Science - April 15, 2004

Aerial photos give away grass secrets

Dr Onisimo Utanga would like to see frequent flights using light aircraft organised over the savannahs of southern Africa. He’s not interested in photographing the animals there, it’s the grass beneath their feet that he’s after.

Park managers in South Africa and Tanzania need more information on the quality of the grass in savannah areas to better understand the massive migration of grazing animals and therefore improve wildlife management. Until now information on grass quality has been gathered by taking samples of grass. Utanga’s PhD research shows that recordings made by spectrometers out of an aeroplane are a good alternative to time-consuming measuring campaigns on the ground.

The ecologist made observations in the Kruger National Park in South Africa using a spectrometer that measures wavelengths from infrared to ultraviolet. He showed that this is a good way of measuring the amounts of nitrogen and potassium in grass. Previous studies have shown that grasses that are rich in nitrogen and phosphorus play an important role in the migration patterns of wildebeest. Picking up potassium shortages is also useful, as these are responsible for weakened muscles, heart and respiratory systems in the migratory animals.

Utanga received his PhD on 7 April. His supervisors were Professor Herbert Prins, chair of the Resource ecology group and Professor Andrew Skidmore, chair of Vegetation and Agricultural land use survey.

Hugo Bouter

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