This study aim to evaluate the dynamics of the main tree species in a seasonal steppe savannah community, located in the Espinilho Park, Barra do Quaraí - RS, throughout a period of eight years (2001-2009). From information on the dynamics, it is possible to assess changes in vegetation structure, based on mortality, recruitment and growth rates of its individuals. Permanent sample plots of 1 ha (100 x 100 m), divided into sub-units of 100 m² (10 x 10 m) were established for data collection. All trees with diameter at breast height (DBH) ≥ 10 cm were measured. Throughout the study period, 178 individuals from eight different species were recorded. The species Aspidosperma quebracho-blanco, Vachellia caven, Prosopis nigra and Prosopis affinis represent 82.58% of all individuals, which 54.49% comprise Prosopis genus only. Individuals were distributed in eight diameter classes, although 91.57% of them were from the first three diameter classes. An annual recruitment rate of 1.61% and a 0.70% mortality rate were observed. The average increase in DBH between the years 2001 and 2009 was 0.053 cm/year. The studied area showed a change in the dynamics with an annual recruitment rate greater than the mortality, indicating that the community is still growing. ; El presente estudio tiene como objetivo evaluar la dinámica de las principales especies arbóreas, en una comunidad de Estepa estacional de sabana, localizada en el Parque Estatal de Espinillo, Barra do Quaraí – Rio Grande do Sul, durante un periodo de ocho años (2001-2009). A partir de informaciones sobre la dinámica, es posible evaluar los cambios en la estructura de la vegetación, con base en las tasas de mortalidad, ingreso y crecimiento de sus individuos. Para el análisis de los datos fue instalada una unidad de muestreo permanente de 1 ha (100 x 100 m), subdividida en subunidades de 100 m² (10 x 10 m). Fueron medidos e identificados todos los árboles con un diámetro a la altura del pecho (DAP) ≥ 10 cm. Durante el período monitoreado fueron registrados 178 ...