Underpinnings of fire management for biodiversity conservation in ...

Underpinnings of fire management for biodiversity conservation in reserves
surfaces can cause sedimentation beyond mitre drains onto previously unaffected land. Thus the
effects of tracks can extend into catchments generally. The following is an example, ‘Roadside
erosion has occurred in all tracts of the Monaro [New South Wales], and at alpine and subalpine
elevations many fens and bogs with their associated peats have undergone desiccation’ (Costin
1954). Eroding tracks can lead to water turbidity in streams, thereby decreasing water quality.
Cornish (2001), in a commercial forest area, found that the ‘construction and use of permanent
roads resulted in increased turbidity levels, but these increases only persisted in the catchment
containing stream crossings’. Contour ditches and culverts can support the temporary ponding of
water. These mini-storages can supply native and feral animals with added water, and thereby help
augment their populations artificially. Changed drainage and sedimentation patterns can affect the
habitats of plants and animals.
2. Tracks change environments and thereby create opportunities for invasion and
persistence of weeds (e.g. Tromblak and Frissell 2000; Goosem 2004). Compaction (Caling and
Adams 1999), soil disturbance and sedimentation create new habitat that is temporarily free of
competition, and this condition is more favourable to the establishment of horticultural and other
weeds. The level of manifestation of weeds will vary according to history and circumstances, and
be affected by the size and composition of the local soil-seed pool (Plate 2.2).
3. Tracks can directly destroy habitat of native plants and animals. The significance of this
effect for conservation in a reserve depends on the extent of the habitat concerned. Small rare
plants and animals are likely to be the most affected. Andrews (1990) noted the case of a powerline
easement just missing the habitat of
Australia’s rarest butterfly.
4. Tracks elicit vehicular access and its
consequences. Vehicular access allows
the spread of weeds via various types
of machinery – from cars (Wace 1977)
to slashers to graders. For example,
there is an Indian grass naturalised in
northern Australia called Grader Grass
(Themeda quadrivalvis) because of its
prevalence along roadsides after grading
(Pitt 1998). Roads may prepare the way
for the invasion of formerly natural
habitat (Gelbard and Belnap 2003). The
sowing of grasses and the placement
of hay bales to slow or prevent erosion
in spoon drains may allow weeds to
enter an area through the materials
used, or indirectly on the machinery
used for the operation. Fungal disease,
such as Phytophthora spp., may spread
along roads and tracks (see Adam 1995;
Trombulak and Frissell 2000; Garkalis
et al. 2004). Tracks may, if open to the
public, allow better access to picnickers,
arsonists and maintenance workers, all
of whom may cause unwanted ignitions
by carelessness or design. Rubbish may
also be dumped along tracks (Nairn
2003, p. 34). Wildness values may be
diminished also. Vehicular access leads
to mortality of any ‘sessile or slow
Plate 2.2 The native grass Themeda australis dominates on the
right-hand side, while exotic species dominate the left, where a
new fuel break had been cut through and allowed to revegetate in
this native grassland in the ACT (Gill 2005).
Fire and adaptive management 15