In the “Protecting and restoring our natural heritage - a practical guide

In this guidebook, “management” means any action taken to prevent or reduce further degradation of native ecosystems. The purpose of management is to encourage natural processes (like plant regeneration and succession) and control weeds and pests that interfere with these processes. You should nearly always protect and manage natural ecosystems (sections 3 & 4) as a priority, before attempting restoration (sections 5 to 10).

Management plans

A management plan (or checklist) helps ensure you address important issues and follow a clear course of action. You should prepare a detailed management plan for large protected areas or those that are publicly funded. For others a simple checklist may be adequate. If the area is to be legally protected, you may have to follow a formal process.

Ensure that your management plan includes the following actions. It should:

  • Describe the remnant, its natural resources, and their importance (e.g., main communities and species, landforms and water bodies).
  • Outline any management issues or threats.
  • State the goals or aims of protection. These should be realistic and straightforward, e.g. Protect the (specified) forest remnant and ensure it is self-sustaining.
  • State objectives that identify what management results are sought for specific issues or threats, e.g. Identify the factors limiting natural regeneration, and take action to restore this process.
  • Detail methods that describe how the objectives will be tackled and in what time frame, e.g. Erect post and wire fences to exclude stock, and hand removal of weeds within 6 months.
  • Specify monitoring methods for assessing the effects of management actions or natural change.
  • Indicate how you will adapt management actions in response to assessment.

Site assessment

Clarifying an area’s ecological values and importance will help justify its protection, and provide background information for use in your management plan. It will also help you identify threats to the ecosystem, and where there are restoration needs. Depending on the size or complexity of the ecosystem and the level of protection/funding being sought, you may need specialist advice or assistance.

Your site assessment should:

  • Describe the main plant/animal communities, and their condition.
  • List the main and any threatened native plants and animals.
  • Describe the main landforms, such as river terraces, fans, ridges and slopes.
  • Identify water bodies and drainage patterns, including wetlands, creeks and damp areas.
  • Identify factors affecting the ecosystem, such as aspect, wind exposure, frost, drains, weeds, animal pests and grazing.

Weed control

Although many introduced plants do not cause problems in natural ecosystems, invasive weeds can limit the regeneration or retention of native plants and animals. Weeds may be herbs, shrubs, vines or trees. They typically invade open or disturbed sites, which are often found in remnant ecosystems. You will nearly always need to control weeds, as they compete for light, space, moisture and nutrients. You have a legislative obligation to control or eradicate weeds identified in your local Regional Pest Management Strategy.

Key management guidelines

  • Prepare a weed management strategy so that weed control is done logically and efficiently.
  • Assess whether weeds really are a problem, or whether attempted control will only make matters worse.
  • Identify and eliminate weed sources within remnants and from adjacent lands, and reduce open areas that could be invaded by weeds (Porteous 1993).
  • Tackle weed control promptly, or the task may get out of hand (‘one years seeding, seven years weeding’).
  • Avoid over-clearing weeds where control could cause disturbance, weed re-establishment or openings for new weeds, e.g., willow removal resulting in blackberry spread.
  • Minimise the use of herbicides by using other weed control methods as much as possible.

Weed control methods

  • Shading - dense planting shades out some weeds and limits their establishment.
  • Hand weeding - labour intensive, but suitable for specific weeds, fragile sites or low levels of infestation. Hard to kill weeds should be removed from the site (Porteous 1993).
  • Ring barking - woody weeds with large stems or trunks (Porteous 1993)
  • Mechanical weeding - e.g. the use of weedeaters and rotary slashers.
  • Controlled grazing - based on carefully applied adaptive management.
  • Biocontrol - introducing biological agents, such as fungi or insects to control specific weeds, e.g. gorse, spider mite.
  • Herbicide use - applied to cut stumps, sprayed onto leaves, injected into the trunk or applied to frills around a trunk (Porteous 1993).

 Caution

Poorly managed weed control is a major cause of native plant death.

  • Weedeaters can ring-bark planted trees.
  • Grubbing can damage sensitive roots.
  • Native plants are sensitive to herbicides, especially podocarps. Spray drift can easily destroy an expensive plant, wasting time, effort, and money.

Animal pest control

Originally New Zealand had no land-based mammal predators or browsers, but human settlement inroduced domestic stock, game animals, vermin and their predators. Wild animals and animal pests are defined by statute, but they are all termed ‘animal pests’ in this guidebook. They include mice, rats, stoats, rabbits, hares, goats, pigs, deer, possums, cats and introduced insects such as wasps. All these need controlling as they eat foliage, fruits and seeds, compete with native animals for food (or eat them as food) and alter ecological processes. You have a legislative obligation to control animal pests identified in your local Regional Pest Management Strategy. Sometimes you will need to co-ordinate any control efforts with adjacent landholders. This is particularly important for large sites and often involves working with regional councils, DOC and Landcare groups.

