Trees full of probiotics could clean up contaminated land - and help tackle climate change. Here’s how

By 2050, as many as 700 million people may have been forced to migrate as the land they live on becomes less able to support them.

Crop yields are expected to drop by a global average of 10% – as high as 50% in some parts of the world – at that point, too. There will also be continuing, catastrophic loss of biodiversity, according to a 2018 report from the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES).

Some of the driving forces behind these interconnected threats are the expansions of unsustainable forestry activities, clearing land for agriculture, urban growth and infrastructure development. All of which put increased pressure on land use, as well as help to amplify many of the consequences of climate change.

Reclaiming pre-used land and making it fit for things like agriculture and human habitation can be hindered by the presence of contaminants such as chemicals, hydrocarbons and other toxic substances. Traditionally, cleaning up contaminated land has been a time-consuming, costly and ultimately unsustainable undertaking, involving heavy machinery excavating large volumes of soil and taking it away to be dumped elsewhere.

Other, greener approaches to cleaning up land have involved planting trees. Phytoremediation, as it is called, is the process of using plants and microorganisms to absorb contaminants from soil, making it safer to use in the future.

It is not a perfect solution, though. Contamination that has penetrated deeper than root-level, for example, will not benefit from planting trees. Plus, some of the poisons found in the land being treated will, ultimately, kill whatever is planted there.

A California-based company called Intrinsyx Environmental thinks it has hit upon a solution to at least one of those problems. It uses probiotics to inoculate trees from the harmful effects of some of the contaminants they will be subjected to.

A small forest of 100 inoculated poplar trees can extract and remediate around 3.8 million litres of contaminated groundwater per year, the company says on its website. While regular, untreated trees have a 30% survival rate, Intrinsyx says its inoculated trees have a 95% survival rate.

The inoculation process involves the use of endophytes, microscopic organisms such as fungi or bacteria, that live within plants. Intrinsyx cultivates specific endophytes to boost the trees’ ability to absorb toxins safely.

Using trees to help reclaim degraded and contaminated land has a useful side-benefit, too. Trees are, after all, a vital part of our global ecosystem. “They sequester carbon, regulate global temperatures and freshwater flows, recharge groundwater, anchor fertile soil and act as flood barriers,” according to 1t.org, which is part of the World Economic Forum’s drive to support nature-based solutions to environmental problems.

The organization’s mission is to conserve, restore, and grow one trillion trees by 2030. By planting new trees, as well as restoring and looking after existing forests, 1t.org hopes to target 2.2 billion acres of degraded land.

Increasing the number of trees on our planet will have beneficial effects on many climate change-related issues. But trees alone won’t solve the problem. As the IPBES points out in its report on land degradation, a large part of the problem is human behaviour.

It singles out “high-consumption lifestyles in the most developed economies, combined with rising consumption in developing and emerging economies”, as well as “continued population growth in many parts of the world”, all of which can drive “unsustainable levels of agricultural expansion, natural resource and mineral extraction, and urbanization – typically leading to greater levels of land degradation.”