Mountains: refuges of life, reservoirs of the future

International Mountain Day is celebrated on 11 December, inviting us to focus on these imposing ecosystems, not only as landscapes of singular beauty, but as true refuges of biodiversity and reservoirs of vital resources.

Mountains cover around 27% of the Earth’s surface and harbour an impressive biological and cultural diversity, home to approximately 15% of the world’s human population and a wide variety of species which adapt to extreme conditions of altitude, temperature and luminosity.

These high-altitude ecosystems are true sanctuaries for endangered species, water reservoirs – half the world’s population depends on mountain water – and custodians of the genetic diversity that sustains life in the valleys and the plains.

Unfortunately, like the rest of the planet, these important life refuges are not immune to climate change, considering that they face increasingly larger and unequal struggles to survive.

High-altitude ecosystems

Mountains are ecosystems of exceptional complexity and beauty, and can be found on all continents and at all altitudes. Their altitude fluctuations create a number of habitats – from forests and bushes on the lower slopes to alpine meadows and rocky areas at higher levels. Assorted microclimates and soil conditions (physical, chemical and biological) assist the growth of endemic species and unique plant communities, many of which adapt to extreme cold, wind and sunlight.

In Portugal, Serra da Estrela, Gerês, Monchique or São Mamede are good examples of this diversity. In them, oak, juniper, heather and broom areas coexist, with clear ecological roles as regards soil retention, natural recycling of nutrients and water regulation. Emblematic species find shelter in their slopes, e.g. the Iberian wolf  (Canis lupus signatus), the wild cat (Felis silvestris silvestris), or altitude birds such as the golden eagle (Aquila chrysaetos) and the blackbird (Cincluscinclus), a bioindicator of the quality of watercourses.

Natural reservoirs of water and diversity

More than majestic landscapes, mountains are the “water reservoirs” of the planet. They are the origin of all major rivers in the world and many smaller ones. They play a crucial role in the water cycle: the rain and snow accumulated in the cold months act as a natural system of storage and gradual release of water, feeding rivers, springs and aquifers. This mechanism is essential for the regeneration of ecosystems and for the balance of biogeochemical cycles.

During the winter, solid precipitation remains in the form of snow and ice; In spring and summer, the thaw slowly releases the water, ensuring supply for riparian ecosystems, agricultural areas and human communities located downstream. Many of the most ecologically and economically important river basins of the Iberian Peninsula are formed in the mountains. In addition, they still preserve a valuable cultural heritage, which includes monuments and traditions created and preserved by the communities that settled there.

In light of the fact that they aggregate such characteristics, the Trans-Border Biosphere Reserves of Gerês/Xurés and the Iberian Meseta, the largest in Europe, are part of the World Network of Mountain Biosphere Reserves.

But these environments are also reservoirs of genetic diversity, essential for the adaptation of species to environmental changes. They are like islands, where isolated populations living at higher altitudes act as “evolution laboratories”, forming unique endemisms (true new species), which we cannot find anywhere else in the world.

The challenge of change

Mountains are particularly vulnerable to change. The degradation of mountain regions caused by both human action and climate change has a large impact on these ecosystems. Unsustainable agricultural practices, commercial mining, deforestation, pollution, poaching and natural disasters have forced ecosystems and the people who depend on them to adapt or migrate.

But climate change is the most striking. Rising average temperatures and changing precipitation regime threaten the fragile ecological balances built up over millennia. The retreat of snow and ice areas alters the availability of water and seasonal changes in the life cycle of the species, causing altitudinal migrations and habitat loss.

Highly specialised species, such as lichens and alpine plants, see their living space shrink, while invasive and generalist species colonise new areas. These imbalances affect not only biodiversity, but also the ecosystem services millions of people depend on.

Taking care of the mountains is taking care of life

Protecting mountains means protecting the ecological base of the planet. The sustainable management of these ecosystems has been increasingly seen as a priority worldwide. This is why it is part of the United Nations Sustainable Development Goals (SDGs) (target four of goal 15).

This management must integrate nature conservation, spatial planning and climate adaptation, valuing the role of local communities that, over the centuries, have developed practices for the sustainable use of resources.

On this International Day of Mountains, let us remember that every slope, every watercourse and every high-altitude forest is a fundamental part of a system that sustains life. Preserving the mountains is ensuring the future of the water we drink, the biodiversity and the natural and cultural heritage that surrounds us.

Did you know that…

• Mount Everest, located in the Himalayas, is the highest mountain in the world, with an altitude of 8,848 meters above sea level. It was first climbed in 1953.
• Mars has the highest mountain in the solar system. Mount Olympus is the highest known mountain, standing about 27 kilometres high above the surrounding countryside.
• The Moon also has its own impressive mountains. Mount Huygens (part of the Lunar Apennine mountain range) is the largest, with altitudes that can reach 5,500 meters above the lunar seas.
• Most of the mountain ranges on Earth are submerged under the oceans. It’s the so-called underwater mountains that rise high above the surrounding landscape, such as the Mid-Atlantic mountain range in the Atlantic Ocean or Mauna Loa in Hawaii, with 9.170m above the seabed.
• Many mountains are of volcanic origin. Mount Fuji in Japan is an iconic example of a volcanic mountain that is still considered active.