Laurisilva of Madeira

Monday, 24 October 2011 00:00

The Laurisilva of Madeira is an outstanding relict of a previously widespread laurel forest type. It is the largest surviving area of laurel forest and is believed to be 90% primary forest. It contains a unique suite of plants and animals, including many endemic species such as the Madeiran long-toed pigeon.

Laurisilva or laurissilva ("laurel forest") is a subtropical forest, found in areas with high humidity and relatively stable and mild temperatures. They are characterised by evergreen, glossy-leaved tree species that look alike with leaves of lauroide type. The members of the Laurel family (Lauraceae) could be prominent, or in association.

Of particular note is the endemic type of humid subtropical laurel forest, macaronesian laurisilva, 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.

In Spanish, the word "laurisilva" is used for every laurel forest: Laurisilva misionera, laurisilva valdiviana, etc.

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 m to 1200 m elevation. Trees of the genera Apollonias (Lauraceae), Ocotea (Lauraceae), Persea (Lauraceae), Clethra (Clethraceae), Dracaena (Ruscaceae), and Picconia (Oleaceae) are characteristic.

The Madeira laurisilva forests, the largest remaining stands, were declared a UNESCO World Heritage Site in 1999.

DATES AND HISTORY OF ESTABLISHMENT
1982: Created as part of Madeira Nature Park by Decrees Nos 12/82/M and later,13/93/M; these
provided for the administration and management of the Park;
1989: The Regional Direction of Forests charged with the protection and surveillance of the Park by
Decree No.21/89/M;
1992: Declared a Council of Europe Biogenetic Reserve, a Special Conservation Zone within the EU
Bird Habitats Directive and a Site of Community Interest within the EU Habitats Directive.

AREA
15,000 ha, entirely within the 27,000 ha Madeira Nature Park. Its buffer zone of 12,000 ha is also within the Nature Park.

ALTITUDE
Sea level to 1,400m.

PHYSICAL FEATURES

The Madeira archipelago is composed of four main islands of which Madeira, at 77,900 ha and some 55 km long, is by far the largest, with a high 30 km long east-west backbone ridge of mountains capped by high plateaus.

The highest point is 1,862m. The islands are of volcanic origin about 6 million years old, evident in the many crags, dykes and basalt columns. The rugged northern slopes are deeply dissected by a series of very steep valleys leading from the plateau and central ridge of the island to the nearly vertical cliffs of the north coast.

They are completely covered up to 1,300m with laurel forest (laurisilva), a type of mountain cloud forest, which occupies some 20% of the island, crossed by many streams in deep v-shaped valleys and spattered with waterfalls. The volcanic ash soils are fertile and the more gradual lower southern slopes have long been cleared and cultivated, irrigated by water channels from the mountains, the lines of which score the precipitous slopes.

CLIMATE

The climate is oceanic but notable for sharp altitudinal and north-south climatic gradients. On the north side of the island the climate is moderated by the surrounding ocean and the prevailing northeasterly winds. It is mild, with a relative humidity of 85% and often cloudy, preserving the conditions in which the Laurisilva once dominated Tertiary southern Europe. This forest needs over 1,700mm of rain a year and the average annual precipitation for the island is between 250 and 750mm. However, 3,000mm has been recorded on the north coast and measured rainfall on the foggy north slopes is probably doubled by condensation. Frost and snow occur above the treeline. The south has a humid subtropical regime. The average annual temperature for the island ranges between 15oC and 20oC.

VEGETATION

Most of Madeira was forested when it was discovered, but the warm southern slopes were earlycleared for sugar cane and for fuelling the refineries. Forests are now found between 300 and 1,300m on the cool wet north slopes and from 700-1600m on south-facing slopes. The north slope forest is a relict: a 90% intact laurel forest, of moist montane evergreen hardwoods with a dense understorey of shrubs and ferns.

