García-Meneses & Ramsay 53 PUYA HAMATA DEMOGRAPHY AS AN INDICATOR OF RECENT FIRE HISTORY IN THE PÁRAMO OF EL ÁNGEL AND VOLCÁN CHILES, ECUADOR-COLOMBIA La demografía de Puya hamata como indicador de la historia de fuegos recientes en el páramo de El Ángel y Volcán Chiles, Ecuador-Colombia PAOLA M. GARCíA-MENESES School of Geography, Earth and Environmental Sciences, Plymouth University, Plymouth, PL4 8AA, United Kingdom. paola.garciameneses@plymouth.ac.uk: Corresponding author PAUL M. RAMSAY Marine Biology and Ecology Research Centre, Plymouth University, Plymouth, PL4 8AA, United Kingdom. pramsay@plymouth.ac.uk Caldasia 36(1):53-69. 2014 http://www.icn.unal.edu.co/ ABSTRACT High-altitude páramo grasslands are important for their biodiversity and the ecosystem services that they provide to Andean people, but they are sensitive to disturbances, such as ire. Understanding the ecological impacts of disturbance is critical for the effective management of páramos. Indicator species studies can provide a relatively eficient way to gain such understanding. Puya hamata is a lagship giant rosette plant and has potential as an indicator of recent páramo ire history. To determine population size structure, mortality, recruitment and growth rates of Puya hamata rosettes, all Puya plants in 400 m 2 plots were surveyed in 2008 and again one year later. Sixteen plots were recorded in both years, containing exactly 1000 plants. Mortality was very low during this period (0.6%). Only 27 new plants were recruited. Three different size distribution patterns were observed in the plots: (1) low plant numbers across all size ranges; (2) a single dominant peak in numbers at a particular size; (3) two dominant peaks in numbers at distinct sizes. Estimated life span of Puya hamata was 28 years based on growth rates, and growth rate declined beyond the size at which most rosettes reproduce. To investigate the impact of different ire intensities on Puya hamata mortality, 400 m 2 plots within a mosaic of unburned and burned patches of different ire intensities were surveyed one month after the ire. Fire mortality was low in the medium and high intensity plots, and ires selectively killed smaller plants rather than larger ones. No mortality was observed in the unburned and low intensity ire plots. It is proposed that Puya responds to burning with pulses of seedling recruitment during periods of open vegetation after ires and very little recruitment at other times. Therefore, surveys of Puya plants can reveal past ire events in their population size structure. The combination of sensitivity to ire at recruitment, low ire mortality rates afterwards, and a 28-year lifespan makes Puya hamata an ideal indicator species of recent ire history in páramos. Key words. Bromeliaceae, burning, Ecuador, giant puya, mortality, páramo, population dynamics, seedling recruitment, semelparity.