Vegetation Zones of the Iberian Peninsula and Canary Islands
The Iberian Peninsula belongs to the Holarctic floral kingdom, which includes alpine and boreal areas. This gives rise to two regions: the Euro-Siberian region, encompassing the Cantabrian Mountains, Pyrenees, and some northern and central sectors of the peninsula; and the Mediterranean region. In the Canaries, the representative region is the Macaronesian region.
Factors Influencing Vegetation
Vegetation formations include scrubland, forest, and meadow. Spain boasts great diversity in vegetation due to a variety of factors:
- Physical factors: Different climates and terrains, as well as the peninsula’s unique position, determine the original vegetation. In the Canary Islands, insularity plays a significant role. This original vegetation is called climax vegetation.
- Human factors: Introduction of species for economic value or degradation of existing vegetation due to human activity results in secondary vegetation.
Vegetation Landscapes
Oceanic Climate Vegetation
1) Deciduous Forests:
- Tall trees with straight trunks and large leaves that fall in autumn.
- Few species, forming large masses, such as oak and beech.
- The undergrowth is characterized by moss and ferns, thriving in the gloomy atmosphere created by the treetops.
- Beech trees tolerate heat poorly and require high humidity. They grow quickly, and their wood is of good quality. Beech often forms mixed forests with oak in the Cantabrian Mountains and the Pyrenees.
- Oak trees do not tolerate hot summers. They require more humidity than beech and are found at lower altitudes. Their growth is slow, and their wood is hard. Extensive oak forests are found in Galicia and the Cantabrian Mountains.
- Chestnut trees have gained ground at the expense of oak.
- Secondary species include hazel and ash.
- In the transition area of the oceanic climate, the forest includes species like the Pyrenean oak.
Over time, extensive deciduous forest areas have disappeared due to traditional uses of wood, replacement with gas, oil, or coal, uncontrolled burning for pasture, and forest fires. Currently, large areas are being reforested with fast-growing species like eucalyptus and pine. However, these reforestations have been criticized because they contribute to soil acidification and impoverishment, and these species burn more easily in fires.
2) Moorland, Heath, and Grassland:
- Moorland vegetation can reach up to four meters in height and includes species like heather, gorse, and broom. It appears as a degradation of deciduous forests or as supraforest vegetation. It serves as bedding for animals and fertilizer.
- Grasslands occupy large extensions of the oceanic landscape in siliceous areas.
Mediterranean Climate Vegetation
These formations are adapted to summer drought, with extended roots and various systems to reduce transpiration.
1) Evergreen Forests:
- Non-straight trunks with thick, rough bark.
- A rich understory exists because the trees are spaced apart, allowing sunlight to penetrate.
- The holm oak is the most characteristic and widespread tree in the Mediterranean climate. It is resistant to drought and adapts to all types of soils. Its acorns are used to feed livestock.
- The cork oak requires mild winters and siliceous soils with some humidity. It is found in the southwestern peninsula and southern Andalusia. Its bark is used for cork production.
- Pine trees adapt to extreme conditions of cold, heat, humidity, and aridity, as well as diverse soil types. They have expanded due to human intervention, their rapid growth, and economic value.
The evergreen forest has seen a reduction in its extension due to the loss of its traditional uses, replacement by other species with greater economic value, mechanization of irrigated land, and forest fires. The “dehesa” system consists of clearing the holm oak forest to combine the use of wood and acorns with extensive grazing and crop rotation.
2) Scrubland:
Mediterranean scrubland is not a climax formation but rather the result of forest degradation by humans. It includes:
- Maquis: Dense and nearly impenetrable, reaching up to two meters in height, with species like rockrose and broom.
- Garrigue: Lower scrubland that allows for the growth of aromatic plants like lavender, rosemary, and thyme.
- Steppe: Found in the semiarid southeastern peninsula and the Ebro Valley. It is characterized by dry, thorny shrubs like esparto and asparagus.
Riparian Vegetation
Along rivers, there is constant humidity that allows certain species to thrive. These species are arranged in parallel bands to the river. Closer to the water, species like alder and poplar are found. Further away, species like ash are present. Riparian vegetation has been reduced by human action, such as canalization and dam construction.
Mountain Vegetation
Mountain vegetation is arranged in tiers according to altitude.
1) Alpine Mountain:
The forest is divided into three levels:
- Subalpine (1200-2400m): Natural conifers like spruce and Scots pine, or mixed forests of spruce and beech.
- Alpine (2400-3000m): Meadows dominate, covered in snow most of the year. In rocky sectors, small rupicolous plants thrive.
- Nival (>3000m): Snow is present all year round, and only mosses and lichens appear on the rocks.
2) Other Mountains:
In mountains without a subalpine coniferous level, the vegetation is characterized by the features of its climate. In the Atlantic area, heather and broom abound, while in the Mediterranean area, shrubs and scrubland are common. There is no supraforest level.
Canary Islands Vegetation
The Canary Islands have extraordinarily rich vegetation, with a significant number of endemic species and relics. The vegetation is divided into tiers:
- Basal (0-500m): Aridity prevails, with scrubland and species like the cardon.
- Intermediate (200-800m): Higher humidity allows for the presence of species like the dragon tree, palm tree, and juniper.
- Thermocanarian (800-1200m): Vegetation adapts to the trade winds, which cause fog. This results in dense laurel forests. The degradation of laurel forests by human action has led to the formation of “fayal-brezal” (heath and heather formations).
- Canary Pine Forest (1200-2000m): Predominance of conifers like the Canary pine and cedar.
- Supracanarian (>2000m): Present only in Tenerife and La Palma, characterized by floral richness.