The Global Tree Assessment, the report of a massive study conducted by the Botanic Gardens Conservation International (BGC) to estimate the conservation status of all of Earth’s trees, was released recently. It warned that a third of the planet’s nearly 60,000 known tree species are facing extinction. About 442 species are on the brink with fewer than 50 specimens left in the wild. The report pointed out that there are twice as many threatened tree species globally as threatened mammals birds, amphibians and reptiles combined.
Extinction of trees is a cause for concern because each tree species has a unique ecological role to play. Trees also provide food and shelter to a number of animals, insects, and birds. Losing tree species can cause cascades of extinction among the many species that depend on them. Further, trees are the “backbone of the natural ecosystem, storing half the world’s terrestrial carbon and providing a buffer from extreme weather such as hurricanes and tsunamis.
What are the threats?
According to the report, the biggest threats to trees, globally are forest clearance for crops (impacting 29% of species), logging (27%). clearance for livestock grazing or farming (14%), clearance for development (13%), and wildfire (13%).
- The BGCI reveals that one in five tree species is directly used by humans, for food, fuel, timber, medicines, horticulture, and more. Many of these trees face extinction as a result of over-exploitation and mismanagement.
- The report finds that one in three trees currently harvested for timber is threatened with extinction.
- Climate change and extreme weather are ranked as emerging threats. At least 180 tree species are directly threatened by sea-level rise and severe weather events. This threat is most severe to island species.
- An increased occurrence of fire due to heatwave is killing many tree species across the globe.
What’s the solution?
The BGCI recommends five key actions for policymakers and experts in order to protect and bring back threatened species. They are
1. Extend protected area coverage for threatened tree species that are currently not well-represented in protected areas
2. Ensure that all globally threatened tree species, where possible, are conserved in botanic garden and seed bank collections
3. Increase availability of Government and corporate funding for threatened tree species
4. Expand sapling planting schemes, and ensure the targeted planting of threatened and native species
5. Increase global collaboration to tackle tree extinction, by participating in international efforts
Significant species under threat
Dipterocarp
- Dipterocarps are a family of around 700 species of trees, known for their characteristic, winged seeds. They are tropical lowland rainforest trees distributed across parts of South America, Africa, the Seychelles, India, Indonesia, Malaysia, and the Philippines. The greatest diversity of dipterocarps occurs in Borneo.
- Dipterocarps are ecologically important. Their canopy gives the rainforests their characteristic layered look. Their fruits, flowers, and sap are an important food source for wildlife.
- These trees possess high-quality timber. Timber export is the major threat to dipterocarps. From the island of Borneo alone, 182 species are threatened with extinction. This includes the tallest known tropical tree species, Shorea faguetiana.
- In Borneo, dipterocarps are also being lost due to the expansion of palm oil plantations. Their decline has led to species such as the Bornean orangutan, becoming critically endangered. The orangutans depend on dipterocarp forests for food and shelter.
Nothofagus
- Nothofagus are deciduous and evergreen forest trees found only in the Southern Hemisphere. Their distribution includes parts of Chile. Argentina, Papua New Guinea, Indonesia, New Zealand, New Caledonia, and Australia.
- Nothofagus trees play a key role in supporting the ecology and biodiversity of the temperate forests in these regions.
- Historically, Nothofagus have been threatened by harvest for timber. Currently the species faces additional threats from mining and wildfires. In the future, populations are predicted to decline due to the effects of climate change.
Magnolia
- Magnolia is a large genus of flowering plant species found in east and southeast Asia, eastern North America, Central America, the West Indies, and parts of South America.
- Magnolia is an ancient genus of plants, which displays many characters that are considered evolutionarily primitive.
- Due to their appealing flowers, magnolias have attracted much interest from horticulturalists. The flowers of many species are considered edible. Parts of the flowers find place in many Western and Asian cuisines. They are also used in cosmetics and medicines.
- Magnolia are principally threatened by overexploitation, habitat loss due to land conversion to agriculture and livestock farming, and impacts of climate change.
- Climate change is particularly of threat to island species.
Oak
- Oaks are trees and shrubs of the beech family. There are about 450 species of oak. They are common in cool temperate and tropical places in the Americas, Asia, Europe, and North Africa.
- Oaks can take 100 years to develop fully and can then live another 900 years. The fruit of an oak tree is a nut called acorn.
- Oak trees support a range of biodiversity, including bird, mosses, fungi, insects, lichens, and mammals.
- The wood of many types of oak is valued in carpentry and building. The bark of the bur oak is used in making leather, while that of the cork oak is used in the making of cork.
- Globally, agriculture poses the biggest threat to oaks. Urban development, climate change, invasive species, diseases, and human activities have also strained oaks globally. And in Latin America, which has the highest number of endemic oak species, the use of oak for charcoal is a threat.
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