Flora of the Canary Islands. Vegetation zones. Supracanarian zone. Flora and vegetation of the Canary Islands

Zone supracanario

From an altitude of 2,000 metres onwards, climatic conditions become considerably harsher, and the pine forest gives way to a shrubby scrubland adapted to these heights: the ‘retamar-codesar’, a type of vegetation in which the dominant species are broom and the summit codeso. It is in this zone that the ‘supracanario’ vegetation zone, also known as the high-mountain zone, is found. This zone is only present on the islands of Tenerife and La Palma, as they are the only ones whose peaks exceed this altitude. Las Cañadas del Teide, in Tenerife, and La Caldera de Taburiente, in La Palma, the two places where this vegetation zone is at its most striking, particularly in Las Cañadas del Teide, owing to its greater altitude and environmental diversity.
The influence of storms does not usually reach these high altitudes, so annual rainfall is low, at around 350–450 mm per year; it occurs almost entirely during the autumn and winter months, and much of it falls as snow, which can remain on the ground for several months, covering part of the vegetation.

     As the intense daytime sunshine causes evaporation in excess of 2,000 mm per year, the air is very dry, with relative humidity levels ranging between 30–50 per cent. Average annual temperatures are around 11 °C, and sub-zero temperatures are common during the coldest months. Frosts are frequent during the winter, and the diurnal temperature variation is considerable, with a difference of up to 15°C between day and night.
    The air, which comes from the north-west, is dry and largely cloudless, meaning that solar radiation is very strong and particularly rich in ultraviolet rays. Winds blow almost constantly and are often very strong, with gusts exceeding 80 km per hour.
     These harsh climatic conditions, combined with the geographical isolation of these areas, have contributed to the establishment in this mountainous region of a very distinctive flora, largely derived from the vegetation dominant at lower altitudes, but which has had to evolve by adopting various mechanisms that have enabled it to survive in these harsh climatic conditions, such as the predominance of shrub-like growth, the expansion of the root system, cushion-like growth, and foliar adaptations designed to minimise water loss through transpiration.

     The air, which comes from the north-west, is dry and largely cloudless, meaning that solar radiation is very intense and particularly rich in ultraviolet rays. Winds blow almost constantly and are often very strong, with gusts exceeding 80 km per hour.
    These harsh climatic conditions, combined with the geographical isolation of these areas, have contributed to the establishment in this mountainous region of a very distinctive flora, largely derived from the vegetation dominant at lower altitudes, but which has had to evolve by adopting various mechanisms that have enabled it to survive in these harsh climatic conditions, such as the predominance of shrub-like growth, the expansion of the root system, cushion-like growth, or foliar adaptations designed to minimise water loss through transpiration.
     The tree species found here are limited almost exclusively to the Canary Island cedar (Juniperus cedrus), of which only a very small number of specimens remain, situated in extremely rugged and almost inaccessible locations due to the excessive felling this species suffered over the centuries to exploit its highly prized timber.
    The dominant shrub communities – broom and codeso thickets – are characterised by an abundance of legumes, such as the Teide broom (Spartocytisus supranubius), on the peaks of Tenerife, or the summit codeso (Adenocarpus viscosus) on those of La Palma, where broom is found only on the steep slopes of the Caldera de Taburiente.

Echium wildpretii

Both the broom thickets and the codesar scrub are accompanied by a wide variety of species endemic to this area, which are notable for the profusion of flowers they produce to increase the likelihood that some of their seeds will have the chance to germinate in such extreme conditions. These include catmint (Nepeta teydea), Teide wallflower (Erysimum scoparium), Descurainia bourgeauana, summit scrophularia (Scrophularia glabrata), rabbit’s-ear (Pterocephalus lasiospermus), the Teide daisy (Argyranthemum tenerifae), the Teide ‘cabezón’ (Cheirolophus teydis), the ‘malpaís’ flower (Tolpis webii), and the iconic red tajinaste (Echium wildpretii), which adorns the landscapes of Mount Teide in a unique way with its impressive inflorescences, up to two metres high, formed by thousands of small, deep red flowers.

Viola palmensis

The peaks of La Palma are home to valuable populations of the beautiful mountain pansy (Viola palmensis), the blue tajinaste (Echium gentianoides) and the pink tajinaste (Echium wildpretii ssp. trichosiphon), as well as the threatened mountain broom (Genista benehaovensis). Other species, such as the silver thistle (Stemmacantha cynaroides) and the Las Cañadas rock rose (Helianthemum juliae), are two species found exclusively in the high mountains of Tenerife and are currently threatened with extinction.