Improving habitat value

 

Habitat for wildlife includes places for living, nesting and roosting; places to hide from predators; food and water; protection from weather and opportunities to find mates. Habitat complexity describes the number and variety of food and shelter opportunities for a wide variety of animals and plants. For wildlife, some of the elements that make up a complex habitat take a very long time to develop in a revegetated site. While leaf litter is often present after one year, fallen logs may take decades to develop and tree hollows may not form for up to 120 years.

 

The diagram below shows some of the 'building blocks' of habitat (Curtis et al., 1994). Remember that not all landscapes have all of these habitat elements. Look at what is appropriate for your area. In order to improve the habitat value of your revegetation site, it may be necessary enhance some of these building blocks artificially.

 

    
Source: Curtis D, Nadolny C, Falconer S, Metcalfe P, Gaynor S, Goldsmith S, Fogarty P, Mills J, Moore A, Hooper S (1994) 'Re-leafing New England: A farmer's guide to trees on farms.' North West Catchment Management Committee, Armidale, NSW.

 

 

Some good general references about encouraging wildlife, including in revegetation, are:

  • Lindenmayer, D., Claridge, A., Hazell, D., Michael, D., Crane, M., MacGregor, C., & Cunningham, R. (2003) Wildlife on farms: how to conserve native animals CSIRO Publishing, Collingwood, VIC. (Bush Tracks review)
  • Breckwoldt, R. (1983) Wildlife in the home paddock: Nature conservation for Australian farmers Angus and Robertson, North Ryde and London. (Bush Tracks review)

Water points

 

A recent study conducted in the Victorian Wimmera (Starks, 2007) showed that open water, provided in shallow artificial dams significantly enhanced the biodiversity value of the native vegetation. The final report of the study  gives details of how to design these water points.

 

Dams and artificial wetlands can be constructed as part of a whole landscape conservation strategy. Diverting floodwaters or environmental flows to periodically inundated areas can also stimulate regeneration of some native plants such as river red gum (E. camaldulensis) and black box (E. largiflorens).

 

Even stock troughs can be a valuable source of water for birds, mammals and insects, enabling them to thrive in the landscape. Existing dams can be modified to make the more wildlife-friendly. This Victorian field note will give you some ideas.

 

On the other hand, in rangeland areas of Australia, feral animals sometimes thrive in environments where water points are too readily available.  If there are problems with feral camels, horses, cattle, goats or foxes, it may be better to remove water points or to fence them off to exclude feral animals.  Gluepot Reserve in South Australia has modified water points by providing raised troughs for birds that cannot be accessed from the ground, and has fenced off dams.  This has been beneficial to bird species and has assisted in the management of feral animals on the Reserve.  CSIRO research in the Rangelands has shown the distances that stock and feral animals are able to travel from a water point influences the extent of lightly grazed vegetation on a property - if waterpoints are placed closer together, the whole property is more heavily grazed, which has negative implications for both native wildlife, and for plant species that are sensitive to grazing pressure.  If the water points are further apart, then there are areas of the property that are only ever lightly grazed, and where biodiversity is higher.  

 

In some cases, too many water points can cause problems with heavy grazing and over-population of some native species, for example wallabies and kangaroos, which can negatively affect both grazing-sensitive native vegetation, and agricultural productivity.  If this is a problem in your region, there are designs for water points that can exclude targeted animals (e.g. see this website and associated references).

 

Artificial hollows and nest boxes

 

Tree hollows are used by many Australian animals for nesting sites and shelter. Hollows take a long time to develop in planted trees, through the action of wood decay, termites and falling limbs. If you are revegetating to increase the habitat available for wildlife, you may need to provide artificial hollows throughout your planting. Many species are dependent on hollows and cannot persist without them. Even if hollows are present, there may be intense competition for them from both native and exotic species (such as Honeybees, Starlings and Indian Mynas).

 

Different animal species (birds, reptiles, mammals and insects) use different size hollows with different opening sizes. You need to choose appropriate nesting boxes or artificial hollows to suit the species you hope to assist. Designs are available for nesting boxes to suit a wide variety of species including birds, arboreal mammals and bats.

 

Nest boxes can be mounted on existing trees or stumps or placed on posts or poles. Ideally they should be set at an appropriate height for the target species, and not be in an exposed position.

 

The following publications, websites and fact sheets will give you some designs for nest boxes.

  • Gibbons, P. & Lindenmayer, D. (2002) Tree hollows and wildlife conservation in Australia CSIRO Publishing, Melbourne. (Read a Bush Tracks Review here)
  • Platt, S (1999) Nest boxes for wildlife Department of Primary Industries, Victoria. Read the article for designs and principles.
  • Douglas, J (2003) Nest boxes for wildlife. Land for Wildlife Note 19. Read the article for designs and principles.
  • Patterns of use of nest boxes by forest vertebrates.  Centre for Research in Environmental Studies, Australian National University.  Read the report..
  • Habitat nest boxes.  City of Ipswich, 2007.  Read the article for designs for SE Qld.

Rocks, logs and leaf litter

 

Ground dwelling wildlife need the shelter provided by structures on the ground. These structures include fallen timber - logs, branches and sticks, a range of rock sizes and leaf litter.

 

Logs provide both habitat and nutrients. As they gradually break down due to the actions of weather, fungi, and termites, they release nutrients into the soil. They also act as mulch, conserving niches of damp soil, which allows soil invertebrates to thrive and even assists plants to germinate and grow. At ground level, logs can act as mini-windbreaks, providing shelter from extreme weather for ground-dwelling fauna. Logs and sticks also trap soil and nutrients that are washed or blown across a site, and are particularly valuable in degraded sites to build up pockets of soil and organic matter for plant germination.

 

Leaf litter is an important source of food and shelter for many soil organisms, reptiles, amphibians and mammals. It is also important in carbon and nutrient cycling and in the frequency and intensity of fire. Litter acts as a mulch for newly germinating seeds and can buffer the soil against temperature extremes.

 

Leaf litter and rocks can act as a mulch for plants.

 

Like leaf litter rocks of all sizes can act as a mulch or provide niches where more water is available for plants and soil invertebrates. Rocks also act as heat sinks, slowly releasing heat through the night that was stored during the day. Cracks and hollows around rocks are important habitat for wildlife, particularly reptiles and amphibians.

 

Logs and sticks can be added to a site if they are not present. Leftover material from woody weed removal can be used, providing there is no risk of re-infestation. Alternatively, trunks and branches from off-site tree removal (clearing, storm damage, arboriculture etc) can be brought to the site and dispersed with a Bobcat or tractor. Adding logs to a site may increase the habitat value for rabbits, so it is essential to monitor rabbit populations and take appropriate control measures when necessary.

 

Leaf litter will build up quickly as your new plants grow, but woodchip or woody mulch can be added to substitute. Mistletoe is a rich source of leaf litter and should not be removed unless it is severely damaging individual trees. Woody mulch acts to reduce the availability of nitrogen on a site and may help to suppress the growth of vigorous perennial grasses.

 

Next  Measuring success - techniques and principles

 

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