Elfin Tree Fern
Elfin Tree Fern
|Listed||June 16, 1987|
|Description||Dwarf tree fern with bipinnate fronds.|
|Habitat||Tropical, high altitude, dwarf forests.|
|Threats||Deforestation, road construction.|
Tree ferns are a tropical species, typically formed of a woody, trunklike stem crowned with a number of large, divided fronds. Elfin tree fern, Cyathea dryopteroides, is a small or dwarf tree fern reaching 24 in (61 cm) in height and approximately 1 in (2.5 cm) in diameter. The fronds are bipinnate, nearly hairless, tapered at both ends, and reach 36 in (91.4 cm) in length and 10 in (25.4 cm) in width. The sori are located dorsally and are enclosed in a cup-shaped indusium.
Fertile fronds have frequently been observed on elfin tree fern at both known sites. The presence of healthy, vigorous plants in all stages of development suggests that successful reproduction and establishment occurs regularly.
Elfin tree fern has also been known as Alsophila dryopteroides.
This tree fern grows at the highest elevations in Puerto Rico, where temperatures as low as 39.2°F (4°C) have been recorded. Vegetation in these areas is variously termed elfin, dwarf, or cloud forest, and is similar to that found in other tropical montane habitats. Elfin tree fern is generally a component of the ground cover beneath stands of sierra palm.
The species is endemic to the Cordillera Central region of Puerto Rico. It is presently known from populations on two peaks that are 12 mi (19.3 km) apart—Monte Guilarte and Monte Jayuya. A 1987 census counted ten trees at Monte Guilarte and 60 trees at Monte Jayuya. Both sites are within the Commonwealth Forest System.
Habitat acreage has steadily declined over past decades because of deforestation and selective cutting. Logging leases on state lands have encouraged harvesting of mature forests, and replanting has changed the composition of the plant community to the detriment of native plants. In recent years, the increasing construction communications facilities and access roads on the highest peaks have disturbed montane forests. Although the Commonwealth of Puerto Rico owns Monte Guilarte and Monte Jayuya, both have been leased to communications companies. Recently, a large number of tree fern plants were destroyed when satellite dish and control facilities were built on Monte Jayuya.
Construction of a highway through the Toro Negro Forest destroyed a number of elfin tree ferns. Many remaining plants are close to the road and are damaged by maintenance work. Commercial collecting could also become a threat, as considerable unregulated trade in similar species already takes place. Because of this possibility, the U. S. Fish and Wildlife Service declined to designate critical habitat for the species, since that would require publishing detailed location maps.
The small and limited populations limit the gene pool and the genetic viability for reproduction, and encourage stochastic extirpation.
Elfin tree fern is an attractive plant and may have ornamental value. Considerable commercial trade in ferns currently exists, and collecting may be a threat or potential threat to this species.
Conservation and Recovery
Although the Commonwealth of Puerto Rico has adopted a regulation that recognizes and provides protection for rare plants, elfin tree fern is not yet on the Puerto Rico list. It is, however, listed in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) as a species to be monitored.
The elfin tree fern's federal listing as an endangered species will protect the plant from the disruptive actions of federal agencies. This is expected to restrict federal funding for additional highway construction and to limit army maneuvers that are regularly conducted in the area.
U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
1875 Century Blvd., Suite 200
Atlanta, Georgia 30345
Howard, R. A. 1968. "The Ecology of an Elfin Forest in Puerto Rico." Journal of Arnold Arboretum, no. 49: 381-418.