Tradeoff between height and relative growth rate in a dominant grass from the Serengeti ecosystem
✍ Scribed by G. Hartvigsen; S. J. McNaughton
- Publisher
- Springer-Verlag
- Year
- 1995
- Tongue
- English
- Weight
- 373 KB
- Volume
- 102
- Category
- Article
- ISSN
- 0029-8549
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✦ Synopsis
We determined the relationship between plant height and whole-plant relative growth rate (g g day) for ten genotypes of Sporobolus kentrophyllus collected from an intensively grazed site on the Serengeti Plains, Tanzania. Plants were grown for 7 weeks in a greenhouse in Syracuse, N.Y., and harvested weekly. Plants that received simulated bovine urine showed a negative relationship between plant height and growth rate, suggesting a genetic tradeoff between competitive ability if ungrazed (height) and ability to recover from grazing (growth rate). There was no height-growth rate relationship under nitrogen addition rates similar to field mineralization rates. In addition, faster-growing, shorter plants tended to have relatively higher above-ground growth rates than slower-growing, taller plants. These results suggest that natural selection has maintained a gradient of morphologies within this species ranging from short, rapidly growing genotypes adapted to intense grazing conditions to tall, slow-growing, grazer-susceptible genotypes that are superior light competitors in absence of herbivory.