Biology Reference
In-Depth Information
Box 2.5. A prickly subject - the staged approach to shrub
regeneration and weed removal
Since European settlement of woodland environments, many areas have lost their
shrub layer. Shrubs, particularly dense, leafy or prickly shrubs, such as Bursaria,
provide excellent habitat for many species of small native birds. In many plantings
or remnants, landholders may feel inclined to remove weeds such as Sweet Briar,
Blackberry or Tree Lucerne, which is undeniably an excellent long-term goal. Such
weedy shrubs, however, can still provide habitat for small birds. For instance, we
have regularly observed the Speckled Warbler and Red-capped Robin at sites with
a dense cover of Tree Lucerne. When removing such weeds, consider taking a
two-phased approach whereby native shrubs are established before, or at least in
conjunction with, the removal of the non-native shrubs. Shrubs are best established
in thickets, leaving some open areas between the thickets.
The overstorey layer
The overstorey layer is usually the most obvious part of remnant native vegetation
and may, in some woodland remnants, be the only remaining layer. Many
characteristics of the overstorey may have a considerable influence on the
suitability of woodland remnants for biodiversity and a subset of these are listed in
Table 2.3. There is also a strong effect of the dominant tree species which
characterises a patch of remnant native woodland. For example, different beetle
assemblages occur under Yellow Box compared with Blakely's Red Gum
10
(see
Box 2.1). Similarly, we found on the New South Wales South West Slopes, the
(a)
(b)
Figure 2.7:
(a) Old-growth woodland remnants. (b) Coppice regrowth woodland. (Photos by David
Lindenmayer)
