Laurisilva
| Laurisilva of Macaronesia* | |
|---|---|
| UNESCO World Heritage Site | |
 Madeira's Laurisilva forest. |
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| Country |  Portugal |
| Type | Natural |
| Criteria | ix, x |
| Reference | 934 |
| Region** | Europe and North America |
| Inscription history | |
| Inscription | 1999 (23rd Session) |
| * Name as inscribed on World Heritage List. ** Region as classified by UNESCO. |
Laurisilva or laurissilva ("laurel forest") is a subtropical or mild temperate forest, found in areas with high humidity and relatively stable and mild temperatures. They are characterized by tree species that look alike with leaves of lauroide type, evergreen, glossy-leaved trees. The members of the Laurel family (Lauraceae) could be prominent, or in association.
The word "laurisilva" in spanish language, is used for every laurel forest: Laurisilva misionera, laurisilva valdiviana, etc. Particularly is the endemic type of humid subtropical laurel forest, macaronesian laurisilva (laurisilva macaronésica), found on several of the Macaronesian islands of the North Atlantic and Macaronesian African mainland enclaves, namely Madeira Islands, the Azores, Cape Verde Islands and the Canary Islands, a relict of the Pliocene subtropical forests, supporting numerous endemic species.
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[edit] Macaronesian Laurisilva Region
The laurisilva forests are found in the islands of Macaronesia in the eastern Atlantic, in particular the Azores, Madeira Islands, and western Canary Islands from 400 to 1200 meters elevation. Trees of the genera Apollonias (Lauraceae), Ocotea (Lauraceae), Persea (Lauraceae), Clethra (Clethraceae), Dracaena (Ruscaceae), and Picconia (Oleaceae) are characteristic.[1] The Madeira Islands laurel forest was designated a World Heritage Site by UNESCO in 1999.
The forests are made up of laurel-leaved evergreen hardwood trees, reaching up to 40 meters in height. Many of the species are endemic to the islands, and harbour a rich biota of understorey plants, invertebrates, and birds and bats.
Laurisilva formerly covered much of the mountain areas of Annobon, Azores, Bioko, Cape Verde, Canary Islands, Madeira, Sao Tome, Principe other atlantic islands and locally on favorable wet climate microenvironments of coastal and coastal mountains of northwest African mainland, but the forests have been much reduced in extent by logging, clearance for agriculture and grazing, and the invasion of exotic species. The most extensive laurisilva forests remain on Madeira, where they are found between 300 and 1400 meters altitude in the northern slope, and 700–1600 meters altitude in southern slope, and cover 149,5 km². In the Canary Islands, roughly 60 km² of laurisilva remain on Tenerife, smallest areas on La Palma, over 20 km² in Garajonay National Park on La Gomera, and relict areas in Gran Canaria. In the Azores, small patches of laurisilva forest remain on the islands of Pico, Terceira, and São Miguel.
The Madeira laurisilva forests, the largest remaining stands, were declared a UNESCO World Heritage Site in 1999.[2] Predominant lauraceous trees include Til (Ocotea foetens), Loureiro (Laurus novocanariensis), Vinhático (Persea indica), a valuable hardwood, and Barbosano (Apollonias barbujana); other important trees include Aderno (Heberdenia excelsa), Pau Branco (Picconia excelsa), the Mocanos (Visnea mocanera and Pittosporum coriaceum), and Sanguinho (Rhamnus glandulosa), and the small trees or large shrubs Folhado (Clethra arborea) and Perado (Ilex perado). The forests support a diverse understory of ferns and bryophytes,[3] which both require moisture for reproduction, evergreen climbing plants like Canarina canariensis, Asparagus species and Araliaceaes (Hedera helix, Hedera canariensis) and of herbaceous plants, including the Leitugas (Sonchus spp.), geraniums (Geranium maderense, G. palmatum and G. rubescens), the Estreleiras (Argyranthemum spp.) and the endemic orchid Goodyera macrophylla.
