Resumo

LOPEZ, Alicia Noemí et al. Seasonal density and vertical distribution of Enchytraeidae (Annelida: Oligochaeta) in different production systems. Cienc. suelo [online]. 2005, vol.23, n.2, pp.115-121. ISSN 1850-2067.

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).

Palavras-chave : Enchytraeids; Abundance; Agroecosystems.

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