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Trees, cataloging them and saving them

The Global Tree Assessment

Completing the efforts of over 500 technicians, botanists, and scientists from over 60 international organizations, Botanical Gardens Conservation International has just released the Global Tree Assessment (GTA), quantifying the conservation status of every known tree species.

The number of tree species in the world was unknown before the GTA. The project, which took more than five years to complete, is the largest biodiversity assessment ever undertaken at a species level.

On an everyday level, it might be easy to understand the conservation plight of songbirds, pond turtles, or ocelots, but trees, as well as other plants, can become endangered or go extinct, too. What may come to mind first when thinking of endangered trees is the American chestnut. This much loved tree was once common throughout the eastern U.S., but since the Asian chestnut blight was introduced to the United States a little over a hundred years ago, the tree has been almost thoroughly wiped out from its traditional range.

The GTA estimates that there are, worldwide, 58,497 tree species, 30 percent of which are threatened with extinction. At least 142 tree species were recorded as extinct. Additionally, data was insufficient for 7,700 (13.2 percent) trees species to assess their conservation status, and 4,790 (8.2 percent) were not evaluated.

The Assessment reveals the differences among the regions of the world and the biodiversity of their trees. The region that the Assessment calls the Nearctic, which comprises Canada, the U.S. and a great deal of Mexico, has a total of 1,432 tree species, while the Neotropics—southern Mexico, Central America, and South America—have a whopping 23,631 tree species. The Neotropics have nearly five times the number of endangered tree species (7,047) than all the tree species to be found in the Nearctic.

Hotspots for conservation, the areas with the most Endangered species, are the Amazon region and Madagascar.

The biggest threat trees face is us cutting them down. Not only do we clearcut forest for timber, but we also convert forests to farmlands, freeways, and office parks. Altogether this makes up over 70 percent of the threat that trees face. Fire and fire suppression are also a great threats to trees, accounting for 13 percent of the threats they face.

To a lesser extent, trees are also plagued by invasive pests. In the countryside close to where I live, I’ve seen entire mountainsides of oak woodland turned into lifeless trunks, due to the invasive gold spotted oak borer. Climate change is also affecting the health and habitats of trees. As far back as 2008, scientists were taking note of how tree species in the eastern part of the United States were migrating north due to climate change.


Sharing the results of their research, BGCI has published GlobalTreeSearch, which gives the native geographic distribution of trees species. Also published by BGCI, The Global Tree Portal gives overviews of the information from all their research. For example, typing “Mexico” into the search bar, the Portal tells me that Mexico has 3,654 trees native to that country, 1,481 of which are endemic. And Mexico has 1,041 species of trees that are Threatened or Endangered.

Putting the Englemann oak, a tree that shades many of my hikes, into the search showed that the tree is native to the U.S. and Mexico and has been introduced to Britain, Eastern Europe, and Australia. It also says that the tree’s conservation status is Endangered. (Among the oaks killed by the gold spotted oak borer mentioned above is the Englemann oak.) The information is not fine tuned at this stage of development of the Portal. Yes, the Engelmann oak is native to the U.S. and Mexico, but its natural range is quite small, from around northern Los Angeles down through the northern Baja Peninsula. Perhaps this level of detail will be forthcoming in the future.


Despite some of the more dire findings of the Assessment, BGCI hopes that the Assessment can aid in restoration and recovery efforts. Among the recovery efforts that BGCI spotlights is the work done by the Global Tree Campaign. Established in 1999 as a joint venture between Fauna & Flora International and BGCI, the Global Tree Campaign has worked in more than 50 countries to conserve over 400 threatened and endangered tree species.

Besides rediscovering at least one species thought to be extinct, the Campaign has trained 10,000 individuals worldwide in tree conservation strategies and skills. They have planted more than 700,000 seedlings of more than 300 threatened tree species. (Botanical Gardens Conservation International)

More good news about trees

The Society for Wildlife Research and Environmental Education, an organization that works to preserve and restore the Atlantic Forest of Brazil, has commenced work to restore 827 acres of forest by planting 250,000 seedlings of native plants.

A significant percentage of the seedlings will be araucaria trees. Also called the Brazilian pine, the araucaria is a great, spreading evergreen native to the Mixed Ombrophilous Forest, one of the ecoregions of the Atlantic Forest. The Brazilian pine serves as the symbol for the southern state of Parana, which lies between the Atlantic Ocean and Paraguay and is the area of concentration for the restoration work. (Landscape News)

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