Bushland Weeds Manual - Environmental Weeds Action Network

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iv Introduction The Banksia, Tuart and Jarrah woodlands, the shrublands and the species-rich heathlands of the Swan Coastal Plain and Darling Plateau are wonderful places. They contribute to Perth’s unique natural landscapes, provide a window into the natural world, habitat for native fauna and support an extraordinarily diverse flora. They are fast disappearing though, mostly under urban development. Those bushlands that remain face a range of threats; one of the most serious is invasion by environmental weeds. The concept of environmental weeds is still relatively new. Although the weediness of plants like Bridal Creeper and Watsonia have become entrenched in the public psyche, there is some way to go before the wider community accepts the extent of the problem. For example, Harlequin Flower (Sparaxis bulbifera) threatens one of the last remaining clay-based wetlands on the eastern side of the coastal plain and yet the species was available this year from a fundraising catalogue in at least one local primary school. Still, it is evident that many people do recognise the threats. Increasingly, community volunteers and state and local governments are involved in on-ground actions to protect bushland from the impacts of environmental weeds. With few resources available, maximising the positive outcomes of these professional and voluntary efforts is critical. For those working on the ground, information on identification and control is available from a number of good books: Managing Perth’s Bushlands (Scheltema and Harris 1995), Southern Weeds and their control (Moore and Wheeler 2002), Bush Invaders of South-East Australia (Muyt 2001), Western Weeds. A guide to the weeds of Western Australia (Hussey et al. 1997) and Environmental weeds: a field guide for SE Australia (Blood 2001). Importantly, this kind of information needs to be taken and applied in the context of particular bushland areas. There are no simple formulas and effective management begins with an understanding and a knowledge of each site. It was with this in mind that, in 1998, the Environmental Weeds Action Network (EWAN), with funding from the Natural Heritage Trust, employed a project officer to work with community volunteers and local and state government land managers at bushland sites across Perth’s Swan Coastal Plain. The underlying objective was to help the various land managers to develop strategies for effective weed management in their bushlands. This manual has grown out of that project. The aim of the manual is firstly to bring together information on the biology and known control methods for the serious weeds of bushlands of the Swan Coastal Plain and Jarrah Forest. Secondly, it is to illustrate, with examples and case studies, how this sort of information can be used to manage weeds in the context of particular sites. Hopefully this will provide the reader with the basic knowledge and the framework needed to begin effectively managing the weeds in their own bushlands. Chapter one provides descriptions of bushlands from where the case studies and examples throughout the text are drawn. Chapter two covers some general principles that should guide weed management in bushland, including the kind of area-specific information required before setting weed management priorities. The next four chapters each cover a different group or lifeform of weeds. The first three groups are all herbs – green non-woody plants: Chapter three covers the grasses, chapter four herbs that die back to corms, bulbs or tubers over summer (geophytes) and chapter five broadleaf herbs, sedges and succulents. The final group, chapter six, includes all the woody plants and a few climbers that are technically herbs, but have control strategies in common with woody climbers. Individual chapters look at the general biology of each weed group and how it relates to dispersal, spread, control and management. Case studies examine control of certain species at particular sites and discuss the management approach taken. They often describe the set-up of trials and monitoring programs. Each weed group has a corresponding table containing a summary of information, gathered from a wide range of sources, on the biology and control of weeds occurring in bushland of the Swan Coastal Plain and Jarrah Forest. The list is based on ‘A Checklist of the naturalised vascular plants of Western Australia’ (Keighery 1999a) and includes species that can have an impact on biodiversity and hamper restoration and regeneration efforts. Finally there are chapters on how to map weed populations in urban bushland, an integral part of weed management and on the issues arising from the use of herbicides in bushland. Ideally, this manual will impart enough information for the reader to devise a strategy for management of their serious bushland weeds. At the same time the authors want to highlight the complexities involved in working in Perth’s bushlands; diverse and wonderful places to get to know and understand. The following chapter provides detailed descriptions of some of those bushlands along with the serious weeds that threaten them and the people who are managing them.
