRO are shallow areas and ephemeral margins looking closely at how micro- as the shallowing of water provides topography within wetlands influences some of the triggers for germination i.e. species composition. The results of this fluctuating levels of light, moisture and work will be useful to guide not just nutrient. Plants need to be rooted in control efforts but also rehabilitation substrate and can tolerate water up to works following. 2 m deep with a preference for 0.1 to 0.6 m. (pers. obs.)
Following control, germination occurs as waters recede and the disturbed seedbank is exposed to the germination triggers of fluctuating light, moisture and nutrient.
Invasive biology 42 Technical overview Dispersal
Hymenachne is able to CASE STUDY reproduce from seed and vegetative In low lying sugar cane farms fragments. Seed dispersal via water of the Herbert River catchment, seed may be the main method of dispersal has been dispersed in flood water (Csurhes et al. 1999). It is suspected and further spread by machinery in that water birds, feral pigs and other the course of routine cultivation and fauna that utilise wetlands are also land management. The bare fertilised responsible for spread. Seed spread soil provides ideal conditions for the from point of origin is generally germination of hymenachne and suspected to be localised (pers. comm. control options are limited by the non- Lynise Wearne) but can be added to by selectivity of herbicides available for other activities in the immediate area. use in crop situations. Fallowing of ground usually occurs in 3-5 year A large portion of medium rotations in sugar production. The distance spread is attributed to water success of fallow strategies to birds, notably magpie geese Anseranas manage hymenachne have been semipalmata (Charleston 2006) and limited because of the longevity, and other species that utilise wetlands. This subsequent reburial and disturbance and other ‘Black Duck’ (pers. comm. of seed. The pressures of generating John Rolfe) theories of spread require profit from production areas mean more research, firstly to establish the cropping is unable to cease for the basis of the assumption and secondly extended periods of time required to to determine the overall contribution of exhaust the seedbank. Seed is also these processes to spread and the risk able to germinate in amongst drills it might pose to introduction into non and along headlands, generally infested areas. anywhere disturbance exposes the seed bank. Plants are able to persist Longer distance dispersal events and reproduce even in the limited have evidently taken place as part of light available under mature sugar deliberate promotion and introduction of and can lead to extensive hymenachne as a pasture species. This contamination of the crop at harvest accounts for the widespread success of time. the hymenachne as an invasive as introductions have historically occurred at any elevation within a catchment. Other spread is linked to general industry and commerce and is associated with the movement of contaminated machinery. These two dispersal mechanisms are difficult to predict outside of targeted survey in particular land use types and ’high risk’ activities.
Dispersal via water is the major source of spread of hymenachne seeds Invasive biology 43 Technical overview Control overview
A plan for management complexities of applying herbicides in requires an integrated and systematic aquatic situations have limited the approach that combines a variety of options available to land managers. short term actions supported by long The use of off label and minor use term objectives. Changes and permits for control of hymenachne has transitions in the focus of management been limited to smaller groups and over time should be anticipated at the regions within single catchments or planning stage. Whilst actions like local government areas. This is largely control initially reduce the visible due to the complexities of negotiating density of a population they also need registrations and permits for herbicide to limit all (or most) reproductive events application in aquatic situations. and manage the dormant seedbank. To do this control needs to be supported An ongoing dependence on non by consecutive actions beyond the act selective herbicide has limited the of herbicide application with plans for extent of integration of selective vegetation restoration, water quality herbicide into programs that would improvement and improved land allow for a transition in management management. Incorporating these approach from control to competition elements into an overall landscape or tactics as densities reduce. The sub catchment management plan will development of regional and state wide assist with longer term issues of registrations of herbicides for the degradation and disturbance that management of hymenachne and other provide opportunities for hymenachne WoNS within waterways has been and other weeds to invade and persist. underway for approximately 10 years and is ongoing. It is imperative the Investment in control is regions continue to support this potentially a wasted resource if it is not process and assist to deliver the complimented with actions that aid the monitoring outcomes that are required recovery from the disturbance for registrations to progress. management actions can cause. To achieve this a threshold needs to be reached where an ongoing management presence can prevent the densities of the infested areas reverting to pre-treatment levels. In this way management actions that are complemented by ongoing monitoring and surveillance may deliver successful location specific eradication events.