This humid subtropical late Tertiary vegetation type dating from 40-15 million years ago once covered much of southern Europe but is now virtually extinct. Its disappearance was due first to glacial advance and later to the dessication of the Mediterranian basin where it grew until 10,000 years ago.

It survives in the Macaronesian archipelagos which retain the constant mild temperatures and high humidity that it requires. Laurisilva once covered much of Madeira, the Azores and the western Canary Islands but the forests were reduced by logging, clearance for crops, overgrazing, and invasion by alien species.

The forest on Madeira is the largest to survive. though there are still 6,000 ha on Tenerife and 2,000 ha at Garjonay on La Gomera.

Elsewhere only small often degraded patches persist in Macaronesia, southern Spain, Portugal and northern Morocco. There are very ancient trees 40m tall, and perhaps 800 years old with huge ferns in the valley bottoms. The precipitous slopes and the luxuriant vegetational structure are more like an East African montane forest than Europe.

The laurisilva is all primary forest except for two portions in the east (10% of the whole) which were cut 40-50 years ago but are now recovering (IUCN,1999). 150 plant species are found in the forest, 66 being endemic to Madeira, representing some 15% and 9% of the endemic species of Madeira and Macaronesia respectively.

Madeiran Laurisilva (the Clethra-Laurion association of Sjögren,1975) is composed of four main trees: Canary laurel Apollonias barbujana, Azores laurel Laurus azorica, foetid laurel Ocotea foetens and Madeira mahogany Persica indica, a valuable hardwood.

The first two, with Picconia excelsa and strawberry tree Visnea mocanera are found in the dry laurissilva on south-facing slopes; Laurus azorica, Ocotea foetens and Persica indica grow on moist north-facing slopes and gorges. The beautiful small endemic lily-of-thevalley tree Clethra arborea is common throughout. Other important trees include beefwood Heberdenia excelsa, Picconia excelsa bay laurel Laurus nobilis, Madeira cheesewood Pittosporum coriaceum, buckthorn Rhamnus glandulosa and the large shrubs Madeira holly Ilex perado and Canary Island holly I. canariensis.

The trees are covered with the bryophytes, dripping mosses and lichens characteristic of unpolluted humid ecosystems and support a huge and diverse understorey of shrubs, ferns, mosses (20 rare spp.) and liverworts (13 rare spp.).

The understorey also includes shrubby sow thistle Sonchus fruticosos, the rare Madeira storksbill Geranium maderense, the endemic Madeira orchids Dactylorhiza foliosa and Madeira goodyera Goodyera macrophylla and the Madeira squill Scilla maderensis. In the ravines of the coast, there is an arboreal community dominated by the endemic wild olive Olea maderensis and a shrub Chamaemeles coriacea of an endemic genus. Above the laurel forest is an endemic highland community dominated by tree heath Erica arborea and besom heath Erica platycodon ssp.maderincola, shrubby Madeira juniper Juniperus cedrus. and heathers Erica spp.

FAUNA

The fauna is relatively poor, but most species are of conservation concern, being endemic to the island. Mammals and reptiles in the forest are represented by only two mammals, the lesser noctule bat Nyctalus leisleri verrucosus and the Madeira pipistrelle Pipistrellus maderensis (EN) and one reptile, the Madeira wall lizard Lacerta duguesii. The wolf spider Lycosa blackwalli is endemic to the forest and there are 500 species of invertebrates and many species of butterflies and molluscs. The Madeira Archipelago has 43 breeding species of birds and the forest contains four of Madeira’s eleven Important Bird Areas. The outstanding endemic forest birds are the Madeira laurel-pigeon Columba trocaz and Madeira firecrest Regullus madeirensis. The forested cliffs may see two other endemics, Zino’s petrel Pterodroma madeira (EN) and Madeira storm petrel Oceanodroma castro.

There are also some interesting sub-species such as the Madeira chaffinch Fringilla coelebs madeirensis, a race of Berthelot’s pipit Anthus bertheloti madeirensis, Madeira rock sparrow Petronia petronia madeirensis and the dark barn owl Tyto alba schmitzi.

