Wetland Plants of the Namoi Catchment 8 References 38 Glossary 39 Index 40
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ACKNOWLEDGEMENT: This publication would not have been possible without the contribution of photographic materials from Steffan Holmes (NSW DPI), Greg Steenbeeke (Orkology), Francesca Andreoni (NSW DECC) and Harry Rose (NSW DPI), so a big thankyou to all of you. Thanks also to Francesca Andreoni and Stephanie McCaffery (NSW DECC) for their hard work editing the document. This document was developed and written by staff from Namoi CMA. DISCLAIMER: The information presented in this document has been compiled from both primary and secondary research carried out or commissioned by Namoi CMA staff and is comprised of general statements. No reliance on the information given in this document should be made without seeking the advice of an expert professional, scientist or technician. Namoi CMA will not be made liable for any consequences arising directly or indirectly from using this publication and any information or material contained in it. Table of Contents Introduction What is a wetland? 3 Why are wetlands important? 3 Why are wetlands at risk? 4 What can you do to help? 5 How can Namoi CMA help? 7 Namoi CMA Catchment Area 7 Wetland plants of the Namoi Catchment 8 References 38 Glossary 39 Index 40 1 2 Introduction The wetlands of the Namoi Catchment are unique, and in need of our help to survive. This book is designed to introduce you to some of the more common plants that are found in and around wetlands. We hope this can inspire you to look more closely at these special and vulnerable ecosystems, and how you might best manage any wetlands in your care. What is a wetland? A wetlands is an area that is inundated, or flooded, some or all of the time. The plants and animals that live in any wetland will either be partly or wholly dependant on water for some part of their life cycles. Moreover, wetland drying cycles are equally important to wetland health as periods of time when wetlands are wet. Floodplains, swamps, billabongs, waterholes on river channels, farm dams, lakes, reservoirs, lagoons and wet pasture are just some examples of the rich variety of wetlands found within the Namoi Catchment. Wetlands that appear and disappear over short time periods are called ‘ephemeral’; those that last longer are referred to as ‘permanent’. Why are wetlands important? Wetlands are vital feeding and breeding areas for a variety of native wildlife. Many plants – such as those featured in this book – rely on wetlands to survive. Wetlands are known to mitigate the effects of extreme weather and regulate surface and groundwater quality. Wetlands provide valuable grazing and cropping opportunities for farmers. Culturally, wetlands are of great importance to Aboriginal communities. The information stored in wetlands can help us understand natural and human induced environmental change. Drought cycles are natural phenomena in the Australian climate and over time wetlands flora and fauna have evolved various ways of coping with the unpredictability of Australia’s wet and dry cycles. Wetlands have a particularly important role during drought cycles. At such times wetlands act as important ‘refuges’ in the landscape for fauna and moisture loving flora. 3 Many species have adapted to survive drought. Molluscs and crustaceans for example survive drought by producing desiccation resistant eggs, or adults burying themselves in the mud where they become encased in a desiccation resistant cocoon. Fish, frogs and freshwater turtle species are also able to survive drying periods in wetlands, either by spending periods buried in protective cocoons under ground or as desiccation resistant eggs. The most easily recognised wildlife values of wetlands are the waterbirds. Links between healthy unmodified rivers, streams and wetlands, and healthy waterbird populations are now well understood. Without major breeding events in wetlands during flood years, many waterbirds are unable to sustain their population levels and local extinctions result. Why are wetlands at risk? Most threats to wetlands in the Namoi Catchment are either the direct result of human interference or occur as a consequence of human activity. The types of threats to wetlands in the Namoi Catchment include: • Clearing, drainage and landfilling • Agriculture including cropping and grazing • Water removal and regulation (groundwater and surface water) • Salinisation, that is the increasing saltiness of wetland water and/or soil • Soil erosion • Sedimentation • Animal pests, for example European Carp • Invasive/noxious plant species, for example Willows or Lippia • Mining and extractive industries • Legal and illegal fishing • Removal of dead wood from floodplain or riparian areas • Discontinuity (the isolation of wetlands from river channels, and barriers that prevent the movement of fauna through the wetland system) • Poor water quality • Inappropriate management Solving many of these issues requires a co-ordinated approach involving many different government and community groups. Solutions also need to address these problems at a local and catchment scale. 