Florida perforate reindeer lichen (Cladonia perforata)
|Also known as:||Florida perforate cladonia, perforate reindeer lichen|
The Florida perforate reindeer lichen is classified as Endangered on the IUCN Red List (1).
Occurring only in the U.S. state of Florida, the Florida perforate reindeer lichen (Cladonia perforata) is an Endangered lichen threatened by the loss of its scrub habitat. A terrestrial lichen, this species forms large, dense clusters, two to six centimetres tall. It is easily recognised by the conspicuous holes at the base of each wide, smooth, yellowish grey-green, forked branch (2).
The branching pattern of the Florida perforate reindeer lichen is rather complex, with roughly equal projections near the tips of the branches and unequal branches below, such that the lichen forms a compressed tuft (2). The branches are typically four to six centimetres long and tipped with reddish spore-producing structures known as ‘apothecia’ (3).
The Florida perforate reindeer lichen occurs in three widely separated regions of Florida: the North Gulf Coast, Lake Wales Ridge and the Atlantic Coast Ridge, with each region supporting many severely fragmented populations. There are only around 30 populations in total, with each one typically occupying an area of less than one square kilometre (1).
The North Gulf Coast has a singe natural population, as well as two reintroduced populations that were established in 2000. The Lake Wales Ridge region supports the bulk of the populations, 22 of 32, but many are so severely fragmented that dispersal among them is highly unlikely. The Atlantic Coast Ridge has two important locations at Jonathan Dickinson State Park and at Jupiter Lighthouse, as well as numerous privately-owned areas that contain small, scattered populations (1).
The Florida perforate reindeer lichen is primarily found on high sand dune ridges, amongst open Florida rosemary (Ceratiola ericoides) scrub. It is most frequently found in open patches of sand between shrubs, in areas with sparse or no herbaceous cover. In the Lake Wales Ridge region, the Florida perforate reindeer lichen occurs on excessively well-drained, nutrient-poor, white sands at relatively high elevations (1) (2).
Lichens are a unique group of organisms that consist of two components, a fungus (called the ‘mycobiont’) and an alga or cyanobacterium (called the ‘photobiont’) that live in a close symbiotic relationship (4) (5). The fungus produces the thallus, which houses the alga or the cyanobacterium, providing protection and creating optimal conditions for the photobionts to photosynthesise. This process produces sugars and nutrients which can then be utilised by the fungus (5).
The Flordia perforate reindeer lichen exhibits an unusual mode of growth as, unlike most lichens, the fruit body does not grow from the vegetative growth. Instead, the fruit body arises from spore-producing structures called ‘apothecia’ (6).
This species is not thought to reproduce sexually. Instead, in a process called ‘vegetative fragmentation’, when a small piece breaks off the main body after it has been disturbed or trampled, the fragment will continue to grow and eventually form a mature lichen (6).
The main threats to the Florida perforate reindeer lichen are loss of habitat from development, and disturbance by fires and hurricanes (1). In 1992, only 15 percent of Florida scrubland remained (6). Many populations of the Florida perforate reindeer lichen are found on high-value real estate, making their long-term survival unlikely without any protection (1). Land conversion to citrus plantations and residential development continues to diminish scrub habitat almost daily (2).
Protected populations of the Florida reindeer lichen are also vulnerable to disturbances. Fires are a natural periodic disturbance in Florida scrubland, but much of this habitat is severely fragmented, meaning these fires can increase in frequency and severity, severely hindering the Florida reindeer lichen’s ability to reproduce (1). This lichen also suffers from trampling by vehicles, and by people using sand dunes for recreational purposes (6).
An additional threat to the Florida reindeer lichen is hurricanes. Extremely high winds and storm surges of a hurricane in 1996 caused the extinction of two populations in the North Gulf Coast regions and reduced a third population by more than 70 percent (7).
In 1993, the Florida perforate reindeer lichen earned the distinction of being the first lichen to be placed on the U.S. Endangered Species List (7). This means that all landowners of state land with populations of this species are responsible for its protection and conservation. Additionally, the state of Florida has an active conservation program which monitors listed species, such as the Florida perforate reindeer lichen, and works to conserve them through land acquisition and management. Under this programme, at least two sites at Lake Wales Ridge have been purchased for conservation purposes (1).
The conservation of the Florida perforate reindeer lichen should be brought about by habitat protection and management (6). Around 16 populations are currently protected on land reserved for conservation (2), while conservation actions have been implemented at other sites, such as at Eglin Air Force Base, which was used as a source population for reintroductions (1). Further priorities for this species include the provision of walkways where trampling is a problem, the management of fire regimes, and the thinning of scrub such that it is not shaded out (6).
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- Alga: a simple plant that lacks roots, stems and leaves but contains the green pigment chlorophyll. Most algae occur in marine and freshwater habitats.
- Cyanobacteria: a group of bacteria that contain the pigment chlorophyll and are able to photosynthesise. Once known as ‘blue-green algae’, cyanobacteria are thought to have been the first organisms to produce oxygen; fossil cyanobacteria have been found in 3000 million year old rocks. As they are responsible for the oxygen in the atmosphere they have played an essential role in influencing the course of evolution on this planet.
- Fungus: fungi are one of the taxonomic kingdoms, separate from plants and animals. They obtain nutrients by absorbing organic compounds from the surrounding environment.
- Photosynthesis: metabolic process characteristic of plants in which carbon dioxide is broken down, using energy from sunlight absorbed by the green pigment chlorophyll. Organic compounds are made and oxygen is given off as a by-product.
- Spores: microscopic particles involved in both dispersal and reproduction. They comprise a single or group of unspecialised cells and do not contain an embryo, as do seeds.
- Symbiotic: describes a relationship in which two organisms form a close association. The term is now usually used only for associations that benefit both organisms (a mutualism).
- Thallus: type of simple plant body that does not have stems, leaves and roots.
IUCN Red List (April, 2011)
- Yahr, R. (1998). Cladonia perforata. In: U.S. Fish and Wildlife Service. Multi-species Recovery Plan for the Threatened and Endangered Epecies of South Florida: The Species. Technical Agency Draft, Vero Beach, Florida.
Florida Natural Areas Inventory - Cladonia perforate (April, 2011)
- Nash, T.H. (1996) Lichen Biology. Cambridge University Press, Cambridge.
- Ahmadjian, V. (1993) The Lichen Symbiosis. John Wiley & Sons, Inc., New York.
- Marshall Cavendish Corporation. (2001) Endangered Wildlife and Plants of the World. Marshall Cavendish Corporation, New York.
- Teague, D. and Ripley, D. (2000) A tale of two organisms. Endangered Species Bulletin, 25: 28-29.