Laurisilva
From Wikipedia, the free encyclopedia
Laurisilva or laurissilva ("laurel forest") is an endemic type of humid subtropical laurel forest found on several of the Macaronesian islands of the north Atlantic, namely Madeira Islands, the Azores and the Canary Islands, a precious relict of the Pliocene subtropical forests.
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 harbor a rich biota of understory plants, invertebrates, and birds and bats, including a number of endemic species.
Laurisilva formerly covered much of the Azores and Madeira and parts of the western Canary Islands, 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 1300 meters altitude, and cover 149,5 km². In the Canary Islands, roughly 60 km² of laurisilva remain on Tenerife and over 20 km² in Garajonay National Park on La Gomera, and small areas on La Palma. In the Azores, small patches of laurisilva forest remain on the islands of Pico, Terceira, and São Miguel.
The Madeira laurisilva forests were declared a UNESCO World Heritage Site in 1999. 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 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.
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 warmer and drier, although some remnants of the laurel forest flora still persist in the mountains of southern Spain 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.
[edit] References
- Madeira: The laurissilva forest of Madeira UNESCO World Heritage Site, 1999.
