Abstract
Plant defense theories suggest that chemical or structural defences should be maximized when and where browsing is most likely to occur. We tested this hypothesis an four evergreen woody species growing in a Mediterranean area with a high density of ungulates. In this system, levels of browsing are more intense in the winter (due to the lack of annual plants) and young foliage is often preferred. Therefore we predicted that the chemical defences of these species, namely their phenolic content, would vary with leaf age, season and damage intensity. In addition, we tested whether ungulates preferentially selected species containing lower phenolic levels, and also whether browsing induced either chemical or morphological changes in damaged plants. Phenolic levels varied greatly between plant species; ungulates browsed preferentially on the species with the lowest phenolic levels. No difference in phenolic content was found between browsed and unbrowsed trees. Morphological changes in heavily browsed trees included an increase in shoot and leaf density and a net decrease in leaf size. We suggest that for Mediterranean plants, which have evolved under high browsing pressure from large mammals, the production of small leaves and dense shoots in response to browsing might decrease ungulate foraging efficiency and hence reduce the rate of further damage as effectively as high levels of chemical defence.
| Original language | English |
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| Pages (from-to) | 18 |
| Number of pages | 8 |
| Journal | Journal of vegetation science |
| Volume | 11 |
| Issue number | 1 |
| Publication status | Published - Feb 2000 |