Canary Islands Ecosystems
Cave Fauna
The cave fauna exhibits varying degrees of adaptation to the cave environment. There are three main types:
- Troglobites: These are obligate cave dwellers with significant adaptations that prevent them from surviving outside the cave environment.
- Troglophiles: These species typically inhabit caves but can also venture outside occasionally.
- Trogloxenes: These are surface-dwelling species that may occasionally enter caves.
The primary threats to cave ecosystems include pollution from surface runoff, construction, agriculture, and human traffic within volcanic tubes. A notable characteristic of cave fauna is depigmentation and the absence of eyes (endemism). The most abundant species are crustaceans (crabs) and polychaetes (marine worms). The Jameito, a small, blind, white crab, is a well-known endemic species.
Of great scientific interest is a crustacean considered a living fossil, belonging to a group that went extinct 250 million years ago. This rare endemic species has the unique ability to swim on its back and is found only in dark cave environments.
Plant Communities
Plant species in the Canary Islands are grouped into communities distributed across different vegetation zones based on altitude and climatic factors. The main ecosystems are shrublands (formed by bushes) and forests (formed by trees). Shrublands are found near the coast and on mountain summits, while forests occupy the middle elevations of the high islands and are influenced by the trade winds and the sea of clouds.
The coastal scrub ecosystem comprises three vegetation units:
- Sand Dune Communities: Plants that thrive in sandy environments are called psammophiles. Those that tolerate high salt content from the sea are called halophiles, either by withstanding high salt concentrations or by expelling excess salt through specialized hairs.
- Coastal Cliff Communities: These communities consist of species adapted to harsh conditions such as wind, unstable terrain, and soil scarcity.
- Tabaibal and Cardonal Communities: These are the most characteristic and widespread vegetation units in the coastal scrub, formed by shrubs and bushes. Tabaibales and cardonales thrive in environments with low rainfall, high year-round temperatures, and intense sunlight. Tabaibas have succulent stems and elongated leaves, while cardones have leafless green stems with spines and can reach impressive sizes. The cardon provides refuge for a diverse group of species.
Endemic Trees
The Canary Island Juniper is a small shrub or tree with tiny, scale-like leaves and red fruits. The Canary Island Date Palm, an endemic species found on all the islands, is a fundamental element of the landscape, typically found below 600m altitude. Its sap is extracted by cutting the terminal bud. The Dragon Tree, one of the most emblematic trees of the Canarian flora and the symbol of Tenerife, thrives in low-lying areas between 200 and 400m. The oldest Dragon Tree is located in Icod de los Vinos (Tenerife), standing about 17m tall with a trunk circumference of 20m and an estimated weight of 65 tons.
Laurel Forests
Laurel forests are evergreen due to the mild climate that allows for continuous biological activity. They are also multispecies, boasting a great diversity of tree species in the forest canopy. Laurel forest species have broad, oval, shiny, and leathery leaves, similar to the laurel tree. The Canarian laurel forest is the most complex ecosystem in the Canary Islands, characterized by a dense tree cover that allows little light to reach the lower strata, resulting in a sparse understory.
The fauna of the laurel forest is abundant and diverse, with a high percentage of endemism. The moist environment favors the presence of earthworms, molluscs, nematodes, and mealybugs. Insects are the most abundant group of invertebrates.
Pine Forests
Pine forests extend from 1,200m to 2,100m altitude on the windward side and from 700-800m to 2,300m on the leeward side. These are monotonous woodlands dominated by the Canary Island Pine (Pinus canariensis), which grows in a dispersed manner, leaving open spaces where an understory of broom, laburnum, rock roses, thyme, and poleos thrives. The Canary Island Pine is distinguished by its long, slender needles grouped in threes. It can reach impressive sizes, up to 60m in height, with a straight trunk, thick bark, and a conical crown.
Broom thickets are more developed in wetter areas but are scattered throughout the pine forest. Laburnum with its yellow flowers is found within the pine forest and along the edges of trails.
High Mountain Vegetation
High mountain vegetation is unique to the Canary Islands within the Macaronesian archipelagos, found only on the islands of Tenerife and La Palma. It extends above the pine forest between 2,000 and 3,000m, where harsh climatic conditions prevent forest growth and determine the type and form of vegetation. Environmental factors influencing this zone include wide temperature fluctuations, with snowstorms in winter and ice for most of the year, dry air, and erratic rainfall often accompanied by strong winds.