Lindley’s false silverpuffs (Uropappus lindleyi) COSEWIC assessment and status report: chapter 5

• Previous page
• Table of contents
• Next page

Habitat

Habitat requirements

Uropappus lindleyi occurs in dry open places in valleys, foothills and plains across its range in the U.S. (Cronquist 1955). Populations in British Columbia are found in, or near, Garry oak^Footnote1 and associated ecosystems in the dry Coastal Douglas-fir (CDF) zone of southeastern Vancouver Island and adjacent Gulf Islands (Nuszdorfer et al. 1991). This area is in a rainshadow belt created by the Olympic Mountains to the southwest and the Vancouver Island Ranges to the west, resulting in a relatively warm and dry Mediterranean-like climate.

The species occurs on sandstone cliffs and steep grassy slopes, and xeric, open deciduous or evergreen forests within the CDF zone. On sandstone cliffs, the plants grow in cracks and on ledges (Figure 5). The few plants growing with U. lindleyi on these cliffs include Alaska brome (Bromus sitchensis), great camas (Camassia leichtlinii), American wild carrot (Daucus pusillus) and Pacific stonecrop (Sedum spathulifolium). The steep, grassy slopes are occupied mainly by alien species such as early hairgrass (Aira praecox), ripgut brome (Bromus rigidus), barren brome (B. sterilis), and Scotch broom (Cytisus scoparius).

The forests associated with U. lindleyi include rocky slopes and cliffs dominated by Garry oak (Quercus garryana) or mixed woodland types with an overstory of Douglas-fir (Pseudotsuga menziesii), arbutus (Arbutusmenziesii) and Garry oak. These dry, open, south- to west-facing forests occur on slopes between 70% and 90%, that are well-drained, gravelly or rocky, and between elevations of 50 to 80 metres. Prominent native species in the understories of the mixed forests include blue wild rye (Elymus glaucus), bladder desert parsley (Lomatium utriculatum)and Wallace’s spikemoss (Selaginella wallacei). Barren brome, early hairgrass, crested dog’s-tail grass (Cynosurus cristatus), Scotch broom, and hairy cat’s-ear are frequent introduced species.

Trends

There is no specific information on the trends of U. lindleyi habitats on southeastern Vancouver Island or the adjacent Gulf Islands, although they almost certainly share the same trends as Garry oak ecosystems with which they are often closely associated. Field surveys indicate that some unoccupied U. lindleyi habitat still exists. Some reduction in these sites is likely however, due to habitat fragmentation that has been severely magnified by urban development.

The major threats that have influenced Garry oak and associated ecosystems over the past century include agricultural development, urbanization and invasion by aggressive introduced species. These factors have reduced Garry oak systems to less than 5% of their original extent in the Victoria area (Lea 2002). Garry oak ecosystems persist largely as isolated pockets of heavily fragmented habitat and lack connections that would allow substantial genetic interchange.  

Habitat protection/ownership

Most habitat occupied by U. lindleyi is located on private land. The only occupied habitat that is found on public land is on Galiano Island where the population extends into a regional park. Although little habitat is legally protected, it is possible that an increased amount will be protected through conservation covenants, since some of the habitat is on steep, seaside cliffs that can be costly and generally difficult to develop. The habitat of one population on Saturna Island is already protected by such a covenant.