Image copyright Toby Pennington Image caption The inga tree's versatility means that it warrants its label as a "miracle tree"

Trees that help keep soils fertile could slow or stop deforestation in Brazil's "arc of destruction".

A project using inga trees hopes to show smallholders that they can earn a decent living from the land.

Inga trees, known as ice-cream bean trees, fix nitrogen into the soil, boosting productivity levels.

Scientists hope the scheme will convince smallholders not to sell their land to large agri-businesses and remain farmers in the Amazon.

Growth of the 'miracle tree'

"It's very much a kind of 'miracle tree' or a super tree because some of the species can do some amazing things," said Toby Pennington, professor of tropical plant diversity and biogeography at the University of Exeter, UK.

Image copyright Getty Images Image caption The growth of vast cattle ranges has contributed to deforestation in the Amazon

"They can grow really fast on very, very poor soils, even soils where a rainforest has been cut down and have become very degraded."

The trees (there are more than 300 species) are in the legume family and that means they can fix atmospheric nitrogen into the soil.

"But even amongst legumes, they have pretty fantastic growth rates," the prof told BBC News.

"More than that, these species have fruits that are edible and often have local markets right across Latin America."

The trees can also be coppiced, providing wood fuel, and the leaves are a good source of forage for cattle.

Hope grows as trees grow

As the tree was common and found throughout the Amazon Basin it was deemed to be a miracle tree or super tree by projects trying to stem the relentless deforestation in the region.

Image copyright Toby Pennington Image caption The trees provide valuable shade for livestock

Prof Pennington said properties like nitrogen fixation and lots of leaf fall, which produces mulch, means that you can grow crops underneath them with low input of fertiliser and herbicides.

"If you had a cup of coffee this morning that came from Latin America, the odds are that it was growing underneath one of these inga trees."

Prof Pennington, who has been studying inga trees for more than two decades, has been working alongside a project that promotes the benefits of the trees to smallholders in southern Brazil's frontier of deforestation - an area known as the "arc of destruction".

Interactive Parts of Rondonia, Brazil, have suffered severe industrial deforestation 2018 1984

Dr Saulo de Souza from the Institute of Green Gold [Instituto Ouro Verde] said the project delivered environmental benefits by introducing tree cover into pastures, encouraging biodiversity while mitigating the worst effects of climate change.

"These plantations would favour wildlife that could use them as habitats or as stepping stones to move between forest remnants," he said.

"By fixing carbon, tree growth in pastures could reduce the ecological footprint of dairy cattle.

"The trees could also increase soil permeability, granting higher loads to the water table and reducing soil erosion."

Dr de Souza told BBC News the trees helped local communities by helping to restore the fertility and viability of the land that had become degraded.

"These systems are more resilient to severe drought and diseases, which have been the main cause of pasture degradation in the region," he explained.

"Communities will benefit from increased food security and income provided by the agricultural species planted, as well as from increased land productivity and premium prices paid for agro-ecological dairy products."

Another important factor of the projects, Dr de Souza said, was the ability to reduce social marginalisation.

"It is of great importance to offer new opportunities and green technologies to help smallholders. Family farming also plays a critical role for global food production. In Brazil, they are responsible for 70% of domestic food consumption."

Image copyright Reuters Image caption Felled timber is also another source of income and another driver for deforestation

By showing that the land could be harvested sustainably and profitably, the land owners were less inclined to sell up to industrial cattle and soy producers, Dr de Souza said. This would allow local communities to thrive and slow the relentless mark of deforestation in the region.

However, the current political situation in the country is making it hard for researchers and NGOs, such as the Instituto Ouro Verde, to operate and continue their work against deforestation.

Bleak outlook

In August, Germany and Norway announced they would suspend money going to the Amazon Fund, a multi-million dollar global effort to tackle deforestation in the region.

Politicians from the two European nations said the Brazilian government, headed by President Jair Bolsonaro, was backing policies that favoured deforestation and was actively pursuing ways to hamper pro-rainforest projects.

Sources on the ground in the Amazon told BBC News that frozen funds, political persecution and misinformation were "definitely undermining" the work that had been built for decades.

Data from Brazil's National Space Research Institute suggests that deforestation for 2019 is up at least 75% on the previous 12 months.

Prof Pennington said: "A lot of that soy [grown on an industrial scale] is coming back to the European Union and to China for animal feed, so we're all implicated in that food chain.

"These massive agricultural businesses are problematic environmentally in many ways.

"They're extremely high input in terms of pesticides, which they're spraying aerially, and the chemicals are getting into water supplies.

"In this part of Brazil, when the area was originally opened up, it was really opened up to a lot of smallholders."

But Prof Pennington explained that, increasingly, the land was being bought by large agri-businesses, who offered the smallholders very good money, which was very hard to refuse.

"But it doesn't just have to be massive cattle ranches or massive soybean plantations," he added.

"There are opportunities for people to have smaller pieces of land that are financially viable for them to have an income and a lifestyle that they feel is more healthy and that they're happy with."