The Wingecarribee Bioregion

Bundanoon bike cafe

overlapping maritime/montane air sheds

dry sclerophyll woodland near Bundanoon

[Below a summary of the Wingecarribee bioregion we live within here in Bundanoon.]

THE WINGECARRIBEE BIOREGION – KEY FEATURES

1. BIOGEOGRAPHIC PROVINCE

The Wingecarribee bioregion is situated within the northern section of the larger Southern Tablelands region of New South Wales, Australia. This stretches roughly from the edge of the Sydney Basin’s Cumberland Plain at Picton in the north to the Snowy Mountains in the south. The Southern Tablelands in turn can be ecologically located within the larger province or biome of the South-East Australian Eucalypt Forests which follow the Great Dividing Range from subtropical northern NSW to the Snowy Mountains and then beyond through eastern Victoria to cool temperate eastern Tasmania.

2. TOPOGRAPHICAL BOUNDARIES

Within the Great Dividing Range, the Wingecarribee bioregion can be fairly clearly bounded geologically by the edges of the Moss Vale Plateau on which it is largely situated. This is a strongly dissected montane tableland (c. 600-800 m) of the Illawarra Plateau within the larger Sydney Basin. The common name for the region is The Southern Highlands. Although all such boundaries are to a large extent arbitrary, the bioregion could thus be seen to begin in the northern foothills rising from the Cumberland Plain at Camden/Picton, then becoming bounded by the Woronora Plateau to the north-east, the sheer Illawarra escarpment to the east, the heavily dissected sandstone gorges of the Shoalhaven River to the south and south-east, and the heavily dissected sandstone gorges of the Wollondilly River to the west and north-west. (The latter in turn borders on the geologically and climatically quite distinct granitic Lachlan Fold belt).

3. CLIMATIC EDGE

The Wingecarribee bioregion is located within a montane transition zone of overlapping maritime and continental climates. Coastal precipitation from the Pacific Ocean (Tasman Sea) is very significant at the eastern edge, providing about 2000 mm/p.a. at Robertson on the Illawarra escarpment. The rainfall isohyets then fall off remarkably quickly as one moves further west, with Bundanoon receiving 1160 mm, Bowral 960 mm, Berrima 700 mm. The distance between Robertson and Berrima is only c. 40 km. There is also a lesser north-south thermal altitudinal effect, with a greater sense of montane coldness south of High Range/Mt Gibraltar (800m) at Mittagong/Bowral. There are also overlapping air sheds from/to Sydney at High Range and from the coastal Illawarra region at the eastern escarpment. Fresh, clean mountain air commonly flows northwards down to the Cumberland Plain/western Sydney Basin in the early mornings.

4. HEADWATERS AND WATER CATCHMENTS

The Wingecarribee bioregion is located within the Southern Highlands Subsystem of the large Wollondilly-Hawkesbury-Nepean Catchment, stretching from Tarago near Lake George in the south through several shires and then western Sydney to enter the Pacific Ocean at Pittwater at the northernmost point of Sydney’s northern beaches region. The Southern Highlands sub-catchment contains the headwaters of three main smaller sub-sub-catchments: the Wingecarribee River Catchment in the centre feeding westwards into the Wollondilly River, the Paddy’s River Catchment in the south also feeding into the Wollondilly, and the Nattai-Bargo-Nepean Catchment in the north feeding into the Nepean River. A few smaller creeks and the headwaters of the Kangaroo River also drain away to the south-east into the Shoalhaven River catchment which enters the sea near Nowra. Since the bioregion is topographically so heavily dissected, there are at least fourteen smaller sub-sub-sub-catchments around the creeks feeding into the above three main sub-sub-catchments. The Wingecarribee bioregion is thus climatically, topographically and hydrologically one of great internal variation, differentiation and edge (it is ecologically ‘fine-grained’) and this is no doubt makes up a large part of its both ecological and aesthetic significance.

