Autumn Colours of Australia

Aussie autumn doesn't kick off in earnest until March. And while you wouldn't usually associate the land of beaches, surfing and summer heat with glorious autumnal colour, some places are really beautiful in Fall. Unfortunately there are not many places in Australia where you can enjoy autumn colours when the leaves start to change colour, from green to yellow, orange and varying shades of red. The cooler areas of Australia are the best for autumn colour - Perth, Melbourne, Sydney, the Adelaide hills, the mountains and Tasmania. The most popular places for enjoying autumn foliage is probably Mount Wilson and Blackheath in Blue Mountains near Sydney, Orange in NSW, High Country in Victoria and especially around Bright and Mount Beauty, Dandenong Ranges, Canberra.

It is the deciduous trees that lose their leaves in the winter and in the process undergo changes in colour in the autumn. While there are deciduous trees in many parts of Australia, they may not make much impact with massed autumnal colour changes.

Autumn colours depend upon the genetic make-up of the particular species, upon the rainfall and hours of sunlight it receives, and the temperatures experienced in autumn, when the plant stores sugars and other nutrients. Cold nights and even frosts are required for the development of the deepest colours in deciduous trees. The production of green chlorophyll falls as the nights become longer and other compounds increase, also assisted by high sugar levels in the leaves. Red and purple pigments come from anthocyanins. In the autumn anthocyanins are manufactured from the sugars that are trapped in the leaf. In most plants anthocyanins are typically not present during the growing season. As autumn progresses, the cells in the abscission layer become more dry and corky. The connections between cells become weakened, and the leaves break off with time. Many trees and shrubs lose their leaves when they are still very colourful. Some plants retain a great deal of their foliage through much of the winter, but the leaves do not retain their colour for long. Like chlorophyll, the other pigments eventually break down in light or when they are frozen. The only pigments that remain are tannins, which are brown.

Temperature, sunlight, and soil moisture greatly influence the quality of the autumn foliage display. Abundant sunlight and low temperatures after the time the abscission layer forms cause the chlorophyll to be destroyed more rapidly. Cool temperatures, particularly at night, combined with abundant sunlight, promote the formation of more anthocyanins. Freezing conditions destroy the machinery responsible for manufacturing anthocyanins, so early frost means an early end to colourful foliage. Drought stress during the growing season can sometimes trigger the early formation of the abscission layer, and leaves may drop before they have a chance to develop autumn colouration.

A growing season with ample moisture that is followed by a rather dry, cool, sunny autumn that is marked by warm days and cool but frostless nights provides the best weather conditions for development of the brightest autumn colours. Lack of wind and rain in the autumn prolongs the display; wind or heavy rain may cause the leaves to be lost before they develop their full colour potential.

Many places like Melbourne, Mount Wilson and Adelaide Hills have beautiful gardens opened to public to welcome the stunning sight of autumn with explosions of gorgeous gold, pink, brown and radiant red colours.