Arbuscular mycorrhizal fungi (AMF) play an important role in natural ecosystems as they influence plant nutrition and soil structure. The aim of this study was to determine the mycorrhizal inoculum potential and the relationship between mycorrhizal mycelium length of AMF and aggregation of riparian soils. Soil samples were collected in riparian areas in the Itajai Açu river watershed, between the municipalities of Gaspar and Navegantes, Santa Catarina, Brazil. Eight areas were sampled within three soil classes: Cambissolo (Inceptisol) (C), Gleissolo (Aquoll) (G), and Organossolo (Histosol) (O). For each area, the following measurements were made: mycorrhizal inoculum potential, number of spores, mycorrhizal mycelium length, and soil physical and chemical properties. Mycorrhizal colonization of Brachiaria brizantha in the inoculum potential bioassay ranged from 13.8 to 55.3 %, and no pattern was observed according to soil class. Mycorrhizal mycelium length ranged from 10.48 to 44.67 m g-1, according to the area sampled. Number of spores ranged from 2.4 to 80 spores in 100 cm3 of soil. A negative correlation was observed between mycorrhizal mycelium length and the proportion of water stable macroaggregates and a positive correlation between the former and the proportion of microaggregates. Results showed that riparian soils from the Itajai Açu river watershed have a moderate to high mycorrhizal inoculum potential sufficient to start colonization of plant roots in a short period of time, an important property to facilitate growth of native woody species used in recovering these habitats.
mycorrhiza; mycorrhizal colonization; environmental restoration; riparian forest; number of spores
