"Africa is a big question mark in the carbon cycle," says Tony Swemmer, manager of the SAEON (South African Environmental Observation Network) Ndlovu Node in Phalaborwa.In an effort to change this, the European Union-funded Carbo Africa has set up a project through which it hopes to get a better understanding of Africa's role in the carbon cycle.
According to Dr Bob Scholes of the Council for Scientific Research (CSIR) in the SAEON newsletter, Africa is a region highly vulnerable to climate change due to ecological and socio-economic factors, but it is the region least covered by studies on climate change.One of the tools used by researchers to understand the carbon cycle is known as a flux tower, or eddy covariance system.
Using sophisticated equipment mounted on a tall tower, a flux tower measures how much carbon dioxide the surrounding vegetation absorbs during the day and releases at night. To do this, the wind is measured in three directions to assess the carbon dioxide concentrations at various points.
A connected high-tech weather station also records factors such as rainfall, temperature, solar radiation and wind direction.Contrary to a vast network of flux towers in the northern hemisphere, the flux network for carbon studies is underrepresented in Africa. With the intention of setting up at least 20 flux towers in Africa, Carbo Africa hopes to increase Africa's data contribution to fine-tuning the global carbon cycle and climate change picture. Existing flux towers can be found in South Africa (Skukuza), Mali, Ghana, Zambia, the Congo, Botswana, Benin and Niger.
The Skukuza flux tower is vital to the project. The tower was erected by Nasa as part of an experiment that looked at the effect of fires on the atmosphere over southern Africa. After the end of the experiment, the tower was donated to the CSIR who has run a series of projects there, including a three-year Carbon Africa project, funded by Nasa and the National Oceanics and Atmosphere Administration (NOAA) and which ended in 2007. This project will feed into the Carbo Africa project.
In South Africa, Carbo Africa obtained funding for three additional flux towers of which the first, situated near the Phalaborwa gate in the Kruger National Park (KNP), was officially opened during the week of March 10 to 14, 2008. This coincided with a training workshop for students and researchers from various African countries held at the SAEON offices in Phalaborwa.
Delegates from South Africa, Zambia, Ghana, Togo, the Congo, Ivory Coast and Zimbabwe made the most of the field trips to the new site to augment their knowledge of setting up and running a flux tower. Dr Scholes introduced the delegates to soil and vegetation characterisation, while Dr Werner Kutsch of the Max-Planck Institute for Biochemistry in Germany enlightened them on the photosynthetic measurements.
His colleague, Lutz Merbold, covered the eddy covariance flux measurements and processing. The Malopeni tower, named after a waterhole nearby, has been erected in mopane veld, which differs from the Skukuza acacia/combretum veld types and will ensure major vegetation types in the Park are covered.
The other two towers will be put up in communal land outside of Kruger to allow for comparative measurements - the effect of different land use practices - protected areas compared to communal land, on the carbon cycle. The second site near Phalaborwa has already been identified, while the third site, required to be a closer match to the Skukuza vegetation, will probably be in the Welverdiend area close to Orpen.
SAEON will support the project by continuing its contribution to the Skukuza flux tower technician's salary,as well as that of a PhD student that will drive the Malopeni tower.
By Lynette Strauss
