Biology Reference
In-Depth Information
(a)
(b)
<2 ha
2-5 ha
5-10 ha
10-15 ha
15-20 ha
>=25 ha
Patch size
Figure 2.10: (a) Relationship between remnant patch size and site occupancy by the Eastern Yellow Robin. (b)
Eastern Yellow Robin. (Photo by Graeme Chapman)
The effects of the hyper-aggressive Noisy Miner on smaller woodland birds
may be less intense in larger patches.
Several of our detailed field studies have demonstrated the importance of large
patches of remnant native woodland for biota. For example, declining or
threatened woodland birds such as the Hooded Robin, Eastern Yellow Robin and
the Brown Treecreeper are more likely to occur in large patches. 4
The value of small remnants
Large remnants typically represent the best habitat for biodiversity, but small
remnants also can be important for conservation. A number of researchers have
demonstrated the importance of small remnants for native woodland plant
conservation and animal conservation. 33, 34, 35 Even 'patches' as small as an
individual paddock tree have been found to be extremely valuable for some
animals 30 (see Chapter 4). Sets of small patches of woodland may support many
species (and sometimes more species) than a single large patch of equivalent area. 35
This can be because a small patch might be part of a much larger network of
patches that together are needed by a range of mobile
species. 36 Further, a small, high-quality patch containing
particular vegetation attributes that are important for a
species of interest (e.g. trees with hollows, or a well-
developed understorey layer) might be more important
than a larger patch in poor condition that does not
contain these features. Small patches are also critical
because most of some woodland communities occur as
small patches (2 hectares or less). 37
Larger patches of
woodland typically support
more species than smaller
ones but small remnants
are often the priority for
conservation on a farm
because they are under
greater threat of being lost
 
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