LEAF DEMOGRAPHY AND GROWTH-RATES OF ESPELETIA-BARCLAYANA CUATREC - (COMPOSITAE), A CAULESCENT ROSETTE IN A COLOMBIAN PARAMO

The production of leaves, inflorescences, and growth rates were measured during 1985 for 547 plants of Espeletia barclayana, a giant rosette species in the high Andes of Colombia. There were differences in leaf production between individuals of different sizes, with a maximum for plants 61-90 cm in height (27.9 leaves yr-1) and a minimum for plants less than 30 cm (5.1 leaves yr-1). For plants more than 61 cm in height there was a minimum in leaf production during February, coinciding with the minimum in rainfall and also during June coinciding with a decrease in rainfall, low temperature, and a peak in fog and condensation. There was a great variation in the number of reproductive plants from one year to the next. There was also a positive relationship between total production of inflorescences at the population level and annual rainfall. Trunk growth rates ranged from 1.1 cm yr-1 for plants less than 30 cm in height to 3.8 cm yr-1 for plants 61-90 cm in height. The tallest plant in the population (150 cm) was about 93 yr old. The results of this study suggest that E. barclayana is subject to seasonal drought and that the variation in water supply and temperature have an effect on leaf production and probably on growth rates. Because of the very slow growth rates of E. barclayana, it will take a considerable time to recover the actual population and vegetation structure of those areas which have been turned into agricultural fields.