They are the lungs of the world, the repositories of life, and among the most wondrously beautiful places on the Earth, and we are cutting them down. Like most people, I knew deforestation was a major problem without knowing any substantial facts about it. So this is my attempt to rectify that.
First of all, forests are not the lungs of the world; they are more like a single lung (notwithstanding the fact that lungs perform the opposite process to photosynthesis in that they use oxygen instead of producing it). It is estimated that at least half of the oxygen we breathe is produced by phytoplankton in the ocean. Though, this number is difficult to accurately calculate and estimates range from 33% to 85%. Either way, forests do play a role in producing the oxygen we breathe. We certainly could not live without them.
The forests of this world are home to 70% of all the Earth’s land animals according to National Geographic. There are even humans that still live in them. And further to this, tropical rainforests harbour half of all plant and animal species. Despite the immense importance of this biodiversity in and of itself, and while we should not be so arrogant and self-important as to justify the importance of forests solely in relation to our own species’ existence, they are a valuable source of a huge variety of products we use. Whether that be the wood, the bountiful crop in the form of fruit, nuts, and berries, fibres, latexes, oils, pulp for paper and boxes and sponges, we have found many things in forests that we have fashioned to our own desires. They have always provided our species and others with food, fresh water, and shelter.
They also have the potential to provide important medicinal treatments. They are an irreplaceable source of new drugs, many of which are used in cancer treatment. And yet, we have screened less than 1% of tropical plants for possible uses in medicine. Plants have unique abilities to synthesize compounds that are used to perform important biological functions and to do so in the lab may present major difficulties. Deforestation results in the extinction of species, meaning we are losing potential medicines.
We are losing dozens of plant, animal, and insect species every day. While we do not know just how many species there are out there, making it difficult to estimate the exact rate of extinction, we can calculate that the current rate of extinction is up to 1,000 times higher than it would be if humans did not exist. This has resulted in many calling this the Holcene extinction period. This is the sixth mass extinction period that has occurred on Earth, but rather than being caused by an asteroid or volcanic activity, humans are the culprit. It is easy to believe when you learn that humans have wiped out nearly 80% of the world’s original old-growth forests, most of which is found in North America, Russia, and Brazil. Today, forests cover a quarter of the world’s total land area thanks to regrowth or secondary forest. About half of this is found in the tropics and in the past few decades, this is where the majority of deforestation has occurred – and the rate of deforestation is only increasing.
One of the most important aspects of forests is their impact on the water cycle. Forest cover intercepts precipitation which then percolates to groundwater systems. Their litter, stems, and trunks slow down surface run-off. Their roots systems increase the infiltration of water. Terrestrial evaporation and transpiration processes control the humidity of the surrounding environment. And of all the fresh water in the world, rainforests produce approximately 30% of it. They also are hugely important to the health of the soil. Once removed, the soil quickly becomes arid rendering it useless, even for agriculture.
Deforestation impacts all of these things. It reduces soil cohesion so that erosion, flooding, and landslides become more common. It results in more surface run-off and less water being trapped in the ground and air. As a result the water runs into rivers creating many problems; the Amazon River has seen an increase in its annual crest, despite there being no increase in rainfall. The disruption to the water cycle can also cause a decrease in rainfall, as was documented in Northwest China where precipitation decreased by a third between the 1950s and 1980s in deforested areas. Tropical deforestation is estimated to contribute to 20-30 percent of greenhouse gas emissions, rivalling that of burning fossil fuels. Furthermore, it also causes carbon stores held in the soil to be released. These are some of the consequences, but what of the causes? And how can we fight it?
According to the United Nations Framework Convention on Climate Change, the overwhelming cause of deforestation is agriculture. Subsistence farming accounts for 48% of all deforestation, commercial agriculture 32%, logging 14%, and fuel wood 5%. 100,000 square kilometres of forest are removed every year, and a further 100,000 square kilometres are degraded. Much of the illegal logging can be difficult to detect even from satellite, as loggers often select specialty wood like mahogany below the canopy. Tropical rainforests once occupied 16 million square kilometres, now they occupy 8 million square kilometres. It is estimated that Latin America and Asia have already lost 40% of their original forest, and Africa little more than half. Up to 90% of West Africa’s coastal rainforests have disappeared since 1990. In Southeast Asia, about 90% has been lost also. Much of what remains globally is in the Amazon. Several countries, most notably Brazil (which has most of its forest intact relatively speaking), have declared their deforestation a national emergency. Despite all of this dire news, much is being done to combat this global problem.
China has established a national tree planting day and since its inception, forest coverage has increased from 12% to 16.55% of China’s land area. Brazil recorded its second lowest rate of deforestation in 25 years this year, although that number is not without dispute. Certification schemes such as the Programme for the Endorsement of Forest Certification and the Forest Stewardship Council encourage market demand for timber from sustainable managed forests. Using fuel from bamboo is being encouraged as it burns cleaner, and it matures much faster meaning the resource can be replenished much faster than conventional fuel wood. Reforestation is becoming increasingly common and in 22 of the worlds 50 most forested nations, the amount of woodland has increased in recent years. With regards to the fight against climate change, the ability of forests to sequester carbon is still a matter for debate. There is good evidence that the regrowth of previously deforested areas in Europe and North America during the 20th Century has sequestered considerable amounts of carbon dioxide from the atmosphere.
It has been suggested that high yielding forest plantations are suitable to meet the worlds’ demand for wood. Calculations show that we could supply all the timber required for international trade on 5% of the world’s existing forestland, five to ten times less than would be required from natural forests. These are things that need to be encouraged on a global scale, but it is a daunting task.
Deforestation is a horrifying reality that reminds us of the incredible negative impact our species can have on this planet, but if we are informed we can begin to encourage change.