Chemical control strategies Herbicide control programs are generally characterised by short term impacts with immediate benefits and broad treatment areas. Herbicide is currently the most cost effective, short term control option available and as such is a fundamental component of a management program. The Control 44 Technical overview Herbicide
Considerations should be made the Polygoniaceae, Cyperaceae and as to the compatibility of a herbicide Juncaceae families are able to gain a regime with the identified management competitive edge within the treatment outcomes and the values intrinsic in the area . In theory the compound effect of treatment area. more competition and more ‘beneficial propagules’ from desirable species in the The primary herbicide available system can benefit the management for hymenachne control are 360g/L effort by gradually restoring system glyphosate based formulations such as health and assisting to suppress the Roundup® Biactive™ and Weedmaster dormant seedbank. Conceptually, a more Duo® which are registered for use in resilient system over time assists aquatic situations and can be applied to management effort by reducing hymenachne under APVMA permit germination and dispersal events, plant PER7485. Within the study area the vigour and density concurrently. This preferred formulation is Weedmaster concept needs to be further evaluated Duo® which anecdotally has a higher within the framework of an adaptive degree of control efficacy (pers. comm. management model. Matt Buckman, Damon Sydes). There are also other suitable generic aquatic formulations of glyphosate on the market. The recommended rate for application of glyphosate is 1000ml/100L of water for hand spraying and 10L per ha for boom spraying. This formulation is also effective for the control of water hyacinth and salvinia.
Several off label and minor use permits exist for the control of hymenachne in the state of Queensland with aerially applied glyphosate and Selective herbicide can be used to target ground based application of verdict 520 hymenachne and retain natives like Sedges all with stipulated monitoring (Carex spp.) and Water Pepper (Persicaria spp.) requirements. Chemical availability also has implications for suitable effective Selective verses non-selective herbicides to recommend to landholders.
The national WONS strategy for It could be argued that the hymenachne acknowledges in 2001 that targeted use of selective herbicide is a “controlling hymenachne, via the issuing currently missing but crucial component of ‘control notices’ will be difficult without of a sustainable management regime a highly effective registered herbicide”. with a long term plan for recovery of The active constituent, haloxyfop, system health. Selective herbicide allows present in Verdict® 520 is the most for a competition strategy from the effective herbicide available for control available beneficial or an introduced (trials PVH 200?). The chemical is not (revegetated) seedbank. Formulations of yet registered for control of hymenachne, haloxyfop like Verdict 520® selectively but is applied in some areas under minor target grasses, (Family Poaceae). use and off label permits from APVMA. Unaffected species notably those from
Control 45 Technical overview Herbicide application timelines
Planning timelines for treatment Based on field observations and follow up is crucial in determining within the region the recommended a resource budget for on-ground works. retreatment rates are 3-5 monthly Management effort should be focused depending on the stage of on incorporating survey and ongoing management. An additional treatment surveillance of an infestation after the two weeks from the initial application to initial control works have taken place. ensure spray efficacy and follow up Timing of consecutive treatments spraying of any missed plants should needs to consider: be planned for. Due to the nature of operator access and the clumping habit maturation rate of dense infestations, spray application • germination to maturity rate of seed may only effectively target 50 - 80 % of established plants the total plant area on the initial application. An additional spray will be control efficacy required in some cases to apply • reshoot or coppice effect of sections herbicide to the untreated area. of the treated population The timing of a control method treatment surface area can be crucial. In the planning stages • growth stage of the plants in the several different scenarios should be treatment cycle considered to account for the unpredictability of factors such as environmental factors extreme or unseasonal weather events. • water levels and inundation cycles Treatment timelines need to be guided by a control calendar, but also be ready to respond to local variations in behaviour.
