EVALUACIÓN DE LA VEGETACIÓN DEL ESTRATO HERBÁCEO DE UN BOSQUE DEL ESPINAL SANTAFESINO (ARGENTINA)

In the Espinal Santafesino only relicts of forests remain. The present study was carried out in the town of Sa Pereira, Argentina, in the herbaceous stratum of an algarrobo forest of approximately 100 ha. The aim was to perform a description of the herbaceous vegetation. Samples were taken in 16 m² plots, using the Braun-Blanquet abundance-cover method (64 plots) on a base transect. Two samplings were performed, one in autumn-winter-spring (AWS) and another in spring-summer (SS). To characterize the herbaceous communities Simpson, Equity and Shannon diversity indexes were used. Three groups of herbaceous communities were identified: “flechillares”, humid prairies and “gramillares”, distinguishing eight variants thereof. There were 45 families and 156 species, with the most represented families Poaceae and Asteraceae (38 and 25 species respectively). On average, 20.8 and 18.1 species were recorded per plot for the AWS and SS samples. In the AWS and SS samples, an average Simpson diversity index of 6.72 and 8.42 was obtained, while the Shannon diversity index was 2.09 and 2.30, respectively. In the AWS samplings, the humid prairies were more diverse according to these indexes, followed by “flechillares” and “gramillares”, whereas in the SS sampling, “flechillares” were the most diverse. The average equitability index for the AWS samples was generally lower than the SS for all the community groups. En el Espinal Santafesino sólo quedan relictos de bosques. El presente estudio se llevó a cabo en la localidad de Sa Pereira, Argentina, en el estrato herbáceo de un bosque de algarrobos de aproximadamente 100 ha. El objetivo fue realizar una descripción de la vegetación herbácea. Los muestreos se realizaron en parcelas de 16 m², utilizando el método de abundancia-cobertura de Braun-Blanquet (64 parcelas) sobre un transecto base. Se realizó un muestreo otoño-inverno-primaveral (OIP) y otro primaveroestival (PE). Para caracterizar a las comunidades herbáceas se utilizaron los índices de diversidad de Simpson, de Equitatividad y de Shannon. Se identificaron tres grupos de comunidades herbáceas: flechillares, praderas húmedas y gramillares, distinguiendo ocho variantes de las mismas. Se registraron 45 familias y 156 especies, siendo las familias más representadas Poaceae y Asteraceae (38 y 25 especies respectivamente). En promedio se registraron 20,8 y 18,1 especies por parcela para los muestreos OIP y PE. En los muestreos OIP y PE se obtuvo un índice de diversidad de