Over four years, project officers have been involved in work at a series of bushlands across the Swan Coastal Plain and one in Western Australian Wheatbelt. The major task over that time has been to work on site with those involved in weed management and bush regeneration, providing both on-ground and technical support. The idea was to select a series of sites that were representative of bushlands on a range of soils and land forms across the coastal plain, had regionally significant conservation values and were managed by people actively involved in on-ground works. The underlying objective has been to work with the bushland ‘managers’, whoever they were, to help them protect their bushland through carefully targeted and strategic weed management. Initially work involved identifying those weeds that were the greatest threats to the conservation values of each site, then mapping their distribution across the bushland. The greatest efforts have been directed to consistent management of these locally serious weeds, taking an integrated approach, addressing the causes of invasion and implementing a range of control strategies. Often trials had to be carried out to determine practical and effective methods. Project officers regularly worked alongside Friends groups, council bushland workers, and others who carried out on-ground works. Sometimes they facilitated the employment of contractors and often worked alongside them, supervising and guiding their work. At all sites monitoring was put in place to measure the effectiveness of control programs and the regeneration of native plant communities over time. For most bushlands, field herbaria of all weeds and some native species commonly mistaken for weeds were compiled. Funding and administration The project was funded through the Natural Heritage Trust and managed and administered by a voluntary steering committee made up of members of the Environmental Weeds Action Network (EWAN): Bob Dixon from Kings Park and Botanic Garden, Gary Matthews community volunteer and EWAN treasurer, Margo O’Byrne from the Department of Environmental Protection and Rod Randall from the Western Australian Department of Agriculture. The sites Shenton Bushland Shenton Bushland, a 21 hectare remnant of Banksia (Banksia menziesii, B. attenuata), Jarrah (Eucalyptus marginata) woodlands lies on Spearwood dunes approximately eight kilometres west of the centre of Perth. With only 18 % of the vegetation complex remaining uncleared the bushland is considered regionally significant (Government of Western Australia 2000). These species-rich woodlands occur on pale yellow to grey calcareous sands derived from Tamala limestone. Rich in perennial herbs, Milkmaids (Burchardia congesta), Vanilla Lily (Sowerbaea laxiflora), Leafy Sundew (Drosera stolonifera), Yellow Autumn Lily (Tricoryne elatior) and the sedge Mesomelaena pseudostygia are common. The open sandy patches are Chapter 1 The Project often colonised by annual herbs such as Slender Podolepis (Podolepis gracilis) and after fire the annual grass, Austrostipa compressa is noticeable, flowering and seeding prolifically. Commonly occurring shrubs include Hairy Yellow Pea (Gompholobium tomentosum), Daviesia nudiflora and Grass Tree (Xanthorrhoea preissii). Around 120 species of natives (Marshall unpubl.) and 65 species of weeds (Brown and Brooks unpubl.) have been recorded. Approximately 50 % of the bushland is in good to excellent condition. The remainder varies from good to degraded with areas of severe localised disturbance (Ecoscape 1994, Government of Western Australia 2000). Weeds that threaten the undisturbed bushland include a number of South African geophytes (plants that die back to bulbs, corms or tubers each year), including Yellow Soldier (Lachenalia reflexa), Freesia (Freesia alba x leichtlinii), Watsonia (Watsonia meriana) and Black Flag (Ferraria crispa). The perennial herbs Geraldton Carnation Weed (Euphorbia terracina) and Rose Pelargonium (Pelargonium capitatum) are serious invaders and many weedy annuals are common, particularly in the highly disturbed areas. These include Flat Weed (Hypochaeris glabra), Ursinia (Ursinia anthemoides), French Catchfly (Silene gallica), and Slender Suckling Clover (Trifolium dubium). Perennial Veldgrass (Ehrharta calycina) is one of the most serious invaders of the bushland often establishing in previously intact areas following fire. For the last nine years on-ground management of Shenton Bushland has been carried out by The Friends of Shenton Bushland (Inc.), a community group formed after the bushland was saved from development in 1993. In 2000, following lobbying from community groups, a bushcare officer was employed to carry out on-ground management of bushlands within the City of Nedlands, including Shenton Bushland. In the past, much of the funding has come from government grants to the Friends. In recent times, however, the City of Nedlands has started to fund the continuation of works programs initiated through grant money. The Friends have a high level of input into management through organisation of works programs and supervision of contractors who do much of the weed management work. Friends of Shenton Bushland and volunteers hand-weeding Yellow Soldier in the Banksia woodland. 1
Page 1 and 2: Bushland Weeds A practical guide to
Page 3: Acknowledgments This manual is the
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Iridaceae Moraea miniata Two Leaf C
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Chapter 5 Broadleaf Herbs, Sedges a
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58 Chapter 5 Broadleaf Herbs, Sedge
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Chapter 5 Annual Broadleaf Herbs, S
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Chapter 5 Annual Broadleaf Herbs, S
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Chapter 5 Perennial Broadleaf Herbs
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Chapter 5 Perennial Broadleaf Herbs
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94 Chapter 8 Herbicide Use in Bushl
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100 Final Note In the end, environm
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102 References 1 Aarssen, L.W., Hal
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104 References 101 Dixon, B. (2002)
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106 References 204 Mann, R. (1998)
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108 307 The Nature Conservancy (200
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