A considerable surface area may need to be treated initially. Ideally follow up needs to occur before stature returns to the pre-treatment height. Control 46 Technical overview Managing herbicide resistance Managing herbicide impacts
At the time of writing there was no evidence to suggest that herbicide Impacts on water quality, resistance is an emerging issue with environmental, agricultural and off- the management of hymenachne in the target damage from herbicide require short term, but it should be a careful consideration when planning control consideration for long term works. The draw down of available management. This situation is oxygen (described as DO, dissolved highlighted by the limited available oxygen,) can have impacts on aquatic herbicide control options for ecosystems beyond the toxicity levels hymenachne in the first instance. The of the chemical compounds. Dissolved potential for resistance can be oxygen levels can significantly reduce managed in several ways. as available oxygen in taken up during the decay of organic matter from Managing herbicide regimes as controlled hymenachne. part of an overall integrated pest management approach is important in There are several impacts of herbicide limiting the potential of developing application in wetland areas. herbicide resistance within a species. 1. potential toxicity of herbicide and Herbicide resistance can occur on a adjuvant on aquatic organisms localised or whole of population scale 2. resultant decline in dissolved oxygen and should be given very serious (DO) levels post treatment consideration in the development of 3. opportunity for re-establishment of long term management for target or other undesirable pest hymenachne. 4. damage to off target (beneficial) vegetation Below are four key factors for the 5. exposure of bare substrates to erosion development of herbicide resistance within a population. Taken from (Pierce Recent studies into the impacts & Pratt, 2002) of a recommended rate glyphosate a) Initial frequency of resistant genes ‘If herbicide regime undertaken in central a herbicide has several sites of action Queensland (Kinnear et. al 2008) within a plant, there will be very few indicate that very low level of DO exist resistant plants in a normal population. within water samples taken within the b) Selection pressure ‘The more vicinity of dense hymenachne efficient the herbicide (it kills a larger infestations. Results from extensive percentage of the weeds present) the studies identify these low initial levels quicker will be the development of of dissolved oxygen in effect mean that resistance’. the impact from a herbicide only c) Fitness ‘If the resistant plants are not ‘causes minor changes to oxygen as vigorous as the susceptible plants, levels and it apparently has little or no then they will take longer to dominate negative effects on biota’. because they will have to compete against the stronger plants.’ Previously recommended d) Seed Dormancy ‘The higher the techniques of spraying treatment areas seed dormancy exhibited by the weed, half /half were not found to be the longer it will take for resistance to necessary, again because initial levels develop fully. This is because large of DO were already ‘exceptionally low’ . numbers of non-resistant seeds will Furthermore, no residues of glyphosate appear in successive years to dilute the were found at any time during the population of resistant plants. study. Control 47 Technical overview
Mechanical control - Weed harvesting
There are limited long term Harvesting does potentially offer mechanical control options for a solution to the accumulation and management although the use of subsequent release of nutrient rich aquatic weed-harvesters in some plant material back into water ways as situations may assist in removing the occurs during herbicide control. nutrient rich plant matter from Strategies of ‘cut and catch’ that have waterways. The Burdekin Shire Council been useful in depleting nutrient has been actively using mechanical reserves in degraded terrestrial harvesters over a number of years to (grassland) systems in southern manage aquatic weeds in deep water Australia (pers. obs.) may be adaptable habitats (pers. comm. Merv Pyott). to wetland management. Access during These areas by virtue of deep water the wet season for control may be largely resist invasion from possible and the use of mechanical hymenachne so management targets in removal may negate the need for this instance are water hyacinth and herbicide in some instances. Where salvinia. Areas subject to harvesting harvesting operations can cut and are followed up by herbicide control to remove hymenachne from 1-2 metres ensure the management investment is below the water surface a control effect protected. The follow up regime aims to may occur. maintain a buffer of 1.5 to 2 metres of vegetation extending from the edge of Pilot works undertaken in the the water body. Fitzroy Basin indicate that mechanical intervention by this method is feasible if Mechanical harvesting is suited it is supported by a rigorous follow up to areas with higher densities where program to manage any vegetative the detriment of reinvasion from some propagules that are an inevitable by- vegetative material is outweighed by product of the technique. This the benefit of removing the bulk of approach aligns well with managing material from the waterway. One of the multiple invasive species key advantages is that this approach simultaneously, notably floating weeds may rapidly increase DO levels and like salvinia and water hyacinth. prevent the release of toxic ammonias by removing the bulk material from the waterway (pers. comm. Damien Burrows). Material gathered during this operation could also be processed after removal and reincorporated into adjoining agricultural land practice as a fertiliser.
The cost of infrastructure and processing and the risk of transporting contaminated material disadvantage the establishment of this style of operation. The ability for financial returns to be seen on the investment in A Truxor amphibious vehicle fitted with an required plant, skills and resources adjustable cutter –source Dorotea Mekaniska AB may also limit its effectiveness.