Lanzarote and Fuerteventura are very close to the African mainland (96 km), and were even closer during the Ice Age of Quaternary (18,000 years ago was 60 km). The vegetation is very similar to the basement floor of the eastern Canary Islands. A large number of plant species and some animals are common, mainly Arthropod, but the most unusual given that many of these taxon are endemic to both regions, the insular and continental. Often displayed species vicarious s within a gender which, in turn, is endemic in both regions:[4] Lotus marocanus / Lotus glaucus; Bubonium intrincatum / Bubonium sericeum; Euphorbia echinus y Euphorbia beaumieriana / Euphorbia handiensis; Kleinia anteuphorbium / Kleinia neriifolia; Lavandula maroccana / Lavandula multifida; Sonchus leptocephalus / Warionia saharae.[5]
The phytosociology of these configurations was described in a paper by Rivas Goday and Esteve Chueca.[6]
It was recently discovered to science a large population of dragos (Dracaena) other vegetation with trees that also live, so relict, in some of the Macaronesian islands. Is the case with juniper forests, wild olive, mastic, etc. While these are all Mediterranean taxa.
The (tabaibas and cactus Euphorbia spp.) Have been considered marker to define the concept of Macaronesian enclave..[4]
[edit] Origin
The laurisilva forests of Macaronesia are relicts of a vegetation type which originally covered much of the Mediterranean Basin when the climate of the region was more humid. With the drying of the Mediterranean Basin during the Pliocene, the laurel forests gradually retreated, replaced by more drought-tolerant sclerophyll plant communities. Most of the last remaining laurisilva forests around the Mediterranean are believed to have disappeared approximately 10,000 years ago at the end of the Pleistocene, when the Mediterranean basin became drier and with a harsher climate, although some remnants of the laurel forest flora still persist in the mountains of southern Spain, north-center of Portugal and northern Morocco, and two constituent species (Laurus nobilis and Ilex aquifolium) remain widespread. The location of the Macaronesian Islands in the North Atlantic Ocean moderated these climatic fluctuations, and maintained the relatively humid and mild climate which has allowed these forests to persist to the present day.
Over millions of years, these vegetation covered much of the tropics of Earth. From the point of view biogeographic, the tropics may extend beyond parallels of Cancer and Capricorn, v. gr., the peninsula of Florida in United States lies in subtropics (greater latitude 23 ° 26'N), but hosts many species characteristic of the tropics New World.
One example is the translation of the Tertiary Atlantic laurisilva to its current location. Many plants of the Macaronesian laurisilva have their closest relatives in geographically remote places like South Africa or South America, the genus Persea, Ocotea and Maytenus, for example, also appear in South American temperate evergreen, which testifies the ancient origin of this flora. Another interesting finding is the presence in various areas of the Mediterranean and the Caucasus until the Himalayas, of plant fossils of 20 million years old, from Tertiary, very similar or identical to those currently living in Macaronesia. This type of forest was extended over the Cenozoic or Tertiary Era, more than 20 million years, over a wide area of the basin of the Mediterranean, Eurasia and northwest Africa where the climate the region was wetter. At that time there was a Tethys Sea that separated the ancient continents of Laurasia and Gondwana, this sea was much more open than the Mediterranean and ocean currents flowed in a different way, bringing tempering moisture and clima, in areas that currently do not have any influence. Subsequently, the Ice Age which took place at the end of that period and for much of the Quaternary were moving the laurel forest to warmer southern regions, where conditions were more conducive to their survival, settling in this way on the northwest coast of Africa and in the Macaronesian archipelagos.
The glaciations occur in Quaternary and expand of the polar ice caps, resulting in widespread cooling of the climate, the flora of central and southern Europe retreated to more southerly latitudes in search of milder conditions. Also the sea level was lower with lands today sumerged, connecting some of them. At the end of glaciations, started the spread of deserts in North Africa, so this type of forest was reduced to those areas, which act as boundaries between temperate and tropical. By then, the climate of southern Europe was warmer and wetter than today, and the vegetation that surrounded the ancient shores of the Mediterranean Sea should be similar to that of the current Macaronesian laurisilva.
