We need to count every tree on the planet – here’s why

Planting trillions of trees won’t replace the 10 million hectares of forest ecosystems lost every year, but documenting them could prevent further losses


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March 2, 2022

michelle d’urbano

SINCE the 13th century, forests have been managed as sources of trees that can be turned into wood. More recently, with growing concerns about climate change, they are often studied as potential carbon sinks because trees are able to sequester greenhouse gas emissions. But what remains largely unknown is the true relationship between a forest and the trees that make it up. Although there is an international commitment to protect biodiversity, the lack of knowledge about forests is a huge barrier to making effective conservation decisions.

With global attention drawn to increasing the number of trees as a means of mitigating climate change, high-profile strategies such as the Million Tree Initiative, the Plant a Billion Trees program and the Trillion Tree campaign have seen the day. The degradation and deforestation of 10 million hectares of forests worldwide each year is dwarfed by these laudable feats.

Many of the trees we are losing are in primary forests – a type of pristine ecosystem that provides irreplaceable ecological and socio-economic benefits, such as being home to endangered flora and fauna, and supporting unique cultures and customs. indigenous communities. Some have survived earthquakes, hurricanes, fires and other natural disasters for thousands of years, but were wiped off the face of the Earth in a short time due to harmful human impacts. We may be able to plant millions, billions, or even billions of trees, but those we plant today can hardly compensate for the forests we are losing, and very few of those trees will ever become primary forest.

When a forest is viewed as just a collection of trees, we miss the holistic value of its biodiversity. From uniform alpine and circumpolar forests to tropical rainforests that are home to a plethora of species, they are the world’s most important repository of terrestrial biodiversity. When a forest is cut down, we also lose other living organisms from which we can draw new materials, processes, designs and inspirations to meet environmental, medical and technical challenges in a world in crisis. For example, in 2019, scientists discovered a new antibiotic in a Mexican rainforest; hundreds of other potential pharmaceuticals are still waiting to be discovered.

To address the lack of knowledge about tree populations, my colleagues and I compiled a unique, soil-based forest database through the Global Forest Biodiversity Initiative. Supported by comprehensive tree-level survey records from over 1 million sample plots in 110 countries and territories, it is a snapshot of forest ecosystems and allows us to estimate important attributes global forest biodiversity. One of these attributes is the total number of tree species in the world. According to our estimate, there are approximately 73,000 species of trees on Earth, and more than 12% of them have not yet been documented. These discoveries remind us of how little we understand about our own planet.

What is still unknown is the number of tree species locally and the even distribution of trees among these species. Mapping them across the global forest is essential for prioritizing global conservation and detecting, monitoring and assessing the rate of extinction, and its impact on ecosystem functionality and human well-being.

To effectively protect forests, international communities must work together to tackle the disproportionate sharing of responsibilities between rich and poor countries, since more than 90% of the most diverse forests are found in low-income countries. Together we can really begin to see the forest for the trees.

Jingjing Liang is co-founder of the Global Forest Biodiversity Initiative

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