Underpinnings of fire management for biodiversity conservation in ...

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moving organism in the path of the road’ during construction, as well as mortality of animals due
to collision with vehicles (Trombulak and Frissell 2000). This can be the cause of the demise of
significant proportions of a wildlife population (Bennett 1991; Taylor and Goldingay 2004).
5. Roads, and associated works, such as culverts and drains, may become barriers to the
movements of animals (Bennett 1991; Goosem 2004) and affect the distribution of animals
(Trombulak and Frissell 2000). One of the examples in Trombulak and Frissell (2000) is from Reh and
Seitz (1990) who found that the barriers created by roads led to genetic differentiation in a common
German frog.
6. Tracks can affect levels of predation. Tracks may show many signs of feral animals, such as
foxes (Vulpes vulpes) and wild horses (Equus caballus), but it is unknown whether tracks always
enhance the presence of feral animals. Feral animals can be predators, such as cats (Felis catus) and
foxes and where dense cover is necessary for the protection and survival of native prey, such as the
Potoroo (Potorus tridactylus), cutting tracks through the habitat, even for research trapping, can
expose them (Claridge 1998). Bennett (1991) noted that lightly used roads are often frequented
by native and introduced predators to the extent that roads are preferred to adjacent non-roaded
areas; presumably roads allow relatively easy access to hunting areas.
7. Tracks can affect ingress or egress of fires. Tracks may act as barriers to the spread of fires
into a reserve, thereby having the potential to indirectly affect the biodiversity of areas much
greater than that of the track itself. Thus by creating artificial barriers to the spread of prescribed
or unplanned fires, tracks can affect fire regimes. This may sometimes be positive in terms of
biodiversity outcomes, but may also be adverse. By changing microclimate along edges, fire
patterns may change. In fragmented Amazonian rainforests, for example, edge effects increased
exposure to fire (Cochrane and Laurance 2002).
8. Wet lines (water dropped from aircraft to suppress fires) may contain chemicals that have
adverse environmental effects (Adams and Simmonds 1999, Bell et al. 2005). In Australia, the
study of the environmental effects of these agents is in its infancy (Adams and Simmonds 1999).
However, effects may be apparent on species’ composition of both plants (Bell et al. 2005) and
animals through their chemical content. Nitrogen may affect legumes’ establishment and change
grazing patterns, while phosphorus can be toxic to some species of plants (Heddle and Specht
1975); weed invasion may be encouraged because of nutritionally richer soils; mortality of aquatic
invertebrates can occur; and foliage death in plants has been noted. ‘A summary of the data
available suggests that there is a significant potential for damage to terrestrial vegetation from
fire retardants, and to aquatic ecosystems from firefighting foams’ (Adams and Simmonds 1999;
also see Brown et al. 1998 for certain frog species). Plant and shoot death of key species has been
recorded in experiments using a P-based retardant in Victorian heathlands (Bell et al. 2005).
9. Roads and road users may alter environmental chemistry. Road use may affect the chemistry
of an area up to 200 m away and further if streams are affected (see Trombulak and Frissell 2000).
The effects of tracks will vary according to many factors, and not all of the changes mentioned above
will be realised in all localities. The extent to which the variety of tracks causes the sorts of changes
mentioned above is often unknown. However, changes will occur whenever a track is placed in a
reserve. Trombulak and Frissell (2000) ‘found support for the general conclusion that they [roads] are
associated with negative effects on biotic integrity in both terrestrial and aquatic ecosystems’. When
contemplating the introduction of a new track, the manager might consider: how long the effects
of this decision will impact on the local environment – 1, 10, 100 or 1000 years; and to what extent
restoration can occur if the decision is reversed.
Based on the possible effects of tracks and track networks mentioned above, in general, it would
enhance the chances of successful biodiversity conservation in reserves if track lengths and widths
and associated verge treatments were minimised (Plate 2.3). But what of the need to suppress and
control fires? Is a trade-off necessary? How important are tracks for fire management, let alone other
operations, such as weed and feral animal control and built-asset maintenance?
Fire and adaptive management Underpinnings of fire management for biodiversity conservation in reserves