The diverse eastern North American deciduous hardwood forest that extends from the Gulf Coast of the United States into southern Ontario is known as the Carolinian Forest. Though the extent of this forest type in Canada is very restricted, covering but a small area of southern Ontario, it contains over half of the country’s native tree species and an incredibly diverse understory. Despite the distance and differences in climate, the vast majority of species from this region can be grown in the Vancouver area. A large number of eastern North American plants have their closest relatives in East Asia, while others have family links in both Asia and western North America. The study of such related, but geographically separated organisms is called biogeography. and because all of these regions are represented in the Garden, biogeography is a common theme in education, conservation and biodiversity research at UBC Botanical Garden.
The Carolinian Forest Garden consists of 12 individual groves, each named for an early North American plant explorer. The groves are planted with hundreds of different tree and shrub species and pathways are accessible to all visitors. The Carolinian Forest region is also noted for the diversity of its herbaceous flora and this is reflected in the numerous and diverse collections of trilliums, aster relatives and ferns that thrive in the shade of the trees and shrubs.
Seasonal Highlights
One of the most distinctive features of the plants of the Carolinian Forest is the colour of the leaves in autumn. Maples, oaks, sumacs, tupelos, sweetgums and sourwoods are all noted for their spectacular effect. Colourful fruits are also a common feature in the Garden. Mountain ash and elderberries contribute colour and considerable birdlife.
Significant Collections
Some of the better-known examples of East Asian-Eastern North American biogeographic disjunctions are illustrated by collections in the Carolinian Forest Garden and David C. Lam Asian Garden. There are examples of magnolia, maple (Acer), rhododendron—especially deciduous azaleas—sweet shrub (Calycanthus), mountain ash (Sorbus), tupelo (Nyssa), dogwood (Cornus) and many others. The American and Chinese tulip poplars—Liriodendron tulipifera and Liriodendron chinense—are one of the best-studied species pairs. Molecular analysis and carbon dating of fossils show the close relationship of these two species. They are virtually identical, genetically, despite being separated for the last 65 million years.
History
The late Gerald Straley (1945-1997), former curator of collections and research scientist at UBC Botanical Garden, and a native of Virginia, had always advocated for a collection of eastern North American hardwoods in the Garden. He argued that there were few examples of this rich and biologically important floristic assemblage displayed locally. In 2006, planting began on the vacant land in the southwest corner of the North Garden. Plants were acquired from a variety of sources with the majority of accessions of known provenance and derived from collectors, botanical gardens and government sources in eastern North America. Echoing the plant exploration theme of trail names in the Asian Garden, plantings in the Carolinian Forest reflect the historical significance of early plant collecting in eastern North America. Individual groves are named for plant explorers, each with signature species that illustrate that history. For example, Franklinia alatamaha, which is extinct in the wild, is one of the featured species in the Bartram Grove. William Bartram (1739-1823) collected seed of this outstanding ornamental in the wild, but was probably the last to do so, as it was never found again.
Feature: Maple
In winter, the blue-green, chalky white-striped stems of the moosewood or striped maple (Acer pensylvanicum) stands out. A strikingly beautiful species, its closest relative is the nearly identical Manchurian maple (Acer tegmentosum) from eastern China, which can be seen in the Asian Garden.
