Ciencia del Suelo (Dec 2005)
Densidad estacional y distribución vertical de los Enchytraeidae (Annelida: Oligochaeta) en diferentes sistemas de producción Seasonal density and vertical distribution of Enchytraeidae (Annelida: Oligochaeta) in different production systems
Abstract
En el sudeste de la provincia de Buenos Aires existe escasa información sobre la actividad de los enquitreidos en diferentes sistemas de producción. Los objetivos de este trabajo fueron determinar: a) la importancia relativa de los enquitreidos dentro de la mesofauna; b) su densidad estacional en relación con el grado de disturbio de los sistemas y c) su distribución vertical. Este trabajo se realizó estacionalmente desde 1998 a 2001 en Balcarce, Argentina (37º 45'S, 58º 18'W), en cuatro lotes experimentales: natural (NAT), ganadero orgánico (GO), ganadero intensivo (GI) y agrícola convencional (AC) y en un suelo Argiudol Típico (NAT) y Hapludol Tapto-Árgico (AC, GI y GO). Dentro de la comunidad mesofaunal, los enquitreidos fueron los más abundantes. GO (78 %) y GI (68.5 %) tuvieron un porcentaje menor que los sistemas más disturbado, AC (84.9 %) y sin disturbios, NAT (93 %). El estudio comparativo de la densidad mostró interacción significativas entre sistemas y estación (p In the Southeastern of Buenos Aires Province little information exists on activity of enchytraeids under different production systems. The aims of this work were to determine: a) the relative importance of enchytraeids among the components of the mesofaunal community; b) the relationship between seasonal enchytraeids density (PD) in different production systems, and c) identify of pattern vertical distribution .This work was done seasonally from 1998 to 2001, on four experimental plots: natural (NAT), organic livestock (GO), intensive fertilization livestock (GI) and conventional agriculture (AC) at Balcarce, Argentina (37º 45'S, 58º 18'W), on soil Typic Argiudol (NAT) and a Hapludol Tapto Árgico (AC, GI y GO). Enchytraeids were the most abundant in the mesofaunal community; GO (78%) and GI (68,5%) to supported a minor average those agroecosystems under intensive cultivation (84,9%) and undisturbed soils NAT (93%). The comparative study showed significant interaction between site and season (p< 0.05) in PD. In general, GO, GI and AC average density were highest during autumn-winter than spring-summer (PD values ranged between 2476-10926 ind m-2 to 1922-0 ind m-2 in GO, 3740-2764 ind m-2 to 165-2 ind m-2 in GI and 8596-4022 ind m-2 to 4185-544 ind m-2 in AC). It was found the same in NAT (2000-2001) whereas there was not significant differences in 1999 between winter and summer. Enchytraeids were more superficially distributed (10 cm) in natural grassland (NAT) and in arable soil (AC) than in cultivated pastures GO and GI (10-30 cm).
