About Garry Oak Ecosystems

What Remains of Garry Oak Systems?

Collectively, Garry oak and associated ecosystems are among the most endangered in Canada. Once common in coastal areas of southwest British Columbia, less than 5% of these ecosystems remain in near-natural condition. Most of the remnants are in isolated, fragmented communities that have no connection to other Garry oak communities, thereby reducing migration of populations or mixing of genetic material of species from one area to another.

At this time, because so much habitat has been lost or degraded, many species of plants, mammals, reptiles, birds, butterflies and other insects are officially listed as “at risk” in these ecosystems.

Why are they disappearing?

Over the past 150 years, waves of settlers have been attracted to Vancouver Island’s southeastern coast. Land conversion for agricultural, residential and industrial development has vastly reduced the extent of Garry oak ecosystems. Less than 5% now remains in a near-natural condition, and that too is threatened.

Threats include habitat loss, fragmentation of larger areas of habitat into smaller, more vulnerable patches, the encroachment of woody species as a consequence of fire suppression, and invasion of exotic species that out-compete native species.

Filmmaker Fran Benton kindly allowed GOERT to use her short film about Garry Oak ecosystems, formerly called One Less Orchid, as an outreach tool.

The film teaches about the ecology of the ecosystems and how they’re adapted to the local climate, First Nations influence on the landscape, threats to Garry Oak ecosystems, and how you can help protect and restore them. It features Dr. Briony Penn and Dr. Brenda Beckwith, Saanich Mayor Frank Leonard, Saanich Planner Russ Fuoco, and former Executive Director of Swan Lake Christmas Hill Nature Sanctuary Terry Morrison. The term “Garry Oak meadow” is used loosely here to refer to all types of Garry Oak and associated ecosystems. View the short film (17 min) One Less Meadow by Fran Benton.

Types of Garry Oak Ecosystems

Originally, two major types of ecosystems occurred in the Garry oak areas: those on deep soils, known as parkland Garry oak communities; and scrub oak ecosystems, found on shallow soils.

Deep soil sites

On Vancouver Island, only 1.5 % of the original deep soil sites remain.

A variety of shrubs, trees, and meadows of flowers and grasses are typical of deep soil sites. Almost all of the deep soil parkland sites in the Victoria region were cleared for agriculture and urban development. Many large Garry oak trees remain, but most have lawns, roads, agricultural fields, golf courses or blacktop beneath them, rather than native plant communities.

Scrub oak shallow soil sites

On Vancouver Island, only 44% of the shallow soil sites remain.

More of the scrub oak shallow soil sites exist then the deep soil sites since many of these rocky areas are difficult to develop. Spring flowers, grasses and mosses originally dominated the understorey of these rock outcrop communities. Many of these native plant communities have been invaded by weedy species such as Scotch broom, daphne, and agronomic grasses.

Historic Range of Garry Oak Ecosystems

Please click on the tabs below to see the maps and tables that compare the distribution of Garry oak ecosystems.  Note that in regions other than Greater Victoria and Saanich Peninsula areas, the dates for comparison are  1800 and 2003.  The dates for comparison on the peninsula are 1800 and 1997. 

The colour gradations on the maps indicate the percentage that is covered by Garry oak ecosystems (Garry oak woodlands, Garry oak meadows, etc.). For example, the areas with the lightest green or red colour patches contain less than 10% Garry oak ecosystems, and 90% is comprised of other habitats, such as conifer forests or wetlands. The darkest shades represent areas that are totally covered by Garry oak ecosystems (100%).

• Greater Victoria and the Saanich Peninsula

  The following map and table compare the 1800 and 1997 distribution of Garry oak ecosystems in the Victoria area. The Municipality of Highlands was not included due to lack of data.  Download the map (PDF 1.3MB).

  The areas covered are where Garry oak (Quercus garryana) was believed to be the dominant tree cover or co-dominant cover with Douglas-fir (Pseudotsuga menziesii) or arbutus (Arbutus menziesii). Other areas may have had and still have Garry oak as a minor component of the ecosystem; however, these areas were not considered for this mapping project. Comparison in the table below is of Garry Oak Ecosystems (both types) by City, Municipality and Indian Reserve.

  Area	Year: 1800 (Cover in hectares)	Year: 1997 (Cover in hectares)
  Victoria	1,460	21
  North Saanich	1,040	25
  Esquimalt	470	20
  Colwood	320	16
  Langford	370	105
  View Royal	270	39
  Metchosin	1,180	49
  Indian Reserves	240	37
  Total	10,443	512

• Cowichan Valley and Saltspring Island

  Download the map (PDF 2.5MB). Comparison in the table below is by Ecosystem Type.

  Ecosystem type	Year: 1800 (Cover in hectares)	Year: 2003 (Cover in hectares)
  Deep soil Garry oak ecosystems	1,824	83
  Shallow soil Garry oak ecosystems	1,301	619
  Total	3,125	702

  Note that only 4.5% of the deep soil sites have not been developed, and the remaining “scrub oak” sites are on rocky outcrops, steep slopes and similar shallow soil areas that are less appealing for agriculture and residential uses.

• Nanaimo, Parksville and Nanoose Area 

  Download the map (PDF 5MB). Comparison in the table below is by Ecosystem Type.

  Ecosystem type	Year: 1800 (Cover in hectares)	Year: 2003 (Cover in hectares)
  Deep soil Garry oak ecosystems	29	29
  Shallow soil Garry oak ecosystems	951	298
  Total	980	327

  In the Nanaimo, Parksville and Nanoose area, only about 33% of the Garry oak habitats from1800 exist today. Most of these fragments are tiny, isolated, and overrun with non-native species such as Scotch broom, Himalayan blackberry and non-native grasses. Although there have been severe losses of Garry oak habitat in the Nanaimo and Parksville area, there is an opportunity to protect several outstanding sites. Harewood Plains and Harmac/Joan Point are relatively intact remnants of shallow soil Garry oak ecosystems, containing several rare plants of provincial and national significance. For example, Muhlenberg’s centaury (Centaurium muehlenbergii) has been found in Canada only at Harmac and at one park in Victoria. All of Canada’s seven remaining populations of bog bird’s-foot trefoil (Lotus pinnatus) are clinging to survival in the Nanaimo area. Experts currently rank Harewood Plains as the highest priority Garry oak ecosystem site on Vancouver Island for conservation.

  A few examples of deep soil Garry oak ecosystems persist in the Enos Lake and Brennan Lake areas.

• Comox Valley with Denman and Hornby Islands

  Download the map (PDF 6.7MB). Comparison in the table below is by Ecosystem Type.

  Ecosystem type	Year: 1800 (Cover in hectares)	Year: 2003 (Cover in hectares)
  Deep soil Garry oak ecosystems	592	18
  Shallow soil Garry oak ecosystems	98	57
  Total	690	75

  No measurable shallow soil ecosystem occurred in the Comox Valley. The 98 ha shown in the table (above) occurred on Hornby Island, with over half still remaining (57 ha).