This park is part of ...
Greater Blue Mountains World Heritage Area
The massive Greater Blue Mountains World Heritage Area was inscribed on the World Heritage list in December 2000. It covers one million hectares – around twice the size of Brunei. Half of it is wilderness.
Eight conservation reserves make up the Greater Blue Mountains World Heritage Area:
Blue Mountains National Park
Wollemi National Park
Kanangra-Boyd National Park
Yengo National Park
Gardens of Stone National Park
Nattai National Park
Thirlmere Lakes National Park
Jenolan Karst Conservation Reserve.
The World Heritage Area is divided into four geographical sectors reflecting changes in landscape and vegetation. Each is named after a local landmark with an Aboriginal name: Monundilla (north-west), Mellong (north-east), Kedumba (central) and Colong (south).
Reason for World Heritage listing
Why was the Greater Blue Mountains area accepted as World Heritage? It's not just because of its magnificent scenery, or the blue mist that covers the landscape, produced by the eucalypt forests as they release fine droplets into the air. It's those forests, more than anything else, which make the area so special.
The Blue Mountains have been described as a natural laboratory for the evolution of eucalypts. In the mountains' diverse plant communities, you can trace the changing nature of the Australian environment – from geological shifts and climate variations, through to the impact of Aboriginal settlement and European colonisation.
More than 90 different eucalypt species are found in the Greater Blue Mountains – some 13 per cent of all eucalypt species in the world. They grow in a great variety of communities, from tall closed forests, through open forests and woodlands, to the stunted mallee shrublands on the plateaus. Among them are rare species like Baeuerlen's gum.
The World Heritage list covers a lot of Australia's biodiversity, particularly in rainforests and desert areas. However, the list has tended to leave out the environments that lie in between the wet and the dry. By including the eucalypt forests of the Blue Mountains, the World Heritage list now holds a more complete picture of Australia's natural diversity.
Why is the mountain vegetation so diverse?
As anyone who's spent time exploring the Blue Mountains can tell you, the mountains can't be taken lightly. Weather and terrain can vary enormously, and you need to prepare for a wide range of environmental conditions. But while we can equip ourselves to cope with different environments, many plants cannot. Particular plant communities can only occur where the conditions are suitable. Since the conditions in the Blue Mountains vary greatly from place to place, the plant communities do as well.
So what's behind the mountains' extreme environmental variability? It's a combination of many factors, including:
Altitude and climate. As the altitude increases, the climate becomes colder and wetter. Frost, fog and some snow can occur in the Upper Mountains, where conditions are generally colder and harsher. However, the climate is much warmer in the lower eastern areas. The boundaries of the Upper and Lower Mountains are at Wentworth Falls (if you're travelling on the railway or the Great Western Highway) and at Mount Tomah (if you're on the Bells Line of Road). You'll notice the change in altitude – and vegetation – as you reach these places.
Rock types. Through the processes of weathering, rock breaks down into soil – and some rocks create more fertile soils than others. The mountains' different types of sandstone break down into relatively infertile soil which holds little moisture – although the Narrabeen sandstone of the Upper Mountains produces more fertile soils than the Hawkesbury sandstone found in the east. Shale and basalt rocks, however, form a brown, loamy soil which is full of nutrients and retains more moisture. Rich plant communities – such as rainforests – are more common on these soils.
Drainage. The plants in most areas of the mountains have adapted to soils that hold little water, but in some places very different conditions prevail. Where there are layers of impervious rock, such as claystone or ironstone, moisture may build up, waterlogging the soil. Specialised swamp communities will be found here.
Fire history. Fire plays an important role in the growth and development of vegetation communities in Australia. Many plants rely on fire to regenerate their populations: some have dormant buds which regrow after fire; others release their seeds into the ground that has been cleared by flame and made more fertile with ash. Many other plants, however, will only thrive in the absence of fire. Before the colonisation of Australia, Aboriginal people used planned fires to create a 'mosaic' pattern of vegetation of different ages. However, since the arrival of European settlers, bushfires have become more frequent and more intense. Changing fire patterns bring about different plant communities.
Aspect. When you go walking in the mountains, you might notice that certain plant communities are more common on slopes facing a certain direction. The aspect of the slope determines how much sunlight it gets, and which winds it is more exposed to. It will attract the plant communities that are most adapted to those conditions.
Slope. The steeper a slope, the more quickly water will run off it, taking nutrients with it. Some plants can grow on steep slopes; others need more level ground.