VEGETATION MANAGEMENT PLAN for Bidjigal Reserve - Land

Vegetation Management Plan - Bidjigal ReserveUrban-Bushland InterfaceMost of this Management Zone comprised cleared Asset Protection Zones (‘APZs’), these beingcreated to protect adjoining residential properties from bushfire. The condition of the bushlandadjoining the urban-bushland interface is highly variable, depending largely on its accessibility andtopography, but of course also being dependent on level of care undertaken by the adjoiningresidents.Where the ground is relatively level, these generally-grassed areas are mown by residents, althoughat times private gardens have been extended into the Reserve. In steeper areas, where the use ofmowers is more difficult, weeds are more prevalent, with weedy bushland at times extending intothe APZs, up to rear property fences. Illegal connections from roof runoff or from swimming poolsalso occurs, as does dumping of garden waste – the latter being a regular occurrence and providingand on-going problem. Major weed infestations occur in a number of locations in this ManagementZone (e.g. western end of Westmore Drive).The extent of weed invasion into core bushland is at times associated with some form of disturbancedownslope (service corridors, vehicle tracks), but where the urban-bushland interface meetsundisturbed bushland, weed invasion is greatly reduced. Weed invasion is also reduced in bushlandupslope from an urban area as weeds are not able to invade areas uphill from infestations asefficiently as in downhill situations. A list of the weed species associated with this Management Unitis in Section 5 of the VMP.Core BushlandThe Core Bushland is generally in good condition and free of most significant weed species.Disturbance and increases in the soil moisture and soil nutrient levels provide optimal habitat formost of our urban weeds. Such impacts occur more frequently along riparian corridors; at theurban-bushland interface; and in disturbed areas in service corridors and on major tracks, especiallywhere fill soils have been imported. The Core Bushland is generally isolated from such impacts(unless of course, where trails or vehicular tracks provide a ‘wick effect’ from external weedy areasinto the core).It is a commonly held belief that weeds do not invade undisturbed bushland, and that core bushlandis relatively immune to weed invasion. While this generally holds true, it is important for landmanagers to understand that some weeds – especially those species whose seeds are spread bybirds or other animals – are able to establish in undisturbed core bushland if a suitable niche occurs(e.g. a gap created by a tree fall, animal digging or bushfire). Weed species that are commonlyfound in ‘undisturbed’ bushland and where soils are unaffected by urban runoff include (amongothers) Cinnamomum camphora (Camphor laurel), Ochna serrulata, Senna pendula (Cassia) andAsparagus aethiopicus (Ground or Fern Asparagus).The greatest potential threat to the Core Bushland Management Unit is fragmentation, which wouldresult if new trails, vehicular tracks or new service corridors are created through the core bushland.Any proposal to create new tracks or trails through Core Bushland should seriously consider theimpacts of fragmentation. Where such disturbance is unavoidable (e.g. where new services arerequired to support residential development), a pre-construction weed control program should bean integral part of the construction process; and weeding should be a permanent feature of anyUBM Ecological Consultants Pty Ltd 69