Soil Organisms (May 2023)
Species diversity of Enchytraeidae (Oligochaeta) in pastures, regenerating secondary forests, and old-growth forests in the southern Mata Atlântica (Brazil)
Abstract
In the framework of the German-Brazilian project SOLOBIOMA (‘Soil biota and biogeochemistry in the Southern Atlantic rainforests of Brazil’), soil invertebrates were sampled in different regeneration stages of forest: pastures, young, medium and advanced secondary forests as well as old-growth forests. Thirty-nine study sites were located in two private nature reserves situated in neighbouring regions of the southern Atlantic Forest (Mata Atlântica) in Paraná, Brazil. All sites were characterized in terms of climate, history of use (age), vegetation, and soil properties. Here we report on the species diversity of pot worms (Oligochaeta: Enchytraeidae) in these sites, sampled with ISO standard methods. At each site ten soil cores of 5.7 cm diameter were taken once between 2003 and 2008, wet extracted and all pot worms identified alive soon after sampling. Most of the 61 species found in this study were new to science. The enchytraeid fauna of the region is dominated by species of the genera Achaeta, Guaranidrilus and Hemienchytraeus. To date, six species of the genus Achaeta, three species of the new genus Xetadrilus and four species of the species-rich genus Guaranidrilus were described by some of the authors. The terrestrial enchytraeid fauna of Paraná is composed partly of (probably) endemic species (e.g. Achaeta paranensis), partly of species with a known wider distribution within South America (e.g. Hemienchytraeus patricii). Species-poor genera are Fridericia, Enchytraeusand Marionina. On average, enchytraeid abundance was low (i.e. less than 5000 ind m-2). Highest abundance was found in old-growth forests. Species assemblages respond to soil type and vegetation type, and some preferences at the species or genus level could be identified. Due to their small size, low abundance and resulting low biomass enchytraeid worms seem to have little ecological importance in terms of energy flux and nutrient turnover, especially when compared with earthworms. However, due to their species richness they may be useful to indicate the biological status of a site in terms of biological soil quality or perturbation.
