by Gabriela SoteloSensitive media
Whether a local park or a strip of wood in the Amazon rainforest, forests do more than support plants and wildlife. They not only offer scenery and clean the air, but can also play a role in protecting people Conserve carbonBut keep at bay diseases that might otherwise spread from wildlife to humans.
When the forest is cleared or fragmented into small patchesThis creates ideal conditions for the development of disease-carrying species, and the consequences for domestic animals and humans can be fatal. This pattern has been linked to disease outbreaks Malaria And Ebola In areas where forests have been cleared for human use, especially agriculture.
Who survives when a forest is cleared?
agriculture Expansion accounts for nearly 90% of global deforestationMainly driven by Increasing demand for meat, Especially beef. Land for cattle grazing In addition to land used for soy crops, about 40% is responsible for deforestation, Most of which are grown as animal feed. In other words, forests are cleared not only for rearing cattle but also for feeding them.
Deforestation has wide-ranging environmental consequences, particularly through its contribution to climate change. When forests are cleared and burned, large amounts of carbon dioxide and other greenhouse gases are released into the atmosphere. At the same time, forest clearing removes a important world order To absorb and store some of the excess carbon dioxide created by humans.
Tropical forests are under particularly serious threat from deforestation from agriculture. When these ecosystems are damaged or removed, their The loss represents a major decline in global biodiversity. More than 8 thousand on Amazon local Plants and 2,300 animals are threatened with extinction due to human activities, such as logging, mining, cattle ranching and agriculture.
this Biodiversity loss is also a key link between deforestation and disease risk. But not all deforestation happens the same way. These differences can lead to different outcomes for ecosystems and disease risk.
When it comes to disease risk, two processes are particularly important: total forest loss and forest fragmentation. Total loss occurs when large areas of forest are completely cleared for agriculture, urban development or other land uses.
Division of forestIn contrast, a continuous forest breaks up into small, isolated patches. Once continuous ecosystems become fragmented. Many species decline or disappear because they lose access to specialized food or habitat, leaving only a subset of survivors.
“The species you lose is not random, and neither are the remaining species,” Felicia Kissing, an ecologist and educator at Bird College, told Sentient.
First to disappear are specialist species that do not adapt easily to changing conditions because they rely on specific habitats, food or environmental conditions. In comparison, survivors can exploit a wider range of resources and environments, allowing these Generalist species To thrive alongside disturbing landscapes and even people.
Surviving species are also more likely to carry and transmit pathogens.
A broken environmental filter for disease
Destruction of ecosystems through deforestation increases the risk of infectious diseases spreading to humans because susceptible species are lost, and what remains are hardy, adaptive generalists. These species grow and become more abundant, concentrating disease risk in small patches of forest or nearby cleared areas, increasing the likelihood of transmission between livestock and humans.
Kissing describes the changing ecosystem and wildlife dynamics as a kind of “filter”. “They’re cutting it (the forest) down for agriculture, or they’re building houses in the middle of it,” Kissing said. And because of this, humans are now closer to, or in, that habitat than before the split. “So you’ve not only created a more dangerous place, you’ve created more communication between people and that dangerous place.”
Rats and bats are well-known examples. These adaptable animals can harbor a wide range of pathogens and often live in close proximity to humans, especially when forests are cleared. Many also carry parasites Such as fleas and ticks that can transmit disease to humans, increasing the potential for spillover.
Mosquitoes are another important example. As forests are fragmented, watercourses can be disrupted, creating permanent water bodies. Combined with potentially warm conditions, these forest edges make ideal breeding grounds. A 2025 study It has also been found that mosquito populations are highest at the edges of rural forests, where different species mix, creating ideal breeding conditions and increasing the risk of disease spread. As the environment expands with deforestation, mosquito populations can increase and spread to new areas, increasing the risk of disease spread.
In case of spread of disease
Deforestation and forest fragmentation are particularly linked to deadly diseases, including malaria, smallpox and Ebola.
In the case of malaria, a study found that a A 1% increase in land clearing in a month in the Brazilian Amazon leads to a 6% increase in malaria cases.. Deforestation alters the environment in a way that favors mosquitoes, especially at forest edges, where cleared areas have partial sunlight, shallow water, and aquatic vegetation where mosquitoes breed. Fragmentation can contribute to a high mosquito population.
As forests are cleared and wildlife declines, mosquitoes also adapt their feeding behavior and move toward humans when they lack animal hosts. At the same time, human activity often increases near these areas, which puts people in close contact with mosquitoes and increases the likelihood of disease transmission.
For Ebola, the earliest cases were discovered near forest fragments, where wildlife can live near places where people live and work, increasing the chance of exposure to the pathogens the animals carry.
But it’s not just forests where this is happening. Kissing describes cases of “high concentrations of closely related individuals,” such as on factory farms, where large numbers of cattle are kept. If they’re kept near a fragmented forest, Kissing says the conditions are ideal for diseases to jump from wildlife to domestic animals. Once a pathogen enters a livestock population, it can spread rapidly among susceptible animals, increasing the likelihood that it will reach humans who come into contact with them.
as global Demand for meat and animal products continues to growThere is increasing pressure on agricultural systems to produce more animal-based food. This pushed both the expansion and intensification of livestock production. Although farming can reduce land use through intensification, producing more food on less land, this system often traps large amounts of animals and their waste. This creates ideal conditions for disease to spread. and in turn Creates an infectious disease trap.
Biodiversity: A Key Defence
All of these human activities create more opportunities for pathogens to move from wildlife to humans, with potentially fatal consequences. These patterns highlight how disrupting natural ecosystems increases the risk of zoonotic diseases. Given the ways in which deforestation and high-density livestock farming can increase the risk of disease, Kissing noted that the main lines of defense may include measures such as vaccines and strong public health systems, but maintaining biodiversity is also important. Some biodiversity researchers have recommended Countries that work together including the Integrated National Action Plan.
“In the ecology space, in my view, protecting biodiversity is the single biggest thing we can do. And that means reducing fragmentation and actually reversing it when we can,” Kissing said. “Because biodiversity is naturally protecting us from these zoonotic pathogens.”
This article originally appeared on Sentient https://sentientmedia.org/how-deforestation-opens-the-door-for-diseases/.
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This story was originally published by sensitive
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