Key management guidelines:

  • Prepare an animal pest management strategy, so control is done logically and efficiently.
  • Identify which pests are problems, and what control methods should be used.
  • Identify possible prey switching that might occur, e.g. increased predation on native birds when rabbit numbers are reduced.
  • Undertake control promptly before pest numbers build up.
  • Work co-operatively with neighbours and other managers if appropriate.
  • Beware of all health, safety and environmental impacts associated with animal control

Animal control methods

  • Poisoning, shooting and trapping - need to avoid killing non-target species.
  • Fencing - excludes some animal pests, and can be cost-effective, e.g. rabbit netting.
  • Shields - to deter possums; moats around wetlands - to reduce pest access.
  • Creating less suitable conditions - such as increasing vegetation cover and moisture to deter rabbits.
  • Biocontrol - using biological agents to control pests, e.g. parasitoid wasps on wasps.
  • Integrated pest management - a combination of these methods, often used in special areas subjected to intensive pest control, e.g. DOC's 'mainland islands'.

Domestic stock

Domestic stock include sheep, cattle, goats, deer and any other farmed animals. Their impacts include grazing or browsing native vegetation, preventing plant regeneration, altering soil and water nutrient levels, compacting soil and spreading weeds. Stock must be excluded from forests and most other protected areas. However, controlled grazing may be used to maintain biodiversity in some induced shrublands and grasslands (see section 4).

Stock control methods

  • Fencing - needs to be appropriate for the type of stock and be regularly maintained.
  • Repellents - realistically an option only where plants are small, e.g. restoration plantings.
  • Co-operation between adjacent landholders - can reduce stock access, but no substitute for secure fencing.

Caution

  • Fences are your only realistic option for excluding stock.

The most elaborate fences, such as those at Karori Wildlife Sanctuary, exclude all land animal pests and stock. A single-strand electric fence may be sufficient to keep cattle out, as long as you check it frequently. Environment Waikato has information about a cheaper predator-proof fence suitable for use by private landowners.

Buffering

You can establish a buffer zone or area around a remnant and manage it to limit adverse effects from adjacent land uses. Buffers may take the form of a shrubby border, which also provides new habitat and increases local species diversity. Specific benefits include:

  • Reducing fire risk.
  • Reducing risk of spray damage.
  • Protecting forest edges from wind penetration and weed ingress.
  • Protecting sensitive plants and animals in the interior.
  • Limiting input of sediments and nutrients (particularly in wetlands and riparian areas), and introduced plant seeds.

Monitoring

Monitoring measures the success of a project in terms of its stated goals and objectives. Whatever monitoring methods you use, they should be as simple as possible (Atkinson 1994), standardised and repeatable.

Formal scientific monitoring is appropriate for large-scale, publicly funded projects. Professional advice will ensure a more reliable evaluation and interpretation of habitat changes. For most small projects, it is enough to take photographs from fixed points at the beginning, and then at regular intervals (e.g. annually). Record the date on them, and choose views that will not be grown out.

For more elaborate monitoring you need to use several indicators sensitive to various kinds of change. Indicators that can be measured include:

  • Spread or incidence of weeds.
  • Damage caused by stock grazing or animal pests.
  • Changes in regeneration patterns after fencing.
  • Build-up of forest litter.
  • Cover of ferns, mosses and lichens, as an indicator of microhabitat development.
  • Bird and invertebrate records as indicators of increasing diversity.

Monitoring methods

  • Fixed sample plots to measure changes in plant species presence, density and regeneration.
  • Photopoints to provide a picture of ecological changes, such as plants regenerating after animal pests have been excluded.
  • Fixed sample plots to measure changes in abundance of pests and weeds (trapping, pellet counts, cover and density).
  • Standardised observations of bird numbers and species (such as 5-minute counts) or sampling of invertebrates (transects and pitfall traps).

Once you have achieved the initial desired vegetation structure, the simplest measures of sustainability are regeneration and resistance to weeds.

Further reading

An illustrated guide to common weeds of New Zealand. Roy B, Popay I, Champion P, James T and Rahman A 1998. [Book – photographs and descriptions of a wide variety of weeds. A number of native plants are listed as weeds, but little explanation is given for their selection. We do not think they should be described as weeds]

Christchurch waterway maintenance plant guide. Weeds, and how to tell them from similar looking plants. McCombs K, Meurk C and Morland K 1999. [Book, available on request from Christchurch City Council – contains clear photographs and descriptions for easy plant identification]

Ecology and management of invasive weeds. Williams PA 1997. [Book – provides in-depth information about weed life forms, dispersal, vegetation succession and weed control]

Gully restoration guide. A guide to assist in the ecological restoration of Hamilton’s gully systems. Wall K and Clarkson B 2001. [Booklet – a step by step guidebook on gully restoration. Includes a gully profile, information on soils, native plants to use, and weed identification and control]

Native forest monitoring. A guide for forest owners and managers. Handford P 2000. [Book – provides detailed information on methods, fieldwork, data analysis, indicators of forest health, and the level of skill and precision needed for the methods used]

Native forest restoration. A practical guide for landowners. Porteous T 1993. [Book – comprehensive coverage of managing remnants, with detailed restoration techniques]

New Zealand’s wetlands. A management guide. Buxton R 1991. [Book – describes different types of wetlands and their functioning, and provides management and restoration guidelines and summaries]

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