The Nature of different greens

Shortly after I moved to Robertson, I was inspired to write a brief poem called "Green Over Grey". Looking at this photo, it should have been called "Green over Blue".

I was writing about the way my view, locally, is dominated by bright or deep green colours - the colours of the Sassafras Trees and other "rainforest plants". However, the distant view, out over Kangaroo Valley and the Shoalhaven, is coloured the familiar bluish-grey tonings of Eucalypt forests. And, of course, on warm days the "Eucalypt haze" which gives the famous "blue" colour to the Blue Mountains, and most of our other distant hills in temperate Australia.

I have been experimenting at creating "panoramic shots", simply using basic cut and paste techniques, to portray the wider vista which my eyes see every morning. This is, of course, a much wider vista than one gets through a camera lens. I have not yet mastered the techniques involved, but hopefully you get the general idea.

Study the colours in the photograph above, and straight away, you will see the different intensity of the greens in the closer trees. Sassafras and Blackwoods have truer greens than gum trees. Of course, the pasture grass areas also have a different green, a lighter, yellower green. But not the blue-greys of the distant forests.<>

There are good "biological" reasons for the different tonings of the typical Australian bush, mostly to do with ultra-violet protection on the leaves, and coatings which minimise transpiration from the leaves. These are classic adaptations made by plants from hot, dry climates. Botanists describe these forests as "dry sclerophyll forest", a reference to the toughness of the leaves of most of the plants which live in such forests.That is how the Eucalypt forests have adapted. Hence their blue-grey colour, which typifies the Aussie bush.

Here is an early photograph showing the trees on my property (just after the paddock had been slashed). Look at the colour of the trees. These "cool temperate rainforest" plants grow in cooler, wetter areas, and often need to survive in low light conditions (as seedlings in a dense forest). Consequently, they are rich in chlorophyll, to maximise their uptake of light. Given that they typically grow in wet areas, they are less stressed by moisture loss, so they have not adapted as much to the UV protections the other native plants use. Put simply, their adaptations are more towards maximising the use of light (in dense forests) than towards adaptation to the typical Aussie dry climate conditions.

I should explain that there are major soil type differences between the Robertson area (deep, rich red basalt soils, high in fertility) and the distant Eucalypt forests, which are growing on Sandstone, (very old, leached out soils, low in fertility). Another difference is rainfall. Robertson is higher than the surrounding areas, and gets more rain, and much more fog. So, the rain which does fall can penetrate deeply into the fertile soil - where the tree roots can utilise it, to support vigorous plant growth.

Visitors to Robertson always remark on how "green" everything looks. It is not just the greenness of the paddocks, though in a wet season that can be pretty remarkable too (not this year). The real difference in "greenness" is from the different adaptation to "light absorbtion" made by the dominant forms of trees in the local area - rainforest trees, contrasted against the "light protecting" adaptation of the typical Eucalypt forest plants.