The growth form composition of plant communities in the Ecuadorian paramos

A growth form classification for the plants of the Ecuadorian paramos is proposed, consisting of ten forms: stem rosettes, basal rosettes, tussocks, acaulescent rosettes, cushions and mats, upright shrubs, prostrate shrubs, erect herbs, prostrate herbs, and trailing herbs. The growth form composition of 192 samples of paramo vegetation from twelve different regions in Ecuador was analysed using multivariate techniques to determine physiognomic types. The distribution of growth forms was significantly related to altitude, rock cover, bare ground and to measures of disturbance and exposure. The dominant growth forms in all the samples belonged to one of Hedberg's (1964) five types, but other forms were also significant components of the vegetation. The majority of Ecuadorian paramo vegetation showed a relatively consistent growth form composition, dominated by tussocks. The accompanying growth forms were mostly acaulescent rosettes, cushions, upright shrubs, prostrate shrubs, erect herbs and prostrate herbs, sometimes with stem rosettes, basal rosettes or trailing herbs. At higher altitudes, the dominance of tussocks was reduced. At first, acaulescent rosettes became dominant, but higher still their dominance was shared with cushions. At the highest altitudes of all, where plant cover was thin, no single growth form was dominant. In other locations where plant cover was sparse, once again no single growth form was dominant. In humid paramos, stem rosettes were co-dominant with tussocks or erect herbs. Basal rosettes, erect herbs and prostrate herbs were locally co-dominant at higher altitudes. The growth form composition of the Ecuadorian paramos showed similarities with other tropical alpine regions, though no comparable quantitative data for these regions are available yet. The quantitative determination of growth form composition may also lead to a better understanding of community structure and the mechanisms which govern it.