Arboretum in Concordia is home to a number of trees endangered in the wild
A recent report from an international group assessing the extinction risk of the world’s plant and animal species shows that a third of assessed tree species from around the world are at risk for extinction in the wild. The report notes that conservation of habitat will be critical for saving these species, but also cites the importance of preserving these trees’ genomes through planting in sites outside their original forests and savannas. Known as ex situ preservation, these plantings in public and private gardens can help partially maintain species under threat from land clearance, forest fires, overharvesting, invasive species, new diseases and pests, desertification, and even rising sea levels.
Fall color of ginkgo (Ginkgo biloba)
Concordia Learning Landscape Arboretum (CCLA) is home to a few species that are considered vulnerable or threatened by extinction. A prime example is Gingko biloba. Tens of millions of years ago ginkgo trees could be found worldwide. By the time of the last Ice Age they were reduced to a single species living in refugia in China. Deforestation in China, largely through clearing for agriculture and grazing, wiped out most ginkgos in the wild. There is some doubt if any truly wild trees remain, with a few groves potentially representing remnant populations. But thanks to humans preserving the trees on temple grounds, and since the 1700s planting them as street and park trees, ginkgos can again be seen gracing multiple continents.
The one ginkgo at CCLA is the lone survivor from a planting done by the school district at Meek Elementary in the first decade of this century. It is recovering from a large wound to its bark at the base, the result of damage inflicted by a riding lawn mower. The trees at Meek are now protected from such injuries because neighborhood volunteers with the Concordia Tree Team annually weed and mulch around the trees.
A relict species hunted to the brink of extinction for its bark
Hardy Chinese rubber tree (Eucommia ulmoides)
Another Chinese species widely cultivated but vulnerable to extinction in the wild is the hardy Chinese rubber tree (Eucommia ulmoides). Overexploitation of the tree for its supposed medicinal properties has led to the near extermination of wild trees, with fewer than 1,000 mature trees believed to still exist scattered in Chinese forests.
Several species of Eucommia are believed to have existed as long ago as the Eocene some 56 to 34 million years ago. Fossils assigned to the genus have been found not only in eastern and central Asia but in Europe and North America. The tree eventually died out on those last two continents, leaving only a relict population of a single species in China.
The Eucommia tree at CCLA can be found in a row of trees planted at the north end of the school’s baseball field. It is the easternmost tree closest to NE 41 st . Largely free of pests and diseases, it is a deciduous tree with handsome, dark green leaves. It eventually forms a rounded shade tree between 40 and 60 feet in height at maturity. It is the only species and genus in its own family – Eucommiaceae.
Dawn redwood (Metasequoia glyptostroboides)
Oregon’s living fossil – the dawn redwood
Another tree with a vastly reduced population in the wild is the dawn redwood (Metasequoia glyptostroboides). This tree flourished in Oregon forests during the Miocene (which lasted from 25 to 5 million years ago), but eventually died out here and everywhere else outside of China.
Indeed, it was first recognized as a 150-million-year-old fossil thought completely extinct. Only when a few living trees were found in central China in the 1940s was it realized to still be in existence.
Today, there may be more dawn redwoods in cultivation around the world than growing wild in China, where fewer than 6,000 trees in nature were counted earlier this century.
Standing tall but endangered – the coast redwood
Lastly, coastal redwood (Sequoia sempervirens) is an endangered species found natively only in coastal California and in Curry County in SW Oregon. The world’s tallest tree, coastal redwood grows only in the fog belt along the Pacific. Vast numbers were felled in the 20th century for outdoor furniture and to build cabins. Today, only unlogged groves that were protected in state and national parks remain.
The coastal redwood at CCLA can be found on the corner of NE 41 st and Alberta Court, growing next to a grand fir (Abies grandis). It can be distinguished from the grand fir by its reddish- brown, fibrous bark, and its short, flat needles.
NE Portland residents are lucky to be able to see in one location so many trees that face potential extinction in their native habitats. Anyone interested in helping weed and mulch these trees and provide summer watering can contact the Concordia Tree Team.
Coastal redwood (Sequoia sempervirens)
For the first time, the majority of the world’s trees have been listed on the International Union for Conservation of Nature (IUCN) Red List, revealing that at least 16,425 of the 47,282 species assessed are at risk of extinction. Trees now account for over one quarter of species on the IUCN Red List, and the number of threatened trees is more than double the number of all threatened birds, mammals, reptiles and amphibians combined. Tree species are at risk of extinction in 192 countries around the world.
“This comprehensive assessment presents the first global picture of the conservation status of trees, which enables us to make better informed conservation decisions and take action to protect trees where it is urgently needed,” said Dr Malin Rivers, Global Tree Assessment lead at Botanic Gardens Conservation International, a Red List Partner. “The work is a global effort, with over 1,000 tree experts involved. We need to continue to work together to scale up local, national and international tree conservation action to support people and the planet.”
The highest proportion of threatened trees is found on islands. Island trees are at particularly high risk due to deforestation for urban development and agriculture at all scales, as well as invasive species, pests and diseases. Climate change is increasingly threatening trees, especially in the tropics, through sea-level rise and stronger, more frequent storms. Addressing the threats that trees face, habitat protection and restoration, as well as ex situ conservation through seed banks and botanic garden collections are critical to prevent extinctions on islands and worldwide. Community action has already led to positive outcomes from the Juan Fernández islands to Cuba, from Madagascar to Fiji.
In South America – home to the greatest diversity of trees in the world – 3,356 out of 13,668 assessed species are at risk of extinction. Innovative approaches are needed to protect the high number of tree species in the region, where forest clearance for crop farming and livestock ranching are the largest threats. In Colombia, Red List assessments have informed national conservation action planning. Seven species of Endangered and Critically Endangered Magnolia have been used for the designation of five new Key Biodiversity Areas, which will be used by local and national government to inform spatial planning.
The IUCN Red List also shows that the loss of trees is a major threat to thousands of other plants, fungi and animals. As a defining component of many ecosystems, trees are fundamental to life on Earth through their role in carbon, water and nutrient cycles, soil formation and climate regulation. People also depend on trees, with over 5,000 of the tree species on the IUCN Red List used for timber in construction, and over 2,000 species for medicines, food and fuels respectively.