Londonderry’s EucFACE experiment making important climate change findings

The acronym actually stands for Eucalyptus Free Air Carbon Dioxide Enrichment. And what does all that mean?

Well, put simply, scientists are blasting some trees in Londonderry with carbon dioxide (CO2) and recording the results.

Western Sydney University Professors Belinda Medlyn and Mark Tjoelker are two of the researchers involved with the project, and they spoke to the Gazette about it.

The purpose of the project is to see how trees, and the ecosystem around them, react to heightened levels of CO2 in the atmosphere.

One of the questions they want answered is whether trees can continue to photosynthesize with higher levels of CO2 in the air – producing oxygen in the process and removing the CO2 – or whether there is a limit to how much they can absorb.

“One of the key scientific questions is how will forests respond to rising atmospheric CO2 concentrations,” explained Professor Tjoelker, who is the theme leader of ecosystem function and integration at the Hawkesbury Institute for the Environment.

“One important things that forests do worldwide is they take CO2 out of the atmosphere and they help mitigate the rising CO2 concentrations that are due to fossil fuel burning and fire and land use change.

“They perform a very important service. The question is will forests in a higher CO2 world continue to take up CO2 or is there some limit to their ability to take up the extra CO2 that we are emitting.”

While driving along Londonderry Road, you may have spotted some odd rings, poking above the trees.

Those rings are an elaborate set up, and are one of the key components of the experiment.

There are six rings in total. Three, the control rings, take normal atmospheric air and then blow it onto the trees.

The other three take CO2 and blow that onto the trees, to simulate a higher CO2 atmosphere. A computer algorithm helps with this. It takes wind direction and speed readings every second, to determine how much CO2 is needed and which part of the ring it needs to be blown out of, to help create a sustained higher CO2 atmosphere.

The scientists then carefully record their observations and data, so that by the end of the experiment, at this stage another five years away, they can come up with their conclusion based upon the research.

The CO2 itself is not produced on site, as site engineer Craig McNamara and site manager Vinod Kumar explained.

It is a byproduct of industrial fertiliser production, and is captured and transported to the facility.

The CO2 released by the researchers, would otherwise have been released into the atmosphere anyway, so the researchers say their carbon ‘footprint’ is quite low, only adding in the emissions required to transport it to Londonderry from where it is manufactured.

The fact the CO2 comes from an industry source is also important for another reason.

“CO2 comes in two flavours, carbon 12 and carbon 13,” said Mark Tjoelker.

“It is the ratio between those two that differs in our current atmosphere and fossil fuels. By having a fossil fuel that has a different signature than the atmospheric signature, that allows us to trace the carbon through the system.”

In other words, the CO2 the researchers are using, has a different isotopic signature to normal atmospheric CO2.

It means the researchers can say for sure that the CO2 they are pumping into their artificial ecosystems in the rings comes from their source, not normal CO2 in the air.

The team have observed many changes in the localised ecosystem, inside the CO2 rings.

Belinda Medlyn, professor of ecosystem modelling, said there had been changes to not just the trees, but living organisms found within the rings.

“The elevated CO2 concentration has also decreased the overall abundance of invertebrates,” she said.

“There were fewer bees and wasps, mites, beetles, and other arthropods. This is concerning because we rely on these critters for many ecosystem services such as pollination of flowers. 

“The number of psyllids also decreased. Psyllids are insect pests that can cause in death in eucalypts – many of the dead eucalypts you can see around Western Sydney have been killed by a recent psyllid outbreak.

“Unfortunately, although there was a decrease in the number of psyllids, each psyllid ate more, so they did not do less damage to the trees growing in elevated CO2.”

Prof Medlyn said the trees had changed too.

“There’s a change in the community of understorey plants,” she said.

“There are two different photosynthetic pathways, the C3 and C4 pathways. C4 plants can concentrate CO2 inside their leaves, so they are less responsive when given higher CO2 than C3 plants.

“As one might expect, we have found that there are fewer C4, and more C3 plants, in the understorey, as the CO2 concentration increases.”

There has not been an increase in the number of leaves or size of the trees either said Prof Medlyn.

This could be due to the naturally low phosphorus content of Australian soil, preventing the trees from converting all the extra carbon into extra growth.

“We are still trying to add up all the numbers to find out where that extra photosynthesis is going,” Prof Medlyn said.

“We think that possibly what is happening is that there is more carbon coming back out of the ground.”

Prof Medlyn added that they were looking at the soil too.

She said there was some evidence that soil organisms were releasing more phosphorus from litter, but had not done enough research to say for sure why that was happening.

Well, in short, yes.

The longer answer is that the experiment is incomplete.

However, the observations they have made so far will likely have implications for future climate modelling.

Scientists use computer models to make predictions for the future, particularly around climate change.

The scientists submitted the research they have worked on the publication Nature: Climate Change, and it was published in April 2017.

In their letter, they said in their opinion the research they had so far conducted was enough to alter any future modelling done, to adjust for nutrient limited ecosystems.

"The findings suggest that Phosphorus availability may potentially constrain CO2-enhanced productivity in P-limited forests; hence, future atmospheric CO2 trajectories may be higher than predicted by some models. As a result, coupled climate-carbon models should incorporate both nitrogen and phosphorus limitations to vegetations productivity in estimating future carbon sinks,” they wrote.

The experiment is still planned to go on for another five years, and the scientists will keep collecting data.

They hope that their work will fill an academic knowledge gap about what happens to ecosystems in an elevated CO2 environment, but where phosphorus and other nutrients are limited in the soil, among other important findings.