Control 48 Technical overview Grazing
The incorporation of grazing regimes into a hymenachne management strategy presents some unique challenges and opportunities. Grazing land in many instances is the initial point source for many hymenachne infestations. This can be attributed to the promotion of olive hymenachne as a ponded and wet pasture grass up until declaration in 1999. In some instances graziers, like many other landholders far downstream from known point sources, have significant infestations of In the Wet Tropics, cattle show preference for hymenachne without ever having pasture grass on drier ground over the aquatic introduced the plant themselves. Other hymenachne. unintentional introductions may have taken place in the movement of stock rather than a control method as it does and industry related vehicles and not disadvantage hymenachne enough machinery between properties. to prevent it from reproducing. The use of 1234 grazing in conjunction with fire and The economic usefulness of herbicide is useful in some hymenachne as a pasture species to circumstances and can form a key graziers is difficult to equate, particularly (transitory) component of an integrated in the Wet Tropics, but has been widely approach. Access can be improved and used as an argument initially against the the surface area to be treated reduced to species declaration, and subsequently deliver a more targeted foliar spray with for its control (on grazing land). lesser amounts of chemical. The Anecdotally the value of the species as a limitations of grazing as a management pasture in the Wet Tropics is generally tool are complex and many and range not realised because the preferred wet from the practical; like the construction of habitat of hymenachne means that it fences in flood prone areas to the remains in constantly waterlogged and political; a declared Class 2 weed and saturated conditions year round. These WoNS species introduced as a pasture areas are often inaccessible to stock for species for generating profit. a large part of the year and are generally avoided by cattle as there is ample Recent studies from CQU in alternative feed available. These factors Rockhampton provide some insight into ultimately effect influence the the complexity and diversity of opinion effectiveness of grazing as a control and capacity amongst landholder to method as seed drop has generally effectively manage hymenachne on their occurred before stock can access to land. The findings of the study should be graze. used to guide the region on how to engage all stakeholders effectively. The Hymenachne and Para grass methodology used also forms the (Urochloa mutica) often coexist within foundation for the replication of a similar wetlands and waterway margins, with approach to understanding the socio- Para grass preferring more elevated, economic considerations of herbicide less water-logged conditions than control in the strategy area. (See hymenachne. Grazing is generally an Kinnear et al. 2008). accepted approach to management Control 49 Technical overview
Fire The use of fire to manage weeds indirect outcomes that can assist in on a variety of scales is a developing larger scale ecosystem management. science. Managing a dynamic ecosystem Outcomes that influence vegetation process like fire for benefits in weed adjacent to infested areas should not be management relies on an intuitive underestimated. Factors like the longer approach guided by a foundation of term restoration of species associated principles and environmental with wetland margins, e.g. Blady grass parameters. One of the major obstacles (Imperata cylindrica) may result in to delivering a successful fire regime in ecosystem benefits that will overtime the wet tropics is the narrow window of assist in returning elements of healthy opportunity to burn with suitable fuel systems. A ‘the hotter the better’ moisture content. In many instances the approach is generally accepted as the use of fire may only be possible as a most effective prescribed burning follow up to herbicide application in an following control. A hotter fire can carry area of dense infestation. further into areas of higher moisture content and create a cleaner area for The use of a variety of burning follow up control and access. A hot fire regimes has been investigated for the may not be desired in all situations and management of Para grass (Urochloa consideration must be given to off target mutica) on the Townsville Town impacts. Common (pers. com. Tony Grice). Applying some of the lessons learnt from this research may assist the management if hymenachne within larger ‘natural’ systems. The habitat preference of the two species differs reducing the suitability of using fire to manage hymenachne in many land types in the study area. Hymenachne prefers slightly deeper water than Para grass and often occupies areas of permanent to semi- permanent inundation.
