Soil aggregation and arbuscular mycorrhizal fungi as indicators of slope rehabilitation in the São Francisco River basin (Brazil)

Abstract

Anthropogenic activity along the Velhas River (São Francisco River basin) has destabilized the banks of the river channel across an urban fragment. To improve the physical stabilization, the base of the slope was stabilized with urban construction waste. After this, the slope was revegetated with native species and arbuscular mycorrhiza fungi (AMF) inoculation was applied with a successfully restoration of the vegetative cover and ecological functions. This study aims to evaluate the role of the AMF population in the soil aggregation and stabilization of the revegetated slope. The soil aggregation was higher at the experimental site than at the disturbed site, especially under the AMF inoculation. The aggregates improvement was accompanied by an increase of soil humic acid and glomalin contents 24 months after the transplantation despite a flood impact 12 months after the transplantation. A scatter plot based on Principal Component Analysis of aggregates Showed that the preserved site samples clustered with most of those from experimental site. However, some samples from experimetal site were found between those from preserved and disturbed sites. This result shows that the recovering site is evolving toward the conditions of the preserved site and that the rehabilitation process is in an intermediate phase related to the aggregate formation. The AMF inoculation of woody species was indicated in the rehabilitation procedures.

Keywords

• glomalin
• humic acids
• landscape alteration
• microbial biomass
• river bank stabilization