Dense-flowered lupine (Lupinus densiflorus) COSEWIC assessment and status report: chapter 7

Habitat

Habitat Requirements

In Canada, Lupinus densiflorus is restricted to the lowland Coastal Douglas-fir biogeoclimatic zone. It occurs in dry to moist grassy openings, clay cliffs, and eroding grassy banks and benches above the seashore, usually with a south or west facing exposure. Shrubs on these eroding upper slopes include Rosa nutkana and Symphoricarpos albus. Associated native herbaceous perennials include Allium cernuum, Armeria maritima, Brodiaea coronaria, Camassia quamash, Danthonia californica, Festuca rubra, Grindelia integrifolia, Lathyrus japonicus, Orobanche uniflora, Pteridium aquilinum and Lomatium nudicaule. Many sites have a high cover of introduced grasses including Dactylis glomerata, Lolium perenne, Bromus hordeaceus, and Bromus sterilis. Lupinus densiflorus occurs in an elevational band up to 10 metres above the shoreline. A portion of population three grows in an atypical habitat --a level meadow with shallow soils that is dominated by introduced grasses and forbs. The other component of population three grows on moderate to steep, unstable slopes similar to the habitats favoured at populations one and two.


Habitat Trends

Less than 1% of the Coastal Douglas-fir biogeoclimatic zone remains in a relatively undisturbed state (Pacific Marine Heritage Legacy 1996). Habitats suitable for Lupinus densiflorus have probably declined proportionally. Surveys of historical sites referenced in the Conservation Data Centre CDC database indicated that considerable habitat loss has occurred as a result of urban development.

Lupinus densiflorus is restricted to benches and banks above the ocean splash zone. Both the benches and banks have suffered from a gradual increase in excessive trampling damage over the past century. Fire suppression has likely favoured the development of dense shrub patches within populations one and two. Several introduced species of grasses and forbs have formed thick swards at all three locations. The dense shrub patches and thick swards appear to have substantially reduced habitat quality for L. densiflorus over the past century.


Habitat Protection/Ownership

The Lupinus densiflorus populations all occur in areas that are federally, provincially and municipally owned. No populations are known to occur on private lands. None of the three levels of government have made provision for the conservation of Lupinus densiflorus in management plans. The species is not afforded protection under any general legislation or regulations in British Columbia.

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