Where the old things are: Australia’s most ancient trees

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Wollemia pine pollen cone. Wollemia pines (found in the wild only in Australia) are one of the most ancient tree species in the world, dating back 200 million years.

Cris Brack, Australian National University and Matthew Brookhouse, Australian National University

They say that trees live for thousands of years. Like many things that “they” say, there is a germ of truth in the saying (even though it is mostly false). The Conversation

The vast majority of trees that burst forth from seeds dropped on the Australian continent die before reaching maturity, and in fact most die within a few years of germination.

But depending on how you define a tree, a very select few trees can live for an astoundingly long time.

What are the oldest trees?

If we define a “tree” as a single stemmed woody plant at least 2 metres tall, which is what most people would identify as a tree, then the oldest in Australia could be a Huon Pine (Lagarostrobos franklinii) in Tasmania, the oldest stem of which is up to 2,000 years old.

However, the Huon Pine is also a clonal life form – the above-ground stems share a common root stock. If that common root stock is considered to be the base of multi-trunked tree, then that tree could be as old as 11,000 years.

But if you accept a clonal life form as a tree, even that ancient Huon age pales into insignificance against the 43,000-year-old king’s holly (Lomatia tasmanica), also found in Tasmania.

King’s Holly, or Lomatia tasmanica, can form clones nearly 50,000 years old.
Natalie Tapson/Flickr, CC BY-NC-SA

Once you accept that a common, genetically identical stock can define a tree, then the absolute “winner” for oldest tree (or the oldest clonal material belonging to a tree) must go to the Wollemi Pine (Wollemia nobilis). It may be more than 60 million years old.

The Wollemi pine clones itself, forming exact genetic copies. It was thought to be extinct until a tiny remnant population was discovered in Wollemi National Park in 1994. The trunk of the oldest above-ground component, known as the Bill Tree, is about 400-450 years old. But the pine sprouts multiple trunks, so the Bill Tree’s roots may be more than 1,000 years old.

There is also substantial evidence that the tree has been cloning itself and its unique genes ever since it disappeared from the fossil record more than 60 million years ago.

How do you date a tree?

If no humans were around to record the planting or germination of a tree, how can its age be determined? The trees themselves can help tell us their age, but not just by looking at their size. Big trees are not necessarily old trees – they might just be very healthy or fast-growing individuals.

A much more reliable way to determine age of a tree is through their wood and the science of dendrochronology (tree-ring dating).

Dendrochronology involves counting tree rings to date a tree. The wider the ring, the more water the tree absorbed in a given year.
sheila miguez/flickr, CC BY-SA

Many trees lay down different types of cell wall material in response to seasonal patterns of light, temperature or moisture. Where the cell walls laid down at the beginning of the growth season look different to those laid down at the end of the season, rings of annual growth can be seen in cross-sections of the tree.

This map of growth patterns can also be cross-dated or correlated with major events like multi-year droughts or volcanic eruptions that spewed material into the atmosphere to be incorporated into the wood of the tree. But the cell walls are more than just calendars.

Why so old?

Individual tree stems can live for so long because of the structure of the wood and the tree’s defence mechanisms. The woody cell walls are very strong and resist breakage.

In fact, scientists have recently discovered that these walls contain a structure – nanocrystaline cellulose – that is currently the strongest known substance for its weight.

Wood can, however, be broken down by insects and fungi. Even though there is little nutrition or energy in wood, there is some – and there are plenty of organisms that will try and use it.

But trees are not defenceless, and can fight back with physical barriers or even chemical warfare. When one tree is attacked by these destructive forces, individuals may even signal to other trees to be aware and prepare their own defences to fight off death and decay.

The death of trees

So why don’t all trees live for centuries or millennia, and why do so many die before even reaching maturity?

Adult Wollemi pines in the wild.
J.Plaza/Van Berkel Distributors

Seedlings and young trees may die because they have germinated in an area where there’s not enough water, nutrients or light to keep them alive as adults. Young trees also haven’t had much time to develop barriers or defences against other organisms and may be browsed or eaten to death.

Some trees simply fall prey to accidents: wind storms, fires or droughts. This is just as well, because there is a vast number of plants and animals – including humans – which rely on the wood and other components of these dead trees for their food and shelter.

But increasingly we may see trees dying because the environment is changing around them and they may not be able to cope. This is not just due to climate change; urban development and agricultural expansion, pollution and even too much fertiliser acting as a poison – even our most remote environments are subject to these changes.

But that doesn’t necessarily mean we will have no more very old trees. The Wollemi Pine’s genes have already survived over millions of years, multiple ice ages and warming periods and even the fall of the dinosaurs and rise of humans. And now,
people have deliberately spread Wollemi Pine trees all around the world so they are living in a wide range of countries and climates, meaning that the risk of them all dying out is substantially reduced.

