Shared between Argentina, Paraguay and Bolivia – with a fragment in Brazil – the Gran Chaco is the second-largest forest in South America, behind only the Amazon rainforest. However, as Dr John Jackson reports, it is disappearing fast.

THE Gran Chaco is a hot, flat and semi-arid lowland region with one of the highest deforestation rates on the planet. Every month, an area over 35,000 hectares is being cleared. Projections point to a loss of millions of additional hectares of native vegetation by 2030.

This vast biome brings together more than 50 different ecosystems, united by the same pattern of vegetation and climate. It also provides an environmental and bioclimatic balance for the subcontinent.

The terrain is largely flat, grading from hot and humid in the north and east to arid elsewhere. The tree-covered areas, known locally as ‘monte’, are interspersed with savanna-like or parkland grasslands.

Two thirds of the Gran Chaco, or roughly 430 square kilometres (just over three times the size of England) sit within Argentina. The once extensive dry forest mosaics are home to unique vegetation and wildlife, including 3,400 plant and 500 bird species and hundreds of mammals, reptiles and amphibians. Nine million people live in the region, including several indigenous communities.

Forestry Journal:

The dominant natural low tree cover or woodland (‘monte’) is made up of ‘quebrachos’. Readers with a smattering of Spanish can fathom out the hybrid word comes from ‘quebrar’ meaning to break and ‘hacha’, an axe. These extremely hard trees of the Schinopsis complex form or formed the high canopy in these hot, dry forests.
The various species of the family and close relatives are often lumped together as ‘the quebrachos’. South America has many such species of tree, but most are of marginal commercial value and of lesser timber and tannin quality. Three valuable ones can be found in the forests in the Gran Chaco region. These are the reds or quebrachos colorados (Schinopsis lorentzii and Schinopsis balansae), together with the white one (Aspidosperma quebracho-blanco).

Then there are about 15 other types of quebracho of lesser stature that are also commercially harvested but are of inferior quality. The two red species are the focus of this article.

These loftier quebrachos colorados can reach heights of up to 20 metres, with branches with a broad scattering of leathery foliage adapted to withstand the challenging climate. The straight trunks can attain a diameter or DBH of over a metre. They are slow growing with a thick, corky, furrowed bark, tinged with brown-grey colouration.

Forestry Journal:

There are trees in the world that are hardwoods and those that are hard woods – quebrachos colorados are both. They are rated as very durable, resistant to insect and fungal attacks, and show excellent weathering characteristics. The heartwood is a luxurious dark red and is well up the ranking of the top ten hardest timbers on the planet. The tough heartwood timber was and is used in construction and for the fence posts to support the wire fence lines that criss-cross the land, marking out boundaries to keep cattle from straying, and for telegraph poles.

For domestic use, it makes excellent parquet flooring and, with its hard, dark-red wood, the quebracho colorado is in vogue for furniture. And the iron-hard firewood makes an excellent high-temperature, odourless and spark-free fuel – the anthracite of the charcoal world – for that icon of local cuisine, the groaning barbeque or asado.

The bark from these slow-growing trees has a wide range of medicinal attributes. It is still widely used in South American ethnic and herbal medicine, primarily for respiratory problems, fever, headache and liver disease as well as stomach ache and syphilis. But it was the high-quality tannin in the heartwood that was the original driver behind the intensive logging of quebracho there.

Forestry Journal:

Foreign interests and capital began to alter the virgin Chaco from about 1880 onwards. Because the wood is so hard and rich in tannin for the leather industry, the quebracho was exploited simultaneously for the laying of the first railway networks in the north of Argentina and for tannin extraction – two key elements for the country’s industrialisation process.

The indiscriminate plundering of quebrachos colorados was carried out, in particular, between 1906 and 1963 by La Forestal, a mainly British monopoly that settled in the Argentine section of the Gran Chaco and became the world’s largest tannin producer.

The company had nine tannin factories, founded numerous villages, owned and laid 400 km of railways in order to push the exploitation frontier further, and had as many as 20,000 employees in an era when workers’ rights were not exactly to the forefront.

