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Biodiversity at the landscape scale
Biodiversity at the landscape scale
There are three ways that native vegetation contributes to biodiversity conservation:
- composition- what species are present,
- structure -how are these species arranged and what are their relative abundances, and
- function -what function is the vegetation carrying out (wildlife habitat, interception of water and nutrients, carbon sequestration, climate amelioration etc).
Each of these elements is important in maintaining biodiversity, but the relative importance of each is different at different scales in the landscape. For example, research (Watson et al., 2001) shows that the Hooded Robin (Melanodryas cucullata) requires large patches of highly complex habitat to live and breed, but it does not require the whole landscape to be covered in this habitat. Composition and structure of native vegetation is important at the patch scale, while at the landscape scale, the spatial distribution of vegetation and its functions are more important.
At the landscape scale revegetation is most useful where it:
increases the size and diversity of existing patches of native vegetation,
connects existing patches of native vegetation,
creates new patches of habitat where there are large gaps in the landscape (stepping stones),
fixes problems with landscape function that threaten biodiversity, such as salinity or soil erosion.
When revegetating for biodiversity, start from existing patches of habitat.
It is important to understand that habitat means different things to different species. It is important to understand something about the species you are trying to create habitat for. A lizard will have very different requirements to a woodland bird. We often think of birds when we are planning new habitat. This approach has been used in the focal species method (Lambeck, 1997), which uses a bird species with very specific habitat requirements to plan conservation and restoration actions for the landscape. This method and other landscape planning methods are reviewed in A review of the focal species approach in Australia (Huggett, 2007).
Elements of an effectively conserved landscape
Conservation nodes - the really big bits that anchor the landscape biota
Stepping stones - Moderate size areas with intact native ecosystems
- Minimum of 40ha depending on the scale of the project
- Collectively represent all ecosystems in the landscape.
- Remnant, regrowth or revegetation.
- If revegetation, then design based on existing vegetation types.
- Actively managed to maintain or improve condition, extent and floristics - fire, weeds, ferals, grazing control, habitat enhancement, flooding, etc.
- Spatial distribution dependant on species modelling.
If revegetated, build out from existing fragments or remnants.
Connectors - the links in the landscape
- Join the conservation nodes and the stepping stones to allow exchange of genes and movement of organisms.
- Less than 1.5 km between habitat blocks, otherwise wide corridors (400m) needed.
- Connectivity appropriate to species of interest
- Paddock trees
- Scattered clumps
- Riparian corridors
- Linear corridors
- Revegetation or fencing/protection of riparian and roadside vegetation
Fragments - small or degraded remnants, paddock trees.
- Maintained or protected through stewardship and incentives
- Land owners supported through extension and training program
- Focus of landcare and individual action.
The Matrix - Soften the agricultural/urban/industrial matrix to the greatest extent possible.
- Native pastures - rotational grazing, time-control grazing, pasture cropping
- Perennial grazing systems - saltbush, acacia
- Perennial production systems - agroforestry, sandalwood, bush food, cut flowers/foliage
- Agricultural enhancement - shelterbelts, woodlots, farm dam revegetation
- Minesite restoration
- Urban enhancement - roadside plantings, native gardens, stormwater reserves.
Next Biodiversity at the patch scale
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