|Scientific Name:||Juniperus bermudiana|
|Red List Category & Criteria:||Critically Endangered A2ace ver 3.1|
|Assessor/s:||Wingate, D.B., Adams, R & Gardner, M.|
|Reviewer/s:||Thomas, P. & Farjon, A.|
Juniperus bermudiana underwent a catastrophic decline of almost 95% between 1946 and 1956. Over the last 30 years, the population has started to recover as a result of natural resistance in part of the remnant population and intensive conservation efforts. Invasive plant species still pose a significant threat. Juniperus bermudiana has an estimated generation length of 25 years so three generations is the equivalent of 75 years. Some of the causes of reduction are not reversible due to urbanization and habitat loss. This species is therefore currently listed as Critically Endangered. Provided that the recovery is maintained, future re-assessments after the three generation period has expired should result in downlisting.
|Range Description:||Juniperus bermudiana occurs throughout Bermuda so the total area of the island is the equivalent of its extent of occurrence (EOO): 57 km².|
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||In a ten year period between 1946 and 1956, almost 95% of the natural population was lost due to the effects of an introduced juniper scale (Carulaspis minima). Over the last 30 years a combination of residual resistance, reafforestation and, to a lesser extent, natural regeneration has led to an increase. The current population is estimated to be well over 10,000 adult trees, possibly as high as 25,000, which represents approximately 10% of its former population density in suitable habitat.|
|Habitat and Ecology:||
Grows in shallow, calcareous soils on hillsides and along marshes and coastlines. Once formed almost pure stands with an estimated density of as much as 500 trees to the acre (
From the time that Bermuda was first colonized in 1609 Juniperus bermudiana has been used extensively for construction purposes and as fuel for cooking. The use was so extensive that by 1622 special legislation had to be introduced (Tucker 1970) to control the export of the island’s most dominant tree species. Between 1693 and 1878, the Bermuda legislature passed sixteen further acts in order to restrict the uses of the juniper. Despite these Acts, the ship-building industry eventually denuded much of Bermuda's landscape by the 1830s. The decline of the ship building industry after 1900, combined with the replacement of local juniper timber for construction with cheaper imported timber from the U.S. and rural electrification, which precluded the need for wood as cooking fuel, enabled a full recovery by the early 1940s. However, it was once more devastated as a result of the accidental introduction of two coccoid scale insects in 1946 (Challinor and Wingate 1971).
The juniper scale (Carulaspis visci) and the oyster-shell scale (Lepidoscaphes newsteadi) were present on ornamental species of juniper which were shipped to the island from California, USA (Bennet and Hughes 1959). In the absence of natural biological controls and genetic traits for resistance the native J. bermudiana suffered rapid defoliation and death, reducing the population by 95% within a period of 10 years (Wingate 2001)
During the following decades the bare landscape was reafforested using exotic species. Casuarina equisetifolia was especially favoured for its rapid growth. Invasive broadleaf plant competitors (which create too deep a shade for seed germination or growth), are now by far the greatest factors limiting the junipers distribution and self-seeding potential. Likewise, germination of the naturalized Ficus retusa in rot hollows of old junipers (which leads to eventual overshading and strangulation) and overshading by taller growing invasive broadleaved trees, especially in sheltered valley situations, is now the major cause of adult mortality.
To add to the problems, J. virginiana and J. virginaina var. silicicola have been introduced to Bermuda from Florida, USA. Both taxa are resistant to the scale insects. They readily hybridize with J. bermudiana causing a depletion of the germplasm through hybridization and introgression (Adams and Wingate 2008) .
Urbanization is also a problem. Today Bermuda is recognized as one of the most densely populated isolated oceanic islands in the world with a mean human population density of five per acre and one third of the country is totally urban (Wingate 2001). About 20% of Bermuda's land area is now paved over with roads, parking lots, buildings and industrial yards. This trend is likely to continue unabated.Ironically, the Bermuda juniper does best today in that approximate one third of the landscape that is maintained largely free of invasive plants in parks and gardens with extensive lawn areas. Most old pure strain junipers that survived the great scale epidemic are found in cemeteries, parks and private gardens where it is now very much in vogue again to plant cedars because they are more hurricane resistant.
Although chemical control of the juniper scale was possible, it was avoided for safety reasons due to the high density of the human population. As a result of rapid natural selection of a trait for scale resistance, which must have survived in about 5% of the population, most seedlings now seem to be partly or totally immune to scale attack, and survive. This enabled intensive re-forestation efforts to begin about 1980 and the species has since recovered to approximately 10% of its former population density in managed parkland and garden habitat. (Procter and Fleming 1999, Wingate 2001)
Juniperus bermudiana is cultivated in gardens outside of Bermuda and some of this material has potential to supplement restoration programmes in
|Citation:||Wingate, D.B., Adams, R & Gardner, M. 2011. Juniperus bermudiana. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 19 April 2014.|
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