Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Brèves → Brèves 2017 → Changing temperatures, precipitation may affect living skin of drylands

Changing temperatures, precipitation may affect living skin of drylands

ScienceDaily (March 15, 2017)

Healthy desert surfaces play a critical role in ecosystems, climate, and human health

Titre : Changing temperatures, precipitation may affect living skin of drylands

Healthy desert surfaces play a critical role in ecosystems, climate, and human health

ScienceDaily (March 15, 2017)
Arid and semiarid ecosystems are expected to experience significant changes in temperature and precipitation patterns, which may affect soil organisms in ways that cause surfaces to become lighter in color and thus reflect more sunlight, according to a new study.

Drylands make up more than 40 percent of Earth’s land surface. The living skin of the desert, called biological soil crusts or biocrusts, is a community of mosses, lichens and/or cyanobacteria that is critical to human and ecosystem health and climate in the Southwest and other dryland areas.
USGS scientists created outdoor testing plots located on the Colorado Plateau, where large squares of biocrusts were exposed to different warming and precipitation factors over time. Researchers not only looked at how the biocrusts responded, but also measured the amount of energy that the different biocrust communities reflected back into the atmosphere relative to how much energy came in from the sun. This effect is known as albedo. Warming and watering treatments had large impacts on biocrust communities, transforming them from the dark to light-colored communities, and causing energy that was previously absorbed by the dark surfaces to reflect back into the atmosphere. These factors led to large increases in albedo and may represent a previously unidentified effect on future climate by slowing how fast Earth warms.
The replacement of biocrust mosses and lichens with light-colored cyanobacteria may also result in increased soil erosion, decreased soil fertility and decreased removal of the greenhouse gas carbon dioxide from the air.
Biocrusts provide soil stability and prevent erosion, and could help prevent the large dust storms that move through big southwestern cities such as Phoenix. Dust storms are a human health issue, as airborne particles can cause lung cancer, asthma and other respiratory problems. Many human activities can be unintentionally harmful to biological crusts. The biocrusts are no match for the compressional stress caused

Story Source  : US Geological Survey.

Annonce (ScienceDaily)

Page publiée le 3 mai 2017