Tag Archives: trees

Trees, the ancient Macedonians, and the world’s first environmental disaster


Anthony Dosseto, University of Wollongong and Alex Francke, University of Wollongong

It’s a simple enough equation: good soil is the key to good food. And good soil starts with trees.

Alexander the Great conquered a vast empire that extended from Greece all the way to India. However, his ancestors’ fortune was a mixed bag. A new series of studies show the ancient Macedonians may have been struck by one of the earliest environmental disasters linked to human activity.

Ancient sediment records sealed in lakes for thousands of years reveals how logging may have affected erosion, which ultimately destroyed the capacity of the ancient Macedonians to grow food.




Read more:
Soil is the key to our planet’s history (and future)


More trees, on the other hand, appears to have made soil erosion less susceptible to climate change. The lessons for modern people – and our future prosperity – are clear.

Soil is a kingmaker

Something wonderful happens when rocks, formed in the guts of the Earth, come into contact with air and water: they break down into clays (and other things) to form soils. Because of their ability to store water and nutrients, soils are the food basket of land plants and all the animals that feed on them, including us.

Preserving soil has been the key for success to all past civilisations. Those who lost it would rapidly be precipitated into oblivion. This happened everywhere: the Middle East, Greece, Rome and Mesamerica.

Preserving our soil should therefore be at the centre of our concerns (although it rarely gets a look-in on the nightly news).

Erosion isn’t just a problem because the land loses soil. This soil enters waterways, increasing the sediment load of rivers. This high sediment load harms freshwater and coastal ecosystems, including fish population and, ultimately, us. We therefore need to better understand how climate change and humans shape soil erosion.

Macedonian timber and the first environmental disaster

The chemistry of sediments deposited on lake’s bottom records how the environment changed over hundreds and thousands of years. Recently, we have studied sediments from Lake Dojran, straddling the border between Northern Macedonia and Greece. We looked at the past 12,000 years of sediment archive and found about 3,500 years ago, a massive erosion event happened.




Read more:
500 years of drought and flood: trees and corals reveal Australia’s climate history


Pollen trapped in the lake’s sediment suggests this is linked to deforestation and the introduction of agriculture in the region. Macedonian timber was highly praised for ship building at the time, which could explain the extent of deforestation.

A massive erosion event would have catastrophic consequences for agriculture and pasture. Interestingly, this event is followed by the onset of the so-called Greek “Dark Ages” (3,100 to 2,850 years ago) and the demise of the highly sophisticated Bronze Age Mycenaean civilisation.

Further to the west, at the crossroads between Albania and Norther Macedonia, Lake Ohrid holds a much longer storyline: an international scientific drilling program is uncovering the past million year of climate and environmental stories locked in Lake Ohrid sediments.

We recently looked at Lake Ohrid on a more modest time scale, similar to the Lake Dojran project: the past 16,000 years.

At Lake Ohrid, there are also signs of increased soil erosion around 4,000 years ago. These results are consistent with previous suggestions of a human role on soil erosion at other lakes in Greece.

Overall, there are clear signs that deforestation and the development of agriculture precedes the Greek “Dark Ages”. While the causal link cannot be established with certainty, this timeline could represent the first negative feedback loop where humans depleted environmental resources, which in turn harmed communities.

Trees can make soil less sensitive to climate change

Lake Ohrid tells us another interesting story: until 8,000 years ago, soil erosion was closely following climate change. During dry and cold periods, erosion was shallow, probably as a consequence of dry conditions; while during warmer periods, higher levels of erosion delivered more sediment to the lake.

Around 8,000 years ago, something interesting happens: trees become the dominant type of vegetation cover. While trees were already abundant in previous warm periods (and less during cold periods), from 8,000 years ago onwards, they overwhelm the type of pollen that fell into the lake and became trapped in the sediment.




Read more:
Forest soil needs decades or centuries to recover from fires and logging


This tree dominance has an important consequence for soil erosion: after 8,000 years ago, soil erosion became shallow and remained so, even while the climate continued to oscillate. We can see soil erosion became less sensitive to climatic fluctuations.

We already knew that trees, thanks to their deep roots, help stabilise soil and prevent its loss; what we learn here is that over a certain threshold of tree cover, they also make soil erosion much less sensitive to climate change.

Lake Ohrid provides us with an important lesson, especially as we are increasingly concerned with how our soil and water resources will be affected by global warming. If we want to preserve our soils and rivers (and feed our communities) we need to ensure that enough of our landscape is covered with trees.

Planting trees and forest management should not be a concern for nature enthusiasts only, but for all us – regardless of political inclination – who enjoy eating. Understanding the past is not simply about learning from our ancestors’ mistakes so we do not repeat them, but freeing ourselves from their grip so new paths unfold ahead of us.The Conversation

Anthony Dosseto, Associate Professor, University of Wollongong and Alex Francke, Research Fellow, University of Wollongong

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Advertisements

Alcohol brewed from trees and other fermented drinks in Australia’s Indigenous history



File 20180807 191022 k13wjv.jpg?ixlib=rb 1.1
A sample of the Eucalyptus giunnii plant, sometimes called a cider gum for its ability to produce an alcoholic drink without human intervention.
Shutterstock/Modest Things

Vladimir Jiranek, University of Adelaide

There is no doubt that Europeans brought a culture of brewing and consuming alcohol during their early migration and colonisation of Australia.

