Earth embraces a variety of ecosystems, which fall under two categories: aquatic and terrestrial ecosystems. An important terrestrial ecosystem is the mountainous environment. Mountains cover almost 24% of the world’s land area and exist at different elevations; they are steeper, larger, and higher than hills, and more than 600 meters in height.
So, how are mountains formed? Well, the continuous movement and collision of the huge tectonic plates that form Earth’s crust create a landform higher than the surrounding land area. Mountains are classified according to the type of rocks they are composed of, their shapes, and their placement on land, such as fold, fault-block, dome, volcanic, and plateau mountains.
Mountainous regions provide homes for distinctive human communities, which represent almost 10% of the world’s human population, and encompass a great diversity of habitats where different species are found. For example, the Sierra Nevada mountain range is estimated to be home to around 10,000–15,000 species of plants and animals.
The characteristics of mountain ecosystems vary according to the altitude, biomes, and bodies of water surrounding the mountain. Climate on mountains tends to be colder and wetter; at the higher altitudes of mountains, the air is thinner where there is less oxygen to breathe, the pressure increases, and the temperature decreases. This climate is called Alpine climate, referring to the weather of the regions above tree-line or highland climate. Summer and Spring are short on mountains; hence, they are covered with snow most of the year.
Due to the harsh climate and fragile nature of the mountains, large numbers of native plants and animals are listed as “at risk” or “endangered” by different organizations worldwide. Mountain ecosystems are subject to both natural and anthropogenic drivers of change; they face a number of natural disasters: avalanches, erosion, lava flows, and earthquakes, which can destroy the habitats. Mountain animals and plants can adapt to the surrounding environment to survive.
Mountainous ecosystems offer many essential ecological services; not only for the people living there and the people living nearby, but they also contribute directly and indirectly to the wellbeing of almost half of the world’s population. They play an essential role in influencing global and regional climates and weather conditions.
The amount of rain that the lowland areas surrounding the mountains receive depends mainly on the mountains, which block wind and receive more rainfall. When air flows over a mountain, it is forced upwards, then it cools, causing moisture to condense and rain falls. When the air descends the protected side, it warms and is drier, because the moisture in the air had faded out during the ascent. Rain falls more on the windward side of a mountain and the leeward side of the mountain receives lesser amounts of rainfall, which may result in drier climates.
The snow covering the tops of the mountains acts as a mirror increasing the amount of reflected solar radiation, which reduces the overall amount of energy absorbed at the Earth surface. As the snow melts, the mirror thins and more solar rays penetrate the Earth, leading to the increase of the Earth temperature and the quantity of water vapor in the atmosphere increases too. Moreover, this continuous rise in temperature will lead to the fast melting of the glaciers and snow on the mountains, which can cause floods.
Mountains provide 60–80% of the world’s freshwater; all the major rivers in the world have their source in mountain glaciers known as “water towers”. In humid areas around the world, the proportion of water generated in the mountains can comprise up to 60% of the total freshwater available in the watershed, while in semi-arid and arid areas, this proportion is over 90%.
Almost half the people on the planet depend on mountain water, either for drinking, as a source of energy, or for growing food. Mountain water is a source of hydroelectric power, most of which is used on the plains below. Historically, water-wheels have provided energy in mountain regions, mainly for grinding grain; currently, hydropower turbines are used to generate electricity. Changes in the volume of mountain glaciers and seasonal melting patterns impact water resources in numerous parts of the world.
The increased rates of environmental changes, accompanied with economic and social changes, affect the ability of mountain ecosystems to provide their usual services necessary for the well-being of the world’s population, not only the mountain community. The challenge is to find new and sustainable opportunities that can benefit both mountains and lowland communities, and help eradicate poverty without contributing to the degradation of the fragile ecosystems.
Among the targets of the Sustainable Development Goals (SDGs) is “to ensure the conservation of mountain ecosystems, including their biodiversity, in order to enhance their capacity to provide benefits that are essential for sustainable development”. International and regional organizations, as well as special groups specialized in saving the mountains, are working hard to enhance the understanding of mountainous ecosystems and the conservation of its biodiversity and sustainable development. They are also working on developing policies that help in the management of mountain ecosystems, including climate change mitigation and adaptation.
References
nationalgeographic.com
sciencing.com
britannica.com
sciencedirect.com
iucn.org
The article was first published in print in SCIplanet, Winter 2019.
Image by wirestock on Freepik.