Biogeography

Azores temperate mixed forests

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Satellite view of the Azores. Source: National Aeronautics and Space Administration

The Azores temperate mixed forests are located on the Azores archipelago; these islands are generally are lush verdant islands situated in an isolated region of the Atlantic Ocean, where temperatures are mild and change little from season to season. Famed for their thermal springs, crater lakes, caverns, and grottoes that result from ongoing volcanic activity, these islands hold many visual as well as ecological attractions. Like other isolated islands, the Azores have functioned as a natural evolutionary laboratory - most of the native plant species are living fossils, phylogenetically primitive, and related to, though divergent from, the preglacial flora of Europe. The archipelago has a significant number of endemic species found nowhere else. Since the arrival of the first settlers to the Azores, the native flora and fauna has suffered severe degradation at the hand of forest clearing, agriculture, and the introduction of exotic species.

Location and General Description 

caption WWF

The Azores (38º30' N 28º00' W) is an archipelago of volcanic islands in the North Atlantic, 1500 kilometers (km) west of Portugal and 3900 km from the eastern coast of the United States. Their location gives them the distinction of being the most remote group of islands in the North Atlantic. Discovered by the Portuguese in the early 15th century, the islands now have their own parliament and government. The islands' chief port and capital, Ponta Delgada is on São Miguel, largest of the nine main islands. Six of the islands, São Miguel, Faial, Graciosa, Pico, Santa Maria, São Jorge, São Miguel, and Terceira, are inhabited with a combined population exceeding 230,000. Two smaller islands, Corvo and Flores, as well as surrounding islets, are unhabited.

The islands rise steeply from rocky coastlines to heights reaching 2381 meters (m) on the island of Pico, formed by a solitary volcanic cone. This also claims the highest point within Portuguese territory. Pico is a relatively recent volcano, and the largest in the central Atlantic. As recently as the 18th century, flank eruptions of lava flows occurred on Pico's mountain. High heat flow from fumaroles at its summit have been routinely observed, and it is believed that a summit lava lake and a scoria cone were formed within the past 1000 years. Situated on the intersection of the tectonic plates of Europe, Africa, and America, the archipelago has an unstable geologic nature and continues to experience earthquakes and volcanic activity. The islands are dotted with formations such as the sulphur grottoes and underground lake of Graciosa, the volcanic cones of Furnas Valley on São Miguel, and the basaltic columns of "Rocha dos Bordões" on Flores. A traditional cooking method of the islands uses volcanic steam vents to prepare a dish called "cozido".

The climate of the Azores is heavily influenced by the Gulf Stream, with no frost below elevations of 500 m and average temperatures of 21°C in summer and 14.5°C in winter. The soil is fertile in some areas, while in areas covered by recent lava the crust is thinner. These regions are often used to grow grapevines for wine, one of the islands' major industries. Prior to discovery, the archipelago was covered in Atlantic-type forests that persist in some places, for example at the top of the Santa Bárbara range on Terceira. In the lowlands, most of which have been highly altered, the evergreen fire tree (Myrica faya) is the main species to have regenerated on old lava flows. M. faya, native to the Azores and Madeira, is an alien species and an invasive problem on other islands, such as Hawaii, to which it was introduced.

Above 500 m, the native fragments of vegetation are dense dark green shrub forest composed of Laurus azorica, Juniperus brevifolia, and Erica azorica. The juniper is endemic to the Azores and has been exploited for timber. These native Macaronesian laurel forests are best preserved on Pico, Terceira, and San Miguel Islands. Associated species are shrubs such as Ilex, Viburnum, Clethra, and a tall bilberry (Vaccinium cylindraceum) that has showy, dark pink flowers. Peat bogs found on Flores and Terceira are very rich in endemic species and are also in immediate danger from overgrazing. The bryophyte flora is very rich in contrast to the vascular flora, with about 450 species and an endemism rate of 5%. Pico is one of the few islands in the tropical and warm-temperate zone high enough to show timberline and alpine vegetation, with a forest line found at significantly lower elevation than those of the mainland.

Biodiversity Features 

caption São Miguel, Azores, Portugal. (Photograph by Jørn Rosekilde)

Resident and migratory bird populations of the Azores archipelago are the islands' most noteworthy fauna. Some 36 bird species are reported to breed in the Azores, seven of which were introduced. The widely-studied Azores bullfinch (locally called Priolo), Pyrrhula murina, is largely confined to native cloud forest in the east of Sao Miguel Island. Pyrrhula murina is listed as endangered on the IUCN Red List, with a population estimated at less than 250 birds restricted to the single island. Birdlife International designates the Azores as a Secondary Area for conservation due to the presence of island canary (Serinus canaria), which is restricted to these islands, Madeira, and the Canary Islands. Breeding seabirds of the Azores comprise 5 species of Procellariiformes, 4 Charadriiformes, and 1 Pelecaniform, and include Fea's petrel (Pterodroma feae), Bulwer's petrel (Bulweria bulwerii), manx shearwater (Puffinus puffinus), little shearwater (Puffinus assimilis baroli) and two temporally-segregated forms of band-rumped storm-petrel (Oceanodroma castro).

Nine species of mammals are recorded from the islands: mouse-eared bat (Myotis myotis), Azores noctule (Nyctalus azoreum) (an endemic bat), Norwegian rat (Rattus norvegicus), black rat (R. rattus), house mouse (Mus musculus domesticus), western European hedgehog (Erinaceus europaeus), European rabbit (Oryctolagus cuniculus), least weasel (Mustela nivalis), and ferret (M. furo). Excluding the bats, all of these appear to have been introduced to the islands by humans.

