Specific functional signature in soil macro-invertebrate biostructures

1. The aim of this study was to search for specific signatures of biogenic structures (i.e. earthworm casts, termite sheathings and mound material, and ant deposits) made by 15 species of soil engineers in a Colombian savanna. We thus investigated the organic matter (OM) biochemical composition of biostructures using near infrared spectroscopy (NIRS) and its relationship with selected biological (respirometry) and chemical attributes. 2. We found significant differences in OM quality and potential respiration rate among biostructures. These results were attributed to production patterns of biostructures and invertebrate feeding behaviour. A multiple co-inertia analysis was performed with NIRS, respirometry and chemical results. It separated (i) carton termite mounds, (ii) earthworm casts and organo-mineral termite mounds and (iii) termite sheathings and ant deposits. 3. These results suggest that NIRS spectra might be used as 'fingerprints' to identify organisms responsible for soil aggregate production. Moreover, the ordination given by the co-inertia analysis is proposed as a basis for a functional classification of soil engineers, assuming that different biostructure properties imply different effects on soil functioning.