4 What can you do to help? As landholders or community members there are many things that you can do to help protect wetlands. Planning: Planning is essential if the full potential of a wetland is to be realised. A management plan will provide the opportunity to identify your aims, issues and management actions. Plans should identify the range of wildlife using the area and connectivity at a landscape scale. At the individual property level, planning should allow for buffer zones around the wetland that will minimise outside disturbances and address issues such as fencing, grazing regimes, weed control, tree planting and impacts of other activities. In most areas of management, a passive approach, allowing natural processes to ‘manage’ the wetlands, is usually preferable to intervention. Careful prior investigation of the potential consequences of active management is essential. Restore natural fluctuation in water levels: Australian wetlands rely upon the fluctuations in water level as much as the wetting effect. Constant or longer periods of inundation do not necessarily lead to an improvement in wetland values and sometimes can do more damage than good. A natural regime of water level fluctuations should be the primary consideration in management. Reduce turbidity and sedimentation: Sedimentation of a wetland reduces its volume; the silt can suffocate plants and animals, and reduce light penetration. Sediments also carry nutrients and possible chemicals with toxic properties into wetlands. Clearing vegetation and allowing stock unrestricted access to wetland areas is a significant source of excess sediment. Maintenance of ground level plant cover and diversity surrounding a wetland is the most significant method of reducing sedimentation and turbidity. The stocking rates or cropping regimes in surrounding paddocks may need to be adjusted with reducing turbidity and sedimentation in mind. Generally speaking this may mean that less stock can be grazed on surrounding paddocks, and cropping areas will need to be worked in ways that will reduce soil erosion. 5 Reduce salinisation: Salinisation of a wetland is generally part of a much wider salinisation problem occurring due to changes in catchment hydrology. Salty run off can be managed by the revegetation of groundwater recharge areas however this is a longer term solution. In the meantime, protection of the wetland can only be achieved by diverting salinised flows which also has implications, and also ensuring that a well vegetated buffer zone occurs around the wetland. Minimise grazing and trampling: Many wetlands offer a degree of richness in plant abundance, growth rate and diversity which make them valuable fattening pastures. Overgrazing is damaging to wetlands and some wetland types will tolerate no grazing at all. Livestock can damage wetlands by grazing all plant species too much, or particular plant species to the benefit of others, compacting soils via trampling, pugging soils when wet therefore changing where water collects or remains in dryer periods, adding nutrients through manure and bringing in weed seeds from other places. These processes contribute significantly to sedimentation of the wetland. On the other hand, well managed grazing can maintain open areas in wetlands that may be preferred by particular species and provide a degree of disturbance to plant communities which provides the opportunity for an increase in diversity. In general, fencing of the wetland is the main management action required so that grazing can be managed in the wetland context. Grazing regimes can then be set to maximise ground cover, with livestock removed completely when the wetland is wet to prevent nitrification and pugging and to allow wetland plants to grow, flower and seed uninterrupted. Control feral animals and weeds: Feral animals and weeds require a particular degree of careful management around wetlands as the use of poisons and toxins in a wetland context can have catastrophic results. Reducing the levels of disturbance to wetland areas can reduce the numbers and types of weeds that grow in a wetlands as can preventing their spread by reducing or managing livestock access to wetlands. Any use of chemical controls near wetlands should be avoided if possible in favour of mechanical removal of weeds; however some particular chemicals are designed with wetland and riparian areas in mind. Careful use of these chemicals in accordance with directions on the label can have good results. 6 Feral animal control is also complex as it is often the values of a wetland that the manager is promoting for wildlife habitat purposes that attracts feral animals such as rabbits, foxes and pigs. A feral animal control plan will need to be developed that takes into account off-target animal sensitivity to particular control agents and a holistic and integrated approach to feral animal management. Namoi Catchment Management Authority, Rural Land Protection Boards and Department of Primary Industries officers can all help with this issue. How can Namoi CMA help? More than 90% of all NSW waterways run through farmland (NSW Department of Primary Industries 2008).