Canary Islands are not only one of the most popular tourist destinations in the world. These subtropical islands also harbor a rich biodiversity, with astonishing ecosystem variety from barren deserts to lush subtropical forests. This diversity is very fragile and sensitive to the impact of invasive species, climate changes and human pressure. We have worked in three islands ecosystems: high mountain shrublands, pine and laurel forests.
In Teide National Park we related the mortality of the dominant Teide broom (Spartocytisus supranubius) with extreme drought events, a major conservation issue. We collaborated with the National Park to implement a management plan. In 2018, we started to work with an elusive species, the Canary Island juniper. A rare species in the National Park, most of its population remains in inaccessible volcanic cliffs. Using dendrochronology, we sampled junipers in areas accessible on foot, and climbed to the cliffs to understand the reason for this strange distribution pattern.
Surprisingly, juniper radial growth is fast, up to XX mm per year in their first decades, a lot considering that mean annual precipitation is as low as XXX mm. Interestingly, it performs much better in the flat areas with deeper soils than in the cliffs. The age structure of the juniper population in the flat areas gave the clue, most junipers in accessible areas established after the creation of Teide National Park, and the removal of goat herds. In contrast, juniper in cliffs were much older, some of them with more than five centuries. It seems that cliffs were a refuge for junipers where they escaped from goat teeth and human axe.
A finding corroborated our findings, an old juniper remains in a remote, but flat, area of the National Park. We studied its age using C14 and it turned to be more than a thousand years old!!! Moreover, archeological findings identified carbon remains of juniper in a nearby area, this supported that junipers were so common that guanches (aboriginal people) used them as firewood.
Promoting juniper recovery in flat areas would contribute to recover the aspect of Teide landscape when aboriginal people found it, two millennia ago. Moroever, not only juniper is much more resistant to drought than Teide broom, but juniper shade might also alleviate Teide broom drought stress, thus making Teide ecosystem more resistant to climate change