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Biodiversity at the patch scale

While ecological function is the most important consideration at the landscape scale, at the patch scale (0-10 ha) the priority is to create quality habitat. At this scale increasing size shape and complexity provide the best value for biodiversity. Revegetation can create specific habitats, restore pre-existing or degraded vegetation associations or expand existing remnants and fragments.

Bark provides habitat for reptiles, insects and spiders. Incorporate a variety of bark types.

Composition and structure

 

Biodiversity consists of the diversity of life at a range of scales from genetic to continental. At the patch scale the composition of the vegetation is important for conservation of the genetic, species and population scales. A diversity of species, providing a structurally complex habitat, is more likely to support a larger range of fauna species than a simple patch of low diversity (Munro et al., 2007). Plants themselves are an important component of the biodiversity. When revegetating a site, the diversity of plant species that are re-established determines the future structure and composition of the vegetation at the site  (see Design - Succession theory).

 

Many woodland and forest plant communities have a diversity of species from a range of plant families and the proportion of these species varies between communities. Often the composition is dictated by climatic, soil and topographic factors, but fire history, seed dispersal mechanisms and other factors also have an influence. Even the tree component is often made up of many species. This diversity is important as it represents different resources (such as food and shelter) for a range of fauna. For example, it is crucial that a bird that is dependant on flowers has something flowering right throughout the year (Barrett, 2000).   

 

Having a range of plant species also provides structural diversity. Different fauna species require different structures as habitat, such as tree branches, hollows, dense or open shrubs, a complex ground layer, a range of bark types, different litter types and root types. The more of these structures that are present, the greater the diversity of fauna that can be supported. Many plant species are also dependent on having a range of fauna species for services such as seed dispersal, pollination and distribution of symbiotic organisms (such as mycorrhizae).

 

 

A diversity of species that flower at different times can be important at the patch scale.

 

Size and shape

 

Some animals, including birds, tree-dwelling mammals, bats and reptiles prefer large patches of remnant vegetation, so it is likely that they will also prefer large patches of revegetation. Size of a patch is particularly important where the patch is isolated from other revegetation or nearby remnants, as it will have to supply most of the resources for the fauna that uses it.

 

The shape of a patch is also important - long, narrow patches will have a higher edge to area ratio than round or square blocks. This increases the area of the patch open to predators and reduces the amount of shelter from weather.

 

A good general rule for revegetation at the patch scale is to expand existing remnants or fragments. This increases the habitat value of those remnants by increasing the size and shape and providing more resources for the fauna they contain. This may increase the viability of small flora and fauna populations. In addition, the remnants or fragments are likely to contain habitat features such as hollows and high roost sites, that will not be present in the revegetation site until it is much older.

 

One of the very best publications to describe the principles behind designing revegetation for wildlife at both the patch and the landscape scale is Revegetation and wildlife: A guide to enhancing revegetation habitats for wildlife conservation in rural environments.

 

Birds on Farms, a publication from Birds Australia, provides some very clear guidance on the requirements of birds in rural landscapes, including ideas for revegetation.

 

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