Fire is a useful post control tool for managing Fire has the potential to deliver a control and stimulating the dormant seedbank effect in several ways: While little is currently known • directly reducing biomass and about the direct mortality of the seedbank germinating a dormant seedbank for it is to be expected that some seeds are subsequent control destroyed and others stimulated to germinate. Rapid flushes of seedlings • seedbank depletion by direct damage have been observed following post to exposed seeds herbicide burns. Seeds not yet integrated in the soil but protected from fire by thick • stimulation of competition by allowing trash of green or uncured fuel have been germination of beneficial species observed in high densities (pers. comm. Damon Sydes). Ensuring follow up Fire has the advantage of being treatments are on hand to take able to be readily integrated into a range advantage of the germination response, of management situations. The benefits or burning prior to seasonal flooding of fire management may also have appear to deliver the best results. Control 50 Technical overview Revegetation and regeneration strategies
A basic hierarchy to guide the seasonal and lifecycle stages of birds, prioritisation of revegetation might go : fish and fauna. Altered hydrology, protect areas of high integrity; repair weed and pest invasion, altered fire degraded areas and then restore the regimes and nutrient and sediment connectivity between the two (adapted input all contribute to threaten from Florabank - Native opportunities for the continuation of Vegetation Management Tool) these processes.
These principles support a The opportunity exists to align proactive and whole of system management and recovery works for approach to weed management, the long term management of particularly if the view is taken that hymenachne with existing plans and weeds are a symptom as well as a objectives that are addressing these form of degradation. The key message issues in the study area. Current plans here is that investing in protecting key and strategies in place incorporate habitat and vulnerable areas should be objectives for protecting remnant considered a priority. The tendency habitat, creating links between with many management programs is to remnants, improving vegetation for concentrate resources in areas where water quality improvement outcomes the issue is the most evident. Often and protecting key conservation areas what is left out of planning for for threatened and endangered species management is the importance of and communities. preventing infestations from establishing or expanding in new areas Examples of recovery plans for and to maintaining areas of high species within the study area include integrity (Bradley 1988). the Mahogany Glider Petaurus gracilis and Southern Cassowary Casuarius Two key underlying approaches to casuarius johnsonii, both of which rehabilitating a site may take place are: utilise habitat or habitat adjacent to those directly or potentially impacted in • Regeneration, as the term implies some way by hymenachne. involves working with existing desirable vegetation to recover system health or restore ‘native’ species composition. • Revegetation involves the replanting of desirable vegetation that is absent from the site, often in the wake of weed control.
Water ways and wetlands form key links between remnant and intact forest, provide essential corridors for the movement of fauna and contribute to connectivity between plant communities. In the Wet Tropics, as in Management of hymenachne can align with many agricultural areas, these regional biodiversity targets in protecting and corridors are often the primary managing landscape icons and significant landscape linkages remaining for species
Rehabilitation 51 Technical overview
Beneficial native species
Incorporating rehabilitation within a techniques by planting nursery stock can control program is an important aspect of be a costly exercise and may not be suited managing weed issues in wetland and to all situations. The opportunity to retain riparian areas. Competition from beneficial desirable species begins with a native species can assist with the long management culture of control that targets term recovery from degradation or and understands the rehabilitation disturbance from control works. process. By working with the strengths and responses of desirable species to A wide variety of anecdotal and field management actions the subsequent based observation of land managers reinvasion by hymenachne or other weeds support the adoption of a competition and can be reduced. nurture approach during weed control. A control program might influence vegetation A simple scenario to illustrate this in two ways; benefit is the value added to a riparian restoration program by retaining naturally • Removal of competition that has been regenerating plant species during control suppressing a dormant, native operations. Delivering revegetation seedbank of naturally regenerating programs costs roughly in the order of $5 essentially ‘free’ plants. per plant to establish (pers. comm. Bart • Making room available for more of the Dryden, Damon Sydes, Ken English). This same or new weeds to establish. equates to an approximate cost of $20,000 per hectare. The concept of the ‘weed shaped hole’ (Buckley et al. 2007) identifies that Careful planning and well informed the lack of foresight of some management operators can be combined to deliver long programs can provide footholds for the term management actions that aid subsequent establishment of weed recovery. This management approach is species into the vacant areas left after most easily applied to establishing an over control. The degree to which this degrades story and other ‘obvious’ vegetation but in the system depends largely on the weed reality should be considered down to species ready to move in when the target ground cover level. Incorporating selective is controlled. herbicide can take some of the guess work out of impacts on off target vegetation. Native species may deliver a variety of benefits directly to the management effort, or may be of special concern from a biodiversity perspective. Well considered application of herbicide can preserve beneficial species. These can then assist both the control and recovery effort by generating shade and competition for available space and nutrients, and by their retention eventually release more beneficial propagules into the managed area.
