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The General Foundation of the University of La Laguna points out that the Canary Islands conserve an important biodiversity of endemic flora exclusive to the high mountains. However, many species have a restricted distribution, preferably occupying rock-dwelling habitats, sheltered from invasive herbivores, or are currently in regression. This reduces their ability to adapt and migrate in response to climate change.

Along these lines, this project seeks, according to the entity, to provide new knowledge on the current problems of the Canary Islands‘ high mountain flora species. The purpose is that this new information allows establishing strategies for the management of these species, in the current context of climate sink supported by montane ecosystems.

To this end, 42 endemic species have been studied according to their migratory capacity (i.e. their dispersal capacity and tolerance to invasive herbivores) and their vulnerability to the speed of climate change. In addition, for threatened species, we wanted to determine whether soil deterioration caused by herbivory (the process by which animals consume living plant tissues, such as leaves, stems, roots or fruits) is responsible for their migration problems.

The general objective of this initiative has been to analyse the vulnerability of the endemic species of the Canary Islands high mountains and their particular types of vegetation (especially the summit pine forest and the summit broom), in order to develop strategies to improve their response to the combined effect of invasive herbivores and climate change.

The specific objectives were as follows:

• To learn about the obstacles to the expansion of 42 endemic species of the high mountains of the Canary Islands, on the islands of Santa Cruz de Tenerife and La Palma.
• To evaluate the speed of advance or constriction of the 42 endemic species selected in the montane ecosystems of the Canary Islands.
• To establish useful conclusions for the conservation and management of each species.
• Develop a regional and international promotion strategy for the project.

• Assessment in the study area of the damage caused by the herbivory of invasive species (specifically, by the European rabbit, Corsican mouflon and ruí) for each selected species.
• Analysis of the expansion capacity of each species based on three parameters: its productivity, its germination success rate and viability, and its seed dispersal capacity.
• Assessment of the effect of the absence of microbiota (set of microorganisms that reside in the body of a living being, whether commensal, mutualistic or pathogenic) of each species in impoverished soils for the expansion capacity of the most restricted species, specifically, four threatened species with small populations (Cistus osbeckiifolius, Helianthemum juliae, Rhamnus integrifolia and Silene nocteolens). The results they have obtained show that the current impoverishment of the microbiome of these soils is hindering the dispersal of some threatened plant species. In addition, within the framework of this activity, a Master’s Degree Final Project has been carried out within the Master’s Degree in Terrestrial Biodiversity and Conservation on Islands of the University of La Laguna.
• Evaluation of the projected speed of climate change for each selected species and their respective expected migration trajectories (allowing the analysis of the main geographical obstacles that may inhibit migration), both in Tenerife and in La Palma.
• Preparation of a report that includes a diagnostic file (with a joint analysis of all the previous actions) of the rate of vulnerability to expansion of each species analysed, with effective management guidelines for each one, and presentation of this report to the administrations responsible for management.
• Dissemination and communication of the project, through the creation of a Facebook page, the holding of information days, the publication of articles in informative magazines and the media, etc.

The project has made it possible to assess the vulnerability of 42 endemic high mountain species on the islands of La Palma and Tenerife, generating an identification file that allows determining which species have the highest priority for action against climate change. To this end, predictive models have been developed that delimit the climatic niche of the species and show their distribution possibilities. For each species, the models of suitability of past, current and future potential area have been determined, while the speed of response to climate change has been analyzed.

Thus, the vulnerability index obtained uses the assessment of the obstacles that may hinder or prevent the migratory response of species, including herbivory, the size of populations and habitats, the productivity of species and their dispersal capacity. The joint analysis of the species has made it possible to conclude, according to the entity, that the high mountains of the Canary Islands are not prepared to face climate change: almost 80% of the species analysed have some limitation to migration, which reduces their capacity to face changes and increases their vulnerability.

In addition, it has been determined that 38% of the flora analysed had high, very high or critical vulnerability in the short term (2041-2060), a value that rises to 79% in the long term (2061-2080). For this verification, the damage caused by herbivory has been analyzed, discovering that 18 of the 42 species analyzed (42.86%) presented a high impact by invasive herbivores. This demonstrates, according to the entity, the compromised situation in which the Canarian flora analysed is currently located, with the European rabbit being the species that most affects its regeneration.

Likewise, the production capacities of these 42 species of flora have been studied, highlighting 4 priority species to be included in future conservation programs (Rhaponticum canariense, Laphangium teydeum, Viola guaxarensis and Silene nocteolens), due to their low production detected in flowers and/or seeds and their state of threat current with reduced distributions and with few troops. Regarding germination success and viability rate, a good correlation has been found in all of them, and it has been found that the most widespread type of dispersal among these species is by anemochory (i.e., it is the wind that carries out the transport), although they may have more than one mode of dispersion. It has also been verified that in rhizospheric soils (areas of the soils that are in contact with the roots of the plants), growth rates are higher than in other soils, confirming the usefulness of the restoration of soil microorganism communities to promote the recovery of threatened plant species in the high mountain environment of Tenerife.

Finally, all these data and results have been included to generate future distribution models for both islands, taking into account different climate change scenarios and including geographical obstacles to migration in order to obtain a tool that allows predicting the occupation potential of each species. These models indicate that the selected summit species will preferably move at altitude as a result of current climate change: in La Palma to older areas, so it will be less of a problem; meanwhile, in Tenerife they would tend to migrate to sectors of greater slope and geological youth, which in this case may be a greater impediment to the establishment of new individuals. In any case, according to the entity, there are long distances to overcome that can be a great geographical impediment, in both cases.

In short, in the opinion of the General Foundation of the University of La Laguna, the results of this study indicate that urgent measures need to be taken to restore habitats. With this project, it has been possible to bring together technicians, managers and specialists from all the competent administrations in the field of biodiversity and conservation in the Canary Islands to discuss the need for new ways of assessing the status of species and ecosystems throughout the island territory.

In addition, dissemination and dissemination actions have been carried out to society in general, through the creation of a Facebook page, the holding of information days for secondary and university students; the development of a university extension course (entitled “New perspectives for the management of flora species and habitats in the Canary Islands”); the publication of articles in popular magazines and the media and participation in the international congress “Early Career Biogeographers Conference 2021” in Amsterdam and in the national congress of the Spanish Society of Plant Conservation Biology in Toledo (I Spanish Congress of Botany), in which the results of the project were presented. It should also be noted that the participation of two university volunteers in the field tasks was achieved. Finally, the entity delivered the final documentation of the work to the administrations involved in the management of the Protected Natural Areas involved (Cabildo de Tenerife, Cabildo de La Palma, Caldera de Taburiente National Park and El Teide National Park).