The laurel forests of Macaronesia are relics of the vegetation that originally covered from the Atlantic to the Caspian Sea before the Ice Age. With the largest periodic drought in the Mediterranean climate due to climatic changes due to changes in ocean currents and continental drift during the Pliocene, laurel forests are gradually removed, replaced by plant communities more sclerophyllous floras drought tolerant. Most of the last remaining temperate evergreen forests around the Mediterranean is believed to have disappeared about 10,000 years ago at the end of the Pleistocene, when the Mediterranean basin became warmer and drier, although some remnants of the laurel forest flora still persist in the southern mountains in Spain, north-central Portugal and northern Morocco, and three constituent species: Laurus nobilis, Ilex aquifolium and Hedera helix are still widespread. A remarkable adaptation is the asparagus, while in the Canaries Islands is preserved the original form, a leafy vine, in the rest of the Mediterranean has evolved into a thorny species. The location of the Macaronesian Islands in the North Atlantic Ocean moderated these climatic fluctuations, and maintained the relatively humid and mild climate that has allowed these cloud forests to persist until today. Almost at the same time began the drying of North Africa, which led to the current Desert Sahara.
Many of the then existing species became extinct because they can not overcome the barriers they supposed alpine mountains and the Mediterranean, but others found refuge as a species relict in coastal enclaves and in the Macaronesian archipelagos, sufficiently far from the ice while protected by the oceanic influence of drying that caused the Sahara. In other parts of the world, including China, Africa or South America, the arrangement of the ridges and mountain ranges extending in the direction from north to south, rather than serve as a barrier, provided that the plant be shifted to more suitable areas and then where it is currently extended.
With the general warming of the atmosphere and the consequent withdrawal of the ice, flora tertiary survivor tries to win its range in southern Europe. But the new post-glacial climate is drier than the Tertiary, and to these new environmental requirements, the primitive tropical European flora evolves and gives rise to the present flora of the Mediterranean sclerophyll. Thus, the Mediterranean flora and fauna Macaronesian have a common origin.
At the same time, isolated from the mainland, the tertiary Macaronesian flora evolved independently, which has led to numerous endemic species. In fact, it should be noted as 50-55% of vascular plants are species unique to the Canary Islands and this proportion increases in more distant islands like Cape Verde, Azores and Madeira. Macaronesian laurel forest consists of about 25 trees that are around 35, if you add the species survived in nearby areas of Eurasia, while in the "laurisilva misionera", exceeding 100 tree species, it is likely that the Atlantic laurel rainforest from the Tertiary, level the number of species of "laurisilva misionera".
[edit] Gallery
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Laurisilva in the Garajonay National Park on La Gomera, Canary Islands.
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Laurisilva in La Palma, Canary Islands.
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Laurisilva canopy in Tenerife, Canary Islands.
[edit] See also
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Wikimedia Commons has media related to: Laurisilva |
[edit] References
- ^ Madeira Laurel Forest, Madeira Wind Birds 2005
- ^ UNESCO: "Laurisilva of Madeira
- ^ Susana Fontinha, et al. Os briófitos da laurissilva da Madeira: guia de algumas espécies ("The bryophytes of the laurisilva of Madeira: guide to some species"), Serviço do Parque Natural da Madeira, 2006.
- ^ a b Francisco García-Talavera C., La Macaronesia (Consideraciones geológicas, biogeográficas y paleoecológicas)
- ^ Cite error: Invalid
<ref>tag; no text was provided for refs namedlaotra; see Help:Cite errors/Cite error references no text - ^ S. Rivas Goday; F. Esteve Chueca, Ensayo fitosociológico de Crassi-Euphorbieta y Estudio de los tabaibales y cardonales de Gran Canaria
- Madeira: The laurissilva forest of Madeira UNESCO World Heritage Site, 1999.
- Madeira Laurel Forest, Madeira Wind Birds 2005
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