Coping with herbivory at the juvenile stage: responses to defoliation and stem browsing in the African savanna tree Colophospermum mopane

Responses of plants to herbivory are dependent on the type of damage and the ontogenetic stage of the plant. We compared the effects of stem pruning and defoliation on seedlings of Colophospermum mopane, an ecologically important tree species widely distributed in southern Africa. The growth of 160...

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Bibliographic Details
Published in:Journal of tropical ecology 2012-03, Vol.28 (2), p.161-169
Main Authors: Hartnett, David C., Ott, Jacqueline P., Sebes, Kathryn, Ditlhogo, Marks K.
Format: Article
Language:English
Subjects:
Abundance
Animal and plant ecology
Animal, plant and microbial ecology
Autoecology
Biological and medical sciences
Biomass
Biomass production
Branches
Colophospermum mopane
Defoliation
Flowers & plants
Fundamental and applied biological sciences. Psychology
Herbivores
Herbivory
Leaf area
Leaves
Plant biomass
Plant growth
Plant species
Plants
Plants and fungi
Pruning
Seedlings
Seeds
Trees
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Summary:Responses of plants to herbivory are dependent on the type of damage and the ontogenetic stage of the plant. We compared the effects of stem pruning and defoliation on seedlings of Colophospermum mopane, an ecologically important tree species widely distributed in southern Africa. The growth of 160 greenhouse-grown juveniles were measured for 6-mo after germination and then 6-mo after treatments including 50% defoliation, 100% defoliation, 50% stem pruning and controls. Pruning resulted in 30% reductions in total leaf area, height and biomass. Partial defoliation resulted in 30% reductions in total leaf area and plant biomass. However, complete defoliation resulted in a 30% increase in biomass production, a doubling in leaf and lateral branch number, a 45% reduction in leaf size, and no change in total leaf area. Thus, completely defoliated seedlings showed greater performance than those that were only partially defoliated, indicating that C. mopane has become adapted to the chronic and severe defoliation inflicted by Imbrasia belina caterpillars. Comparison of our results with other studies indicates that C. mopane seedlings are less herbivory-tolerant than adults and that pruning has more negative effects than defoliation. Thus, seedling browsers may constrain recruitment in C. mopane, influencing its population dynamics and abundance.
ISSN:0266-4674
1469-7831
DOI:10.1017/S0266467412000028