Botanic Gardens Trust, Sydney, Australia

Climate, physical features and habitats

Climate

Climate has a major impact on Cumberland Plain Woodland ecology; rainfall and temperature patterns have a strong and direct influence on vegetation.

Rainfall

Averaging rainfall figures for recording stations in the Australian Botanic Garden area gives a long-term average of about 730 mm per annum for the period 1850 to 1960, with a higher average of about 830 mm for 1950 to 2004. Rainfall since 2000 has been considerably lower with all years (up to 2006) receiving less than 700 mm (based on records for Eaglevale). Recent figures are well below all long-term averages.

Long-term average annual rainfall records are 747 mm at Campbelltown (period 1845-1961); 764 mm at Camden (Bowling Club) (1883-1968); 683 mm at Menangle (Camden Park) (1878-1968); 828 mm for Camden Airport (1943-2004); 830 mm at Campbelltown Swimming Centre (1959-1984).

Mean monthly rainfall peaks in February (99 mm) and March (94 mm), and is lowest in September (43 mm) (based on Camden Airport records 1943-2004).

Temperatures

Temperatures are important for seed germination. Air temperatures are hottest in January with a mean daily maximum  of 29.2 °C and a highest recorded maximum of 45 °C. Temperatures are coldest in July with a mean daily minimum of 2.9 °C and a lowest recorded minimum temperature of -6 °C (based on Camden Airport records).

We have recently begun monitoring soil surface and subsurface temperatures, in shaded and unshaded sites in the woodland, to relate laboratory experimental work to field conditions. For images and graphs of recent climatic events go to Climate picture gallery. You can also see today's weather details at the Australian Botanic Garden.

Diary of seasonal conditions

To give an idea of seasonal conditions in the woodland we’ve included a month by month account based on Jocelyn Howell's diary records in 2001-2003, with some delightful illustrations by Nancy Rollason. If you would like to look at this diary see A Year in the Woodland.

Soils and geology

The Conservation Research Woodland occupies a gentle east-facing slope from a ridge running along Mount Annan Drive about 130 m elevation to Mount Annan Creek (110 m elevation), a change in elevation of about 20 m.

Soils are derived from Bringelly shales in the Wianamatta Group, and are yellow podzolic on the hillside with some alluvium along Annan Creek.

Localised habitats

While the woodland vegetation has been our main area of interest, sites with particular soil, topographic or past management conditions within the general woodland context provide localised habitats and microhabitats for particular plant species . These are important to maintain the full range of local biodiversity. Within the woodland localised habitats include

  • Dry gully habitat in the northern part of the woodland provides locally moister conditions and habitat for the ferns Asplenium flabellifolium and Pellaea falcata, and the climbers Cayratia clematidea and Parsonsia straminea.
  • Shady area habitat on slopes provides habitat for Plectranthus parviflorus, Scutellaria humilis and Ranunculus lappaceus
  • Under tree habitat has a species composition that includes a higher proportion of species with fleshy fruits such as Einadia nutans subsp. linifolia and Einadia nutans, and the woody weed African Olive *Olea europea subsp. cuspidata though the more shaded conditions may also influence species composition.
  • Bare area habitat may be temporally colonised by ephemerals during wet periods, such as Crassula sieberiana, Ranunculus sessiliflorus, and mosses, lichens and algae.
  • Mown area habitat, though favouring exotic grass species such as couch, *Cynodon dactylon and Paspalum, *Paspalum dilatatum, may sometimes provide habitat for ephemeral herbs such as Solenogyne bellioides and Solenogyne dominii, depending on weather conditions.
  • Roadside habitat and paths provide habitat for a number of weed species as well as Chloris truncata, Bothriochloa macra, Cotula australis

Away from the woodland are other important habitat areas including

  • Riverflat forest habitat along Mount Annan Creek on the eastern side of the woodland, with some very large trees of Eucalyptus tereticornis. The creekline itself includes sedges and Typha (Bullrush).
  • Dam habitat at a small dam below the woodland as well as larger ones further along Mount Annan Creek. These provide habitat for aquatic and semiaquatic plants. Additional native species, not necessarily local ones have been established in the larger dams.
  • Grassland habitat - there are some large areas of open, periodically mown grassland adjacent to our woodland, and elsewhere in the Gardens. Grassland /woodland interfaces are currently the focus of some of our ecological studies.
  • Woodland Picnic area a gardened habitat providing picnic facilities. Even during dry seasons visitors can see a range of woodland plants in flower as a result of irrigation water.

Asterisk * indicates exotic species naturalised at Mount Annan Botanic Garden.

Ecology of Cumberland Plain Woodland

Annual rainfall
Annual rainfall 1986-2005 (Mount Annan area)

Rainfall 01-05
Monthly rainfall 2001-2005 (Mount Annan area)

Annual temperatures
Air temperatures for Mount Annan area 2001-2006

Soil profile
Woodland soil profile showing shallow A horizon (5 cm ) over clay B horizon.