Whilst a highly effective approach, the revegetation of areas after the application of herbicide or other control
Rehabilitation 52 Technical overview
Aligning with other management programs
Incorporating multiple Informing professionals involved management targets into field based in NRM business of the locations of at survey and control programs is a way of risk and unknown areas for ensuring that often limited resources hymenachne distribution as they go can be used to the best advantage. about their ‘core’ business is a target of Research shows that strategies like this strategy. The development of early detection are best delivered by regional mapping protocols and data staff operating in a weed or related field. share agreements have already made Detection of new locations of species much of this information available to a targeted by Four Tropical Weeds wider audience. Identifying ways to Eradication Program by professional maintain a management presence, weed staff numbered 48 % of total particularly in areas that are considered detections over public information 18 %, to be free of hymenachne, needs to be tracing plant movements 14 % and a key component of prevention and specific searching 6 % (Brooks 2008). early intervention strategies.
Within local government, 70 supporting the development of staff to be multi-skilled across the disciplines of 60 pest management and landscape
50 restoration is the key driver to this approach. Several successful 40 olive operational models already exist. Most native 30 local government are now structured to house pest management and 20 revegetation in the same operational
10 area.
0 right don't w rong total know tested
Ability of pest management practitioners to identify H. amplexicaulis and or discriminate from H. acutigluma. Weedbuster week, 2008.
One of the tasks undertaken by participants during a Biosecurity Queensland weed awareness workshop over the course of 2008 was to discriminate between Olive and Native hymenachne. In summary 21.5% of respondents correctly identified native and 86% correctly identified olive; 42.5% did not know native and 12% did Multi-skilled staff that are fluent in both not know olive and 36% incorrectly weed control and landscape restoration identified native and 2% incorrectly add value to management programs identified olive. The majority of incorrect beyond the act of ‘killing weeds’. identifications for native hymenachne identified it as Para grass. Effort alignment 53 Technical overview
Aligning with other management programs
Other significant progress is in place with management actions targets (MAT’s) set within the Water Quality Improvement Planning (WQIP) process. The nature of the planning for water quality improvement outcomes establishes many objectives which both directly in indirectly impact on specific waterway and wetland management issues like aquatic weeds.
Specific actions for the management of identified priority pests and weeds are key goals of the planning process and set aspirational targets of what objectives management intervention would see achieved in the life of the WQIP. This strategic plan aims to build on these WQIP objectives by identifying where prioritised investment can best direct resources to achieve and maintain these objectives, and provide a budget forecast of the required works program.
Other landscape management targets
Aligning the management targets and aims of a hymenachne management plan with other existing plans and priorities is necessary to ensure that a return on management investment is realised. There is a net benefit on all fronts when a coordinated and inclusive approach to landscape health is incorporated into a weed management plan.
The table overleaf illustrates the legislative priorities of the weed species with a management presence/ priority that occur in the proximity of hymenachne infestations within the Other invasive species like Salvinia (top) Water study area, Olive hymenachne is Lettuce (centre) and Water Hyacinth (bottom) are included for comparison. often present in the same systems as hymenachne. Management approach needs to account for the response of these species to control efforts.
