One of the biggest afforested areas in South America is being increasingly destroyed, according to World Wildlife Fund campaigners.

Spanning 1m square km across Argentina, Paraguay, Brazil and Bolivia, the Gran Chaco indigenous forest has suffered immeasurable harm to local fauna and flora as sunflowers, soyabeans and livestock take over. South America’s second largest forest is often in the shadow of the Amazon Rainforest, but campaigners believe more needs to be done to stop its destruction.

According to WWF, Chaco's woodlands – which stretch to an area bigger than France – have been gradually replaced with cropland and ranches over several decades, but had accelerated in recent years.

From 2010 to 2012, Argentina, Paraguay and Bolivia – the three countries that share most of the Chaco forest – lost native vegetation at an average rate of more than an acre per minute. By 2030, the Gran Chaco is projected to lose millions of additional acres of native vegetation.

The area is rich in flora and fauna, with at least 3400 species of plants, 500 species of birds, 150 species of mammals and 220 species of reptiles and amphibians. Iconic species, such as the Jaguar, giant ant eaters, mane wolves and armadillos, all used to thrive there.

Attempts to slow the deforestation via the Paraguayan Liberal Party, which proposed the 'Deforestacion Zero en el Chaco', failed to get a majority in parliament. Since 2007, a law was supposed to regulate and control timber felling in the Argentine Gran Chaco, but illegal logging continued.

At COP26, in Glasgow, Argentina joined 100 other nations in a commitment to stop deforestation altogether, but there are reports of continued cutting.

In some places, as far as the eye can see, slow growing carob trees uprooted by heavy machinery lie waiting to be taken away and used as charcoal, tannin, furniture and railway sleepers, for which this dense hardwood is particularly prized. The land is then turned to crop and pasture with significant investment from multi-national companies to drive demand.

Agricultural engineer, Inés Aguirre, from the Chaco Argentina Agroforestry Network – speaking to the International Business Times – said: "Practically all of Chaco Province used to be covered by forests. But when the technological package of genetically modified soyabeans appeared in the 1990s, the Chaco zone began to be colonised."

Two of Argentina's main exports, soya and genetically-modified corn and sunflowers, thrive in the semi-arid Chaco region. Accurate figures for deforestation are difficult, but Aguirre put it in the region at around 40,000 ha (154 square miles) a year, peaking at 60,000 ha on occasions.

Micaela Camino, a biologist at CONICET and Whitley Found for Nature award winner, said: "What generally happens is that before logging, the rights of those families were violated. They were swindled [out of their land] and forced to leave their home."

A local Wichí ethnic group leader, Audencio Zamora Leckott, argued that 'the places where vegetation and the environment are preserved are where we, the indigenous peoples, live. Deforestation is the destruction of our cultures, knowledge and wisdom.'

To reverse the trend, environmentalists argued that a massive tree planting programme needed to be initiated before it was too late, starting with the carob tree. Inés Aguirre said: “The carob tree, which is a legume, produces a reaction between bacteria and the tree's roots that recomposes the nitrogen in the soil. It's amazing, the growth is incredible."

According to studies carried out by Argentinean and German researchers, the carbon stored in the forest is 19 times higher than previously thought, a value that continues to surprise scientists themselves.

Tobias Kuemmerle, from the land use program of the geography department of the Humboldt University, in Berlin, said: “Only for the dry Gran Chaco, there are some 4.65 giga tonnes of carbon stored in the vegetation. This is a very considerable amount of carbon. It is reasonable to think that not everything is going to be sent out.

"But we have proved, in terms of the amounts of emissions going into the atmosphere, that those of the Gran Chaco are comparable to those in the Amazon or Indonesia. And those are the sites that relate to the big discussions about climate change."