Tree Trends

The Vascular Plant Red Data List, a compilation of the status of rare, threatened and endangered British plants shows that about 20% of British plant species are under threat, and there are many species whose populations are declining. Many of the species are upland plants in forests, but a surprising number are plants of arable lands that were previously thought to be safe in the margins of tilled farm lands. However, the increased intensity of agriculture has pushed many of these plants into ever-shrinking space.

British efforts to conserve endangered species have been quite successful. However, many other species have become dramatically less common. The Red List, a statistical analysis of the New Atlas of British Flora, enables conservation biologists to focus efforts on these declining species. New agricultural methods, which stress preservation of natural lands and the restoration of habitat, hold the promise of returning many of these plants to healthier population levels.

This approach, combining detailed spatial analysis of plant distributions with statistical analysis of abundance, is an important conservation tool. Unfortunately, many of the press accounts of the Red List's publications were quite hysterical. The BBC got it right, but the AP story had the header "British flora faces extinction." Other American accounts were equally overblown. This kind of coverage of natural resource issues is not helpful, as it gives readers the impression that everything is going to hell and there is no point in caring. The more optimistic interpretation of the news, and I think the correct one, is that the Red Data List provides guidelines for helping these species recover.

Ohio has begun planting American chestnut on surface mines in the eastern part of the state. The project is part of the American Chestnut Foundation's effort to restore chestnut to its former glory, uses blight-resistant hybrids of American and Chinese Chestnut. The breeding project, expected to take at least 100 years, mates American chesnuts with Chinese chestnuts and selects resistant progeny. These will then be backcrossed through consecutive generations to select for trees with nearly pure American chestnut characters and genes, but with the blight resistance of Chinese chestnut.  The project is led by Brian McCarthy, a forest biologist at Ohio University.

American chestnut was once the dominant species in mid-slope Appalachian forests. They accounted for up to 70% of the stocking (basal area of all the trees) in these forests. Chestnuts produce starchy nuts rich in protein and fat and were an important food resource for wildlife, and for people and their livestock. The tree was wiped out by an epidemic of chestnut blight, caused by the fungus Endothia parasitica. The blight killed billions of trees in only a few years as it swept down the Applachians.  My friend Junior Marshall recalls that one year at Robinson Forest the fall colors of the chestnut were magnificent and the following year (1939), they were all dead.

Surface mines may seem an odd place to plant chestnuts. However, they appear to do well in some mine sites. I have found American chestnut on mine spoils in eastern Kentucky.

Wollemi pine (Wollemia nobilis), one of the most ancient and rare trees in the world, has a new home at the Royal Botanical Garden, Kew. Sir David Attenborough planted the tree at Kew, and Kenneth Branagh planted one the same day at Wakehurst Place, Kew's garden in Sussex. These planting are the first of this extremely rare and newly discovered tree. Other botanical gardens are in line to plant Wollemi pine, and the species will be commercially available within the next year.

Wollemi pine was known only from the fossil record. An ancient lineage in the Araucariaceae, Wollemi pine dominated much of the southern world in the Cretaceous. Fossils resembling parts of Wollemi pine are known from Cretaceous sediments in Australia, and possibly are found in New Zealand, South America and India. During the Cretaceous, these regions were part of a single southern continent, Gondwanaland. Wollemi pine may have been a dominant species in southern forests from the Cretaceous to at least the Tertiary, a span of 143 million years. The oldest known fossil (the type specimen) of Wollemia dates from 90 Mya. The discovery of living specimens means that the genus, if not the species, has been around for at least 145 million years and possibly as long as 200 million years.

In 1994, David Noble, a National Parks and Wildlife Officer in New South Wales, Australia, found Wollemi pines in a deep gorge in Wollemi National Park in the Blue Mountains only 200 km from Sydney. Since then, two other small stands have been located in the same area. The exact location is a closely guarded secret to protect the trees from collectors. The botanical description of the genus and species were publihed in 1995 (Jones, WG, Hill, KD & Allen, JM 1995. Wollemia nobilis, a new living Australian genus and species in the Araucariaceae. Telopea 6:173-176).

Horticultural interest in the tree is extremely high. The Royal Botanical Gardens, Sydney (RBGS), has established a Wollemi Pine site to provide information about the availability of plants for commerce, as well as general information about the tree. RBGS also has an informational site with detailed information about this fascinating plant.