J. Ruiz del Castillo et al. / Invest Agrar: Sist Recur For (2006) Fuera de serie, 24-39
High mountain type
Alize tradewinds forests type
Extra-Alize tradewinds forests type
Zonal vegetation in Canary Islands
Below potential forest belt
Below the potential forest belt ss. str.
Figure 4. Diagram of the zonal climatic-structural types of Canary Islands.
ted between 500 and 1,500 m. It has a windward orien- tation towards the wet alize tradewinds (alisio) provo- king extremely abundant fog. This is the area of the laurisilva and most of the fayal-brezal. Its dominant tree species belong to the genera Laurus, Ocotea, Erica, Myrica etc.
Extra Alize tradewinds forests ype (SE). Located in Gran Canaria, Tenerife, Gomera and El Hierro, in a wide altitudinal belt between 500 and 2,000 (2,500) m, to leeward to the alize tradewinds, therefore without condensations from its fogs. Most characteristic species belong to the genera Pinus and Juniperus, along with others which are less frequent, like Olea, Pistacia, Phoenix, Dracaena etc.
In the lower belt, outside the domain of potential forests, the CST can be distinguished between the following:
Below the potential forest belt sensu stricto ype (I). An arid climate prevails within this domain, with rainfalls between 150-250 mm, hot temperatures and an almost permanent dry period. It is located between sea level and about 500 m. Several scrub communities dominated by genera Euphorbia, Senecio, Rumex, Hypericum etc. occur.
Hyperxerophile ype (H). It represents the most acute dryness within the above mentioned type, with annual precipitations below 150 mm. The thermic pattern is hot. When present, it occupies a strip between 0 and 400 (500) m. Plant communities are basically very sparse scrubs, the most characteristic taxa being of genera Launaea and Euphorbia.
There is also a set of intrazonal vegetation types in areas where some local predominant soil features con- dition the composition, structure and physiognomy of the high specialized existing plant covers, either forested or non arboreous (Fig. 5): communities belonging to the Glycohydrophile Type (damp soils with non salty
water in river banks, mires, springs, banks and inner areas of shallow lakes etc.), the Halohydrophile Type (salty wetlands), the Gypsophile ype (gypsum or chalky soils), the Haloxerophile Type (salty soils), along with the Stony areas Type, Karstic limestone sites Type, Psammophile Type (sandy sites) and the Rocky sites Type are the main examples of intrazonal vege- tation.
Intrazonal types in Canary lands are similar and have de same denominations of those of continental Spain. A Subhydrophile variant stands out since its is significant of vegetations where Phoenix canariensis occurs.
The vertical structure component
The importance of structural traits has been high- lighted by many authors, as Tomaselli (1982), and Küchler (1988). The vegetation structure refers to the density of communities and spatial distribu- tion pattern of dominant species along with the prevailing height in woodstands. The MFE2C takes into account six height categories based on Ruiz de la Torre & Ruiz del Castillo (1977) and Ruiz de la Torre
Arboreous height. Dominant species exceed 7 m.
Subarboreous height. Dominant species reach
between 3 and 7 m.
High scrubs. Dominant species reach between
and 3 m.
Medium scrubs. Dominant species reach between
and 1.5 m.
Low scrubs. Dominant species reach between
and 0.5 m.
Dwarf or creeping scrubs. Dominant species do
not reach 0.05 m.