5. SOIL ZONES

The region contains four main soil types and their associated soil and plant communities. Low-fertility Hawkesbury Sandstone soils define the rugged edges, often still in wilderness condition, to the north, north-east, west and south. Medium-fertility Wianamatta Shale soils (over sandstone bedrock) are located mostly around the centre of the region. Higher-fertility Tertiary Basalt soils (over shales) occur in important pockets to the east and south of Moss Vale. Alluvial soils are found along the rivers and on the Wingecarribee floodplain.

6. MAIN PLANT ASSOCIATIONS

The bioregion contains four main native plant associations, closely linked to soil types, rainfall patterns and fire regimes (or lack thereof).

(a) Closed Forest, or Warm and Cool Temperate Featherwood and Plumwood Rainforest.
Originally in the high rainfall, maritime-influenced areas near the eastern Illawarra escarpment and mostly on fertile basalt soils. Cleared in the nineteenth century for dairy and potato farming, only very small remnants of this unique type of rainforest remain. Main species: Polyosma cunninghamii, Doryphora sassafras, Quintinia sieberi, Ceratopetalum apetalum, Eucryphia moorei, Eucalyptus fastigata, Acacia melanoxylon.

(b) Tall Open Eucalypt Forest (Wet Sclerophyll).
Mostly on shale soils. Dominant species: Eucalyptus viminalis, E. obliqua, E. macarthurii, E. radiata, E. cypellocarpa, E. quadrangulata. Much of this association has also been cleared for farming, particularly beef cattle.

(c) Open Eucalypt Forest (Dry Sclerophyll).
Mostly on sandstone soils to the north, west and south. Dominant species: E. sieberi, E. sclerophylla, E. agglomerata, E. piperita, E. mannifera, E. pauciflora.

(d)‘Fire Climax’ Tall Eucalypt Woodland.
This is a more conjectural association based on early explorer documents which all speak of an ‘English woodland or park’ impression, a landscape created by the ‘fire stick farming’ practices of the original indigenous inhabitants.

(e) The fifth association is one composed of introduced pastures and trees (especially Pinus, Salix, Cupressus in the rural areas) and now dominates much of the central and eastern rural sections of the bioregion, albeit sometimes with surviving remnant native trees, often senescent.

7. HUMAN COMMUNITY

From 1816 onwards the hunter-and-gatherer practices and fire-stick farming of the Gundungurra tribe was replaced by a European cattle grazing, cropping (vegetables, potatoes, apples) and small town services regime. Little is known about the Gundungurra tribe. Its tribal area is deemed to have gone beyond the Wingecarribee bioregion proper to include the Colo River catchment of the Blue Mountains to the north down to the Goulburn region in the south. The original population was probably no more than 400. There was a massacre of the tribe by government troops near Appin in 1816. The last original Gundungurra died out around Goulburn in the 1840s and in the wild Warragamba catchment around the beginning of the 20th century. The first white settlers were invariably amazed at the ‘English parkland’ look of the central area of Wingecarribee, a grassy, open-wooded landscape on fertile soils – ideal herbivore habitat – that was a product of Gundungurra firestick regimes. White settlement of course quickly produced a European class society, with wealthy large grazing properties (and later less wealthy dairy farms) on the better soils and the less wealthy on the poorer soils or (as tradesmen, small retailers or service personnel of the wealthier) in the small towns and villages. This basic class and settlement pattern has in essence continued to this day. From the late nineteenth century onwards, the area (known as the ‘Southern Highlands’), became known as a summer escape haven for wealthy Sydneysiders and, later, a highland tourist destination for all classes. With the gradual eclipse of farming since the 1950s, tourism, education and local government have now become the major sources of local employment. This trend, expanded freeway connections to Sydney (about 120 km away) and the resulting real estate- and car-driven suburbanization have greatly increased local real estate prices, helped decrease the viability of farming even further and increased environmental pressures on the bioregion (particularly on rivers). The current population of the Wingecarribee Shire (c. 2 500 km2) is about 45 000. Both older people/retirees and young children are over-represented, the suicide rate is alarmingly high and the ethnic makeup is overwhelmingly Anglo-Celtic.

~ by Peter Lach-Newinsky on November 6, 2011.