Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Kalahari Desert soils and climate change

03.04.2008
The sands of the desert are an important and forgotten storehouse of carbon dioxide taken from the world’s atmosphere, scientists heard today (Wednesday 2 April 2008) at the Society for General Microbiology’s 162nd meeting being held this week at the Edinburgh International Conference Centre.

“Desert soils are unusual because the sand grains at the surface are bound together into a crust by bacteria, reducing wind erosion and adding nutrients to the soil. Deserts cover over one third of the world’s land surface and yet our understanding of their contribution to the atmospheric carbon dioxide balance is poor”, says Dr Andrew Thomas of Manchester Metropolitan University.

Sands like those in the Kalahari Desert of Botswana are full of cyanobacteria. These drought resistant bacteria can fix atmospheric carbon dioxide, and together they add significant quantities of organic matter to the nutrient deficient sands.

“We know that globally there is a huge exchange of carbon between the atmosphere and the soil. As average global temperatures rise, scientists are concerned that bacteria will break down organic matter in soils more rapidly, releasing more carbon dioxide into the atmosphere”, says Dr Thomas. “However, there have been very few actual field studies of this carbon exchange through world soils and little information on how they respond to temperature and moisture changes. This is particularly true for deserts. Here the bacteria have to be able to cope with long periods without rain and extreme temperatures, so they lie dormant in the desert soil only springing to life when there is enough moisture”.

The exchange or flux of carbon between the soils and the atmosphere is much smaller over deserts than for areas with more organically rich soils, but the sheer size of deserts makes it globally significant. Even small changes in the carbon balance of desert soils will also be important locally, where soil organic matter underpins fragile ecosystems currently supporting millions of poor pastoral farmers.

“We discovered that even after light rainfall, the gains and losses of carbon dioxide through the sands of the Kalahari Desert were similar in size to those reported for more organic rich grassland soils. Despite being short lived, these raised pulses of activity are a significant and previously unreported contributor to atmospheric carbon dioxide” says Dr Thomas. “Global climate change models have forgotten them”.

Dr Thomas with his colleagues, Dr Stephen Hoon and Dr Patricia Linton also of Manchester Metropolitan University, found that in some conditions, the cyanobacteria in the surface crust were taking net amounts of carbon dioxide out of the atmosphere as they photosynthesised. But after heavy rainfall other types of bacteria deeper in the subsoil became active and their activity masked the uptake of carbon by the surface cyanobacteria by consuming the organic matter in the soil, releasing large quantities of carbon dioxide.

“We also discovered that the fluxes of carbon dioxide from the soil were highly sensitive to temperature. Warmer air but similar soil moisture levels caused greater losses of carbon from the desert soils to the atmosphere”, says Dr Thomas. “These desert soils are contributing significantly to the global carbon dioxide budget. Until recently they have been ignored”.

“We need to know exactly what is happening as a better understanding of the factors controlling activity of the surface living soil cyanobacteria could help inform grazing policy. Millions of poor semi-subsistence pastoral farmers rely on the soils of the Kalahari to provide nutrients for grazing. The carbon produced by the cyanobacteria is a major contributor to the fertility of the soil and it is essential we understand how their metabolism is affected by environmental conditions”, says Dr Thomas.

Lucy Goodchild | EurekAlert!
Further information:
http://www.sgm.ac.uk

More articles from Earth Sciences:

nachricht How much biomass grows in the savannah?
16.02.2017 | Friedrich-Schiller-Universität Jena

nachricht Canadian glaciers now major contributor to sea level change, UCI study shows
15.02.2017 | University of California - Irvine

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>