In general, high altitude plants have the same potential 'armory' of traits as lowland plants which enable them either to deter herbivores or to tolerate the effects of herbivory.

High belowground resources increase the tolerance to above ground removal of biomass. Adventitious buds at or below the surface enable the plant to regenerate after browsing.

High levels of certain secondary metabolites, e.g. alkaloids, make plants relatively unpalatable to most herbivores. Such plants are particularly common where large herbivores are concentrated.

1 - Gentiana punctata (54K)

Spiny and hairy leaves are often an effective protection against vertebrate herbivores. For example, Carduus keniensis is very common in and around hyrax (Procavia johnstonii) colonies on Mount Kenya. Although it is not usually eaten by hyrax, the leaf tissue is palatable to these animals. In a study in which the spines were experimentally removed, all leaves were eaten within one hour.

However, spines normally do not protect against insect herbivores, and may even protect insects against predators. Slugs also do not seem to be deterred by spines.

2 - Cirsium spinosissimum (62K)

A very compact growth form with leaves appressed to the ground, commonly found in alpine plant species of exposed habitats, is also a good protection against most vertebrate herbivores.

On the other hand, some species in tropical alpine regions escape herbivory by growing tall. Taller plants and flowers higher up on inflorescences are less susceptible to herbivory by small mammals.

3 - Seed set in Lobelia (10K)

29 August 2011
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