Maybe we can do the same for other trees, ensuring that trees will outlive us all.

Cris Brack, Assoc Professor Forest measurement & management, Australian National University and Matthew Brookhouse, Research fellow, Australian National University

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

The ‘clean coal’ row shouldn’t distract us from using carbon capture for other industries

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Has carbon capture and storage been tarnished by its association with the coal industry?
Peabody Energy/Wikimedia Commons, CC BY-SA

Alfonso Martínez Arranz, Monash University

Since the February blackouts in South Australia, the Australian government has increased its interest in carbon dioxide capture and storage (CCS). However, in Australia and elsewhere, CCS is closely associated to so-called “clean coal” technologies. The media sometimes treats them as one and the same thing. The Conversation

Given the negativity with which the general public, and expert commentators view “clean coal”, this confusion is distracting attention from other sectors where CCS can make a unique and substantial contribution.

CCS is vital for “clean coal”. Even the most efficient coal-fired power plants emit huge amounts of carbon dioxide. Unless these emissions are captured and stored in rock formations thanks to CCS, meeting climate targets with coal power is impossible.

But here’s the thing: carbon dioxide can be captured from any large-scale source. This means that CCS has a valuable role to play in other industrial sectors – as long as clean coal’s bad reputation doesn’t drag CCS down with it.

Other industries

About half of the global potential for CCS by 2050 has been estimated to lie in industry. Some sectors like synthetic fuels and hydrogen production may not grow as predicted. But others such as cement, steel and ammonia, are here to stay.

Several recent UK reports on industrial decarbonisation argue that CCS brings emissions reductions beyond the 50% needed by 2050 required in most sectors and countries.

For cement in the UK, the report argues, efficiency and other measures could deliver a roughly 20% emissions reduction by 2050. But adding CCS could bring this figure to 54%.

Meanwhile, the British steel industry could cut emission reductions by 60% compared to 34% without CCS. For UK chemical manufacturers, these figures are 78.8% versus 34%. These processes often produce a high-purity stream of carbon dioxide that avoids the costly capture methods used for power applications.

So why aren’t industries like these the stars of carbon capture and storage right now?

Money and hype

Unlike the power sector, which is under pressure to reduce emissions, other high-carbon industries currently have little incentive to pay the estimated cost of US$50-150 per tonne of carbon dioxide captured. Carbon pricing has been hard to introduce even far below such levels.

However, if CCS is to be deployed by mid-century, concept demonstration and confirmation of suitable storage sites needs to start now, and on a wide enough scale to deliver useful emissions cuts. Other strategies may be needed to incentivise it.

CCS was first mooted in 1976, but it only caught world leaders’ attention in the mid-2000s. However, over the past decade its popularity seems to have waned, perhaps because of the “clean coal” issue.

In 2005, WWF joined Europe’s CCS platform, and the following year the environmentalist George Monbiot described the technology as crucial.

But over the ensuing ten years, as a “hype process” around CCS for clean coal developed, industrial CCS was largely ignored. At its peak in 2007, proponents announced some 39 CCS power projects, most of them coal-fired, aiming to capture an average per project of 2.2 million tonnes (Mt) of carbon dioxide per year.

Yet by early 2017, only two large-scale power projects have been completed around the world: Boundary Dam, capturing 1Mt per year, and Petra Nova, capturing 1.4Mt per year.

Number of carbon capture and storage projects by type since first concept. Mature refers to projects in sectors in which capture is routinely commercial, such as in natural gas processing. Immature refers to projects in sectors where capture is not the norm, including power generation, steelmaking, and certain chemicals. The share of power generation projects among immature is highlighted.

Cynicism around the technology has grown, with the Australia-founded Global CCS Institute recently being described as a “coal lobby group”. Unfortunately for CCS, the focus has been mostly on the gap between announced and successful “clean coal” projects, rather than on its contribution to industrial emissions reduction.

Last year, Emirates Steel Industries completed its steelmaking CCS project, which now captures 0.8Mt of CO₂ per year.

Australia will soon be host to the world’s largest CCS development, at the Gorgon LNG Project, which will store 4Mt a year from 2018.

Steel, gas-produced ammonia and other industrial products will be fixtures of the 21st century, whereas coal-fired electricity has no such certainty. Economies that aspire to 100% renewable energy will have no room at all for coal, “clean” or otherwise.

Even if our electricity and transport were to become 100% renewables-based, there will be parts of the economy where greenhouse emissions are hard to eliminate. It is important that the unpopularity of “clean coal” does not distract from the importance of CCS in decarbonising other industries.

Alfonso Martínez Arranz, Lecturer, Monash University

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