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Chapter 7 - How Trees and Grasses Grow and Compete

from Part II - The Savanna Garden: Grassy Vegetation and Plant Dynamics

Published online by Cambridge University Press:  09 September 2021

Norman Owen-Smith
Norman Owen-Smith
Affiliation:
University of the Witwatersrand, Johannesburg
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Summary

This chapter considers the mechanisms of growth and competition among trees and grasses in the context of seasonally restricted and erratic rainfall. Competition operates largely below-ground, for water and nutrients, rather than for light, and primarily between grasses and tree seedlings. Fires promoted by seasonally dry grasses restrict growth by tree saplings. Grasses are the superior competitors unless the woody canopy closes. Most savanna trees are deciduous, while grasses become dormant and dry above-ground during the dry season, providing fuel for fires. Deeper roots enable trees to access water at deeper levels, but grasses capture water and nutrients at shallow depths faster than trees. C4 photosynthesis enables grasses to grow rapidly while moisture is available despite low atmospheric carbon dioxide. Grasses produce more biomass annually than woody plants in savannas.

Keywords

seasonal growthdeciduous habitfire toleranceanti-herbivore deterrentsrooting patternsC4 photosynthesislawn-forming grassesfruiting patterns.
Type
Chapter
Information
Only in Africa
The Ecology of Human Evolution
 , pp. 97 - 117
Publisher: Cambridge University Press
Print publication year: 2021

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References

Suggested Further Reading

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