Earthworm assemblages in different intensity of agricultural uses and their relation to edaphic variables

• Published in: PeerJ preprints
• Main Authors: Falco, Liliana B, Sandler, Rosana V, Momo, Fernando R, Di Ciocco, César A, Saravia, Leonardo A, Coviella, Carlos E
• Format: Journal Article
• Language: English
• Published: San Diego PeerJ, Inc 18.12.2014
• Subjects: Aporrectodea; Community structure; Enzymatic activity; Grasslands; Grazing; Introduced species; pH effects; Soil properties; Species composition; Worms
• DOI: 10.7287/peerj.preprints.722v1

The objective of this study was to relate earthworm assemblage structure with three different soil use intensities, and to indentify the physical, chemical, and microbiological variables that are associated to the observed differences in earthworm assemblage structure between soils. Three soil uses were evaluated: 1- Fifty year old naturalized grasslands; 2- Cattle-grazing fields converted to feedlot within the two years before the start of this work, and 3- Fifty year old intensive agricultural fields. Three different sites for each soil use were evaluated from winter 2008 through summer 2011. Nine earthworm species were identified across all sampling sites. The sites shared five species: the native Microscolex dubius, and the introduced Aporrectodea caliginosa, A. rosea, Octalasion cyaneum, and O. lacteum, but they differed in their relative abundances according to the system. The results show that earthworm community structure is linked to and modulated by soil properties. Both, species abundance and diversity showed significant differences depending on soil use intensity. A PCA analysis showed that species composition is closely related to the environmental variability. The ratio of native to exotic species was significantly lower in the intensive agricultural system when compared to the other two, lower disturbance Systems. Microscolex dubius was shown to be related to the naturalized grasslands and it was associated to Ca, pH, Mechanical Resistance, and to respiration. Aporrectodea caliginosa was related to high K levels, low enzymatic activity, slightly low pH, and low Ca, and appeared related to the highly disturbed environment. Eukerria stagnalis and Aporrectodea rosea, commonly found un the cattle-grazing system, were related to high soil humidity, low pH, low Ca and low enzymatic activity. These results show that earthworm assamblages can be good descriptors of different soil use intensities. In particular, Microscolex dubius, Aporrectodea caliginosa, and Aporrectodea rosea, showed different temporal patterns and species associations, due to the changes in soil properties attributable tos oil use intensity.