Experts explain the effect of the Amazon wildfires on people, animals and plants

Fires in the Amazon are nothing new. Part of the forest burns every year in the dry season (July to October). However, this year, fires are spreading out of control at a record rate.

Satellite pictures from NASA show that in the middle of August, total fire activity in the Amazon basin was actually slightly below average in comparison to the past 15 years - although activity has been above average in some states.

Nevertheless, there have been a record number of individual fires this year. The Brazilian National Institute for Space Research (Inpe) has reported an 84% increase on 2018's statistics, recording more than 74,000 fires between January and August.

Wildfires are usually started by people who wanted to clear land for cattle ranching and other agriculture. Often, fires are started on land which is owned and managed by Indigenous People. With fires out of control, the lives of more than a million Indigenous People are at risk.

 In the #AmazonRainforest, fire season has arrived.

The MODIS instrument on NASA’s Aqua satellite captured this images of several fires burning in the Brazilian states of Rondônia, Amazonas, Pará, and Mato Grosso on August 11, 2019. pic.twitter.com/btulI01v5n

— NASA Goddard (@NASAGoddard) August 21, 2019

Dr Sandy Knapp, head of the Museum's Algae, Fungi and Plants Division, explains, 'These fires are heartbreaking and terrifying. Deliberate deforestation is usually how fuel is made so that fires start in this otherwise wet habitat. This year the forest seems to have been particularly dry and fires that were started to clear a small patch have gone out of control and into the forest.

'People chop down trees and other vegetation in the wet season and then let the wood and land dry out. Then they burn it, and if the summer has been too dry, that fire can spread into the surrounding forest and becomes out of control.

'This year has seen record high temperatures all over the world and it seems to me that it is no coincidence those warm temperatures have triggered fires in dry and vulnerable forests all over South America.'

Conservationists have accused Brazil's President, Jair Bolsonaro, of exacerbating the problem by encouraging deforestation, although he denies this.

What are the effects on biodiversity?

A tropical forest's trees and understory can be devastated by raging fires. Trees suffer badly, but plants and animals living closer to the ground are also extremely vulnerable.

Sandy says, 'The Amazon is far more than just trees. The understory (shrubs and herbs) contains half of the species diversity in the forest, and that really gets damaged in a fire, especially if the heat builds to very high levels.'

Much of the Amazon rainforest is particularly vulnerable because it is made up of lowland, wetland forests which are not well-equipped to deal with fire.

Some forests - like those in the western part of the United States - are adapted to fire and it is an important part of a forest ecosystem's natural cycle.

Even in the wider Amazon basin itself, the Cerrado region is fire adapted. It is a large savannah, and lots of plants there have thick, corky, fire resistant stems.

However, that region faces additional risks: namely, deforestation to make way for soy plants.

Sandy says, 'As tragic as this summer's wildfires are, the Cerrado region is even more vulnerable than the areas being affected right now. This habitat is smaller in extent than the wet forests of the Amazon, so when it is converted to agriculture, less remains.

'It is a beautiful area full of endemic species, and it is being cleared now partly because of the world's demand for soy products.

'We are converting land for our own use at the expense of all kinds of habitats.'

Plants aside, millions of animals also rely on the Amazon. Mammals including jaguars, capybara, freshwater dolphins, sloths, armadillos, and tapirs.

It is also home to more than 1,000 bird species, including macaws, owls, vultures and kingfishers.

Experts believe that there are many species deep in the Amazon that are still unknown to science - and once gone, they will remain unknown forever.

On the forest floor

Once a fire destroys a habitat, every animal that relied on it suffers as well, losing shelter and food.

A lot of carbon in a big forest is contained in its soil. Layers or organic matter sit on top of soil, which in turn provide a vital home for small invertebrates. All this organic matter burns up in a wildfire's high heat.

That soil can also move around after a fire into places it isn't supposed to be – including into waterways from uncontrolled run-off.

Prof Beth Okamura, a merit researcher at the Museum, studies invertebrates in aquatic environments.

These animals live underwater so they are not directly exposed to fire - but that doesn't necessarily protect them.

Beth says, 'If the fires remove trees that are regularly submerged during the wet season when rising waters flood vast areas, then this would be a drastic alteration of a habitat with likely knock-on effects.

'For example, the invertebrates that I work on grow on the submerged trees. Fish and other vertebrates forage extensively in the flooded forest areas during substantial periods.

'Run-off from fires will pollute aquatic environments and this could be harmful. All this adds to the recently noted substantial amount of plastic waste accumulating in aquatic Amazonian environments.'

And what happens next?

Large areas of forest create their own weather. If wildfires ravage them, a delicate balance is upset.

It is possible that the Amazon will be caught in a vicious circle that could dramatically speed up forest loss and take the ecosystem past the point of no return, despite its large size. As forests are less able to regulate their own rainfall and weather patterns, they can become progressively drier and prone to fires. 

Water released by rainforests influences the water cycle of the entire planet. The Amazon alone contributes to 20% of the world's oxygen through the process of photosynthesis. As the rainforest decreases, so does its ability to support the rest of the planet. Large forests absorb carbon from the atmosphere, slowing the pace of climate change. Burning the Amazon means humanity is sabotaging its own life support system.

If nothing changes soon, we can expect the degradation of freshwater systems, loss of biodiversity, soil washing into the sea, smaller agricultural yields, increased insect infestation, and the spread of infectious diseases.

A global problem

Deforestation on this scale doesn't just happen in the Amazon - a similar amount of forest is lost in Indonesia every year.

And you may not know it, but similar mass deforestation has already happened in Europe.

Sandy says, 'This tragedy has been caused by choices we have made. Cheap beef comes from farms in the Amazon, and so does soy milk. It is easy to blame Brazilian farmers but the rest of us provide the demand.

'This is a problem which is truly global. All tropical forests are under threat.

'The good news is that forests can and will recover because life finds a way. The evidence is there, they do come back if we let them. The plants may not all be the same, but the diversity of life will eventually be restored, and that is what is truly important.'