Amazonia’s Trees Threatened

The Amazon River and Basin (Amazonia) need no introduction. The river itself is by far the biggest on Earth; in fact, its average discharge or flow rate exceeds the next six largest rivers combined (Congo, Ganges, Orinoco, Madeira, Yangtze and Negro). Our own Mighty Mississippi places 9th on this procession of goliaths, with an average discharge a mere one-tenth of the Amazon’s.

Every minute, enough water pours into the Atlantic from the Amazon to fill about 9,000 Olympic-sized (50-meter) swimming pools. Amazonia holds a quarter of the world’s non-frozen freshwater.

The enormous Amazon is one of the Wonders of the World.

It is no surprise that a river carrying this much water drains a basin containing the greatest living rainforest on Earth. Tropical rainforests are teeming nurseries and laboratories of life. 

• The Amazon rainforest is, by far, the largest tropical rainforest on Earth, covering more than 5.5 million square kilometers (2.1 million square miles or 1.4 billion acres), an area equivalent to two-thirds the size of the contiguous 48 United States.

• Ten percent of the world’s known species live in the Amazon rainforest and 20 percent of the world’s bird species. 

• An estimated 40,000 plant species live the Amazon rainforest. 

• To date, approximately 2.5 million insect species have been catalogued in the Amazon. 

The “Emerald Forest,” the Amazon Rainforest, teems with life, but its survival is now imperiled, according to scientists.

While all forests consist of much more than their trees alone, trees are the dominant vascular plant by volume, biomass and structure. Unfortunately, deforestation is destroying the Amazon’s trees as the basin’s human population expands exponentially and as resource exploitation explodes, including mining, oil and gas exploration, dam construction, cattle ranching and farming. Since the start of the new century, an area equal to 50 soccer fields has been destroyed every minute in the Amazon rainforest.

According to The New York Times, more than half of the Brazilian cities that have at least doubled in population over the past decade are in the Amazon. Altogether, the region’s population jumped 23 percent between 2000 and 2010, twice the rate of Brazil as a whole, which grew 12 percent. 

Torrid pace of construction in the Amazon accommodates rapid population growth.

Human settlements now dominate landscapes where once virgin rainforest predominated.

Amazonia’s future? Lots of wood, but in houses, not tree trunks and branches.

Amazonia’s trees were the focus of a recent research reported in the journal Science Advances. In this huge field study, researchers including 160 botanists, ecologists and taxonomists from 97 institutions surveyed 1,485 sites in the Amazon basin. They identified 4,953 species of trees. From this baseline, and using a biodiversity model, the scientists inferred that there must be approximately another 10,000 tree species, especially towards the isolated center of Amazonia where human population densities are still very low.

Then they prepared species spatial distribution maps which they compared to maps of deforestation to predict how tree species might be threatened under two scenarios: business as usual (deforestation continues unabated at its current pace) and an “Amazon-friendly” scenario, in which government and corporations collaborate to reign in forest clearing.

Given current trends, the research team found that at least 36 percent, and up to 57 percent, of all Amazonian tree species are likely to qualify as globally threatened under International Union for Conservation of Nature (IUCN) Red List criteria. Moreover, in extrapolating their findings to the entire world, the researchers showed that the trends observed in Amazonia also extend to trees throughout the tropics. They predict that more than half of Earth’s more than 40,000 tropical tree species now qualify as globally threatened.

As Tibi Puiu, writing at ZME Science, notes:

The environmental consequences are stark. The Amazon rainforest acts like a huge carbon sink, and destroying it will cause more carbon emissions to stay in the atmosphere, further warming the planet. Loss of habitat will force many species of animals into extinction, but also tree species themselves.

Unthinkable as it may seem, the survival of Amazonia itself is now in question. The Science Advances report emphasizes the role that protected areas (e.g., national parks), indigenous peoples (e.g., Amazonian tribes) and improved governance (e.g., greater transparency, less corruption and collusion) play in “preventing large-scale extinctions in the tropics in this century.”

It may not be politically expedient to say so, but curtailing human population growth in Amazonia, both by reducing the birth rate of the region’s current residents and reducing in-migration from elsewhere in Brazil (and other South American countries), also is necessary to avert large-scale extinction of the region’s flora and fauna in this century.

Brazil, like most of Latin America, has made amazing progress in reducing fertility rates in recent decades. Indeed, Brazil’s total fertility rate (TFR) is now at or below replacement level, which means that its population will eventually stop growing. However, the operative word is “eventually,” because demographic momentum, from earlier much higher fertility rates, casts a long shadow. Now at about 200 million, Brazil is projected to grow to about 230 million by 2050.

For years, Brazilians and other South American countries (which possess portions of the Amazon’s headwaters) regarded the virgin, untapped Amazon basin like Americans in the 19th century regarded the Wild West: as a region whose settlement, development and exploitation would propel their growth and augment their glory. The Brazilian government encouraged settlement by building roads and offering other incentives. The notion that wilderness or wild areas, “áreas selvagens” in Portuguese, and “áreas silvestres” in Spanish, should be simply left alone and intact for the benefit of their indigenous human and non-human residents was simply beyond the pale.

Those benighted attitudes may have diminished somewhat, but the juggernaut of growth in the Amazon has already been unleashed, and containing it will prove very, very difficult.

Primeval paradise is threatened by human encroachment.