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How plants survive in the driest place on Earth and what they can teach us about climate change

How plants survive in the driest place on Earth and what they can teach us about climate change

Tillandsia in the Atacama Desert

The Atacama Desert, north of Chile, is the most dry place on Earth. It’s located in the Atacama desert. On average, less than a millimetre of rainfall falls there each year.

It is difficult to imagine plants growing in such hostile conditions. They do, however: Tillandsia landbeckii, a genus of plant from the pineapple family (Bromeliaceae), survive in the desert by ‘combing’ water out of the fog that rolls in from the nearby coast.

These plants also serve as indicators for climate change and for the availability foggy water, which can be used by humans to provide a sustainable water source.

Desert fog

The Atacama Desert’s climate can be largely shaped and influenced by a quasi permanent high-pressure system over the South Pacific coast of Chilean-Peruvian. thermal inversion layer – where the air increases in temperature the higher you get in the bottom part of the atmosphere. The inversion layer is where the Pacific’s moist, cool air is separated from the warm, dry air masses above.

The result is that large stratocumulus clouds are formed in the air layer closest the ground. However, they don’t bring any rain. This process is supported in part by the Humboldt Current – a cold Pacific current that flows north along the coast of South America.

Fog forms along the coast where the cloud layer touches the ground. The dryness of Atacama Desert can make this fog penetrate several kilometres inland. Fog frequency, intensity, and spread are all subject to change. strong fluctuationsIt is determined based on the season, time of day and other factors.

Adapting to desert life

Changes in fog intensity and frequency are extremely dangerous for Atacama ecosystems. Tillandsia landbeckiiIt has evolved to extreme drought and is now an endemic species in the fog ecosystems at the Atacama Desert.

The plant does not have roots. Instead, it sticks to the sand with its older, more decayed parts. The plants use their thin leaves and shoots to remove the moisture from the mist. They swell when they come in contact with water.

The nocturnal dew is another source of water, especially in the summer months with little fog. Together, these groups of plants are known as ‘lomas vegetation’.

Tillandsia in the Atacama Desert

Tillandsia live by ‘combing’ water out of the fog.
Alexander Siegmund, Fourni par l’auteur

Collecting fog

This type of vegetation is restricted to the Atacama desert, where fog is common. The distribution of fog ecosystems is limited by the Pacific’s distance, the prevailing winds direction and topography (height, elevation and exposure to the main wind directions)

We can see this by analysing satellite data TillandsiaStocks are located between 800 m to 1,250 m above the sea level, and 3 km to 45 kilometers inland. They are mostly found on sandy plains with fog corridors or slopes that face west or south.

Groups of Tillandsia landbeckiiYou can stand up to half a meter tall in a ribbon-like structure running perpendicularly to the wind direction. The TillandsiaSo they are optimally exposed for the supply of nutrients and moisture. The amount of fog water is an indicator of general water availability. This affects row spacing, width, density.

We can use drone and satellite data to determine the location. analyse and model the plant populationTo better understand the prevailing conditions, you can also use this information, including growth rates as well as genetic variability between plants.

We compare the results from TillandsiaDistribution with data from seven climate measurement stations, which are located at different heights and distances to the sea. These stations can measure the air temperature, relative humidity and wind speed and direction. The data can also be transmitted via satellite to the Department of Geography of Heidelberg University of Education.

We measure the amount of water in the air using standard fog collectors – a one square meter frame covered with a special net, which is set up at a height of two metres, perpendicular to the main wind direction.

Fully automatic THIES climate station of the Geography Department -- Research Group for Earth Observation (rgeo), e.g. for measuring the fog water with a Standard Fog Collector (SFC)

The fully automated THIES climate station has a standard fog collection for measuring moisture in air.
Alexander Siegmund, Fourni par l’auteur

Within one week at the climate station in Cerro Oyarbide, 15 km from the coast, we measured 6.7 litres of fog water an altitude of 1,077 m. Just 2.5 km away, we measured 14.4 litres at an altitude of 1,218 m. At another nearby climate station at an altitude of 1,350 m, we only recorded 0.1 litres – this station is above the inversion layer, over which the fog does not appear.

We can see that the data is averaging over time between 1998 and 2014 shows a slight decreaseThis is due to the decrease in fog-generated water. This is accompanied by a decrease of the thermal inversion layers. This lowers the stratocumulus cloud coverage and the fog that is generated from it.

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Based on this, it’s fair to say that, in the future, some of the higher areas of TillandsiaThey will not be able collect water in the areas they aren’t allowed to.

Fog as a sustainable source of water

Research over many years has shown that the hardy desert plant can be used by humans to trap their own water from fog.

Water resources are extremely limited in coastal cities such as Iquique and smaller fishing villages near the edge of the desert. Water rights are being privatized and consequently very expensive. Due to the extensive extraction of copper and lithium for the production of batteries, which requires huge amounts of water, the demand will continue rising in the coming years.

Although domestic and drinking water have been primarily obtained from groundwater, there could be lessons for humans regarding the distribution and behaviour these plants.

There are close connections between ribbon-like structures of the TillandsiaStocks, their growth rates, and measured fog water quantities. We can then develop a geoecological niche modeling of this unique fog ecosystem.

This can be used, for example, to determine the best locations for fog trap nets. Fog water can then be collected as a sustainable source of water for the local population.

For 50 years, the UNESCO Man and the Biosphere Program(MAB) has combined social, natural, and exact sciences to find solutions in 714 exceptional sites (129 Countries) of biosphere reserve biosphere reserves.

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