ANALYSIZING the DNA of soil microbes is the newest tool to solve the global problem of deforested and degraded land.
Researchers in South Australia have developed a technique that uses DNA sequencing to study microbial communities to determine the changes in soil characteristics in order to rehabilitate land better and quicker.
The technique – high-throughput amplicon sequencing of environmental DNA (eDNA), otherwise known as eDNA metabarcoding – identifies and quantifies the different species of bacteria in a sample.
The research from the University of Adelaide also found that rehabilitating degraded land through revegetation with indigenous species could be achieved within seven years. This is significantly less time than the 20-40 years previously believed necessary to return land to a fully functioning ecosystem.
Key researcher Andrew Lowe said the process could be used for different projects such as carbon sequestration, soil erosion control, water purification, reclaiming farmland, flood/landslide mitigation and more specific services such as pollination.
The restoration-monitoring tool is now being applied in a range of locations and projects around the world including the United Kingdom, China and India.
“It is a very significant industry with approximately a third of the world degraded to some extent,” Professor Lowe said.
“We saw there were a number of shortcomings of the more conventional approaches including how to tell if the undertaken restoration is useful at the end of the day.
“Our new monitoring technique uses the analysis of DNA in soil to assess the microbial community and how it has recovered with restoration activity because they break down organic compounds and help with nitrification processes within the soil.”
The technique was recently tested on farming land in South Australia that had been cleared and grazed for a century. The researchers analysed soil samples at a restoration site in the Adelaide Hills and compared them with neighbouring wilderness areas as “reference sites”.
Picture: Study site localities and panoramas at the time of sampling.
The results demonstrated that bacteria associated with the original sites increased in frequency as restoration continued.
These microbes are essential in many important processes such as the break down of organic carbon and the provision of nitrogen, which is essential for plant growth and animals health. It is a major component of chlorophyll as well as amino acids, proteins and DNA.
Professor Lowe said there were very ambitious ecological restoration targets set under the Bonn Challenge and extended at the 2014 UN Climate Summit in New York. The Bonn Challenge is a global effort to restore 150 million hectares of the world’s deforested and degraded land by 2020 and 350 million hectares by 2030.
“The success of these impressive goals will rely on delivering effective restoration interventions, but there are concerns that intended outcomes are not being reached,” Professor Lowe said.
“Most projects are insufficiently monitored, if at all, and where it does occur the monitoring is logistically demanding, hard to standardise, and largely discounts the microbial community.”
Land degradation is a major problem globally that has been linked to food scarcity and vulnerability to climate change. The area of degraded land is expected to increase worldwide by about two million hectares annually according to a PlosOne Study.
The peer-reviewed journal also estimated the global environmental restoration industry to be valued at about US$25bn per year.
The University of Adelaide team has made the technique available worldwide and can process samples once schedules have been arranged.
The study titled Revegetation rewilds the soil bacterial microbiome of an old field has been published in the journal Molecular Ecology.
South Australia’s capital Adelaide has three long-standing public universities, Flinders University, University of South Australia and the University of Adelaide, each of which are consistently rated highly in the international higher education rankings.