Temporally Variable Rainfall Does Not Limit Yields of Serengeti Grasses
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Date
1998
Journal Title
Journal ISSN
Volume Title
Publisher
Wiley
Abstract
Temporally variable rainfall, on scales ranging from intraseasonal to decadal, is
characteristic of the climate of dry grassland ecosystems. A growth chamber experi-
ment indicated that the Serengeti ecosystem's most abundant and widespread grass,
red oat grass (Themeda triandra), collected at locations with different rainfalls,
growing seasons, and grazing intensities, is insensitive to an ecologically realistic
range of rainfall events if the total amount of rain is constant. The result was
confirmed under field conditions since plots did not respond to different temporal
variances in water supply, although they did respond to levels of water supply. The
results suggest that these grasses are water "spenders", using it as fast as they can
when it is abundant, and then being semi-dormant in intervals between downpours.
This characteristic could provide a competitive advantage in environments character-
ized by infrequent thundershowers. The ability to tolerate intervals between showers
without losing living tissues, or dying, can contribute to the success of grasses in
highly variable climates, and will tend to quench potentially drastic fluctuations of
energy flow through the food web.
Description
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Citation
Williams, K.J., Wilsey, B.J., McNaughton, S.J. and Banyikwa, F.F., 1998. Temporally variable rainfall does not limit yields of Serengeti grasses. Oikos, pp.463-470.