Effort alignment 54 Technical overview
Aligning with other management programs National State FNQ BDT 4 2 3 1
Common name Species Olive Hymenachne Hymenachne amplexicaulis √ 2 2 2,W
Brillantaisia Brillantaisia lamium - 2 A Cabomba Cabomba caroliniana √ 2 2 W Guava Psidium guajava • - 4 WR Guinea grass Panicum maximum - - Lantana Lantana camara 2 2 W Limnocharis Limnocharis flava • 1 1 1 Miconia tree Miconia calvescens • 1 1 1 Mikania vine Mikania micramtha • 1 1 1 Para grass Urochloa mutica - Parramatta grass Sporobolus africanus 2 4 2 Pond apple Annona glabra √ 2 2 2,W Salvinia Salvinia molesta √ 2 2 2,W Siam weed Chromolaena odorata 1 1 1 Sicklepod Senna obtusifolia 2 3 2 Snake weed Stachytarpheta cayennensis 4 -
Water hyacinth Eichhornia crassipes 2 2 2
1 National level of priority WoNS- √ National Eradication Program—• 2Declared pest, Land Protection Pest and Stock Route Management Act, 2002 3 Far North Queensland Regional Pest Management Plan 4 Burdekin Dry Tropics Regional Pest Management Plan, High priority includes all Class 1 & 2 weeds (1,2), WoNS (W), high priorities in adjacent areas (A) and identified by BDT weed risk assessment (WR)
Effort alignment 55 Technical overview Mapping , monitoring and data collection
The technologies, techniques and program on the ground. standards of mapping and recording of on-ground works have evolved since the The quality and detail of data initial declaration of hymenachne. It is captured can determine its end expected that the level of information usability as well by making it required for reporting to funding bodies compatible with desired forms of and stakeholders will continue to query and scrutiny, data can be value increase. As noted in (Csurshes et. al added by being multi faceted in its 1999), the degree of detail required will output. This way data capture is an vary with the nature of the task at hand. integral part of learning as we go With this in mind a national standard for management because it supports an the reporting and mapping of weeds, environment of meaningful query of (McNaught et. al,2002), outlines the past management actions that assist standards that are required to capture to inform of how management data of a national standard. continues to respond to the pest in the landscape. The mapping and monitoring of control works to date has varied in Regional pest mapping and data method and output between regions and sharing project land managers. Developments are continuing in aligning efforts in data In 2007, a regional project was capture towards a unified system with established to map and distribute data sharing as the norm. It is likely that data on pest distribution and density in order to secure the funding required for to assist with regional planning and larger and more regionally collaborative collaborations. Project partners management programs and strategies Terrain NRM, FNQROC, local that a higher degree of accountability will governments Cassowary Coast be attached to this information. It is Regional Council, Tablelands important then, that future funding Regional Council, Hinchinbrook Shire applications acknowledge the level of Regional Council, Cairns Regional resources required to achieve this. Council, Cook Shire Council, State Natural Resources and Water, The benefits of data capture are Queensland Parks and Wildlife and , well established; CSIRO. The key outputs of this project are 1km pixel distribution • assist in making more informed mapping. management decisions; • legislative requirement; • establish a degree of program memory • provide justification of resource allocations • analytical tool for seeking funding or altering work practices to utilise resources more economically
Additionally data collection and reporting can assist in determining the efficacy of many aspects of the control Monitoring and data collection 56 Technical overview Recommended minimum standards for data capture
Attribute Description
1. Data record Unique identifier for the site record. Allocated and maintained by data custo- dian 2. Name of weed Common name, genus, species, sub-species, variety, hybrid. Any uncertainty on naming recorded in the ‘comments’ field
3. Day/month/ year Collection/observation date or the date the survey commenced. Prefer DD- MON-YYYY, e.g. 12-DEC-2001 as this format is less error-prone than pure numeric dates
4. Source of data Name of collector or institution, identifies either personal contact details or the name of the institution where the record is derived
5. Purpose of visit Reason/s site was chosen. For example, to assess type and extent of WONS prior to treatment or monitoring to determine effectiveness of management ac- tion after treatment 6. Place name or locality Plain language description of location e.g. “10 km west of Bourke”. Provides a useful cross-check against specified geocode (latitude and longitude) 7. Latitude Latitude in degrees, minutes and seconds. Prefer decimal degrees or AMG coordinates with Zone and datum noted – for GPS entries 8. Longitude Longitude in degrees, minutes and seconds. As for latitude
9. Precision of latitude- Precision of measurement in its locating the site. Measured in meters. Records longitude how the latitude/longitude was determined (GPS, topographic map or esti- mated) 10. Area Area of the infestation measured in hectares. Area of the infestation defined by the outside boundary. For infestations measured by transect, indicate length of transect (in metres)
11. Cover / density Density measured by class intervals. Prefer data that records raw density as a percent. For rapid survey density data may be collected as classed data e.g. 51-100% cover = dense 12. Treatment/s Type/s of control and/or management. Management could include subcatego- ries of mechanical, chemical, biological. No treatment should also be recorded 13. Comments Qualifications and factors likely to affect the adequacy of the record. e.g. inade- quate time spent. Anecdotal observations of the site or photograph/s 14. Core site number of Number of records for the site or overlapping site. Records multiple sites spa- records * tially or multiple visits over time. May be left blank
15. Land use category * Land use/s observed at the site according to agreed national classification. Select from Australian Land Use and Management Classification land use cate- gories
Taken from—Richard Thackway, Ian McNaught and David Cunningham Monitoring and data collection 57