SANTA CRUZ DE TENERIFE 4 December (EUROPA PRESS) –
Researchers Cristina González Montelongo and Israel Pérez Vargas, from the Department of Botany, Ecology and Plant Physiology at the University of La Laguna, have recently released a publication in the journal ‘Journal of Fungi’ where they have examined epiphytic lichens—organisms that complete their life cycle on tree bark—to assess the conservation status of the monteverde or Canarian laurisilva.
This research has revealed signs of an “extinction debt” in Tenerife, likely stemming from the decline of this habitat over the last few centuries.
Moreover, it has identified that La Gomera is notable for its superior conservation level of the laurel forest when compared to Tenerife and La Palma.
Following a substantial impact on an ecosystem, such as deforestation or wildfire, species intricately tied to it can endure in untouched refuges for a period and, as a result, do not vanish simultaneously with the disturbance, as noted by ULL in a statement.
The species continue to persist, the researchers highlight, despite lacking the essential conditions for survival, and their extinction is merely a matter of time unless measures are taken to remedy the damage.
Lichens are composite organisms, consisting of at least one fungus and a photosynthetic partner living in a symbiotic and obligatory relationship. These entities, found in all known terrestrial ecosystems and capable of thriving on nearly any substrate, have been extensively utilised due to their unique properties as bioindicators and monitors of environmental pollution, air quality in urban areas and industrial regions, as well as changes in land use, among other factors.
In this study, they have been employed to comprehend the conservation status of the Canarian monteverde, an exceptionally threatened endemic forest of the Macaronesian region.
However, until now, the impact of human activity on this forest environment through the study of lichens had not been assessed.
Within this investigation, the research team established 18 study plots of 100 square metres across the islands that possess the finest and most extensive representations of Monteverde in the archipelago: La Palma, La Gomera, and Tenerife.
Consequently, the epiphytic lichens of the most prevalent species in this forest (holly, laurel, faya, and heather) were analysed, and lichen samples were collected from each tree covering a total area of 500 square centimetres across the main orientations (North and South) for subsequent identification in the laboratory.
As a result, a total of 165 lichen species were identified: 96 species for Tenerife, 82 for La Palma, and 70 for La Gomera.
ONLY 24% SHARED SPECIES
Out of the total species, merely 24% were common among all the islands: 9% between La Palma and Tenerife, 6% between La Gomera and Tenerife, and 5% between La Palma and La Gomera.
The number of species across the different islands did not display significant disparities, which contradicts the most widely accepted theory of island biogeography at present, which posits that larger islands should host a greater number of species than their smaller counterparts, as noted by ULL.
To evaluate whether any patterns exist in the distribution of lichens as a result of human-induced changes in the Canarian monteverde, the research group analysed the distribution of these organisms relative to the actual vegetation (currently seen in the area) and the potential vegetation (which natural succession would lead to if human intervention ceased).
It was during this process that indications of a possible extinction debt concerning the diversity of epiphytic lichens in the Canarian Monteverde were identified.
To determine if this phenomenon is indeed occurring in the Canarian monteverde in relation to lichens, and consequently verify the conservation status of the monteverde, the team undertaking this project examined the areas of potential and actual vegetation as if they were islands and discovered that the most significant discrepancies between potential and actual Monteverde occur in Tenerife, followed by La Palma and lastly La Gomera.
These findings support the idea that La Gomera showcases the most substantial representations of Canarian Monteverde, which is currently safeguarded under the designation of Garajonay National Park.
Conversely, on the island of Tenerife, the overall area currently occupied by the monteverde should not exhibit such a large diversity of species, should the theory of island biogeography hold true.
