The media has been roaring in the past year about a climate disaster that affected the entire planet: the Amazon forest fire. World leaders have reacted strongly to the disastrous extent of wildfires in the Amazon that led to a huge release of carbon monoxide in the atmosphere, affecting all of us in the long term. These historic events have sparked intense discussions on deforestation and the need to repopulate the vast damaged areas with trees.
But what if someone told you that tree planting can actually make matters worse? You would surely consider it counterintuitive, to say the least. In a search for the truth, we will further explore how planting a tree doesn't always have the desired effect. On the contrary, in some instances, it can lead to global warming, forest fires, and drought.
Planting trees is widely seen as one of the best solutions to fight climate change, so how can that be possible? After all, trees are extremely efficient at capturing the carbon in the atmosphere. In the popular collective conscious there’s almost no negative connotation to tree planting, and the scientific community aligns with this idea, but recent studies show that in certain areas of the world forestation is actually done to the detriment of other ecosystems: grassland biomes.
Grasslands and the Need to Conserve Them as They Are
Grasslands are vast terrains that mainly grow grasses and are either dry or moist, depending on the subclimate in the area. The soil is thin and doesn’t provide enough moisture in the deeper layers for trees to start taking over, which leads to an apparent scarcity in trees. There is a common misconception that grasslands are degraded terrains because of their inability to encourage tree growth, but their specific characteristics sustain rich, unique ecosystems that are perfectly adapted to the conditions. Think about the African savannah, the Russian and Asian steppes or the South American pampas.
What happened in the 20th and 21st centuries is that forestation, as benign as it mostly is, caused an invasion of trees in these ancient grassy biomes, altering their function and the equilibrium of the fauna and flora typically found there.
Forestation as a Carbon-Capturing Technology
The principles behind forestation as a way of cooling down the planet are pretty simple: trees, as they grow, convert carbon dioxide and water into oxygen. By reducing the carbon levels in the atmosphere, forests reduce their warming effect. Besides, they release water vapors that turn into clouds and raise the precipitation levels.
But what should be known and taken into account is that forestation outside of tropical climates actually has a global warming effect. It happens by covering large areas that would otherwise be covered in reflective snow, and by absorbing heat from the sun due to their dark green color. In temperate areas, this warming effect actually counteracts the cooling effect of capturing the carbon from the atmosphere.
This kind of realization should dramatically change the way we do forestation, as it’s not such a simple matter of putting more trees to work and planting as much as we can, wherever we can. We will talk further about the implications held by extending forest areas into other types of terrains.
When Does Tree Planting Become Damaging?
As advanced as humanity has become in researching and tackling the climate change problem, we still have no alternative as efficient as simply planting more trees to capture the atmospheric carbon and release oxygen. So what’s the issue with this initiative?
Forestation has been done in many areas by planting straight-line monocultures: the same tree species laid down in a thick pattern, basically planting them in a row. While this has successfully brought a significant extent to the forests in areas typically affected by irresponsible deforestation done by the timber industry, researchers have been observing some unsettling effects of having a forestation plan that doesn’t take into account the specific function of grassy or wetland terrains.
When planting trees in a large area, with the purpose of deforestation, cost evaluation often leads to a specific solution: planting fast-growing trees like pines, casuarina, or eucalyptus. This leads to monospecies plantations that, despite their benign effect on the carbon emissions in the area, can have controversial effects on the ecosystem they practically invade. We are now debating tree planting in the context of building self-sustaining environments, and forests that were not planted with this aspect in mind are actually damaging.
Studies in South Africa show that planting trees aimlessly in regions typically covered by savannah or grassland are damaging to these ecosystems, determining certain species that thrive in open areas to migrate. In addition to that, the landscape changes the way the vegetation renews itself in these areas. Wildfires are quite common in grasslands, but the vegetation needs this kind of regeneration. By burning taller shrubbery and dry grass, wildfires promote new growth, which a lot of animals, including big ones like zebras or wildebeests, rely on.
By planting forests in areas where grasslands or wetlands should be, we humans shift the entire function of the area, creating cascading effects with long-term consequences.
Where and When Is the Best Time to Plant a Tree?
Because we have begun to understand the effects of unresearched forestation, modern environmentalists are focusing more and more on how it should be done. Unfortunately, policymakers continue to identify areas that should be otherwise preserved as they are, such as grasslands or wetlands as potential forestation areas. This mistake needs to be avoided before the trees are actually planted, changing these biomes and the life they support.
Choosing damaged forest terrains for tree planting is obvious, and it does happen, but it should also be done by using endemic species, not invasive, fast-growing ones. Furthermore, the density and positioning of the newly planted trees should be established by taking natural occurring forests as models, as planted ones can rarely replicate their biodiversity and complex structure.