Very limited known area of occupancy (AOO) of 16 km2 and extent of occupancy (EOO) of 7.65 km2. Threatened by invasive species such as Mesobryanthemum. Climate change could affect the species through decreased fog regime and potentially sea level rise.
In 1996, N. ramosissima was separated from N. homalea (Ach.) Rundel & Bowler (Spjut 1996). Subsequently, it was lumped back into N. homalea (Bowler and Marsh 2004), but this broad interpretation has since been disputed. The species has morphological features and habitat differences that separates it from N. homalea (Knudsen & Wheeler 2015).
Why suggested for a Global Red List Assessment?
This species is a narrow endemic to San Nicolas Island, California, USA.
This species is a narrow endemic to San Nicolas Island, California. All observations are from the south-south east end of the island, but it could have a slightly wider distribution on the island.
Population and Trends
The species is common on San Nicolas Island, where it can dominate large patches of soil on the south-southeast end of the island. Currently, it appears to be stable.
Population Trend: Stable
Habitat and Ecology
Niebla ramosissima is a terricolous species growing on calcareous soil rich in gypsum. It is an asexual, clonal species spreading by fragmentation. Wind or erosion easily break off branches that then form a new individual. The south-southeastern part of the island where the lichen occurs is dominated by canyons. The vegetation consists mainly of low-growing sub-shrubs and herbs, but the majority of the ground cover consists of soil-crusts. San Nicolas has a semi-arid climate with Mediterranean characteristics. Although the island only receives around 200 mm precipitation a year, dense fog is a common phenomenon.
Mediterranean-type Shrubby Vegetation
Several invasive plants (e.g. Mesobryanthemum ssp.) have established on the island, and could pose a threat in the future. Climate change could affect the species through decreased fog regime and potentially through sea level rise.
The island is owned by the Navy and are not open to the general public. Some areas of the island, including areas where the species occurs, are off limit to most Navy personnel. The species is currently not officially protected. Federal protection would require the Navy to take protective actions.
The species would greatly benefit from removal of invasive plants such as Mesobryanthemum that tends to dominate areas where it establishes. This may prove to be extremely difficult because of the very rugged terrain on the island.
Site/area managementInvasive/problematic species controlNational level
More accurate estimates of population size and trend would inform threat assessment.
Population size, distribution & trends
Use and Trade
Niebla ramosissima, close up. @Rikke Reese Næsborg.