
Macaronesia
Macaronesia is a biogeographical region consisting of the archipelagos of the Canaries, Selvagens, Madeira, Azores and Cape Verde1. Although Macaronesia does not belong to the actual area of this website, the region is especially interesting because it includes the only humid evergreen broadleaf forests close to Europe. In the Mediterranean region, there are evergreen broadleaf forests, too, but they are sclerophyllous forests with long, dry, hot summers. The low elevations on the Macaronesian islands are dry, too, but in the cloud zone of the northeastern trade winds, water condensing from fog compensates the lack of summer rains, drought stress being absent during the whole year2. The laurel forest “laurisilva” (also called monteverde forest) of this humid zone also includes the least disturbed forests of Macaronesia. The laurel forest is considered to be an impoverished relict of similar forests that covered large areas in the Mediterranean region during the late Tertiary period but subsequently went extinct there due to the onset of the Mediterranean climate with dry summers1.
At drier low elevations, the vegetation consists of open woodland, shrubland and grassland3 4. The highest elevations are also drier because they lie above the cloud belt6; their vegetation mainly consists of shrubland3. On the Canary Islands there is a coniferous forest zone above the laurel forest, consisting of Canary Island pine (Pinus canariensis) 3. If the Canary Islands were considered a part of Europe, Canary Island pine would be the fourth tallest native tree of Europe: the tallest, famous individual on Tenerife is 56.7 m 5.
Originally the laurel forest existed on all the Canary Islands (on Lanzarote and Fuerteventura only as tiny relicts) 7, on Madeira and on its neighbouring island Porto Santo, and on the Azores4. Currently only 12.5% of the original “laurisilva” remains, mainly in Garajonay National Park on the island of La Gomera (one of the Canary Islands) and on Madeira1. For example, Gran Canaria’s laurel forests have dwindled to less than 1% of their original extent7 and what remains is far from the natural conditions8. Porto Santo, Lanzarote and Fuerteventura have completely lost their laurel forest4 7. On the Azores, the forest is rather degraded9.
Garajonay National Park is the largest (40 km2) and the best preserved example of “laurisilva” on the Canary Islands10. Garajonay is also a World Heritage Site. In the literature and nature documentaries Garajonay is often considered to be primeval forest but true primary forest can only be expected on steep slopes and in ravines7. Old cut stumps can be seen in places near the park boundaries. Old trees are often missing from larger valleys, some valleys even showing signs of past settlement. However, on slopes and in smaller valleys there are areas that look rather undisturbed. Grazing continued until the 1940s and its impact on the understory was significant; particularly Garajonay’s southern part (including the highest mountain tops) is seriously degraded10. However, for several decades there has been very little human intervention10. Introduced rats, mice, rabbits and cats are abundant11.
There was no human settlement on Madeira before the arrival of the Portuguese in the 1400s. The original forests have since been completely destroyed on the drier southern half of the island4, but on the northern slopes there are still places very close to their primeval state12. The best preserved sites have special protection as Nature Reserves4. A large part of the forests has also been protected as a World Heritage Site – “Laurisilva of Madeira”. As compared with Garajonay, the Madeiran forest is much larger (some 150 km2), better preserved, more luxuriant with slightly taller trees, wetter, cooler and growing on steeper slopes9. Due to the wetter climate, the Madeiran “laurisilva” occurs at lower elevations.
As these volcanic islands have never been connected to any continent13, subtropical luxuriance is here combined with low diversity in both plants and animals. The laurisilva is formed by only about 20 tree species, about half of these being very scarce. The more abundant species are Laurus novocanariensis (the most abundant species in the Canarian laurisilva), Stinkwood (Ocotea foetens, the most abundant species in the Madeiran laurisilva), Persea indica, small-leaved holly (Ilex canariensis), candleberry-myrtle (Morella faya) and Picconia excelsa; also Viburnum tinus subsp. rigidum on the Canaries and lily of the valley tree (Clethra arborea) on Madeira. In the exposed sites and close to the forest limit, tree heath (Erica arborea) is common, on Madeira also besom heath (E. scoparia) and Vaccinium padifolium. Stinkwood is the tallest species, reaching about 40 m on Madeira and on the Canaries slightly over 30 m; on the northwesternmost Canary Island, La Palma, it may become slightly taller. Note: the claim by identification guides that small-leaved holly reaches only 10 m 3 6 is incorrect, the tallest specimen I have measured being 28.0 m tall. Similarly, lily of the valley tree does not reach “up to 8 m” 4 but up to about 20 m (measurements using TruPulse 200X laser). Most of the abundant tree species have a peculiar habit of continuously developing basal sprouts; individual trunks do not become thick but eventually die and are replaced by younger outer trunks. The process has resulted in the trunk bundles characteristic of this forest type. In particular, old P. indica and stinkwood develop enormous basal burls from which the sprouts emerge. Tree heath often grows on slopes almost horizontally. Almost all the species are evergreen. The differences between many of the species are small but learning to identify the main species is relatively easy. The basal sprouts help identification if the canopy leaves are high out of reach. Abundant moss grows on trunks. Undergrowth is rather sparse, mainly consisting of tree seedlings and saplings; ferns occur in places.
Madeira’s levadas (aqueducts with accompanying paths) are a popular destination, hiking along them being very easy (if you have no fear of heights!). In Garajonay, most trails are located close to the park boundaries and roads.
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References:
- Nogué, S. et al. (2013): The ancient forests of La Gomera, Canary Islands, and their sensitivity to environmental change. Journal of Ecology Volume 101, Issue 2, pp 368–377.
- Izquierdo, T., de las Heras, P. & Márquez, A. (2011): Vegetation indices changes in the cloud forest of La Gomera Island (Canary Islands) and their hydrological implications. Hydrol. Process. 25, 1531–1541.
- Schönfelder, P. (2012): Die Kosmos-Kanarenflora. Kosmos.
- Press, J. R. & Short, M. J. (1994): Flora of Madeira. The Natural History Museum, London.
- https://www.monumentaltrees.com/en/
- Hohenester, A. & Welss, W. (1993): Exkursionsflora für die Kanarischen Inseln. Ulmer.
- Kunkel, G. (1993): Die Kanarischen Inseln und ihre Pflanzenwelt, 3. ed. Gustav Fischer Verlag.
- Airaksinen, O., Bäck, S. & Mäkelä, K. (1987): Gran Canarian metsistä 2. Los Tiles de Moya – ikivihreä laakeripuumetsä. Sorbifolia 18(2).
- World Heritage Nomination – IUCN Technical Evaluation: The Laurisilva of Madeira (Portugal).
- https://www.gobiernodecanarias.org/parquesnacionales/
- Führer des Nationalparks Garajonay und der Insel La Gomera. CNIG.
- Costa Neves, H. et al. (1996): Laurissilva da Madeira, caracterização quantitativa e qualitativa. Governo regional.
- Wildpret, W. & Martín, V. E. (1997): Laurel forest in the Canary Island: biodiversity, historical use and conservation. Tropics 6(4): 371–381.