From the late 19th century, the British laid down most of the rail network radiating out from distant Buenos Aires. That needed sleepers – and what better than the resilient trunks of the rot-free quebrachos, ready to hand? Quebrachos for sleepers were also felled, loaded onto wagons and transported by the new rail networks to elsewhere in Argentina and for shipping overseas. But by the 1960s, the exploitation was no longer economically viable, so the company upped sticks and moved on to South Africa to harvest mimosa for tannin instead.

As an aside, the British companies also imported ‘futbol’ to Argentina in the late 19th century. The legacy persists in the names of major clubs in large cities such as River Plate, Boca Juniors or Newell’s Old Boys. The capital of the Chaco province – Reconquista – boasts the team ‘Chaco for Ever’, albeit in a lower league.

Forestry Journal:

Large-scale deforestation is nothing new, even if the modern-day Chaco lacks the glamour, appeal, profile and media coverage of Amazonia further north. Through to this day, international multinationals and big bucks exert enormous pressures on land use in the Gran Chaco, notably through ongoing forest clearance for growing soya for export, often using agrochemicals and genetically modified seed that are banned in the main importing nations of the northern hemisphere.

For the past 30 years, the expansion of the agricultural frontier in Argentina’s section of the Gran Chaco has been relentless and devastating. This time, trees are razed not for their use but to clear the land for the subsequent cultivation of soya and some cattle raising through bulldozing and indiscriminate fires.

Since the introduction of genetically modified (GM) seeds (the ‘RR’: Roundup Ready seed) and glyphosate from 1996, soybean began to dominate the agricultural production market, making it the country’s main cash crop. The final destination of practically all of Argentina’s soya production (as beans, oil and meal) is the world scene. It is equivalent to around 25 per cent of the country’s total exports.

To give some idea of the scale, up until 1980 there were about 40,000 hectares of soybean across the Argentine Chaco, a number that soared to 20 million by 2018 – a 500-fold expansion. This trend is mirrored in neighbouring countries sharing the Gran Chaco, notably Paraguay.

Forestry Journal:

Practically none of the cleared, slow-growing quebracho monte has been replanted or the woodlands managed sustainably. Things are changing slowly, but the ‘get-rich-quick’ ethos is prevalent.

Back in 1956, Schinopsis balansae was declared Argentina’s National Forest Tree. Federal legislation (La Ley de Bosques) dating from 2007 indicates that, on paper at least, certain areas can be harvested while others are untouchable, but illegal clearance persists and less than 5 per cent of the Argentine Chaco biome is protected in one form or another.

Argentina has a rapidly expanding chain of over 30 federal national parks. Three are in the Chaco region – El Cópo, Río Picomayo and El Impenetrable. 

This latest was established in 2014 on the lands of the former Estancia La Fidelidad. The national park opened to visitors in 2017 and is the largest in northern Argentina at some 128,000 hectares – a touch larger than Bedfordshire or Fife.

It is worth remembering that large-scale loss of forests is not confined to the tropics. The Great British public is quick to criticise other nations presently clearing their forests for food and financial gain, but often forget that it happened long ago here in the UK and in the last century in the Chaco with UK funding.

The tall, heat-loving quebrachos are not so special to look at, so appear to be very rare or absent in tree collections in the UK. At worst, you can still admire the toughness of the timber in the odd remnant derelict railway sleepers stacked away in a siding or garden centre somewhere.

Nowadays, only four million hectares of the original Gran Chaco vegetation remain relatively untouched (of which only 30 per cent boasts some degree of legal protection), and the mainstream quebrachos colorados are growing scarcer by the day, although not yet on international danger lists.

So far, over a quarter of the Gran Chaco in Argentina has been cleared for agriculture, mainly extensive crop and livestock production, and mostly in the last 20 years. Variations in climate have contributed to rapid deforestation, soil degradation, and biodiversity loss too.

The relentless advance of the agricultural frontier with deforestation in the Chaco seems set to continue to produce soya for a hungry world as long as it is profitable and the climate and soils permit.

With the current rate of clearance, will the handful of national parks and provincial and private reserves end up as isolated oases in less than a few decades? Watch this space.