Though the outbreak of the Covid-19 pandemic largely took citizens and governments worldwide by surprise, many scientists had been predicting such an event for a long time. Studies linking the health of humans and forest go back more than 40 years, and evidence has increasingly pointed the finger of blame at human-caused damage to forests.
In 2001, a study by the University of Edinburgh’s Centre for Tropical Veterinary Medicine indicated that 75 per cent of all infectious diseases emerging in the last 50 years came from wildlife. These are known as zoonoses, and include HIV, H5N1 bird flu, hantavirus, and most recently, Covid-19.
Subsequent research has linked new infectious diseases to deforestation. Though focusing on different diseases and different regions of the world, these studies have concluded that as forests are destroyed, animals that live in them and can carry diseases to humans, such as rats and bats, are forced into ever smaller areas. This brings them closer to humans, and therefore increases the likelihood of diseases ‘spilling over’, in other words, gaining the ability to jump from one species to another.
One well-known example is the Ebola virus epidemic of 2014–16, which is estimated to have killed over 13,000 people since its discovery in Africa in 1976. The disease was found to have been spread to humans from fruit bats.
Research published in Nature in 2017 found a significant link between outbreaks of Ebola along the edge of rainforests and forest losses within the previous two years. Preventing the loss of forests could reduce the likelihood of future outbreaks, it concluded.
A Link to Deforestation
The devastation caused to lives and livelihoods by Covid-19 has put an increasing spotlight on the issue. As countries worldwide went into lockdown in March 2020, the Executive Director of the United Nations Environment Programme, Inger Andersen, warned that nature was sending humans a message: “Our continued erosion of wild spaces has brought us uncomfortably close to animals and plants that harbour diseases, which can jump to humans.”
Earlier this year, French researchers Serge Morand and Claire Lajaunie made the first attempt to investigate on a global scale whether the loss and gain of forest cover can promote outbreaks of zoonotic diseases. It examined global trends between changes in forest cover in recent decades and epidemics of infectious diseases in humans. Their research documented that increases in outbreaks of zoonotic and vector-borne diseases from 1990 to 2016 are linked with deforestation, mostly in tropical countries.
However, there are still plenty of unanswered questions. Julia Fa, Professor of Biodiversity and Human Development at Manchester Metropolitan University who co-authored the study on Ebola and deforestation, said that though there was a strong link between deforestation and Ebola, they did not know what occurred in the two years between the two events.
“That’s the million-dollar question! The simplest way of looking at it is that there’s a balance between viruses, pathogens, and animals and if you suddenly disrupt that balance viruses grow in numbers and become much more active in certain periods, and if you have people in between there’s going to be a spread of viruses into animals, and then from animals to people,” she said.
The increased activity of viruses when disturbed has been dubbed ‘viral chatter’ by US researcher Nathan Wolfe.
“If the equilibrium between pathogens and receptors is broken, you’re giving advantage to certain pathogens over others,” Fa continued.
“The key missing piece of the puzzle is the linkages between pathogens, animals, and human beings, and the mechanism that promotes the surge of viruses,” she added. “This would enable the prediction of future outbreaks.” Fa and her team are working on compiling all existing information to develop a map of areas that are likely to be prone to diseases.
“More research needs to be done to uncover what viruses are present in areas that have suffered deforestation ten, five, two years ago, and currently to understand what is happening to viruses and pathogens through time,” she said.
Reforestation Needs to Benefit Biodiversity
Links have also been found between reforestation and disease outbreak, since planting trees can also result in disturbing balances in a forest and bring animals and humans closer together.
Morand’s research found this mostly to be the case in temperate countries, and was mainly caused by the planting of monoculture plantations or when land that had previously been savannah or grassland was converted to forests.
“Reforestation programmes such as the UN’s REDD+ programme – which encourages developing countries to reduce forest loss and degradation and expand existing forests – need to benefit biodiversity and human health, and not just focus on climate change”, Morand said.
To effectively protect forests and prevent disease spillover, experts agree that indigenous people need to be actively involved. Indigenous communities live in a way that aims to preserve the balance of their ecosystems as well as their biodiversity.
Research published in 2017 identified for the first time the global extent of indigenous lands and found that they manage or have tenure rights over at least 38 million km2 in 87 countries or politically distinct areas on all inhabited continents.
This represents over a quarter of the world’s land surface, and intersects about 40 per cent of all terrestrial protected areas and ecologically intact landscapes (for example, boreal and tropical primary forests, savannas, and marshes). It concluded that collaboration between conservationists, indigenous peoples, and governments would be highly beneficial for ecosystem protection.
This conclusion is echoed by other reports, including one by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), which has recommended that the knowledge of indigenous peoples and local communities is involved in pandemic prevention programmes.
Indigenous people will also be key to initiatives using the One Health approach, which is endorsed by the World Health Organization (WHO) and involves the designing of programmes and policies locally, nationally, and globally to attain the best health for the planet as a whole — people, animals, and the environment.
For example, the UN’s Convention on Biological Diversity – the body that manages the global treaty on the protection of wildlife and plants – has recommended that policies to protect habitats such as forests consider the use of natural resources by indigenous and local communities, and that human health is considered when carrying out ecosystem restoration.
Protecting Forests Protects Public Health
Human health will also be a key component of research being carried out by a new global panel on forests and human health, convened by the International Union of Forest Research Organizations. Morand, one of the panel’s members, explained that it will consider not only the negative aspects of forests and infectious disease for humans, but also how protecting forests benefit well-being and good health for people. “I think this work will really provide science-based evidence to policy on this issue,” he said.
Kim Carstensen, FSC Director General:
Protecting forests is crucial for many reasons – and preventing future disease outbreaks is one of them. Now people, companies, and governments are becoming more aware of the essential role forests play worldwide. As FSC®, we have been contributing to forests and biodiversity protection for more than 26 years, and we will continue with full dedication. Together we can work to protect Forests For All Forever.