There are also Eurasian sparrowhawk Accipiter nisus granti, and plain swift Apus unicolor and common canary Serinus canaria canaria. Madeira has Fea’s petrel Pterodroma feae, and 13 marine sub-species including little shearwater Puffinus assimilis baroli, white-faced storm petrel Pelagodroma marina hypoleuca, kestrel Falco tinnunculus canariensis, and yellow-legged gulls Larus cachinans atlantis.

There are also regular visitants like little and cattle egrets Egretta garzetta and Bubulcus ibis, whimbrel Numenius phaeopus, dunlin Calidris alpina, turnstone Arenaria interpres and occasional vagrants like laughing gull Leucophaeus atricilla, and Eurasian spoonbill Platalea leucorodea (Madeira Wind Birds, 2005).

CULTURAL HERITAGE

Madeira was discovered in 1419 by the Portuguese navigator Joao Gonçalves Zarco. In the 16th and 17th centuries the southern half was developed for the production of cane sugar. To irrigate this crop, an impressive system of 80-150cm-wide water channels (levadas) with narrow paths alongside were cut in and some tunnelled through the steep mountainsides.

LOCAL HUMAN POPULATION

The site is uninhabited and uncultivated but approximately 500 people live in the buffer zone. This pressure is decreasing as the hardships of traditional terrace farming are abandoned for employment in the heavily populated south where tourism prospers. Some small-scale cutting of tree heather is permitted to local people.

VISITORS AND VISITOR FACILITIES

Thousands of tourists visit Madeira and visitors are permitted in parts of the Park but access is not easy: the widespread but narrow maintenance paths along the water channels are often too dangerous to allow their use by the public. In 1999 visitors had to take a guide and travel in groups of 20 on prescribed paths. But a report from the state party in 2008 mentions climbing and canoeing as well. Only two roads cross the range, one now in a tunnel. However, a projected cable car to the mountain has one station in the property which will allow access to about 500 visitors per day during the summer half of the year or some 90,000 annually The existing visitors’ centre is to be enlarged to include an auditorium, library, shop, improved sanitary installations, car park and emergency services
(UNESCO,2009).

SCIENTIFIC RESEARCH AND FACILITIES

Scientific research has been mainly conducted by Madeira Botanical Garden on indigenous and endemic plant species and their re-introduction into the natural habitat. From 1992 to 1995, staff now of the Madeira Nature Park conducted an exhaustive ecological survey of the forest using transects and 1155 study sites. The results were published in Laurisilva da Madeira in 1996 and in the Atlas do Ambiente by the Directorate General of the Environment in 1997.

CONSERVATION VALUE

The Laurisilva, still 90% primary growth, is the largest such forest in the Macronesian Islands. Its level of endemism in plants and animals is very high and it is essential to protect the island’s micro-climate and water supplies. The Park lies within a Conservation International-designated Conservation Hotspot, a WWF Global 200 Eco-region, a WWF/IUCN Centre of Plant Diversity and a BirdLifedesignated Endemic Bird Area.

CONSERVATION MANAGEMENT

The Park is managed by the Regional Directorate of Forests under the Regional Secretariat for Agriculture, Forests and Fish and is well supported by the regional government The zoning and management plan defined by Regional decrees 19/82/M and 12/95/M provides for the territorial organisation of the region. This is a land use plan for the whole island which is also the management plan for the Laurisilva, including general guidelines on planning and development, land tenure and protection of the natural heritage. Within this strategic frame the Nature Park is guided by annual operational plans. In 1980, a program to remove all alien species led to the recovery of a large area of primary forest. Goats have been a serious threat to the forest since colonial times but following eradication campaigns stray goats are now only occasionally seen. Encroachment by alien species such as Norway maple Acer sycamorus and Kahili ginger Hedychium gardnerianum could crowd out recovering forest on abandoned terraces and there are programs to eradicate these.



Source: http://www.unep-wcmc.org