VEGETATION MANAGEMENT PLAN for Bidjigal Reserve - Land

Vegetation Management Plan - Bidjigal Reserve6.12.3 Loss of Pollination Vectors & Seed Dispersal AgentsSome of the effects of inappropriate fire regimes on native fauna and their habitats have beendescribed above. Too much or too little fire may result in a loss of species and/or populations, and ifthe bushland is a small, simplified remnant, isolated from other bushland areas, local extinction ofsome fauna species is possible. This is particularly true of those species that depend on theavailability of a specific habitat type or food source.It is generally accepted that there has been an incremental loss of many birds, reptiles and nonarborealmammals from urban bushland remnants as habitat values decline and these remnants arefragmented and degraded by a range of impacts.A decline in vigour and/or the loss of fire-adapted species in long-unburnt bushland will generallylimit opportunities for flowering and fruiting. Where this is the case, there is likely to be a decline inpollinating insects and birds. As many of the larger fauna responsible for seed dispersal have alreadyleft the smaller remnants, or are thought to visit only infrequently, this would have seriousimplications for the viability of the bushland as a self-sustaining ecological unit.When considering rehabilitation strategies for small, fragmented or isolated bushland remnants, itmust be recognised that the full range of flora and/or fauna species once known for the area/localitymay never be restored. Certainly planting programs can re-establish the floristic component of thehabitat (within reason), but unless (faunal) pollination vectors and seed dispersal agents are present(or can be re-established), the system will not be self-sustaining.It must also be acknowledged that very few faunal re-introductions carried out in the past beenwholly successful, even in wilderness areas, so that the prognosis for such a strategy in the urbanenvironment is poor. However, for bushland remnants close or adjacent to larger bushland areas, orfor those sites where connectivity can be re-established to encourage faunal migration, theprognosis for re-establishing a functional habitat is much greater (see Section 6.9).6.12.4 Loss of Ecosystem ResilienceEcosystem resilience is defined as “the degree, manner and pace of restoration of the structure andfunction of the original ecosystem after disturbance” (Westman 1978).When assessing ecosystem resilience, key indicators will include the diversity and abundance of thestanding biomass, the potential reservoir of propagative material (seeds, spores, rhizomes) in thesoil seed bank (although this is difficult to assess without extensive trials), and the vicinity to otherbushland. Although site resilience is more correctly defined as in situ potential, in practice thepotential for recruitment of plant material from nearby bushland must also be considered.A fundamental tenet of the Bush Regeneration Movement (Bradley 1988) is the ability of thebushland to heal itself through a process of natural regeneration. In practice, this approach dependson the sites resilience. Various techniques, including scarification of the soil surface and pile burnsare used to stimulate this seed reservoir; with varying degrees of success.The resilience of bushland remnants in the Shire will be highly variable. For small, isolated orfragmented reserves, site resilience may be low as a result of past land uses, changes to the soilprofile and soil chemistry, suppression of the natural fire regime, dominance of the understorey byUBM Ecological Consultants Pty Ltd 130