The islands still house US Navy SEALs training facilities, including Naval Auxiliary Landing Field San Clemente Island. Wildlife The Channel Islands form part of one of the richest marine ecosystems of the world. Many unique species of plants and animals are endemic to the Channel Islands, including fauna such as the Channel Islands spotted skunk, ashy storm-petrel, and flora including a unique subspecies of Torrey pine. Flora Flora on the Channel Islands include a unique subspecies of pine, oak, and the island tree mallow. Santa Rosa Island holds two groves of the Torrey pine subspecies Pinus torreyana var. insularis, which is endemic to the island. Torrey pines are the United States' rarest pine species. The islands also house many rare and endangered species of plants, including the island barberry, the island rushrose, and the Santa Cruz Island lace pod. Giant kelp forests surround the islands and act as a source of nutrition and protection for other animals. Invasive species, such as the Australian blue gum tree, olive tree, sweet fennel, and Harding grass, threaten native species through competition for light, nutrients, and water. The Australian blue gum, for example, releases toxins in its leaf litter which prevents other species of plants from growing in the soil surrounding it. The blue gum, as well as other species including the Harding grass, are much more flammable and better adapted to wildfires than native species. Earthworms, thought to have come from mainland topsoil imported for road construction, are altering the unique ecosystem and microbial communities on San Clemente Island, threatening biodiversity. In this formerly earthworm-free region, they change the distribution of plants and vegetation, making it possible for non-native plants to invade. Fauna The Channel Islands and the waters surrounding hold many endemic species of animals, including fauna such as the Channel Islands spotted skunk, island scrub jay, ashy storm-petrel, San Clemente loggerhead shrike, and the San Clemente sage sparrow. Two breeds of livestock, the Santa Cruz sheep and the San Clemente Island goat originate from here. Many species of large marine mammals, including pacific gray whales, blue whales, humpback whales, and California sea lions breed or feed close to the Channel Islands. Current occurrences of the critically endangered North Pacific right whales and historically abundant Steller's sea lions in these areas are unknown. Seabirds, including the western gulls, bald eagles, pigeon guillemots, and Scripps's murrelets use the islands as well for shelter