The stately salmon gum tree native to western Australia, can grow in access of seventy feet tall with a diameter of thirty inches or more. The bark is reddish pink in color, hence the name Salmon, but fades to grey in late summer. Its branches spread upward and outward forming a glossy green canopy or umbrella crown.
The wood is very durable and has many uses. Its reddish color and smooth grain makes it ideal for flooring, paneling, furniture, and musical instruments; while its strength lends its use to bridges and mining timbers.
A study on the salmon gum in a patch along the northern wheat belt of western Australia began in 1978. This patch was a breeding area for six species of cockatoo, two of which were on the endangered list. The trees were measured and photographed and further visits from 1981 through 1997 showed an alarming decline in the condition of the trees. Based on the rate of decline in this time period is was predicted that by 2125 only eleven percent of those trees would still be in existence in that area.
In 1929 this patch had been cleared for agricultural use and domestic livestock grazing. There had been, according to the study, no regeneration of the woodland trees since that time. This deterioration of native woodland is symptomatic over vast areas because of Australia’s excessive clearing of the wheat-sheep regions. The future of woodland patches such as the one in the study looks bleak for not only the trees and vegetation, but the animals that depended on those areas for food, breeding sites, and shelter.
At this time, measures are being taken to counter-act this problem, including fencing to exclude domestic animals from grazing the area. However fencing alone will not save this majestic tree since seedlings are failing to establish and no new trees are taking hold.
Dr. Colin Yates began studying the salmon gum several years ago to find out why this is happening.
According to Dr. Yates report, the salmon gum was once very widespread, but after the clearing for agriculture they are extremely restricted in the wheat belt although they are still widespread in an area east of there in the goldfields area. However, almost 97% of them have been lost from the Australian landscape.
In the goldfields area, the tree is regenerating after disturbances such as fires, floods, and drought. Yet in the wheat belt area, where the trees were producing viable seeds, they were not regenerating and their ability to establish seedlings were diminished. Dr. Yates believes livestock grazing is one of the key factors associated with this problem and that extensive grazing has resulted in the loss of root system species and has damaged the soil cryptogramic mats which are important for nutrient cycling.
Quoting Dr. Yates, “These are lichens, blue green algae, mosses and that’s about it. They are quite important in those woodland ecosystems in that they protect the soil from raindrop splash, protecting the soil surface from erosion, but they are major pathways for fixing nitrogen into the ecosystems and also contribute to the soil organic matter and nutrient cycling in general. So, the loss of under storey resulted in changes to the micro climate. Processes like soil watering filtration and nutrient cycling and what was most evident was that soil water infiltration, in the heavily grazed degraded remnants was about 50% compared to remnants which hadn’t been grazed.”
Because of these conditions the water infiltration rates are so diminished that the water, which is very limited in this area, is running off the remnants and not penetrating the soil. Therefore the seedlings are finding it difficult to survive especially while competing with weed species or the area.
Dr. Yates along with Dr. Richard Hobbs has completed a three year study regarding the rehabilitation of the woodlands in Australia, and its findings show that the salmon gum is the worse case among the tree species. The study shows, however, that the young salmon gums can establish successfully with help of human intervention and at this time they are helping land owners access and restore their woodlands.
Also lending a hand, according to the Australian Aboriginal Culture & Didgeridoo News there is a project at work for the re-vegetation on degraded lands. According to their article, the over clearing done as early as the 1830’s has resulted in woodlands which are very poorly represented in small and isolated reserves. Those that remain on private land have been degraded by grazing and weed invasion. This project is helping land owners plant 4500 seedlings under the title of “Farm Tree Help Scheme” of the “Men Of The Tree” organization to strengthen and re-vegetate the farms with a vision of creating a better future.
However, there is another problem Australia must deal with and that is the spreading expanses of farm lands that are no longer fertile because of the advance of sheets of surface salts. This is the “White Death” that may have destroyed ancient irrigation systems, civilizations, and eco-systems. It is presently attacking Australia’s precious resource of agriculture.
There are vast amounts of salt everywhere in Australia, mostly underground It has been building up for many thousands of years from the weathering of rock minerals and the simple act of sea salt dropping from rain and wind storms. The native Australian vegetation evolved to be salt-tolerant. The woodland species for example have deep roots and a high demand for water. While the system was in balance, the salt stayed put, but with the arrival of European farming, native species were replaced with crop and pasture plants. These plants have shorter roots and need less water and the inevitable happened! With each rain, the unused water drained down to the water table, raising it, and bringing the salt water to the surface.
Under the Western Australian wheat belt the salt water is so immense and the movement of the sub-surface water is so slow, that restoring that area to fertility may take generations. Sadly some areas may never recover.
However, there are initiatives calling for involvement by the government, environmental groups, community groups, land care associations, farmers and concerned individuals to try to make a difference by getting involved and searching for solutions to fight salinity and land degradation.
At the same time the “Men Of The Trees” have set objectives for the replanting by:
1. Assisting with contour banks and gullies in absorbing or diverting surface and underground water seepage thereby slowing soil erosion and the rise of salty water.
2. Creating windbreaks assisting in reducing wind erosion responsible for large amounts of top-soil loss.
3. Lowering the water table level where it is increasingly saline, to reduce the loss of native vegetation and fertile land suitable for commercial crops.
4. Vegetating dams combining water supply, wildlife habitat reserves, fish and crustacean breeding for food supply.
5. Wildlife corridors connecting high rocky outcrops to creeks and streams, working as whole on the rehabilitation of the re-vegetated farms.
The Australians have been sitting up and taking notice and they are aware that they have a huge battle on their hands to restore their land back to its former fertility. They are taking measures at this moment to create a better future for their descendants. Hopefully their efforts will pay off not only for human habitation, but for the salmon gum and others trees that are presently endangered.
My hat is off to you, Australia!
Sources:
http://www.wadidge.com.au/didgeridoo-news
http://www.cat.inist.fr
http://www.abc.net.au/rn/science/earth/stories
