Small-flowered tonella (Tonella tonella) COSEWIC assessment and status report: chapter 5

• Previous page
• Table of contents
• Next page

Habitat

Habitat requirements

The Tonella tenella population in British Columbia is found in the Quercus garryana (Garry Oak)^Footnote1 ecosystem in the dry Coastal Douglas-fir zone (Nuszdorfer et al. [1991]) of southeastern Vancouver Island. This area is in a rainshadow belt created by the Olympic mountains to the south, resulting in a relatively warm and dry Mediterranean climate.

Within this region, Tonella tenella occurs on west-facing slopes on gravelly rock outcrops or stable talus. This talus occurs in open Acer macrophyllum (big-leaf maple)-Arbutusmenziesii (Arbutus) forests, where associates include Galium aparine (cleavers), Cardamine oligosperma (little western bitter-cress), Claytonia perfoliata (miner’s-lettuce), Vicia sativa (common vetch), Bromus sterilis (barren brome), and Collinsia grandiflora (large-flowered blue-eyed Mary) or in open Douglas-fir -Arbutus -Garry Oak forests with Kindbergia oregana (Oregon beaked moss), Dicranum sp. (heron’s-bill moss), Melica harfordii (Harford’s melic), Galium aparine, Torilis japonica (upright hedge-parsley) and Bromus sterilis.

Trends

Habitat trends are mainly dependant on the development activities at the sites.  Development would likely eliminate or reduce the extent of T. tenella habitat at the site.

Protection/ownership

The single occurrence of T. tenella in British Columbia occurs on private property.