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Share to FacebookShare to TwitterShare to LinkedinNAIROBI, KENYA – MAY 10: Residents of Dagoreti Constituency take part in tree planting at Ndurarua … [+] Primary School on May 10, 2024 in the Dagoretti area of Nairobi, Kenya. Kenyans today from Dagoretti and various parts of the country participated in the national tree planting day, part of the plan to plant 15 billion trees by 2032. (Photo by Donwilson Odhiambo/Getty Images)

Getty Images Our planet is in a state of global warming. Trees absorb carbon emissions that contribute to warming. Therefore, planting trees will help in saving the planet. That is straightforward, right? Unfortunately, it is more complex than this and, hence, requires a science-based discussion. Such a discussion is critical because millions of dollars will flow into tree planting. At the start of this year, as many as 100 big companies pledged to grow over 12 billion trees in 100 countries over the coming decade, including big names such as MasterCard, which committed to restoring 100 million trees by 2025.

Various initiatives at different levels are adding momentum to the efforts to increase tree cover. The Bonn Challenge is a worldwide effort to restore 350 million hectares by 2030. Similarly, the African Forest Landscape Restoration Initiative is a country-led effort to restore 100 million hectares of land in Africa by 2030. Complementing these restoration efforts is the private sector, driven by increasing awareness about sustainability and the need to set net-zero targets, seeking options such as carbon offsets where land restoration is a crucial feature. As these initiatives gain more ground, it is critical to understand better when tree planting can go wrong.

Simply put, tree planting should not come at the expense of local ecosystems, which include trees, plants, birds and animals interacting in a specific environment. There is evidence that tree planting has sometimes reduced native biodiversity. Biodiversity refers to the variety of life on earth. For example, in Chile, the government’s afforestation policy from 1974 to 2012 inadvertently led landowners to cut native trees to plant new ones, increasing biodiversity loss despite expanding tree cover. That said, some tree-planting initiatives now recognize the importance of avoiding a narrow focus on climate and include necessary checks. For instance, Trillion Trees, a global multi-organization initiative, has an investment tool that guides and supports investments in creating positive social, biodiversity, and climate impacts.

Increasing Trees On All Types Of Land Is Not A Solution Tree restoration efforts are expanding into areas where they should not be happening. Scientists have mainly raised concerns about recent mass tree-planting initiatives in grasslands —landscapes characterized by grass-dominated environments.

Serengeti National Park. Blue Wildebeest (Connochaetes taurinus) herd migrating through savanna. … [+] Tanzania. (Photo by: Godong/Universal Images Group via Getty Images)

Universal Images Group via Getty Images MORE FOR YOUSee A Total Eclipse Of A Star As Manhattanhenge Returns The Night Sky This Week The Acolyte Episode 3 Review One Of The Most Disappointing Star Wars Episodes Ever MadeSteve Bannon Requests His July 1 Prison Reporting Date Be Dropped An area the size of France is threatened by inappropriate restoration work involving tree planting in the African savannahs, according to findings from a recent article published in the Journal of Science. The authors argue that this problem is not unique to Africa and could also occur in other areas, such as India and Brazil, with similar grassland ecosystems. Savannas are areas with less than 10% tree cover and are often home to local specials. In African savannas, wildebeests, zebras, cape buffalos, elands, hartebeests, waterbucks, and gazelles benefit from the lack of tree cover in their ecosystem as they feed on the grasses.

Some scientists argue that the reason why such inappropriate expansion is happening is due to limited clarity on the definition of forests . Forests are defined as areas with more than 10% tree cover, while grasslands have less. Many savannahs in Africa are on the margins of this number, making them appear to be degraded forests and, therefore, needing reforestation. Other scientists point out that the understanding of grasslands and the definition could have historical roots, making the problem more complex. The confusion can be dated to as early as the 19th century when savannahs were seen only as a successional state of an area that had been degraded by fire.

Nonforest Ecosystems Are Also Essential Nonforest ecosystems also help mitigate climate change by absorbing carbon. Grasslands—a nonforest ecosystem—can store 150-200 tonnes per hectare of carbon under the soil. This level of carbon storage is not significantly less than the numbers for a tropical rainforest, which stores 320-400 tonnes per hectare.

Grasslands can sometimes be more resilient in storing carbon because they can store it under the soil. Tree plantations, often part of afforestation drives, allocate a large share of carbon above ground in their wood at the expense of roots. A study highlights that grasslands may be more reliable carbon sinks than forests in California because the region is vulnerable to fire, and the unique ability of grasslands to store carbon underground is advantageous. Several other studies show that the carbon sequestration potential of these new forest plantations is much less than the carbon sequestration potential of mature, native forests.

Monarch butterfly (Danaus plexippus) on a milkweed plant flower. (Photo by Creative Touch Imaging … [+] Ltd./NurPhoto via Getty Images)

NurPhoto via Getty Images Another related challenge is converting grasslands, to other nonforest uses, such as croplands, which also risks the ecosystem of local species. A study published in Nature, titled Cropland Expansion In The United States Produces Marginal Yields At High Costs To Wildlife, highlighted that converting parts of the Northern Prairies—a type of grasslands, into croplands reduced the density of milkweed plants, which are essential for the survival of Monarch butterflies—a species vulnerable to extinction. In addition, despite the significant biodiversity impact on these butterflies and other species, the yield from these new croplands was much lower than the national average.

To sum up and answer the question we started with, planting trees can help tackle climate change. However, it is essential to approach it carefully with respect to the local ecosystem and biodiversity. Imagine the delicate Monarch butterflies in the prairies of North America coming back to find the milkweed plant they feed on is replaced by a tree, or the shock to the hairy wildebeest in the savannahs of southern Africa, seeing the grasses it was feeding on have been removed. Is this the outcome we desire?

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