Santa Barbara Island Liveforever

Dudleya traskiae

Description

The Santa Barbara Island liveforever, Dudleya traskiae, also known locally as rock lettuce or cliff lettuce, is a perennial herb that establishes 20-100 rosette clusters per plant. Each rosette is composed of 25-35 oblong or lance-shaped, succulent leaves. The gray-green leaves are 1.6-6 in (4-15 cm) long, smaller at the top and increasing in size to the base of the plant. Bright yellow flowers, frequently tinged with red along the mid-vein, bloom from April to May. A powdery bloom (whitish coating) often covers the leaves and may assist in the collection of dew.

Habitat

Santa Barbara Island liveforever prefers the thinnest and coarsest soils on the most exposed sites. Most plants occur on the steep, rocky sea cliffs but smaller populations are found among sparsely vegetated rock outcrops in the canyons. It can grown on the nearly vertical cliffsides. The habitat is hot and dry with no fresh water other than rainfall, which occurs November through April. This liveforever does not occur on the north side of the island, although a few plants have been located on north-facing slopes that retain more moisture through the wet season.

Distribution

According to surveys conducted between 1982 to 1984, only ten colonies, survived on the island, totaling about 230 mature plants. Most colonies were highly restricted. For example, the Cave Canyon colony consisted of one large plant of about 20 rosettes, spread over nearly a square meter, with several solitary rosettes scattered across the rocks nearby. Other colonies were found on the south-to southeast-facing slopes of Cave and Middle canyons and on the north-facing slope of Middle Canyon. The Signal Peak colony was the largest on the island and consisted of at least 84 mature and 534 total plants. However, during a 1984 survey only 58 individuals were observed blooming at this site, suggesting that the natural reproductive potential of the plant is limited. The low productivity could be a result of low recruitment, or because native deer mice, which are seed eaters, browse the ripening fruit.

Threats

Feral goats were abundant on the island from 1846 to about 1915, and their foraging inflicted severe damage to the natural vegetation. The goats were especially fond of the liveforever and it was almost extirpated. The goats were finally removed, but in 1942, New Zealand red rabbits were introduced, starting another attack on native vegetation. The Park Service was able to remove this pest by 1954, but the damage caused by both goats and rabbits was so extensive that the island's flora may never fully recover.

Aggressive species such as common goosefoot, iceplant, and cheeseweed, introduced around 1900, have displaced many of the remaining island plants. Few liveforever seedlings have been noted by researchers. The 1984 survey noted only 673 total live-forevers, indicating that seedling growth is not abundant.

Conservation and Recovery

The Fish and Wildlife Service published a Recovery Plan for the Santa Barbara Island liveforever in 1985. The island is protected by the National Parks Service, and farming has ceased and the damaging non-native goats and rabbits have been removed. The populations of the Santa Barbara Island liveforever should be monitored, and research undertaken into its biology, habitat needs, and beneficial management practices. The rare plant should be propagated in captivity, to provide stock for out-planting to establish additional populations in suitable habitat on Santa Barbara Island.

Contact

U.S. Fish and Wildlife Service
Office of the Regional Director
Eastside Federal Complex
911 N.E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6118
Fax: (503) 231-2122

References

Philbrick, R. N. 1972. "The Plants of Santa Barbara Islands, California." Madroño 21:329-393.

U.S. Fish and Wildlife Service. 1985. Santa Barbara Island Liveforever (Dudleya traskiae ) Recovery Plan. U.S. Fish and Wildlife Service, Portland.