Pressures on the Park
The narrow Berowra Valley is surrounded by developed or developing suburbs, all on higher ground. Water, eroded soil, chemicals and solid wastes move down-slope from these suburbs into the bush.
Rubbish and erosion
Rubbish spilling into the Park along creeks from the edges of ring roads and from adjacent backyards, or left behind by visitors, is an eyesore and a threat. Erosion caused by stormwater from the built-up areas, and
siltation from soil washed down from housing developments, are particularly harmful to creek beds. All major creeks have suffered severe damage, and new housing development close to the Park exacerbates this problem.
More widespread and serious, yet less obvious to the casual observer, is the fact that much more water enters the Park from the surrounding suburbs than comes from undeveloped land. Every stormwater outlet serving backyards
and streets releases water into the Park containing such chemicals as phosphorus that act as plant fertilisers. This water encourages the growth of weeds, which flourish and displace the native plants. Why this happens is
because the native plant species in the low-phosphorus and quick-drying sandy soils of the Park, through long adaptation, do best under conditions of low levels of nutrients and a fluctuating water supply. When there is
plenty of polluted water around, it is other plants that thrive: the weeds.
The consequences can be seen all around the edge of the Park and along all creeks. Wherever stormwater enters the Park, wherever garden refuse has been dumped, and wherever new soil has come in or fill has been dumped,
patches of privet, Honeysuckle Lonicera japonica, Lantana Lantana camara, Kikuyu Grass Pennisetum clandestinum, Tradescantiafluminensis, Blackberry Rubus fruticosus, Crofton Weed Ageratina
adenophora, and many other weeds run rampant. The limits of each infestation show precisely how far the increased ‘nutrients’ or increased water have reached.
Weeds and introduced plants are listed in the Appendix entitled ‘Introduced plant species’. While not all of these plants are present in the Park, they have been recorded in the broader Berowra Valley. This list
is included in this Guide to encourage people to recognise such plants, to remove weeds from their gardens, and to seek Council advice about eliminating weeds from nearby areas. This will help prevent the spread of weeds into the Park.
The Berowra Valley Regional Park and adjoining land provide a habitat for a wide range of flora and fauna. Carefully planned fire management is essential in protecting the Park and the species found within and around it.
For this reason a draft fire management plan was developed and exhibited in 1999–2000, and forwarded to the Minister for the Environment for final approval. The aim of the plan was ‘to manage the vegetation of the
Park so that bushfire hazard levels do not surpass acceptable risks to surrounding areas, while achieving conservation, recreation and aesthetic goals, and thus conserving biodiversity’.
Fire has an important role in bushland communities. Many plants in the Park are associated with Hawkesbury sandstone conditions and may require fire and/or drought at some stage in their life
cycle. Current research suggests that the Aboriginal people of Sydney burnt the bush in a complex series of mosaics, and that they may have chosen the windiest months, August and September, for burning. On the slopes and some
plateaus the bush appears to have been burnt at intervals of around ten to fifteen years, whereas the more fertile valleys and ridge tops may have been burnt as frequently as every four years. As the numbers of Aborigines
fell, so did their springtime burns decline. This resulted in the massive accumulation of fuels, which led to devastating fires in the late 1890s and through to the present day. Since the 1950s authorities have tried to
emulate the Aboriginal use of fire by developing a policy of hazard reduction controlled burning.
Such controlled burns were first carried out in the autumn or early winter but, in the light of increased ecological knowledge, they have been held progressively later in the year, in line with Aboriginal practices.
Fire management is necessary also for the protection of both life and property. Owing to prevailing north-westerly winds on high fire-risk days in summer, wildfires have the potential to
spread from adjoining bushland to the north and north west of the Park, threatening populated areas on the Park’s eastern and southern boundaries. Minimisation of fire risk to residents
involves cooperation and coordination with the community, through volunteer bush fire brigades and the responsible actions of residents.
Fire breaks are provided by natural features within the Park: these include streams, exposed rock outcrops, and south facing slopes, which generally have a higher moisture content.
In areas of the Park where there are insufficient natural features, fire trails provide fire breaks and also allow access for inspection, hazard reduction and firefighting purposes.
Since 1976, no wildfire has evaded suppression within the Park. Since the 1960s unscheduled fires were controlled using the resources of Hornsby Shire Council and the Volunteer Rural Fire Service. Since the gazetting of the
Regional Park in March 1998, these resources have also included those of the NSW National Parks and Wildlife Service.
The Park is assessed for fire hazard on the basis of fuel loads present, the topography, ecology and proximity of residential areas. Hazard reduction burns are conducted, if required, during the cooler months of the year.
The conservation and protection of cultural, scenic, aesthetic and recreational opportunities within the Park are an important part of fire management, and are considered carefully before any action is undertaken.
Auld, B.A. & Medd, R.W. 1987, Weeds: An Illustrated Botanical Guide to the Weeds of Australia, Inkata Press, Melbourne.
Draft Fire Management Plan for the Berowra Valley Regional Park, NPWS and BVRP Trust, 2000.
Hornsby Shire Council, Water Catchments Team, Environment Division 1995, Berowra Valley Bushland Park: Draft Plan of Management: Stage 2, Hornsby Shire Council, Hornsby.
Hornsby Shire Council 1997, ‘Noxious Weed List’, NSW Government Gazette, 7 Feb.
Parks and Gardens Branch 1990, ‘Berowra Valley Bushland Park: Draft Plan of Management Stage 1’, Hornsby Shire Council, Hornsby.
Swarbrick, J.T. & Skarratt, D.B. 1994, The Bushweed 2 Database of Environmental Weeds in Australia, 2nd. edn, University of Queensland Gatton College.
Water Catchments Team, Environment Division 1996, ‘Berowra Valley Bushland Park – Plan of Management Stage 2’, Hornsby Shire Council, Hornsby.