Included here are the Azores a group of nine volcanic islands situated in the North Atlantic. The three largest islands, São Miguel, Terceira and Pico represent about 69% of the total area of the archipelago.

Azorean Laurel Forest

These broad-leaf evergreen forest, are largely dominated by Laurus azorica (a Macaronesian endemic) and Myrica faya and are considered to be the natural climax vegetation up to an altitude of about 600m. Similar laurel forests can be found in Madeira and the Canaries, and all are thought to be the relicts of vegetation that was once widespread in southern Europe before climatic cooling during the Pleistocene. These macaronesian forests are rich in endemics. On the Azores they include Ilex perado subsp. azorica (Aquifoliaceae) and Notelaea azorica (Oleaceae) among the trees, Euphorbia stygiana (Euphorbiaceae), Picconia azorica (Oleaceae), Prunus lusitanics ssp. azorica (Rosaceae), Rubus hochstetterorum (Rosaceae), Vaccinium cylindraceum (Ericaceae), Viburnum tinus var. subcordatum (Adoxaceae) among the shrubs and Hypericum foliosum (Hypericaceae), Rubia peregrina var. azorica (Rubiaceae), Sanicula azorica (Apiaceae), Senecio malvaefolius (Asteraceae), Lactuca watsoniana (Asteraceae) and Selaginalla azorica in the field layer. In the central islands three sub formations are recognized – mesic forest, humid forest and hyper-humid forest. In mesic forest the environmental conditions are characterized by moderate winds, high levels of precipitation and low humidity, and usually have high levels of floristic diversity. Among the trees there is typically a high level of codominance. In addition to Larus azorica include Myrica faya and the endemic Frangula azorica (Rhamnaceae) and Picconia azorica (Oleaceae). The herbaceous layer is usually dominated by pteridophytes like Diplasium caudata and the endemic Dryopteris azorica and D. crispifolia (Dryopteridaceae). Other herbaceous elements may include the endemic Bellis azorica (Asteraceae), Platanthera azorica and P. micrantha (Orchidaceae). Humid laurel forests have elevated levels of both floristic and structural diversity and as implied occur in areas of high atmospheric humidity and rainfall, and usually have a degree of soil saturation at certain parts of the year. In addition the Laurus azorica they are typically dominated by the endemic Erica azorica (Eriaceae), Frangula azorica (Rhamnaceae) and Ilex perado subsp. azorica (Aquifoliaceae). Ferns again dominate the herbaceous layer with species such as Diplazium caudatum, Dryopteris affinis, Pteris incompleta and the endemic Dryopteris azorica (Dryopteridaceae). Hyper-humid laurel forests occur at high altitudes where human intervention has been less pronounced and as a consequence these now represent the commonest form of laurel forest in the Azores. Both strong humid winds and high levels of precipitation characterize the environment of these upland areas. In floristic terms, one of the main differences between these and other laurel forest is the absence of Erica azorica, which is replaced by its upland counterpart the endemic Vaccinium cylindraceum (Ericaceae). They also tend to have a less complex vertical structure but a more complex horizontal structure with many hummocks and hollow. Many of the low-lying areas are permanently saturated making germination difficult. Nevertheless, the herbaceous ground layer is well developed particularly with species such as Culcita macrocarpa and the endemic Dryopteris azorica, but the filmy fern Trichomanes speciosum may also be common.

Azorean Fayal Forest

Forest dominated by Myrica faya (fayal) mostly develops on recently developed lava soils rich in potassium. The local climate also has to be moderate with reduced exposure, moderate temperatures and good amounts of precipitation. They tend to have a simple structure but the endemic tree Picconia azorica (Oleaceae) is often a conspicuous component. At ground level the herbaceous layer typically includes the endemic Carex hochstetteriana (Cyperceae) and Polypodium azoricum (Polypodiaceae).

References

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