Garry Oak Quercus garryana

Researchers Patrick Lilley and Andrew Burkinshaw examine plants in a Garry Oak meadow on Salt Spring Island

A Garry Oak meadow on a sunny spring day is a feast for the senses. Lush, bright wildflowers, colourful dancing butterflies, rustling oak leaves and sweet ocean scents make these sites special places to experience and study creation.

Garry Oak is the only oak tree native to British Columbia, Canada. Thriving in the shallow soils and Mediterranean-like climate of southwestern BC, the oaks are restricted to sites on Southeast Vancouver Island, the Southern Gulf Islands and several spots in the Lower Fraser Valley. The trees shape the landscape in a variety of ways, sometimes forming shady woodlands, sometimes scattered across open meadows or clinging as single trees on rocky outcrops.

Although Garry Oak habitats cover less than 0.1% of BC's land area, they are disproportionately rich in flora and fauna. For example, almost 700 species, subspecies and varieties of plants have been identified there, approximately 140 of these being found only within Garry Oak communities.

More recently, Garry Oak woodlands have been threatened by urbanization and development. Today, less than 5% remain in a natural state. Introduced plant species, such as Scotch Broom and Sweet Vernal Grass, have begun to out-compete native plants. In the past, the woodlands benefited from the fires set by First Nation peoples to encourage the growth of their food plants. Now, fire suppression is allowing shrubs and other trees to establish in areas once dominated by the oaks.

This combination of limited distribution, species richness and significant threats makes Garry Oak ecosystems some of the most endangered in BC and of particular concern to conservationists. More than 100 associated species are at risk of disappearing from the area. These include the little-known Sharp-tailed Snake and the Propertius Dusky-winged Butterfly, the latter dependent entirely on Garry Oak for larval growth. Others have already become extirpated, or locally extinct.

Common Camas (left) and White Fawn Lily (right) carpet many Garry Oak meadows in early spring. Camas bulbs were a staple food source for the Coast Salish First Nation peoples living in the area.

A Rocha has been contributing to Garry Oak ecosystem study and preservation. Since 2000, researchers have helped inventory a site on Thetis Island, develop a management plan and oversee restoration work. In 2004, A Rocha formed a new partnership with Trinity Western University in Langley, BC. This partnership has seen A Rocha involved in ongoing research at the University's Crow's Nest Ecological Research Area on Salt Spring Island. Studies there are examining important issues such as the effects of sheep and deer grazing on species diversity and persistence. Through helping to increase our understanding we hope to help preserve our remaining Garry Oak habitats.

Patrick Lilley
Originally in A Rocha International News
Issue 35, July 2004