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, t ussocks, acaulescent rosettes, cushions and mats, upright shrubs, pros trate shrubs, erect herbs, prostrate herbs, and trailing herbs. The gr owth form composition of 192 samples of paramo vegetation from twelve different regions in Ecuador was analysed using multivariate technique s to determine physiognomic types. The distribution of growth forms wa s significantly related to altitude, rock cover, bare ground and to me asures of disturbance and exposure. The dominant growth forms in all t he samples belonged to one of Hedberg's (1964) five types, but other f orms 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 domina nt, 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, o nce again no single growth form was dominant. In humid paramos, stem r osettes were co-dominant with tussocks or erect herbs. Basal rosettes, erect herbs and prostrate herbs were locally co-dominant at higher al titudes. 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 quantitativ e determination of growth form composition may also lead to a better u nderstanding of community structure and the mechanisms which govern it .