Current Status

caption São Miguel, Azores, Portugal. (Photograph by Jørn Rosenkilde) Human pressures on the fragile ecosystems of the Azores Islands have been severe since the time of settlement. Breeding seabird populations on the Azores are believed to have declined dramatically since the time of human settlement. The main islands were once important breeding places, but now most sites are restricted to small islets or precipitous cliffs, probably due to predation by introduced mammals. Cattle raising and chemical applications compromise freshwater quality. The Lagoa das Furnas on Sao Miguel, for example, has suffered significant eutrophication. Native vegetation that has escaped clearing for pasture is threatened by introduced species such as Japanese red cedar (Cryptomeria japonica), the Incenso tree (Pittosporum undulatum), kahili ginger (Hedychium gardnerianum), Hottentot fig (Carpobrotus edulis), Gunnera tinctoria, and Clethra arborea (native to Madeira Island). Only about 2% of the native laurel forest remains on the islands. Loss of native forest also crowds the endemic bullfinch, Pyrrhula murina, as exotic forests of Cryptomeria japonica and Pittosporum undulatum are too dense for the birds' natural feeding habits. A common bird until early in the 20th century, its distribution area has shrunk drastically, not in small part due to aggressive collecting of the rare and distinctive bird for museum collections. For some time farmers were compensated by the government to kill many native birds, including the bullfinch, as they were considered agricultural pests.

A European Union-funded program was initiated by the local forestry service in 1995 to restore and expand laurel forests in an effort to increase the population of the Azores bullfinch; the laurel forest around the Pico da Vara summit was also designated a Natural Forest Reserve. The University of Azores and Faial Island Botanical Garden have done much to collect and study native and endemic flora of the islands, and also propagate certain plants in project sites.

Types and Severity of Threats

A large percentage of exploitation in the Azores has occurred very recently, with as much as 50% of remaining natural areas have been converted to pasture for dairy cows in the last decade or so. This drastic development was due in part to the Azores' entry into the EU and subsequent availability of agricultural subsidies, grants, and quotas. The archipelago has no national parks, and protected areas that do exist lack appropriate legal protection. Some steps have been taken to establish an official system of protected areas with an integral government conservation policy and strategy.

Justification of Ecoregion Delineation

The mos remote group of islands in the North Atlantic, the Azores Archipelago is of evolutionary interest. As a result of their isolation, most of the native plant species on the Azores are living fossils, phylogenetically primitive, and related to, though divergent from, the preglacial flora of Europe. The archipelago has a significant number of endemic species found nowhere else. Birdlife International has designated the Azores as a Secondary Area for conservation of avifauna.

Additional Information on this Ecoregion

Further Reading

  • Aubrecht, G. 2000. The azores bullfinch - Pyrrhula murina Godman, 1866: the history of a bird species: persecuted - missing - rediscovered - protected (Including a list of all known specimens and syntypes). Annalen Des Naturhistorischen Museums in Wien Serie B Botanik Und Zoologie 102B:23-62.
  • Hilton-Taylor, C., compiler. 2000. 2000 IUCN Red List of Threatened Species. IUCN, Gland, Switzerland and Cambridge, UK.
  • Leuschner, Christoph. 1996. Timberline and alpine vegetation on the tropical and warm-temperate oceanic islands of the world: elevation, structure and floristics.
  • Matthias, M. L, Ramalhinho, M. G., Santos-Reis, M, Petrucci-Fonseca, F, Libois, R, Fons, R, Carvalho, G. Ferraz De, Oom, M. M, and Collares-Pereira, M. 1998. Mammals from the azores islands (portugal): an updated overview. Mammalia 62:397-407.
  • Monteiro, L. R, Ramos, J. A, and Furness, R. W. 1996. Past and present status and conservation of the seabirds breeding in the azores archipelago.
  • Monteiro, L. R, Ramos, J. A, Pereira, J. C, Monteiro, P. R, Feio, R. S, Thompson, D. R, Bearhop, S, Furness, R. W, Laranjo, M, Hilton, G, Neves, V. C, Groz, M. P, and Thompson, K. R. 1999. Status and distribution of fea's petrel, bulwer's petrel, manx shearwater, little shearwater and band-rumped storm-petrel in the azores archipelago. Waterbirds 22:358-366.
  • Pereira, Ma. J, Moura, M, Maciel, G. B, and Oliveira, J. B. 1998. Conservation of natural vegetation in azores islands. Boletim Do Museu Municipal Do Funchal 0:299-305.
  • Ramos, Jaime A. 1996. Introduction of exotic tree species as a threat to the azores bullfinch population. Journal of Applied Ecology 33:710-722.
  • Ramos, J. A. 2000. Azores Bullfinch Pyrrhula murina. Bulletin of the African Bird Club.
  • Reis Maduro Dias, F. Zona Classificada de Angra do Heroísmo - History of the Azores. Retrieved 2001.
  • Robertson, G. 1997. The Azores: A Haven of Tranquility, Islander Magazine Issue 4.
  • Stattersfield, A. J., M. J. Crosby, A. J. Long, and D. C. 1. Wege. 1998. Endemic Bird Areas of the World: Priorities for Biodiversity Conservation. BirdLife Conservation Series No.7., Cambridge, U.K.Conservation. ISBN: 1560985747 

 

Disclaimer: This article is contains information that was originally published by the World Wildlife Fund. Topic editors and authors for the Encyclopedia of Earth have edited its content and added new information. The use of information from the World Wildlife Fund should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.

 

 

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Citation

Fund, W. (2014). Azores temperate mixed forests. Retrieved from http://www.eoearth.org/view/article/51cbed067896bb431f68f1c1

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