Earthworm populations sampled using collection methods in atlantic forests with Araucaria angustifolia

Abstract

Araucaria angustifolia, also known as the Paraná Pine is an endangered tree species in Brazil and little is known of the diversity of soil invertebrates inhabiting these forests. Therefore, the present study was set up to evaluate the biomass and diversity of earthworms in natural and reforested Araucaria plots, impacted or not by fire, and to identify the most efficient earthworm collection method. Four study areas included: native forest with Araucaria (NF); Araucaria reforestation (R); Araucaria reforestation submitted to an accidental fire (RF); and native grass pasture with native Araucaria and submitted to an intense accidental fire (NPF). Five soil samples containing the earthworm community were taken in a 0.3 ha area in each of the forest sites, close to five Araucaria trees selected at random. Three collection methods were tested: application of dilute Formol (0.5%) to the soil surface, handsorting of small (25 <FONT FACE=Symbol>´</FONT> 25 cm) or large (40<FONT FACE=Symbol>´</FONT> 40 cm) monoliths. Five earthworm species were found: the native Glossoscolex sp.1, Glossoscolex sp.2, Glossoscolex bondari and Urobenus brasiliensis (Glossoscolecidae), and the exotic Amynthas corticis (Megascolecidae). Formol was more efficient for collecting A. corticis, found in much higher abundance and biomass in NF than in the other areas. Larger handsorted samples were more efficient for capturing Glossoscolex species, mainly present in RF and NPF. For adequate characterization of earthworm abundance and biomass in these Araucaria forests, both the Formol and the larger monolith methods are recommended.