But there is also evidence that Aboriginal people were already aware of fermentation processes to make beverages, in much the same way that many other cultures around the world have done for millennia.




Read more:
‘Digital land rights’: co-designing technologies with Indigenous Australians


For example, social anthropologist Maggie Brady’s 2008 and 2014 work pulls together early European accounts of some Aboriginal practices. They involved the collection and production of sugar-rich solutions and extracts followed by an “incubation” to allow fermentation to occur.

I’m interested to know more about the nature, composition, flavour and aroma of the materials used in any Aboriginal fermentations, as well as the microbiology involved.

When members of the Tasmanian Aboriginal Centre (owners of the Trawtha Makuminya reserve) heard about this project, they kindly invited my research group to examine and sample Eucalyptus gunnii trees on their reserve.

A drink from sap

The Eucalyptus gunnii trees originate from the Central Highlands of Tasmania at about 1,000 metres above sea level. Perhaps the easiest material to use from these trees is the sap.

Dotted around frost hollows in poorly drained soils, prone to extreme cold, attack from animals and insect borers – presumably for the sugary bonanza they represent in their environment – the trees appear to cling to existence.

One subspecies (divaricata) is listed as endangered, and is apparently suffering the effects of climate change and grazing.

In the past, Aboriginal people tapped the trees to allow the sap, resembling maple syrup, to collect in hollows in the bark or at the base of the tree. Ever-present yeast would ferment the liquid to an alcoholic, cider-like beverage that the local Aboriginal people referred to as Way-a-linah.

The cider gums

The practice was adopted by the European settlers, such that when the species was described in 1844 for the first time by the British botanist Sir Joseph Dalton Hooker it was already known as the cider tree or cider gum.

In the absence of any detailed investigation of cider gum sap and the indigenous microflora inevitably associated with it, work was initiated late in 2016 to collect samples for analysis and yeast isolation.

Considering the remoteness of the trees, it was hoped they would yield novel strains of known yeasts, if not new species. Over the course of two field trips to central Tasmania, some 20 trees scattered across three large reserve areas were sampled.

Given their endangered status, no tapping was performed, nor was any required given pre-existing flows via fissures in the bark or holes produced by boring insects.

The presence of exposed runs readily attracted insects and supported a microbial population evident from the distinct vinegar-like aroma detected as one approaches the trees.

About 130 samples of sap droplets on the trees or larger volumes from pools, bark and soil were collected.

Natural sugars

Compositional analysis revealed sugars such as glucose, fructose and maltose as well as several organic acids and alcohol (ethanol). Across the samples there were clearly differences in the extent to which they had already fermented.

Thus sugar contents ranged from trace to several hundred grams per litre, while ethanol ranged between 0-6% alcohol by volume. By comparison, a full strength beer or cider contains about 5% alcohol.

Clearly the indigenous microflora are capable of producing an alcoholic beverage without needing human encouragement.

Extraction of DNA from relevant samples, followed by sequence-based attempts to identify the fungal species present (yeast is a micro fungi) revealed a highly variable and complex microbial population with between 10% and 90% of all sequence fragments failing to align with a known fungal genome.

In some cases these unknowns will have arisen out of sequencing issues or limitations in online fungal genome sequence databases. But new species or genera of yeast are possible and at least new strains of known yeast are highly likely. Certainly the uniqueness and isolation of the source sites would suggest this.

Since the above sequencing approach only recovers DNA, effectively telling us what was in the samples, parallel efforts sought to recover living yeast by traditional microbiological culture methods. To date we have preserved a small subset only, but even this represents about 1,500 individual isolates.

All are undergoing sequence-based identification. It’s noteworthy that the typical beer/wine/baking yeast, Saccharomyces cerevisiae, is virtually absent, while so-called non-Saccharomyces species such as Hanseniaspora osmophilia and H. valbyensis predominate.

Previously isolated examples of H. osmophila have been linked to high sugar environments (e.g. dried grapes) and are able to produce ferments with up to 11.6% alcohol, well within the level anticipated in fermented cider gum sap.

Low temperatures

Interesting properties have already been observed including good growth at low temperatures – lower than is tolerated by non-Saccharomyces that are already sold for wine fermentation. Such cold tolerance makes sense given the very harsh winters that are common where cider gums are found.




Read more:
Aboriginal traditions describe the complex motions of planets, the ‘wandering stars’ of the sky


We are also looking to identify all recovered isolates. In some cases this has only been possible to a genus level – perhaps implying new species. In other cases no definitive identification could be made, suggesting entirely new species.

<!– Below is The Conversation's page counter tag. Please DO NOT REMOVE. –>
The Conversation

As our work progresses we will publish our findings and report back to the Aboriginal communities that have supported the study. We have also begun to extend the study to other substrates as well as the anthropological and cultural significance of these unique fermentation practices.

Vladimir Jiranek, Professor in Oenology, University of Adelaide

This article was originally published on The Conversation. Read the original article.


Article: WWI – Fake trees


The link below is to an article about fake trees and how they were used in World War I.

For more visit:
http://bldgblog.blogspot.com.au/2012/06/op-tree.html


%d bloggers like this: