'Green gold' tree offers Brazil deforestation hope

The genus Inga includes hundreds of tree species that fix nitrogen and improve soil productivity.

Aproject 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 agribusinesses and remain farmers in the Amazon.

"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.

"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.

"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.

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.

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".

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 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.

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.